Assessment of urinary mutagens presence in a population of non smokers

The paper presents the early results of a study involving a group of 312 non smoking and not professionally exposed subjects (144 males and 168 females) in order to evaluate the probable presence of urinary mutagens possibly derived from aspecific exposures. Urine samples were assayed by the Ames test on the YG1024 Salmonella typhimurium strain in the presence of S9 mix with plate incorporation method with preincubation. At the moment of sample collection, the subjects were invited to fill a questionnaire on their main characteristics and lifestyle. On the basis of laboratory data analysis, it emerged that, on 288 samples with a valuable mutagenic activity, 20 urinary extracts (8 of which were males and 12 were females) showed mutagenicity levels twice as much as spontaneous revertants. Diet and indoor exposure to passive smoking, fireplace and cooking fume exposure seemed to play a major role among the lifestyle behaviours investigated in generating positive mutagenic response with a statistically significant difference between positive and negative samples induction (Chi square, P = 0.0057 and P = 0.0168 respectively). After correction of induced revertants by means of creatinine excretion determination, it appeared that females, who had the higher mean urinary mutagenic activity, showed a mutagenicity level twice as much as men (364 +/- 491 revertants/mmole creatinine for males against 605 +/- 868 revertants/mmole creatinine in females, Mann-Whitney U-test, z = -3.97, P < 0.0001) possibly in consequence of their greater cooking fumes exposure. The study, that carefully evaluated the characteristics of involved subjects, reveals the presence, even though modest, of mutagens in urine of an apparently not significantly exposed population. In addition, standardization of method leads to suppose little feasible a confounding influence of considered features. Moreover, it would be therefore rather interesting to study the effect of low exposure time persistence.

[Acute effects of environmental pollution on the urban vigilants airways]

AIM OF THE STUDY

The purpose of this study was to evaluate whether the acute exposure to air pollution, in a group of policemen of Padua, is correlated with increased inflammatory biomarkers (exhaled nitric oxide, feNO) and alterations of bronchiolar cells (assessed by CC16 Clara cell-specific protein).

METHODS

We studied 44 healthy, non-smokers divided in exposed to traffic and controls (office workers). Before and after the Monday shift serum and urinary concentration of CC16, feNo and spirometry were measured in each subject. Data on air pollutants, PM2.5, PM10, SO2, NO2, CO, O3 were collected from official bulletin online (ARPAV).

RESULTS

In exposed policemen serum CC16 decreased after shift (before 4.6 +/- 0.2 vs after 6.4 +/- 0.8 ng/ml, = 0.02), while feNO increased significantly (33.2 +/- 4.4 vs 29.7 +/- 3.9 ppb, p = 0.02). feNO cross-shift changes were positively correlated with environmental SO2 levels (rho = 0.48; p = 0.01).

CONCLUSIONS

Our results suggest that in healthy and nonsmokers subjects the exposure to air pollution is associated with subclinical airway inflammation and decrease of bronchiolar epithelium function.

[Anti-B[a]PDE-DNA formation in lymphomonocytes of humans environmentally exposed to polycyclic aromatic hydrocarbons]

[Anti-B[a]PDE-DNA formation in lymphomonocytes of humans environmentally exposed to polycyclic aromatic hydrocarbons] We are currently evaluating anti-benzo[a]pyrenediolepoxide-(B[a]PDE)-DNA adduct levels in lymphomonocytes of humans exposed to polycyclic aromatic hydrocarbons (PAHs) to validate this indicator of biologically effective dose in a surrogate tissue. The study protocol (October 2002-June 2005) implies: (a) a signed informed consent by each participant; (b) recruitment of 600 Padua municipal workers during visits at our outpatient clinic; (c) administration of a questionnaire regarding non occupational sources of PAH (B[a]P) exposure; (d) collection of blood (15 ml) and urine (200 ml) samples. Anti-B[a]PDE-DNA adduct levels in lymphomonocytes are detected by HPLC-fluorescence analysis. To date, 438 subjects have been examined (age range 20-62 years; 52% males). We found that: (i) anti-B[a]PDE-DNA adduct levels are significantly lower than those we previously found in coke-oven workers (N=95) occupationally exposed to high levels of PAHs (1.51 +/- 2.68 versus 4.07 +/- 3.78 anti-B[a]PDE-adduct/10(8) nucleotides, p < 0.001; 37% versus 97% positive subjects with > or =1 adduct/10(8) nucleotides; p < 0.001); (ii) smokers (23%) have significantly higher adduct levels than non smokers (p < 0.001); iii) non smokers who consume PAH-rich meals > or =52 times/year (142 subjects, 42%) have significantly increased adduct levels than those <52 times/year (p < 0.01). Dietary and smoking habits did not influence the occupationally-induced adduct levels in coke-oven workers. This is the first study that examines anti-B[a]PDE-DNA adduct levels in a large cohort showing that anti-B[a]PDE-DNA adducts can be detected in humans environmentally exposed to low doses of PAH (B[a]P and are modulated by smoke and dietary habits.

[Biologically effective dose biomarkers]

Biologically effective dose markers--DNA and protein adducts--are classified among exposure biomarkers, and are currently used to assess the biologically active fraction of xenobiotics, which is capable of interacting with cellular macromolecules at the target site. Macromolecular adducts should not only be considered as exposure indicators; indeed, their biological significance can also be extended to biomarkers of effect and of susceptibility. The achievement of such a goal needs research programs aimed both at studying molecular mechanisms related to each step along the continuum of events between exposure and disease, and at establishing quantitative relationships between exposure levels and adduct formation, between adducts and early biological effects, effects and cellular structural/functional modifications, leading to the development and eventual increase in incidence of specific diseases. Moreover, different factors must be considered during data evaluation, such as interindividual variability, the background levels of biomarkers in non occupationally exposed population, the gradually decreasing doses of genotoxic agents involved in occupational exposure, and confounding factors such as diet and smoking habits. Despite the large body of literature documenting DNA and protein adduct molecular dosimetry for many carcinogen exposures, many authors highlight the need for systematic interlaboratory comparison and collaboration by measuring the same biomarkers using different techniques and/or different biomarkers related to the same exposure levels. There is also general agreement about reducing costs, so that dosimetric analyses can become economically more advantageous and accessible in all cases where they prove to be useful in preventing health risks.

[Individual susceptibility to occupational carcinogens: the evidence from biomonitoring and molecular epidemiology studies]

This paper reviews the literature on the influence of metabolic and DNA repair polymorphisms of biological indicators of genotoxic risk commonly used in biomonitoring occupational exposure to carcinogens. Genetic polymorphisms which influence biomarkers (urinary metabolites, protein and DNA adducts), include P450 cytochromes (CYPs) and glutathione S-transferases (GSTs) in exposure to polycyclic aromatic hydrocarbons (PAHs), and acetyltransferases (NATs) in exposure to aromatic amines (AAs). As regards exposure to benzene, also relevant is the influence of epoxydohydrolase (EPHX) and NAD(P)H quinone oxidoreductase (NQO1) on the urinary excretion of t,t-muconic and phenylmercapturic acids. With respect to occupational exposure to styrene, EPHX significantly influences the levels of Chromosome Aberrations (CAs), strongly predictive genotoxic biomarkers of cancer risk. Some recent studies examine the role of polymorphisms linked to DNA repair genes in the modulation of genotoxic risk associated with PAH exposure, both for life-style (dietary and smoking behaviour) and for occupational reasons. In addition, molecular epidemiology studies (case/control studies) of lung cancer in smokers published since 2000 may also be viewed as representing models of effects due to exposure to carcinogenic mixtures, some of which are present in the working environment (e.g., BaP, benzene, AAs). Almost all studies show the clearcut influence (i.e., increased lung cancer risk with OR > or = 2) of genetic polymorphisms linked to PAH metabolism (in particular, CYPIA1, GSTM1 and P1). Among the risk factors are the different mutagen sensitivity towards, for instance, bleomycin and BaP (tested in vitro), the reduced repair capacity to DNA damage induced by BaP, and increases in some biomarkers of early biological effect (DNA adducts and stable CAs). Other risk factors, such as heredity (siblings of cancer patients have a risk factor > or = 3 with respect to the general population), ethnicity (Chileans > Caucasians; Japanese > Americans) and gender (women > men), have still not been clearly characterized and these are also reported in this paper. It is clear from the above that genetic differences underlie individual susceptibility to lung cancer, whether caused by exposure to tobacco smoke or to occupational carcinogens like PAHs. Some of these indicators of exposure/individual susceptibility can be evaluated in groups at high risk of occupational lung cancer, such as coke-oven and aluminium workers and those exposed to coal tar fumes and soot, etc., with the aim of identifying subjects who are susceptible due to the high concentrations of carcinogens found in their working environment.

Non-smoking coke oven workers show an occupational PAH exposure-related increase in urinary mutagens

We examined the urinary mutagenicity in the YG1024 Salmonella typhimurium strain in the presence of S9 mix, of 31 male non-smoking coke oven workers and an equal number of controls matched for gender and dietary habits. Occupational PAH exposure to the workers was assessed by means of the individual urinary post-shift excretion of 1-pyrenol (mean +/- S.D.: 5.41 +/- 6.06 micromole/mol creatinine). Eleven urinary extracts of workers (35.5%) were clearly mutagenic (with at least a doubling of the number of spontaneous revertants), against only two samples in the control group (6.5%) (chi2-test; chi2 = 7.883; P < 0.01). Moreover, the mean mutagenic activity level corrected for dilution/concentration of the urine was about three times higher in coke oven workers than in matched controls (mean +/- S.D. (range) 495 +/- 407 (89.7-1603) versus 186 +/- 113 (14.2-524) net revertants/mmol creatinine; Mann-Whitney U-test, z = 3.86, P < 0.001). Simple linear regression analysis showed that the coke workers' urinary mutagenic activity is associated with the PAH occupation-related urinary excretion of 1-pyrenol (r = 0.41, P = 0.0215). This study definitely demonstrates an occupation-related exposure of coke oven workers' bladder epithelium to mutagenic PAH metabolites. This factor, mainly in the case of high exposure studied here, may account for a higher bladder cancer risk in coke oven workers.

