Trends in occupational exposure to styrene in the European glass fibre-reinforced plastics industry

Aim: This study presents temporal trends of styrene exposure for workers in the European glass fibre-reinforced plastics (GRP) industry during the period 1966–2002.

Methods: Data of personal styrene exposure measurements were retrieved from reports, databases and peer-reviewed papers. Only sources with descriptive statistics of personal measurements were accepted. The styrene exposure data cover personal air samples and biological monitoring data, that is, urinary styrene metabolites (mandelic acid and/or phenylglyoxylic acid) and styrene in blood. Means of series of measurements were categorized by year, country, production process, job and sampling strategy. Linear mixed models were used to identify temporal trends and factors affecting exposure levels.

Results: Personal exposure measurements were available from 60 reports providing data on 24145 1–8-h time-weighted average shift personal air samples. Available data of biological exposure indicators included measurements of mandelic acid in post-shift urine (6361 urine samples being analysed). Trend analyses of the available styrene exposure data showed that the average styrene concentration in the breathing zone of open-mould workers in the European GRP industry has decreased on average by 5.3% per year during the period 1966–1990 and by only 0.4% annually in the period after 1990. The highest exposures were measured in Southern Europe and the lowest exposures in Northern Europe with Central Europe in between. Biological indicators of styrene (mandelic acid in post-shift urine) showed a somewhat steeper decline (8.9%), most likely because urine samples were collected in companies that showed a stronger decrease of styrene exposure in air than GRP companies where no biological measurements were carried out.

Benchmark guideline for urinary 1-hydroxypyrene as biomarker of occupational exposure to polycyclic aromatic hydrocarbons

Many individual polycyclic aromatic hydrocarbons (PAH) are genotoxic carcinogens. One of the parent PAH, pyrene, undergoes simple metabolism to 1-hydroxypyrene. 1-Hydroxypyrene and its glucuronide are excreted in urine. Biological monitoring of exposure to PAH has rapidly been expanded since urinary 1-hydroxypyrene was suggested as a biological index of dose of pyrene. Since pyrene is always present in PAH mixtures, the biological indicator is not only an indicator of uptake of pyrene, but also an indirect indicator of all PAH. At present, several hundreds of papers reporting on urinary concentrations of 1-hydroxypyrene in workers' urine are available. It appeared that urinary 1-hydroxypyrene is a sound biomarker and that the analytical method is robust and non-laborious. Since epidemiological studies of cancer mortality related to long-term average urinary 1-hydroxypyrene concentration are lacking, a sound health-based limit value of 1-hydroxypyrene in urine cannot be set as yet. Since PAH exposure is widespread and the dermal uptake is substantial among exposed workers, an attempt was made to propose a three-level benchmark guideline for urinary 1-hydroxypyrene. The reference value as a 95th percentile in non-occupational exposed controls is 0.24 micromol mol(-1) creatinine and 0.76 micromol mol(-1) creatinine for non-smokers and smokers, respectively. This is the first level of the benchmark guideline. A no-biological-effect-level of 1-hydroxypyrene in urine of exposed workers was found at 1.4 micromol mol(-1) creatinine. It is the lowest reported level at which no genotoxic effects were found and therefore the estimate for the second level of the benchmark guideline. In two types of industry, coke ovens and primary aluminium production, the regression of airborne PAH concentrations and urinary 1-hydroxypyrene concentrations in exposed workers has been studied. The correlation of airborne concentrations and urinary 1-hydroxypyrene in urine of workers from coke ovens and in the primary aluminium industry was used to estimate the level of urinary 1-hydroxypyrene equal to the present occupational exposure limit (OEL) of PAH. The concentration of 1-hydroxypyrene in urine equal to the OEL is 2.3 micromol mol(-1) creatinine and 4.9 micromol mol(-1) creatinine, respectively, in these two industries. These latter values present the third level of the benchmark guideline.

Urinary 1-hydroxypyrene as a biomarker of polycyclic aromatic hydrocarbons exposure of workers on a contaminated site: influence of exposure conditions

The aim of the study was to determine the exposure levels of workers to polycyclic aromatic hydrocarbons on gasworks sites by the measurement of urinary 1-hydroxypyrene. Start-shift and end-shift urine samples were taken every day during an entire week (Monday to Friday), once in November and a second time in June. Four groups of workers were selected according to their activity. Increased exposure was only found among volunteers involved in the remediation of a site, 0.16 to 2.31 mumol/mol creatinine in non-smokers. The median of the non-smoker referent group was 0.02 mumol/mol creatinine (95% confidence interval, 0.01 to 0.04). Smokers had greater exposure levels than non-smokers in every group. Within and between variability was around 200%. Assessment of the exposure of persons on contaminated soil is possible, with the condition that the exposed subjects come in direct contact with the soil.