[Molecular epidemiology in occupational medicine: methodological features and impact of individual genetic susceptibility]

A review of main methodological questions regarding biomarkers is reported focusing on validation, laboratory variability, study design and statistical analysis. The indicated perspective is the setup of protocols finalized at the study of multiple panels of genotoxicity biomarkers taking into account the influence of gene-environment interaction at low doses, of the modulation of the biomarkers associated to the genetic polymorphism. An overview on the influence of metabolic and DNA repair polymorphisms on biological indicators of genotoxic risk in occupational, environmental or life-style exposure is also presented. Genetic polymorphisms that influence human genotoxic risk are those of glutathione s-transferase and cytochrome P450 in exposure to polycyclic aromatic hydrocarbons (PAHs), those of N-acetyltransferase in both occupational and environmental exposures to aromatic amines (AAs) and similar compounds. Lastly recent and important studies, on the effect of the newly discovered polymorphisms affecting DNA repair enzymes on the modulation of genotoxic risk linked to life style (i.e., aflatoxin and PAHs from diet) and smoking behaviour and to environmental genotoxic exposure, are reported. To date biomarkers represent a new tool for epidemiological research in occupational medicine and they could represent a valid instrument for group evaluation but they are not useful for the risk assessment on individual basis. To achieve this objective it is necessary to demonstrate a stronger association with the endpoint that perhaps the future development of genetic and molecular epidemiology will make possible.

[CYP1A2, NAT2, and GSTM1 phenotype/genotype modulate human exposure and various environmental mutagens: our experience]

Since some years in our research group has been studied the influence of metabolic genotypes on two biomarkers of genotoxic risk (BPDE-DNA adducts and urinary mutagenicity) in humans exposed to polycyclic aromatic hydrocarbons (PAHs) and aromatic amines. The aim was to identify possible genetic susceptible factors capable of modulating individual response to these carcinogens. Humans exposed to PAHs: dermatological patients therapeutically treated with coal tar based ointments (CT), coke oven workers and chimney sweeps. People exposed to aromatic amines will be volunteers after a meal of pan-fried hamburgers and smokers. An overview of the results we found until now will be presented.

Polyaromatic hydrocarbons administered in humans by dermal route increase total IgE

Inhalation of polyaromatic hydrocarbons (PAHs) extracted from diesel exhaust particles (DEP) enhances local (nasal) production of IgE in humans. The aim of the present research is to investigate whether in humans dermal exposure to PAHs which are not extracted from DEPs increases serum IgE, and whether host factors modify the immunologic effect. In thirty-two patients with acute psoriatic lesions, a cream containing 3% of coal tar (which holds a variety of PAHs) was applied to the skin for 24 hours. Serum IgE were measured before (IgE0) and four (IgE4) and eight (IgE8) days after application. Replicated means were compared by analysis of variance for repeated measures and by the Newman-Keuls' test. IgE0, IgE4 and IgE8 were 151.19, 159.69 (a 6% excess) and 170.90 kU/L (a 13% excess) respectively; pairwise comparison showed IgE8 was significantly higher than IgE0 (p<0.05). At multiple linear regression analysis, the percentage increase in serum IgE across observation days was the dependent variable against age, sex, cigarettes/day, urinary 1-pyrenol, atopy, skin area treated, and grams of cream. Of the independent variables, only age had a significant (p<0.028) influence: the younger the age, the higher the IgE response to PAHs. We conclude that whatever the source and the route of entry (skin or respiratory tract), PAHs increase total serum IgE, mainly in younger age groups.

Role of metabolic polymorphisms NAT2 and CYP1A2 on urinary mutagenicity after a pan-fried hamburger meal

In this work the phenotyping approach was used to study the influence of metabolic polymorphisms NAT2 and CYP1A2 on S9-mediated urinary mutagenicity, detected with Salmonella strain YG1024, in 50 subjects after a meal of pan-fried hamburgers. All 50 post-meal samples, but not pre-meal ones, were clearly mutagenic (number of urine samples able to double number of spontaneous revertants was 50 to 0, respectively). CYP1A2 positively influences urinary mutagenicity: a rise in CYP1A2 activity increases levels of post-meal urinary mutagens (1.16+/-0.91 vs 1.72+/-1.19 7-h minimum mutagenic doses (MMDs)/intake), especially in NAT2 slow acetylators (2.18+/-1.33 vs 0.90+/-0.54 7-h MMDs/intake, Mann-Whitney U-test, P<0.05). NAT2 rapid acetylators exert lower post-meal urinary mutagenicity than slow ones (1.41+/-1.02 vs 1.77+/-2.45 7-h MMDs/intake) and even more if the latter are extensive CYP1A2 metabolizers (1.41+/-1.02 vs 2.18+/-1.33 7-h MMDs/intake), but the difference did not reach statistical significance. In conclusion, this study indicates that CYP1A2 and NAT2 activities influence the presence of urinary mutagens after a meal of pan-fried hamburger (rich in HHAs) and consequently their potential genotoxic risk.

Biological indicators of genotoxic risk and metabolic polymorphisms

International scientific publications on the influence of metabolic genotypes on biological indicators of genotoxic risk in environmental or occupational exposure are reviewed. Biomarkers of exposure (substance or its metabolites in biological fluids, urinary mutagenicity, protein and DNA adducts) and of effects (chromosome aberrations (CAs), sister chromatid exchanges (SCEs), micronuclei (Mn), COMET assay, HPRT mutants) have been evaluated according to different genotypes (or phenotypes) of several activating/detoxifying metabolic activities. In less than half the studies (43 out of 95), the influence of genotype on the examined biological indicator was found, of which four report poorly reliable results (i.e., with scarce biological plausibility, because of the inconsistency of modulated effect with the type of enzymatic activity expressed). As regards urinary metabolites, the excretion of mercapturic acids (MA) is greater in subjects with high GST activity, that of 1-pyrenol and other PAH metabolites turns out to be significantly influenced by genotypes CYP1A1 or GSTM1 null, and that of exposure indicators to aromatic amines (AA) (acetylated and non-acetylated metabolites) is modulated by NAT2. In benzene exposure, preliminary results suggest an increase in urinary t, t-muconic acid (t,t-MA) in subjects with some genotypes. On urinary mutagenicity of PAH-exposed subjects, the effects of genotype GSTM1 null, alone or combined with NAT2 slow are reported. When DNA adduct levels are clearly increased in PAH-exposed group (18 out of 22), 7 out of 18 studies report the influence of GSTM1 null on this biomarker, and of the five studies which also examined genotype CYP1A1, four report the influence of genotype CYP1A1, alone or in combination with GSTM1 null. A total of 25 out of 41 publications (61%) evaluating the influence of metabolic polymorphisms on biomarkers of effect (cytogenetic markers, COMET assay, HPRT mutants) do not record any increase in the indicator due to exposure to the genotoxic agents studied, confirming the scarce sensitivity of these indicators (mainly HPRT mutants, Mn, COMET assay) for assessing environmental or occupational exposure to genotoxic substances. Concluding, in determining urinary metabolites for monitoring exposure to genotoxic substances, there is sufficient evidence that genetically-based metabolic polymorphisms must be taken into account in the future. The unfavourable association for the activating/detoxifying metabolism of PAH is also confirmed as a risk factor due to the formation of PAH-DNA adducts. The clearly protective role played by GSTT1 on DEB (and/or related compound)-induced sister chromatid exchanges (SCEs) should be noted. The modulating effects of genotypes on protein adduct levels in environmental and occupational exposure have not yet been documented, and most studies on the influence of genotype on biological indicators of early genotoxic effects report negative results.

[Biomarkers of gentotoxic risk and metabolic polymorphism]

This paper reviews studies published in the international scientific literature evaluating the influence of genetically based metabolic polymorphisms on biological indicators of genotoxic risk in environmental or occupational exposure. Exposures due to life style (i.e. diet or smoking) were not considered. Indicators are subdivided into internal dose indicators (concentration of the substance or its metabolites in biological fluids, urinary mutagenicity, adducts of hemoglobin, plasma proteins and DNA), and early biological effects (chromosome aberrations, sister chromatid exchanges, micronuclei, COMET assay, HPRT mutants). The metabolic genotypes (or phenotypes) examined by various authors are: ALDH2 (aldehyde dehydrogenase), CYP (P450 cytochrome) 1AI, CYP1A2, CYP2E1, CYP2D6, EPHX (epoxidohydrolase), NAT2 (N-acetyl transferase), NQO1 (NAD(P)H: kinone oxidoreductase), PON1 (paraoxonase), GST (glutathione S-transferase) M1, GSTT1 and GSTP1. In more than half the studies (52 out of 96), no influence of genotype was found in the biological indicator. This may be due either to the poor sensitivity of the indicator used, or to low exposure. In studies examining the effect of genotype on the indicator, the biological plausibility of the result was evaluated, i.e., whether the effect is consistent with the type of enzymatic activity expressed. Four studies reported not very reliable results and suggest either the unfavourable influence of genotype GSTM1 with high detoxifying activity, or enzymatic activity poorly involved in the metabolism of the xenobiotics in question (NAT2 in the case of PAH). As regards urinary metabolites of genotoxic agents, eight studies reported the modulating effect of genotype. The urinary excretion of mercapturic acids was greater in subjects with high GST activity. In exposure to PAH, urinary 1-pyrenol and PAH metabolites turn out to be significantly influenced by genotypes CYP1A1 or GSTM1 null; in exposure to aromatic amines, the influence of NAT2 on exposure indicators (levels of acetylated and non-acetylated metabolites) was confirmed. Exposure to benzene led to an increase in t-t-MA in some genotypes, although experimental verification is still necessary. As regards urinary mutagenicity, the effect of genotype GSTM1 null is reported, and of the same genotype combined with NAT2 slow, in non-smoking individuals subjected to high exposure to PAH and in cigarette-smoking/coke-oven workers. Lastly, the determination of urinary metabolites in monitoring exposure to genotoxic substances, provides sufficient evidence that genetically based metabolic polymorphisms must be taken into account in the future. There is still little evidence regarding the importance of genotype on the level of protein adducts in environmental and occupational exposure. A relatively large number of publications (22) dealt with DNA adduct levels in PAH exposure. In 18 studies, the biological indicator clearly increases with respect to values in control subjects. Of these studies, seven reported the influence of GSTM1 null on DNA adducts and, of the five studies which also examined genotype CYP1A1, four reported the influence on DNA adduct level of genotype CYP1A1, alone or in combination with GSTM1 null. It therefore seems as if the unfavourable association for the activating/detoxifying metabolism of PAH is a risk factor for the formation of PAH-DNA adducts. Most publications (25 out of 41; 61%) dealing with metabolic polymorphisms in effect indicators (cytogenetic markers, COMET assay, HPRT mutants) did not report any increase in the indicator due to exposure to the genotoxic agents studied. These indicators of genotoxic damage, including mainly the frequency of HPRT mutants (100%), Mn (90%) and the COMET assay (67%), are not sufficiently sensitive in revealing exposure, confirming that they are not particularly suitable for measuring exposure to genotoxic substances in occupational or environmental exposures. It is therefore difficult to assess the influence of metabolic genotypes by means of this type of biological indicator. The few positive results reported for SCE in occupational studies mentioned the influence of genotype ALDH2, either alone or in combination with genotype CYP2E1 in exposure to CVM, or in combination with GSTM1 null in exposure to epichlorohydrin. For CA the results showed unfavourable combinations of genotypes CYP2E1, GSTM1 and PON1 in exposure to pesticides, and GSTM1 null in combination with NAT2 slow in exposure to urban air. All the remaining studies on the effect of genotype on biological indicators of cytogenetic damage reported negative results.

[Assessment of occupational exposure to aromatic polycyclic hydrocarbons determining urinary levels of 1-pyrenol]

In conformity with Italian law 626/94, occupational exposure to Polycyclic Aromatic Hydrocarbons (PAH) in several types of work environments was assessed by analysing urinary levels of 1-pyrenol. A total of 231 non-smokers exposed to PAH (82 workers, employed in two different thermoelectric power plants using combustible oil (30 subjects from plant A and 52 from plant B), 18 subjects working for a company recovering exhausted oils, 12 working on rubber production, 10 on road surface asphalting operations, 22 working in the anodizing section of an aluminium plant, 27 chimney-sweeps, and 60 coke-oven workers (30 topside workers, and 30 doing other jobs)) were enrolled. There were also 53 non-smoker control subjects, not occupationally exposed to PAH. Current smokers were excluded, since smoking is an important confounding factor when occupational exposure to low PAH concentrations are monitored. Confounding factors, i.e., diet and passive smoking, were checked by means of a questionnaire which, in addition to personal data and habits, also requested specific details about the type of diet followed and possible exposure to passive smoking during the 24-hour period preceding urine collection. In controls, exposure to PAH in the diet significantly increased 1-pyrenol levels in urine: in subjects introducing > or = 1 microgram of pyrene with the diet, the mean urinary level of 1-pyrenol was significantly higher than that introduced with < 1 microgram (high versus low dietary intake, mean +/- SD, 0.08 +/- 0.13 and 0.04 +/- 0.06 1-pyrenol mumoles/mole of creatinine, respectively; Mann-Whitney U-test Z = 2.67, p < 0.01). Conversely, passive smoking did not influence 1-pyrenol levels. In the overall population (controls and exposed), multiple linear regression analysis showed that levels of urinary 1-pyrenol were significantly influenced by occupational exposure to PAH in asphalt workers, anodizing plant workers, chimney-sweeps, and coke-oven workers, both those working at the top side of the oven and those doing other jobs (t = 2.19, p = 0.02; t = 2.56, p = 0.01; t = 5.25, p = 0.001; t = 3.34, p = 0.001; t = 7.82, p = 0.001, respectively; F = 9.7, p < 0.01), but not in power plant workers in contact with combustible oils, workers recovering exhausted oils, or rubber production workers. Diet and passive smoking did not influence urinary 1-pyrenol levels in the entire sample population. This biomarker also allowed an assessment of exposure levels among certainly exposed subjects. The percentage of subjects with urinary 1-pyrenol values higher than the 99th percentile of the reference population (0.67 mumoles 1-pyrenol/mole of creatinine) was significantly higher than that of controls in asphalt workers (20%), anodizing plant workers (14%), chimney-sweeps (13%) and coke-oven workers (33%) (chi-square test: asphalt workers = 6.1, p = 0.01; anodizing plant workers = 4.3, p = 0.04; chimney-sweeps = 7.1, p = 0.008; coke-oven workers with other duties = 4.4, p = 0.04; top side workers = 16.5, p < 0.001). In chimney sweeps and top side workers, respectively 2 and 4 subjects (7% and 13%) exceeded the precautionary level of 1.4 mumoles 1-pyrenol/mole of creatinine; of these, 1 chimney sweep and 3 top side workers (4% and 10%) exceeded the recommended biological threshold of 2.3 mumoles 1-pyrenol/mole of creatinine.

Influence of GSTM1, GSTT1, GSTP1, and EPHX gene polymorphisms on DNA adduct level and HPRT mutant frequency in coke-oven workers

To evaluate the influence of individual susceptibility factors on the level of polyaromatic (PAH) hydrocarbon DNA adducts and hypoxanthine guanine phosphoribosyl transferase (HPRT) mutants in peripheral lymphocytes, 70 coke-oven workers exposed to PAH were genotyped for four metabolic enzyme polymorphisms of potential importance in PAH metabolism. The examined genetic polymorphisms concerned glutathione S-transferases M1 (GSTM1; gene deletion; 96 workers), T1 (GSTT1; gene deletion), P1 (GSTP1; Ile-->Val substitution at codon 104 or Ile-->Val at codon 104 and Val-->Ala at codon 113), and microsomal epoxide hydrolase (EPHX; Tyr-->His substitution at codon 113 and His-->Arg at codon 139). The workers were classified in a high- and low-exposure group on the basis of urinary concentration of 1-pyrenol. The GSTM1 null genotype increased the number of DNA adducts in smoking coke-oven workers with high PAH exposure. DNA adducts were affected by PAH-exposure in non-smokers and in GSTM1 null smokers and by smoking in GSTM1 null individuals. In a multiple linear regression analysis, the interaction of the GSTM1 genotype was statistically significant (p = 0.04) with smoking (yes/no) and of borderline significance (p = 0.06) with PAH-exposure (high/low). As smoking also increased urinary 1-pyrenol, the genotype modification seemed to concern DNA adducts due to smoking rather than occupational exposure. GSTT1 positive individuals showed an elevated level of DNA adducts in comparison with GSTT1 null subjects (p = 0.04), and EPHX genotypes associated with slow hydroxylation reaction yielded a higher (p = 0.05) HPRT mutant frequency than fast EPHX genotypes; these findings were, however, based on small numbers of subjects and need to be clarified in further studies. In conclusion, our findings indicate that homozygous deletion of GSTM1 results in an increased sensitivity to genotoxic PAHs in tobacco smoke, which is seen as an increase in aromatic DNA adducts in blood mononuclear cells.

The influence of cytochrome P450 1A1 and glutathione S-transferase M1 genotypes on biomarker levels in coke-oven workers

The present study has the aim of evaluating gene-environment interaction on the levels of different biomarkers in coke-oven workers exposed to PAH. In order to assess whether the levels of some biomarkers (PAH-DNA adducts, nitro-PAH adducts to Hb and MN frequency) could be modulated by the genetic metabolic polymorphisms for CYP1A1 and GSTM1, we analysed in 76 coke-oven workers and 18 controls the CYP1A1 (MspI and Ile/Val sites) and the GSTM1 genotypes by a PCR assay. In individuals with shared setup of CYP1A1 or GSTM1 genotypes, we analysed how the specified biomarkers correlated with total PAH exposure (urinary levels of 1-hydroxypyrene) both by a stratified analysis and logistic regression modelling. Statistically significant (P = 0.03 and P = 0.01) higher percentages of the more susceptible GSTM1- subjects compared to the GSTM1+ subjects and of the more susceptible CYP1A1 Ile/Val individuals compared to the CYP1A1 Ile/Ile individuals were detected for high levels of PAH-DNA adducts in the high exposure group (namely high levels of 1-OHP). A statistically significant association was observed between increased PAH-DNA adduct levels and the more susceptible GSTM1- genotype (P.O.R. = 4.18, P = 0.03) in a logistic regression modelling and a significant interaction between PAH exposure and GSTM1-genotype was found for PAH-DNA adducts. No effect of these metabolic genotypes was observed for MN frequency and nitro-PAH adducts to Hb. In conclusion, a gene-environment interaction between PAH exposure and two metabolic genotypes involved in activation (CYP1A1) and detoxification (GSTM1) of PAHs, respectively, has been identified.

Influence of GSTM1 genotypes on anti-BPDE-DNA adduct levels in mononuclear white blood cells of humans exposed to PAH

OBJECTIVE

Association between genetic deletion polymorphism of GSTM1 (*0/*0 or active) and levels of anti (+/-)-r-7,t-8-dihydroxy-t-9,10-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene (anti-BPDE)-DNA adducts in the peripheral blood lymphocyte plus monocyte fraction (LMF) of PAH-exposed subjects was investigated.