Methods for routine biological monitoring of carcinogenic PAH-mixtures

The ability of a biomarker to provide an assessment of the integrated individual dose following uptake through multiple routes is especially valuable for mixtures of polycyclic aromatic hydrocarbons (PAH), due to methodological and practical difficulties of collecting and analysing samples from the various environmental compartments like air, water and soil and various media such as diet, cigarette smoke and workroom air. Since 1980, a large variety of novel approaches and techniques have been suggested and tested, e.g. urinary thioethers, mutagenicity in urine, levels of PAH or PAH-metabolites in blood and urine and methods for determination of adducts in DNA and proteins. Two approaches are more frequently reported: PAH-DNA-adduct monitoring in blood cells and urinary 1-hydroxypyrene monitoring. A large research effort has been made to use the extent of binding of PAH to DNA as a biomarker of exposure. The 32P-post-labeling assay detects the total of aromatic DNA-adducts and the adduct level in white blood cells is claimed to be an indicator of the biological effect of the PAH-mixture. However, the levels of aromatic DNA-adducts may be subject to appreciable analytical and biological variation. The present technical complexity of the method makes it more convenient for research applications than for routine application in occupational health practice. Pyrene is a dominant compound in the PAH mixture and is mainly metabolised to the intermediary 1-hydroxypyrene to form 1-hydroxypyrene-glucuronide, which is excreted in urine. Since the introduction of the determination of 1-hydroxypyrene in urine as a biomarker for human exposure assessment in 1985, many reports from different countries from Europe, Asia and America confirmed the potential of this novel approach. The conclusion of the first international workshop on 1-hydroxypyrene in 1993 was that urinary 1-hydroxypyrene is a solid biological exposure indicator of PAH. Studies with a comparison of several biomarkers confirmed that 1-hydroxypyrene in urine is a valid and sensitive indicator of exposure. Periodical monitoring of 1-hydroxypyrene appears to be a powerful method in controlling occupational PAH-exposure in industries. The reference level and the biological exposure limit of 1-hydroxypyrene in urine are discussed.

Uptake of polycyclic aromatic hydrocarbons among trainers in a fire-fighting training facility

The exposure of fire-fighting trainers to polycyclic aromatic hydrocarbons (PAH) was assessed by personal air sampling. Uptake of PAH was determined by biological monitoring, measuring a metabolite of pyrene, 1-hydroxypyrene, in urine. Eight-hour time-weighted average concentrations benzo(a)pyrene of 0.029 microgram/m3 (instructor), 0.045 microgram/m3 (safety officer), and 0.16 microgram/m3 (fire assistant) were found. Both tobacco smoking and exposure to smoke from fire appeared to be significant sources of increased 1-hydroxypyrene concentrations in fire-fighting trainers. There was evidence of exposure and uptake of PAH among fire-fighting instructors despite the short time of effective exposure and the routine use of protective respirators and protective clothing. Though the uptake of PAH was much lower than found in coke-oven workers, who are known to have an increased relative risk of cancer, a long-term health risk for fire-fighting trainers cannot be excluded. Biological monitoring with urinary 1-hydroxypyrene may be useful in tracing highly exposed persons and in monitoring the effectiveness of control measures.

Dermal absorption of polycyclic aromatic hydrocarbons in the blood-perfused pig ear

Urinary 1-OH-pyrene, a metabolite of pyrene, is a sensitive biological marker for dermal absorption of pyrene in man. In order to determine whether this metabolite is a reliable biomarker of cutaneous absorption of other polycyclic aromatic hydrocarbons (PAHs), the blood-perfused pig ear model was used to compare the dermal absorption flux of pyrene with nine other PAHs after coal tar application. Cumulative absorption of PAHs into the perfusion blood, 200 min after application of an overdose of coal tar, ranged between 830 pmol cm-2 for phenanthrene to less than 4 pmol cm-2 for benzo[b]fluoroanthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenzo[ah]anthracene and indeno[123-cd]pyrene. The results of this study show that when pyrene is used as a marker compound for PAH absorption through pig skin, the cumulative absorption of PAHs with a lower molecular weight will be underestimated: fluorene, tenfold; phenanthrene, 12-fold; anthracene and fluoranthene, ca. twofold. The percutaneous absorption of PAHs with a higher molecular weight than pyrene will be overestimated: e.g. benzo[a]pyrene, sevenfold; indeno [123-cd]pyrene, ca. 100-fold. It is likely that this conclusion is also valid for dermal PAH absorption in man.

Polycyclic aromatic hydrocarbon-DNA adducts in white blood cell DNA and 1-hydroxypyrene in the urine from aluminum workers: relation with job category and synergistic effect of smoking