METHODS

A total of 94 Caucasian subjects comprised the sample population: 13 coke-oven workers, 19 chimney sweeps, 36 aluminum-anode plant workers, and 26 non-occupationally PAH-exposed subjects (controls). PAH exposure was assessed in each group by means of the urinary excretion of 1-pyrenol (mean group levels 1.2, 0.7, 0.3, and 0.1 mumol/mol creatinine in coke-oven workers, chimney sweeps, aluminum-anode plant workers, and control subjects, respectively). Anti-BPDE-DNA adducts were detected by HPLC/fluorescence analysis of anti-BPDE tetrols (tetrol I-1) released after acid hydrolysis of DNA samples.

RESULTS

In coke-oven workers the percentage of cases with adduct levels exceeding the 95th percentile control value (4.4 adducts/10(8) nucleotides) was significantly higher in the subgroup with the null GSTM1 genotype (*0/*0) (100%) than in that with active GSTM1 (43%; chi 2 test, P < 0.05). In the other groups with different and lower levels of PAH exposure the percentages of positive samples were always higher in the subgroup with GSTM1 *0/*0 than in the active one, although the differences were not statistically significant. Univariate (odds ratio) and multivariate (relative risk) analyses showed that the risk of having high anti-BPDE-DNA levels increased with occupational exposure to PAH. Such risks, moreover, were further significantly increased by the lack of GSTM1 activity (RR = 5.94; CI = 1.15-30.7; P < 0.05). In coke-oven workers, chimney sweeps, and aluminum workers, respectively, the multiplicative effect of the null genotype with occupational PAH exposure gives risks of 162 (= 27.2 x 5.94), 10 (= 1.70 x 5.94), and 3 (= 0.50 x 5.94) times higher probability (risk) of high BPDE-DNA adduct formation than that of non-exposed subjects with the active GSTM1 genotype.

CONCLUSION

Our results indicate a greater risk of anti-BPDE-DNA adduct formation resulting from occupational high-level PAH-exposure in GSTM1 null (GSTM1 *0/*0) workers.

Influence of metabolic genotype GSTM1 on levels of urinary mutagens in patients treated topically with coal tar

Fifteen hospitalized, non-smoking, dermatological patients were treated with ointment containing 2% coal tar (CT) in order to assess the influence of metabolic genotype GSTM1 on urinary mutagen levels. Urinary 1-pyrenol, the main metabolite of pyrene, was used to check the high exposure to PAH of this population. The mean levels of urinary 1-pyrenol found in the 24-h urine of our patients were 467. 8+/-211.0 nmoles-24 h (range 94.6-890.1 nmoles-24 h). Mutagenicity was assessed on urine samples collected over a period of 24 h, after three consecutive days of topical application, using the bacterial mutagenesis test on Salmonella typhimurium strains TA98 and YG1024 in the presence of microsomal enzymes. The latter strain turned out to be more sensitive than the former in revealing urinary mutagens in these patients (42 693+/-30 867 vs. 6877+/-6040 net revertants-24 h). The mutagenicity on YG1024 strain and 1-pyrenol levels of urine samples were correlated (Spearman's rank correlation coefficient=0. 6678, P<0.01, z=2.795). The influence of genotype GSTM1 on urinary mutagen levels was assessed on strain YG1024. The values of urinary mutagenicity of subjects with genotype GSTM1-null (n=6) were on average higher than those of GSTM1-positive subjects (n=9) (55 498+/-45 957 vs. 34 156+/-11 933 net rev.-24 h), a non-significant statistical difference. The mean total excretion of mutagens corrected for PAH exposure (net rev./nmoles of urinary 1-pyrenol) in GSTM1-null patients was double that of GSTM1-positive ones (136. 8+/-34.7 vs. 70.8+/-23.3 net rev./nmoles of urinary 1-pyrenol; one-tailed Mann-Whitney U-test, U=11.5, P<0.05). These results indicate a greater body burden of promutagens, resulting from skin application of CT, in GSTM1-null subjects.

HPLC/fluorescence determination of anti-BPDE-DNA adducts in mononuclear white blood cells from PAH-exposed humans

The aim of this study was to compare (+/-)-r-7,t-8-dihydroxy-t-9,10-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene (anti-BPDE)-DNA adduct levels in groups of humans subjected to various levels of polycyclic aromatic hydrocarbon (PAH) (benzo[a]pyrene) exposure. An HPLC/fluorescence method was applied to detect specifically anti-BPDE-DNA adducts in mononuclear white blood cells [lymphocyte plus monocyte fraction (LMF)] from humans exposed to PAHs. A total of 130 subjects comprised the sample population: 26 psoriatic patients (3 days after clinical coal tar treatment of the skin), 15 coke oven workers, 19 chimney sweeps, 36 aluminium anode plant workers and 34 non-occupationally PAH-exposed subjects (controls). PAH exposure was assessed in each group by means of the urinary excretion of 1-pyrenol (mean group levels: 1.2, 0.7, 0.3, 65.0 and 0.1 micromol/mol creatinine in coke oven workers, chimney sweeps, aluminium plant anode workers, psoriatic patients and non-occupationally PAH-exposed subjects, respectively). HPLC/fluorescence analysis of BPDE-DNA adducts showed that the percentage of subjects with adduct levels exceeding the 95 percentile control subject value (8.9 adducts/10(8) nucleotides) was significantly high in coke oven workers (46.7%) and chimney sweeps (21.0%) (chi2 test, P < 0.01 and P < 0.05, respectively) but not in aluminium plant workers (11.1%) and psoriatic patients (0%). The increase in BPDE-DNA adduct levels in LMF (Ln values) was significantly related to chronic inhalatory and high PAH exposure (linear multiple regression analysis, F = 6.37, P < 0.01; t = 4.2, P < 0.001). Skin acute (or short-term) and high PAH exposure, charcoal-grilled meat consumption and smoking habit did not seem to influence BPDE-DNA adduct formation in LMF.

Urinary mutagenicity on TA98 and YG1024 Salmonella typhimurium strains after a hamburger meal: influence of GSTM1 and NAT2 genotypes

Mutagenicity on TA98 and YG1024 Salmonella typhimurium strains of pan-fried hamburger extracts and of 24 h post-meal urine from 32 non-smoking volunteers was evaluated. Each participant in the study was GSTM1 and NAT2 genotyped. After cooking the meat showed mutagenic activity (mean +/- SD) on strains TA98 and YG1024 of 114 +/- 129 and 1437 +/- 1536 net revertants/g respectively. Twenty three of 32 urine samples showed clear mutagenic activity (i.e. caused at least a doubling of the number of spontaneous revertants) on the O-acetyltransferase over-producing strain YG1024, while none of the post-meal 24 h urine samples was clearly mutagenic on strain TA98. Total 24 h post-meal YG1024-active urinary mutagens were well correlated with the levels of mutagen intake with the meal (r2 = 0.5977, F = 44.58, P < 0.01). In the group under study GSTM1 genotypes did not influence urinary mutagenicity. Highly exposed subjects (n = 15) with the NAT2-ss genotype showed significantly increased levels of urinary mutagenicity on strain YG1024 in comparison with NAT2-R subjects (mutagen intake-adjusted total 24 h mutagen excretion = 1.00 +/- 0.29 versus 0.66 +/- 0.32, Mann-Whitney U test, U = 12.5, P < 0.05). Our results suggest that the levels of urinary mutagens derived from diets rich in heterocyclic aromatic amines, which are specifically detected by the YG1024 Salmonella strain, are modulated by NAT2-dependent enzyme activity, slow acetylators having higher levels of mutagens in their urine. Subjects with the rapid acetylator genotype, who are known to be at risk for colon cancer, seem to be partially protected with respect to the risk of bladder cancer.

[The toxicology and prevention of the risks of occupational exposure to aromatic polycyclic hydrocarbons. I. Guide lines for the prevention of the risks of occupational exposure to aromatic polycyclic hydrocarbons. Società Italiana Valori di Riferimento and Cattedra di Medicina del Lavoro, Università di Brescia]

These guidelines mainly deal with prevention of carcinogenic effects following occupational exposure to polycyclic aromatic hydrocarbons (PAH). After some toxicological remarks, the guidelines define a possible method to demonstrate and evaluate occupational exposure to PAH. In particular, it is illustrated the strategy of environmental monitoring and indicated which PAH should be measured, with suggestion about the most appropriate analytical techniques. As regards biological monitoring, the 1-OH-pyreneseems to be currently the most useful indicator since it reflects the recent and global exposure to PAH. The guidelines also give elements to interpret monitoring data, taking into account environmental and biological reference and limit values suggested by some authors, Associations, or current regulations. The most important health effects are carcinogenic and excess risks have been described mainly for lung, bladder and skin cancer in some PAH exposed workers. The studies on cytogenetic effects showed contradictory results. On the basis of such information and current regulations, the guidelines show how to perform health surveillance in preventive and periodical examinations and how to proceed for the information and formation of exposed workers. It is not advisable, on the basis of the current scientific data, to screen asymptomatic PAH exposed workers for early diagnosis of lung or bladder cancer, nor it is opportune the use of tumor markers for health surveillance nor is genetic screening applicable for individual susceptibility evaluation outside research programs.

[The toxicology and prevention of the risks of occupational exposure to aromatic polycyclic hydrocarbons. II. Toxicology. Exposure assessment. Environmental and biological monitoring]

The evaluation of exposure to polycyclic aromatic hydrocarbons (PAH) should firstly comply with current regulations (D.Lgs. 626/94), that is, identify the compounds and exposed subjects, quantify exposure, adopt preventive measures and health and epidemiological surveillance. Environmental monitoring should take into account the technological cycle and the tasks with higher PAH exposure risk, and the main sources of emissions. In the case of skin contamination, it should be considered the measure of skin PAH by means of sampling or removal techniques; moreover, the determination of urinary hydroxypyrene (1-HP) should be performed. It is mandatory to analyse (Benz[a]) anthracene; Benzo[b]fluroanthene; Benzo[j]fluoranthene; Benzo[k]fluoranthene; Benzo[a]pyrene; Dibenzo[a,h]anthracene, i.e. the PAH marked with the R45-R49 phrase. When 1-HP determination is planned, Pyrene should be added. Biological monitoring has been addressed mainly to hydroxylated metabolites of pyrene and among these 1-HP, the main metabolite of pyrene, although non occupational factors, such as tobacco smoking and consumption of smoked foods are potentially confounding. Urinary mutagenicity tests which are heavily influenced by non occupational factors such as tobacco smoking and diet are not advisable. The determination of DNA and protein adducts is a promising test for evaluation of metabolic active dose but at the moment it is not suitable for routine use in occupational medicine. In order to interpret environmental and biological data, it will be useful to consider appropriate reference values ("limit" "guide", "operative", "maximum admissible") such as 0.1 mg/m3 for total PAH extracted with benzene, 5 micrograms/m3 for the mixture of 15 PAH listed by US NTP, the limits varying from 0.1 to 5 micrograms/m3 for Benzo[a]pyrene, and 2.7-4.4 micrograms/g creat, for 1-HP.

[Genotoxicity of urban air particulate matter]

This paper reviews the genetic toxicology of urban air particulate. Dusts present in the urban environment are composed of a special type of soot, currently mainly emitted by motor vehicles. This soot contains variable quantities of adsorbed highly active genotoxic compounds (polycyclic aromatic hydrocarbons and their nitro derivatives, i.e., nitroarenes). Nitroarenes are among the compounds with the highest genotoxic activity according to the Ames test (genetic point mutation on bacteria), and are particularly abundant in ultrafine particulate matter (< 1.1 microns) emitted by diesel engines, mainly trucks. Diesel emissions have been considered as probable carcinogenic agents for man by the International Agency for Research on Cancer (IARC). Highly mutagenic activity is present in the air of all the cities in the world, and there is increasing concern about possible carcinogenic effects on the general population as a result of exposure to urban particulate matter. Early epidemiological studies on city-dwellers exposed to heavy pollution indicate an excess of lung tumours. Lastly, there is a possible carcinogenic risk for occupationally exposed workers, such as traffic police and those working for city road cleaning services, etc., who are constantly obliged by their jobs to be exposed to polluted city air at work.

GSTM1 and NAT2 genotypes and urinary mutagens in coke oven workers

The influence of the metabolic genotypes GSTM1 and NAT2 on the urinary excretion of mutagens in 46 coke oven workers (27 of them smokers) was studied. Exposure to polycyclic aromatic hydrocarbons (PAH) was estimated from urinary 1-pyrenol levels, which varied from 0.23 to 5.59 micromol/mol creatinine. Fourteen urine samples (30.4%), all but one belonging to smokers, were positive for mutagenic activity (i.e. at least one of the assayed doses was able to double the number of spontaneous revertants). Nine of the urine-positive subjects were both GSTM1-null and NAT2-ss (64.3%), while the same combination of genotypes was found in nine out of 31 urine-negative subjects (29.0%) (P < 0.05). Significantly more smoking workers with the genotype combination GSTM1-null/NAT2-ss showed positive urine mutagenicity than the other subjects (75.0 versus 28.6%, P < 0.05). Smokers with the slow acetylator genotype showed a significantly higher frequency of positive urine samples than smoking fast acetylators (64.7 versus 22.2%, P < 0.05). Our results suggest that smoking coke oven workers with genotypes unfavourable for detoxification of aromatic amines (NAT2-ss) and PAH (GSTM1-null) may have an increased risk of developing bladder cancer.

Mutagenicity and contents of polycyclic aromatic hydrocarbons in used and recycled motor oils

Thirteen samples of used motor oil and 33 recycled fractions, obtained in the laboratory by means of a recovery process similar to that currently used in Italy (vacuum distillation followed by thermal clay treatment) were examined. The Ames test (standard and modified version according to Blackburn) was used to determine the mutagenicity of the extracts and their contents of polyaromatic fraction (PAF) (IP346/80 method) and polycyclic aromatic hydrocarbons (PAH) (Grimmer's method). Used motor oils are mutagenic, both directly and indirectly. The highest values have been found in used oils from motor vehicles using leaded petrol (up to 118.8 revertants/mg). Samples from vehicles using unleaded petrol or diesel fuel are less mutagenic (up to 31.1 and 16.4 rev/mg, respectively). The enrichment in mutagens due to the use of oil in the three types of engine ranges from mean values of 6.2, 1.1 and 0.4 rev/mg per 1000 km, respectively. Recycled oils are almost completely devoid of direct mutagenic activity (33 samples: mean +/- SD = 1.6 +/- 1.5 rev/mg). Most recycled distillates show considerable mutagenic activity in the presence of microsomial enzymes (up to 82.5 rev/mg), although this is reduced with respect to the original oils (recycled, mean +/- SD = 13.8 +/- 15.5 rev/mg; original oils, mean +/- SD = 30.7 +/- 35.2, Mann-Whitney U-test, z = 1.793, p < 0.05). Both PAF and PAH contents are high in used oils from the two types of petrol engine but not in those from diesel engines. Recycling reduces PAF contents only in used oils from petrol engines, from a mean value of 13.91 +/- 7.32 to 4.23 +/- 2.90% (comparison with original used oils, Mann-Whitney U-test, U = 8, p < 0.01). The light distilled fractions have greater concentrations of indirect mutagens, PAF and PAH than the others. The increase in PAH in light recycled products with respect to the original used oils is significant (Wilcoxon's t-test, z = 2.306, p < 0.05). Benzo[a]pyrene (BaP) is found in appreciable quantities (> 10 ppm) in all used oils from petrol engines and in most of their recycled products. Recycling generally recovers 50% of mutagens and PAF and about 80% of PAH. Considered together, recycled products have in any case contents of mutagens and PAF which are significantly lower than those in the parent oils, but not of PAH (Wilcoxon's t-test; mutagens, z = 2.935, p < 0.01; PAF, z = 3.145, p < 0.01; PAH, z = 1.397, not significant). Lastly, many recycled oils have PAH concentrations which are equal to or higher than those of the original used oils. The health risks linked to professional exposure to these types of oils and the inadequate recycling process currently used (redistillation and thermal clay treatment) in reducing mutagenic and cancerogenic substances from used motor oils are stressed.

[Urban air pollutant exposure among traffic policemen]

Exposure to dusts and benzene was studied in 65 traffic policemen. Samples of total dusts showed that mean personal exposure was 0.44 (SD = 0.30) mg/m3, with peaks of about 2 mg/m3. Exposure to 1-nitropyrene (1-NP), the main compound occurring in emissions from diesel engines, which was estimated from concentrations in dusts collected with high-flow samplers, was 0.28 (SD = 0.19) ng/m3 (range: 0.06-1.24 ng/m3). The mean concentration of benzene in the breathing zone was 41 (SD = 20) micrograms/m3, although a level of 100 micrograms/m3 was slightly exceeded in one subject. In urine samples collected before and after workshifts, two biological indicators of exposure to benzene were measured, urinary benzene and urinary trans, trans-muconic acid (MA). The mean values of urinary benzene before and after workshift were similar (98, SD = 81 and 83, SD = 55 ng/l; n = 63; Wilcoxon's T-test = not significant), while a moderate increase in the metabolite was observed (MA = 0.08, SD = 0.11; 0.11, SD = 0.09 mg/g creatinine, in pre- and post-shift samples respectively; Wilcoxon's T-test, z = 3.00; p < 0.01). The levels of exposure to dusts and 1-NP deriving from diesel engine emissions were comparable to those of other occupational groups with this type of risk (garage mechanics, workers operating diesel engine machinery, etc.). Traffic police exposure to benzene was similar to that of the whole population of Padova (40 micrograms/m3, mean annual 24-hour value). However, the values of urinary MA, like those reported by other authors for non-smoker controls, increased after the workshift, indicating low occupational exposure to this pollutant. It should be noted that traffic police exposure to benzene is much lower than that of other occupational categories, e.g., fuel pump distributors.

[Criteria and methods for the study of occupational exposure to antineoplastic agents]

Risk assessment for occupational exposure to antiblastic chemotherapeutic drugs (ACD) is carried out by means of environmental and biological monitoring. These practices are not widespread and furthermore their results are frequently difficult to interpret. This paper discusses some of the most important aspects of risk assessment for ACD and in particular for their exposure evaluation. The following guidelines are proposed: a) working rooms, working procedures, type and quantity of drugs, and preventive measures must be checked using a standardized scheme for collecting data: an example of a check list experimented in some Italian hospitals is presented; b) cyclophosphamide, 5-fluorouracil, and Pt coordination compounds have been identified as tracers of drug mixtures usually administered, and their determination is recommended both in environmental and biological samples; c) for a correct evaluation of exposure, ACD should be determined firstly on the contaminated surfaces or on work clothes and secondly in urine of workers; the measurement of ACD in air must be limited to well documented conditions of high exposure and the urinary mutagenicity tests should be avoided; d) the biological monitoring practices should be enhanced, in particular the determination of ACD adducts to proteins and nucleic acids as promising indicators of effective dose.

Excretion of mutagens, nicotine and its metabolites in urine of cigarette smokers

Urine samples from 26 cigarette smokers on a restricted diet were collected in the late afternoon. Urine extracts on XAD-2 resin were tested for mutagenicity in the microsuspension assay using Salmonella typhimurium strain TA98 in the presence of metabolizing and deconjugating enzymes. Levels of urinary nicotine plus metabolites and cotinine were determined. Eighteen samples were clearly mutagenic, i.e. capable of doubling the number of spontaneous revertants at one of the assayed doses of urine. Urinary mutagenic activity ranged from 193 to 8462 net revertants/mmol of creatinine, while urinary nicotine plus metabolites and cotinine levels varied from 0.007 to 1.366 and from 0.011 to 0.297 mg/mmol creatinine. Urine samples with nicotine metabolite levels of < 0.33, 0.33- < 0.66 and > 0.66 mg/mmol creatinine had mean values +/- SD of mutagenic activity of 490 +/- 222 (n = 10), 964 +/- 560 (n = 9) and 2692 +/- 2807 (n = 7) revertants/mmol of creatinine, respectively, the statistical comparison between the groups being positive (Mann-Whitney U-test, P < 0.05). The mutagenic activity of urine samples from smokers correlated well with urinary nicotine plus metabolite levels (r = 0.658, P < 0.01). A less close correlation was found between urinary mutagenic activity and other indicators of tobacco smoke exposure, such as urinary cotinine (r = 0.504, P < 0.05), number of cigarettes smoked during the day of urine collection (r = 0.399, P < 0.05) and machine smoking-derived nicotine deliveries of the total number of cigarettes smoked (number of cigarettes multiplied by the nicotine content of each cigarette, as indicated by the manufacturer; r = 0.439, P < 0.05). These results suggest that the mutagenic activity of smokers' urine may be predicted by the urinary level of nicotine plus metabolites. The low degree of reliability of many presumptive indicators of exposure to tobacco smoke and the different urinary excretion kinetics of tobacco smoke mutagens with respect to cotinine (a frequently used biomarker for monitoring exposure to tobacco smoke) are both emphasized.

Mutagenicity and contents of polycyclic aromatic hydrocarbons in new high-viscosity naphthenic oils and used and recycled mineral oils

Mutagenic activity on the Ames test was evaluated in 15 samples of naphthenic high-viscosity mineral oils and 12 samples of used lubricants (recovered and pooled) and their recycled products. Bacterial mutagenesis was assayed using both the standard technique and Blackburn's modification. The contents of polycyclic aromatic hydrocarbons (PAH) was also evaluated, as polynuclear aromatic fraction (PAF) and total PAH, determined respectively with the semi-quantitative dimethylsulphoxide-refractive index method and the Grimmer method. Only four samples (three acid-treated naphthenic oils and one recycled fraction of a used oil) showed mutagenic activity higher than 6 revertants/mg of oil, considered by Blackburn and coworkers as indicating a potential carcinogenic risk for these compounds. Limited mutagenicity was found in all used and recycled oils, but also in samples of acid- or solvent-treated oils. No hydrogen-treated naphthenic oils turned out to have any mutagenic activity. PAF contents of oils were closely correlated with those of total PAH (n = 15, r = 0.83; n = 12, r = 0.91; p < 0.01 for both naphthenic and used/recycled oils respectively). No recycled oil had high PAF contents. Eleven samples had PAF contents higher than 3%, the arbitrary danger threshold suggested by the CONCAWE (1988). Of these 11 samples, the majority were acid-treated products, although there was one hydrogen-treated oil and one used and recycled oil. No mutagenic activity could be demonstrated in almost half the oils with PAF > 3%. In this study, the presence of mutagens was not correlated wither with PAF or with total or mutagenic PAH. The difficulty of predicting the mutagenicity of mineral oils is stressed. Most naphthenic and some recycled oils clearly have components which inhibit the metabolizing system in the bacterial mutagenesis test, with consequent possible false negative results.

Urinary excretion of mutagens in coke oven workers

The influence of occupational exposure to polycyclic aromatic hydrocarbons (PAHs) on urinary mutagenic activity was assessed in 75 coke oven workers, using a highly sensitive bacterial mutagen technique (extraction with C18 resin and liquid micro-preincubation test on strain TA98 of Salmonella typhimurium in the presence of metabolizing and deconjugating enzymes). Exposure to PAHs was assessed according to the urinary excretion of 1-pyrenol; the main confounding factors were checked by the number of cigarettes smoked per day and the levels of nicotine and its metabolites in urine, or by ascertaining whether recommended dietary restrictions had been followed. Of the 20 urine samples which turned out to be positive (producing at least double the number of spontaneous revertants), 19 (95%) belonged to smokers. Only one non-smoker had obvious urinary mutagenic activity, and was highly exposed occupationally to PAHs (urinary 1-pyrenol of 3.930 mumol/mol of creatinine). Of the five urine samples from subjects who had not followed the recommended diet, two (40%) were clearly mutagenic. Multiple regression analysis (n = 67) showed that the presence of samples positive for urinary mutagenic activity depended only on smoking habits, if this confounding factor was assessed according to the number of cigarettes smoked per day, while the significant influence of exposure to PAH could be shown when the confounding factor was objectively estimated according to the urinary levels of nicotine and its metabolites. Assessment of the mutagenic potency of urinary extracts (net revertants/mmol creatinine) confirmed the strong influence of smoking habits on urinary mutagenic activity (all smokers 2156 +/- 2691 versus non-smokers 939 +/- 947 net revertants/mmol creatinine; Mann-Whitney test: P < 0.01). In smokers highly exposed to PAHs, greater excretion of mutagens with respect to low-exposure smokers was revealed (3548 +/- 4009 versus 1552 +/- 1227 net revertants/mmol creatinine; Mann-Whitney test: P < 0.01). Multiple regression analysis showed that the mutagenic potency of urinary extracts of coke oven workers depended on exposure to PAHs, tobacco smoking habits, and consumption of fried, grilled or barbecued meat. Increased urinary mutagenic activity strengthens epidemiological evidence of the increased risk of renal and urinary tract tumours in these workers. The presence of mutagenic metabolites in urine as a result of occupational exposure to PAH may be demonstrated only by using highly sensitive techniques for assessing urinary mutagenic activity in studies which include careful checking of the main confounding factors.

Mutagens in indoor air particulate

Twenty-seven extracts of airborne particulate from domestic environments, both in the absence of sources of pollution and during activities such as smoking tobacco, using a fireplace, and cooking using grills and barbecues, and eight control samples of outdoor particulate were tested using the Salmonella/microsome assay on strains TA98 and TA98NR. Dust levels and mutagenic activity in the indoor environments turned out to be very low in the absence of polluting sources, with highest mean values in winter of less than 0.1 mg/m3 and 6 and 12 revertants/m3, respectively without and with S9. The specific mutagenic activity of indoor dust ranged from 22 and 137 revertants/mg, with a contribution of nitroarene compounds of about 50%, indicating that, in city indoor air, the main cause of background particulate pollution is very probably penetration of traffic fumes from the outside. In contrast, in a country house far from traffic, very low dust and mutagenicity levels were found, without the influence of nitroarene compounds. The presence of autochthonous polluting sources, such as tobacco smoke and fumes from cooking and wood or charcoal burning, greatly increased indoor dust levels, especially during cooking operations, which reached 25.5 and 31.6 mg/m3. The particulate produced by the various indoor pollution sources showed varying specific mutagenic activities. The highest values were found for fumes produced by burning charcoal and wood, smoking tobacco, and cooking foods with high animal protein contents. Mutagens responsible were mainly direct-acting in the case of fumes from burning wood or charcoal, and required mammalian metabolic activation in the case of fumes from tobacco and meat, with a lower contribution (maximum 33%) of nitroarenes than in urban particulate.

[Dosimetry of DNA and protein adducts in occupational health]

Genotoxic carcinogenic compounds react chemically with DNA and proteins to form covalent adducts which, in the case of DNA adducts, are strongly believed to be the first step in cancer process (biologically effective dose). The paper reviews the main studies on the dosimetry of adducts in the biological monitoring of occupational exposure to mutagens and carcinogens. Dosimetry of DNA adducts has been used to assess exposure to polycyclic aromatic hydrocarbons in environments such as foundries, coke ovens and the aluminium industry. In many cases, adduct levels higher than those of control populations were found in exposed workers. Only one study reported increased levels of DNA adducts in workers exposed to styrene. Dosimetry of hemoglobin adducts has been used to identify occupational exposure to ethylene oxide, styrene, BaP and arylamines. The results obtained in the last few years confirm the usefulness of dosimetry of DNA and protein adducts in assessing occupational exposure to genotoxic carcinogens occurring in working environments, even at very low exposure levels, but the methods in question require high standardization and validation if systematic errors in measurement are to be avoided. In the coming years, dosimetry of adducts, together with evaluation of individual genetic sensitivity to mutagens and carcinogens, will be one of the new frontiers in research on the prevention of occupational cancer. Current research already makes use of sophisticated analytical techniques such as mass spectrometry, and both specificity and sensitivity in the determination of adducts have been considerably improved. In the future, therefore, dosimetry of adducts may also be applied to industrial health practices.

[Reference values in biological monitoring of occupational exposure to mutagens and carcinogens]

This work reports values of biological markers indicating mutagenic/carcinogenic risk in professionally non-exposed populations. The main confounding factors for most of these biomarkers are tobacco smoke, diet and air pollution. With the sole exception of compounds specifically present in work environments, in which determination in biological fluids of unchanged substances or their metabolites has high sensitivity and specificity (e.g., some aromatic amines), other biomarkers (urinary mutagenicity, DNA adducts and cytogenetic analyses), in order to be used properly as reference values, require ad hoc study of suitable control groups paired for the main confounding factors. Analytical determination of some protein adducts appears to be promising, due to its sensitivity and specificity.

Urinary excretion of 1-pyrenol in automotive repair workers

The urinary excretion of a pyrene metabolite was evaluated in 65 automotive repair workers whose skin was exposed to used mineral oils, and in 41 controls. Pyrene contents were determined in oily material taken from cloths used to clean various types of engines (n = 8) and were found to vary (mean +/- SD) from 2.8 +/- 0.4 ppm for dirty matter obtained from diesel truck engines to 9.3 +/- 8.2 ppm for that from petrol car engines. Tobacco smoking and polycyclic aromatic hydrocarbon (PAH)-rich diets were considered as confounding factors. At both the beginning and the end of the working week, the values of urinary 1-pyrenol were slightly higher in exposed subjects (0.178 +/- 0.150 and 0.194 +/- 0.135 mumol/mol creatinine on Monday and Friday, respectively) than in controls (0.124 +/- 0.090 mumol/mol creatinine) (Mann-Whitney test, z = 2.741, P < 0.01). The urinary 1-pyrenol values were higher in both smoking and non-smoking subjects than in controls. The highest values were found in urinary samples of smokers exposed to used mineral oils (0.259 +/- 0.201 mumol/mol creatinine). In non-smoking workers (n = 40), post-shift 1-pyrenol values were 0.154 +/- 0.105 mumol/mol creatinine, as against 0.083 +/- 0.042 mumol/mol creatinine for the 19 non-smoking controls (Mann-Whitney test, z = 2.765, P < 0.01). In automobile repair workers, urinary 1-pyrenol values before the beginning of the weekly workshift did not differ substantially from those measured at the end of the week, not being related to the subjective degree of dirty skin as stated by workers.(ABSTRACT TRUNCATED AT 250 WORDS)

Mutagens in urban air particulate

Extracts of airborne particulate matter were demonstrated to be mutagenic in the Salmonella/microsome test. Urban airborne particulate was collected with high-volume samplers in an Italian town mainly polluted by traffic exhaust fumes. After being weighted for determination of total dust, the particulate was extracted with CH2Cl2/methanol and assayed by Salmonella/microsome assay on strains TA98, TA100 and TA98NR. All samples were mutagenic on strain TA98, with a mutagenic potency of 50 +/- 14 (-S9), 128 +/- 63 (+S9) and 104 +/- 51 (-S9), 211 +/- 97 (+S9) revertants/mg of particulate for summer (n = 23) and winter (n = 22) determinations, respectively. The mutagenic activity on strain TA98NR was about one-half that on strain TA98, indicating a large contribution of nitroaromatic mutagenic compounds. Mutagens from airborne particulate were less active on strain TA100. The summer and winter mean values of urban total dust were 0.15 +/- 0.07 and 0.35 +/- 0.18 mg/m3 respectively, and the mutagenicity of urban air on strain TA98 was 8 +/- 5 (-S9), 22 +/- 17 (+S9) and 30 +/- 11 (-S9), 61 +/- 21 (+S9) revertants/m3 in the two seasons, respectively. In winter, besides an increase in urban air mutagenicity, there also was a change in direct particulate activity per milligram, which was double that of summer.

[The urinary mutagenicity test in monitoring exposure to aromatic polycyclic hydrocarbons in workers in the aluminum industry]

The sensitivity of 3 urinary mutagenicity tests was assayed: the plate test, the fluctuation test and the micropreincubation test, in order to assess their possible use in monitoring human exposure to polycyclic aromatic hydrocarbons (PAH). Urine samples from workers of an anode production plant exposed to coal tar and from psoriatic patients undergoing treatment with coal-tar ointments were tested for mutagenic activity on strain TA98 Salmonella typhimurium, in the presence of the microsome fraction and deconjugating enzymes. Parallelly, the urinary concentration of PAH metabolites or one of their trace metabolites, 1-hydroxypyrene, was determined. Increased levels of PAH metabolites were observed in the urine of anode production workers after a work shift compared with controls. Results of the plate test and the fluctuation test performed on urine of exposed subjects, both smokers and nonsmokers, showed mutagenicity values similar to the controls. Much higher 1-hydroxypyrene concentrations were found in the urine of psoriatic patients treated with coal tar than in post-shift urine of anode production workers. The urine of the former was also mutagenic in the 3 mutagenicity tests used. The minimum mean dose of PAH metabolites was calculated, expressed as quantity of 1-hydroxypyrene, that would give a mutagenic response in the 3 tests: the micropreincubation test was found to be about 100 times more sensitive than the plate test and about 30 times more sensitive than the fluctuation test. The theoretical minimum urinary concentration of 1-hydroxypyrene detectable by each test was determined: the micropreincubation test was 15 times more sensitive than the plate test and 7 times more sensitive than the fluctuation test.(ABSTRACT TRUNCATED AT 250 WORDS)

[The prevention of tumors in the aluminum industry]

Aluminium industry workers are exposed to various carcinogenic substances, the most important of which are asbestos and coal pitch and tar fumes. Primary prevention of cancer risk can be achieved either by eliminating the carcinogenic agent from the working environment, or by reducing the exposure levels or the number of exposed workers. In the aluminium industry the first type of approach is possible in the case of asbestos, which can be substituted with MMMF (man made mineral fibers), with the cancer risk thus passing from group 1 to group 2b of the IARC Classification. Complete abolition of exposure to pitch and coal-tar fumes is not feasible, but a reduction in risk can be achieved by using the pre-bake anode cell process instead of the Söderberg process, since the former reduces exposure of potroom workers to pitch and coal-tar fumes. A further reduction of exposure in pot-rooms can be achieved, as demonstrated by direct experience in an aluminium plant at Port Marghera (Province of Venice). Environmental monitoring performed from 1978 to 1989 showed a decrease in levels of total dust concentrations and thus of PAH and BaP concentrations as a result of a series of technical and/or organisational improvements. In biological monitoring, which can detect any skin absorption of the carcinogen, the concentrations of urinary hydroxypyrene confirmed low levels of exposure in the plant under study, excluding the pitch plant workers.(ABSTRACT TRUNCATED AT 250 WORDS)

Micronucleated cells in nasal mucosa of formaldehyde-exposed workers

The frequency of micronuclei (MN) and cytology of respiratory nasal mucosa cells were evaluated in 15 non-smokers exposed to formaldehyde in a plywood factory. Each subject was paired with a control matched for age and sex. Mean levels of exposure to formaldehyde ranged from about 0.1 mg/m3 in the sawmill and shearing-press departments to 0.39 mg/m3 in the warehouse area. There was a contemporary exposure to low levels of wood dust (inspirable mass ranged from 0.23 mg/m3 in the warehouse to 0.73 mg/m3 during sawing operations). Nasal respiratory cell samples were collected by an otorhinolaryngologist near the inner turbinate using a brush for endocervical cytology. After staining (Feulgen plus Fast Green and Papanicolaou's method for MN analysis and cytology, respectively), about 6000 cells were screened for micronuclei and scored in parallel for cytology according to a histopathological scale. A higher frequency of micronucleated cells was observed in the exposed group than in the controls (0.90 +/- 0.47 vs. 0.25 +/- 0.22, Mann-Whitney U test: p less than 0.01). Cytological examination indicated chronic phlogosis in the nasal respiratory mucosa of plywood factory workers, with a high frequency of squamous metaplasia cells (mean score 2.3 +/- 0.5 vs. 1.6 +/- 0.5 in the control group, Mann-Whitney U test: p less than 0.01).

Sensitivity of different bacterial assays in detecting mutagens in urine of humans exposed to polycyclic aromatic hydrocarbons

The urine mutagenicity and excretion of 1-hydroxypyrene (1-OH PYR) in non-smoking psoriatic patients treated topically with coal-tar-based ointments were analysed in order to find the most appropriate procedure for monitoring occupational PAH exposure. The bacterial mutagenicity assays used were the plate incorporation, macro-scale fluctuation and microsuspension tests, all on Salmonella typhimurium strain TA98 in the presence of S9 mix and beta-glucuronidase. The sensitivities of the three assays in detecting mutagenic urinary PAH metabolites were compared. The efficiencies of XAD-2 and C18 resins for concentrating PAH urinary mutagens were evaluated in the microsuspension assay. The plate and fluctuation tests on XAD-2 urine extracts were shown to be insufficiently sensitive to detect low urinary levels of mutagens, being positive on urine samples with very high PAH metabolite content, estimated as more than 30 micrograms/g of creatinine of 1-OH PYR. The microsuspension assay on XAD-2 or, even better, on C18 urine extracts was very sensitive in detecting up to 5 micrograms/g of creatinine of 1-OH PYR. It therefore seems to be applicable to the biological monitoring of most occupational low exposures to coal tar.

Detection of benzo[a]pyrene-diol-epoxide-DNA adducts in white blood cells of psoriatic patients treated with coal tar

An enzyme-linked immunosorbent assay (ELISA) was used to detect BPDE-DNA adducts in white blood cells of 23 psoriatic patients undergoing clinical coal tar therapy. Ten of these patients were reanalyzed 2-5 months after the end of the coal tar treatments. The results show that the mean adduct level during the treatment period was 0.26 +/- 0.16 fmole BPDE/micrograms DNA (7.7 +/- 4.9 adducts/10(8) nucleotides), while 2-5 months later the mean adduct level had decreased significantly (P less than 0.005) to 0.11 +/- 0.08 fmole BPDE/micrograms DNA (3.3 +/- 2.4 adducts/10(8) nucleotides). No relationship could be ascertained between the level of exposure and the amount of BPDE-DNA adducts. In addition, no difference in the level of DNA adducts was found between smoking and non-smoking patients.

The mutagenic activity and polycyclic aromatic hydrocarbon content of mineral oils

Naphthenic distillates (raw or acid-treated) and motor and emulsifiable aluminium rolling oils were tested for mutagenicity in the Salmonella/microsome assay using the TA98 and TA100 strains. The polycyclic aromatic hydrocarbon (PAH) content of oil samples was also determined in parallel. In the presence of metabolic activation, both untreated and acid-treated naphthenic distillates were found to be mutagenic on a modified Ames test. One untreated sample showed the highest value of mutagenic potency (50 net revertants/mg oil for strain TA98). The PAH content of naphthenic distillates was about 10% (w/w) and was slightly reduced by sulfuric acid/earth treatment (1%). Non-mutagenic paraffin- and solvent-extracted crankcase oils became active, both with and without enzyme activation, after long use as gasoline engine lubricants, whereby their PAH content doubled (from 1.5% to 3%, w/w). A refined emulsifiable mineral oil also became directly mutagenic in both Salmonella strains after prolonged use in an aluminium hot-rolling mill. As the PAH levels found in used rolling oils was very low, we cannot explain their mutagenic activity. Mutagenicity was greatly reduced following careful cleaning of the oil bath and of the entire rolling machine. The present data reveal both the potential risk of occupational exposure to unrefined or mildly treated oils and the formation of mutagens in highly refined oils if the latter are used at high temperatures. The formation of mutagens in oils used in the metal-working industry can be prevented by careful industrial hygiene measures.

[Mutagens and carcinogens in city air]

Many urban air pollutants are recognized to be mutagenic and carcinogenic agents. Combustion processes, which generate gaseous and particulate complex mixtures, are responsible for the major part of urban air pollution. Emissions from automotive sources are estimated to be nowadays the main cause of mutagenic/carcinogenic risk for people living in urban areas of industrialized countries. Increasing vehicle traffic also contributes to the presence in urban air of valuable concentrations of asbestos fibers and benzene, both well-known potent carcinogens.

[Leather azo dyes: mutagenic and carcinogenic risks]

The paper reviews the carcinogenicity and mutagenicity data on azo dyes used in the leather industry. Two water soluble benzidine-based dyes were classified as "probably carcinogenic to humans" by the International Agency for Research on Cancer (IARC). No other dyes have been evaluated by the IARC. Of the 48 azo dyes assayed in the Salmonella/microsome test, 20 gave positive results. Attention is drawn to the important role of the in vivo metabolism of azo compounds, which includes a preliminary reduction of the azo bonds and subsequent release of the aromatic amines of the dye. A useful assay (Prival test) for evaluating the mutagenic properties of azo dyes involves a reductive step that permits the release of any genotoxic agents present in the compounds. A list of leather azo dyes is furnished that are considered as potentially harmful due to the presence of a carcinogenic aromatic amine (benzidine, p-aminobenzene and derivatives) in their formulae.

[Identification of genotoxic compounds used in leather processing industry]

The release of mutagens from 7 carbon black-based leather dyes and from leather samples at various stages of finishing was determined. After vigorous treatment with toluene, 4 commercial dyes yelded mutagenic extracts on Salmonella typhimurium in the presence of microsomal enzymes. Only in one case were the responsible chemicals identified as polycyclic aromatic hydrocarbons. The low bioavailability of mutagens contained in carbon black and their low mutagenic activity suggest that the risk associated with the use of these dyes is probably negligible. Soxhlet extracts with ethanol from finished leather were mutagenic on strain TA98 of Salmonella typhimurium in the absence of S9 mix. Analysis of extracts of leather samples at various intermediate stages of processing showed that mutagenic activity was detectable after the colouring process. The responsible compound was identified as a nitroazo dye (Colour Index: Acid Brown 83), with a mutagenic potential of about 4 revertant/micrograms. Eighteen commercial tannins containing mainly Cr(III) sulphates were assessed for genotoxicity. Most were contaminated with Cr(VI), a known mutagenic and carcinogenic agent, at levels sufficient to induce an increased frequency of SCE (sister chromatid exchanges) in mammalian cells (CHO, chinese hamster ovary) tested in vitro.

[The AMES test in environmental and occupational medicine]

The authors review the use of the gene mutation test on Salmonella typhimurium, better known as the Ames test, in environmental and occupational health. This test, which was originally intended as a predictive test of the carcinogenicity of chemical substances, has been widely applied in in vitro screening of complex mixtures of substances present in the environment and in the biological monitoring of high risk populations. Data are reported on the main environmental exposures that were positive with the Ames test and it is stressed how this biological assay has contributed to the identification of new classes of genotoxic compounds (nitropyrenes, mutagen X). The Ames test performed on extracts of human urine was used to study exposure to carcinogenic substances in the working environment. Many occupational exposures can cause an increase in mutagenic activity in the exposed subjects (cytostatic drugs, rubber manufacture, polycyclic aromatic hydrocarbons). It is recommended to restrict the use of the urinary mutagenesis test to group studies and carefully check confounding factors (e.g., smoking and diet).

[Urinary excretion of mutagens and cisplatin among the nursing staff at a medical oncology department exposed to cytostatic drugs]

Exposure to cytostatic drugs was assessed in a group of 9 nurses employed in a hospital cancer therapy department by measuring the post-shift levels of urinary mutagens and cis-platinum. A slight but significant increase in urinary mutagenic activity compared to 11 controls was observed in the non-smokers: the mean values of mutagenic activity on the Ta100 strain in the presence of both microsomal and deconjugating enzymes were 4418 +/- 1186 and 2468 +/- 1681 respectively. Conversely, the urinary platinum concentration was below the detection limit of the analytical method (10 micrograms/l) in all samples. The increased urinary mutagenic activity in the exposed group can probably be attributed to the absorption of cyclophosphamide either during preparation and administration of the drug, or due to accidental contact with contaminated biological fluids, in view of the fact that the level of mutagens in urine samples from cyclophosphamide-treated patients is extremely high (up to 319,478 revertants/g creatinine in the case we examined).

Release of mutagens from finished leather

Extracts of a leather widely used in the furniture and dress-making industries were tested for their mutagenic activity in the Salmonella/microsome assay. Extracts obtained after vigorous treatment of leather samples in a Soxhlet apparatus with toluene or ethanol were mutagenic in strain TA98 of S. typhimurium in the absence of S9 mix. The analysis of extracts of leather at various intermediate stages of processing showed that the mutagenic activity appeared after the coloration process. The responsible compound was identified to be an azo dye (Color Index: Acid Brown 83) whose mutagenic potency was about 4 revertants/micrograms.

Biological monitoring of human exposure to coal tar. Urinary excretion of total polycyclic aromatic hydrocarbons, 1-hydroxypyrene and mutagens in psoriatic patients

Three methods for the biological monitoring of human exposure to coal tar were compared. Levels of 1-hydroxypyrene(1-OH PYR), polycyclic aromatic hydrocarbons (PAH) and mutagens (Ames plate incorporation assay using Salmonella typhimurium strain TA98 in the presence of S9 and beta-glucuronidase) were determined in urinary samples from psoriatic patients undergoing topical treatment with mineral coal tar. A single sample of urine with a high content of PAH was diluted with urine of nonexposed, non-smoking subjects in order to obtain nine samples with a decreasing content of PAh metabolites. Mutagenicity of the extracts was detectable down to the dilution corresponding to a content in 1-OH PYR of about 50 micrograms/g creatinine and total PAH of 7 micrograms/g creatinine. In a second phase the three indicators of exposure to PAH were compared in 16 urinary samples from four psoriatic patients. The total PAH levels determined by the acidic deconjugation/reduction method were confirmed to be nearly always lower than the corresponding levels of 1-OH PYR alone. Most of the extracts were mutagenic, however, some of the samples with a high content in PAh metabolites were not mutagenic. In all the urinary samples analyzed the excretion of 1-OH PYR was markedly greater than in control subjects. 1-OH PYR and urinary mutagenicity levels were well correlated. The present data suggest that both the determination of mutagenicity and 1-OH PYR in urine may be used to monitor occupational exposure to PAH, the latter method being cheaper and of greater specificity and sensitivity.

Induction of SOS response in Escherichia coli strain PQ37 by 16 chemical compounds and human urine extracts

The SOS Chromotest on Escherichia coli strain PQ37 was used to detect DNA damage induced by 16 chemical compounds and urine samples from smokers and a non-smoking psoriatic patient treated with mineral coal tar. The results confirmed the strong SOS inducing activity of 2-aminoanthracene and benzo[a]pyrene with metabolic activation and N-methyl-N'-nitro-N-nitrosoguanidine, mitomycin C and 4-nitroquinoline-N-oxide without metabolic activation. A weaker response in the absence of microsomal enzymes was observed with hydroxyurea (only at high doses) and the soluble Cr(VI) compounds potassium chromate and potassium dichromate. No effect was observed with ampicillin, cadmium chloride, cyclophosphamide, griseofulvin, the insoluble Cr(VI) compound lead chromate, the soluble Cr(III) compounds chromium nitrate, chromium chloride, chromium potassium sulphate, and the chelating agent sodium nitrilotriacetate. Among the Cr(III) compounds only chromium acetate produced a low but significant increase of SOS inducing activity. Solubilization by nitrilotriacetate of genotoxic Cr(VI) from insoluble lead chromate was observed, whereas no interaction occurred between nitrilotriacetate and the soluble Cr(VI) and Cr(III) compounds. Using urinary XAD-2 extracts, we found the SOS Chromotest poorly sensitive to the mutagens present in urine from tobacco smokers which, on the other hand, were detected by the gene mutation assay in Salmonella typhimurium (Ames test). A urine sample obtained from a psoriatic patient, therapeutically treated with mineral coal tar, had a significant SOS inducing activity with and even without metabolic activation, whereas in the Ames test it was active only in the presence of metabolic activation.(ABSTRACT TRUNCATED AT 250 WORDS)

Sister chromatid exchanges and DNA repair capability in sanitary workers exposed to ethylene oxide: evaluation of the dose-effect relationship

Determination of ethylene oxide (EtO) in the working environment and induction of sister chromatid exchanges (SCE) and unscheduled DNA synthesis (UDS) in peripheral lymphocytes of 10 exposed sanitary workers and 10 control subjects matched for sex, age, and smoking habits are reported. The relationship between the external dose of EtO and the frequency of SCE was determined in the above group and in a group of 41 sanitary workers previously studied. The 10 newly examined workers were exposed to EtO concentrations (1.84 ppm as time-weighted average) intermediate between the high (10.7 ppm) and low (0.35 ppm) levels of exposure of the two previously examined groups (19 and 22 workers, respectively). A statistically significant (p less than 0.002) increase of SCE frequency was observed between the present control and exposed groups. The inducibility of unscheduled DNA synthesis by gamma rays was lower in the lymphocytes of the exposed workers than in controls, but the difference was not statistically significant. A significant relationship between the frequency of SCE and the level of EtO exposure for the three exposed groups was demonstrated by two different statistical methods. It is suggested that the present Italian threshold limit value for EtO (3 ppm) may not protect the exposed workers against possible genotoxic effects and that even a chronic exposure to 1 ppm may not be devoid of genotoxic risk.