We examined a group of 105 workers from a primary aluminum plant for the presence of polycyclic aromatic hydrocarbon (PAH)-DNA adducts in their WBC and 1-hydroxypyrene in their urine. Workers were recruited from five job categories with different PAH exposure: the anode factory; the bake oven; and the electrolysis and the pot-relining departments. Unexposed workers from the foundry department served as the control group. The exposure to PAH was measured by personal monitoring, and the average PAH concentrations in the work atmosphere ranged from 0.4 micrograms/m3 in the foundry to 150 micrograms/m3 in the pot-relining department. The average exposure to benzo(a)pyrene was under the Swedish exposure limit of 5 micrograms/m3. The internal dose of pyrene was measured utilizing the 1-hydroxypyrene concentration in pre- and postshift urine samples. Higher exposure to PAH in the work atmosphere was associated with increased concentrations of 1-hydroxypyrene in the urine. The average increase in concentration of 1-hydroxypyrene ranged from 0.2 mumol/mol creatinine in the control group to 5.9 mumol/mol creatinine in the pot-relining department; an accumulation of 1-hydroxypyrene over a 5-day working period was observed. A good correlation was found between PAH exposure and the concentration of 1-hydroxypyrene in the urine on a group level (rs = 0.90; P = 0.02). PAH-DNA adducts were determined by 32P-postlabeling analysis (nuclease P1 enrichment procedure).(ABSTRACT TRUNCATED AT 250 WORDS)

Reduction of urinary 1-hydroxypyrene excretion in coke-oven workers exposed to polycyclic aromatic hydrocarbons due to improved hygienic skin protective measures

The effect of hygienic skin protective measures on the internal exposure to polycyclic aromatic hydrocarbons (PAHs) was studied in 13 coke-oven workers. The study took place over 2 consecutive weeks. In 1 week the subjects worked under the normal circumstances, in the other week extra hygienic skin protective measures were instituted: laundered working clothes and a new pair of gloves before each 8-h work shift, and the washing both of the hands and of the face before each break. Biological monitoring was undertaken to measure the effect of the extra hygienic measures on the urinary 1-hydroxypyrene excretion, which is a measure of the internal PAH exposure. The increase of the urinary 1-hydroxypyrene concentration over the 4-day workweek was on average 37% lower when extra hygienic measures were taken, being 1.3 instead of 2.3 mumole 1-hydroxypyrene per mole creatinine (P = 0.03, N = 13). This study demonstrates that simple hygienic skin protective measures result in a significant reduction of the internal PAH exposure.

Biological monitoring of environmental exposure to polycyclic aromatic hydrocarbons; 1-hydroxypyrene in urine of people

A biomarker of human exposure to chemical agents provides a valuable parameter for assessing the extent and significance of the uptake by giving a measurement that is direct and integrated over time and exposure routes. Urinary 1-hydroxypyrene is currently tested as a biomarker for the assessment of low level environmental exposure of people to polycyclic aromatic hydrocarbons (PAH). Five examples of the application of urinary 1-hydroxypyrene methodology in the assessment of environmental exposure to PAH are presented: inhalation of tobacco smoke; inhalation of urban outdoor air; windsurfers sailing on polluted water; absorption of contaminated food; exposure in an urban area with many heavy industries. The examples illustrate that the urinary 1-hydroxypyrene test is sufficiently sensitive. Urinary 1-hydroxypyrene is an effective biomarker for the assessment of human environmental exposure to PAH.

Smoking and dietary intake of polycyclic aromatic hydrocarbons as sources of interindividual variability in the baseline excretion of 1-hydroxypyrene in urine

Seventy-six male volunteers, who were not occupationally exposed to polycyclic aromatic hydrocarbons (PAHs), participated in a study on the effect of tobacco smoking, alcohol consumption, dietary PAH intake, age, and body fat content on the baseline excretion of 1-hydroxypyrene in urine. Major determinants of urinary 1-hydroxypyrene excretion were smoking, dietary PAH intake, and age. The mean 1-hydroxypyrene concentrations in the urine of the volunteers in this study ranged between 0.05 and 0.79 mumol/mol creatinine. Smokers excreted on average 0.25 mumol/mol creatinine (range: 0.10-0.79 mumol/mol creatinine), and nonsmokers on average 0.12 mumol/mol creatinine (range: 0.04-0.29 mumol/mol creatinine). The average number of cigarettes smoked per day correlated well with urinary 1-hydroxypyrene concentrations (rs = 0.67, P < 0.001). The consumption of PAH-containing food products and active smoking account for 99% of total pyrene intake. The effect of age on 1-hydroxypyrene excretion is probably caused by a lower creatinine excretion in the elderly. Passive smoking and fat content had a statistically significant, but negligible effect on urinary 1-hydroxypyrene excretion. Passive smoking and the inhalation of ambient air are relatively in important for total pyrene intake (both account for less than 1%). Neither the consumption of alcohol nor the inhalation of ambient air significantly affected urinary 1-hydroxypyrene excretion. It is concluded that when urinary 1-OH-pyrene excretion is used in the assessment of PAH exposure, one should particularly be aware of the interindividual variability of the baseline excretion of PAH metabolites due to tobacco smoking and dietary PAH intake.

Estimation of individual dermal and respiratory uptake of polycyclic aromatic hydrocarbons in 12 coke oven workers

Twelve workers from a coke plant in The Netherlands participated in an intensive skin monitoring programme combined with personal air sampling and biological monitoring during five consecutive eight hour workshifts. The purpose of the study was to make a quantitative assessment of both the dermal and respiratory intake of polycyclic aromatic hydrocarbons (PAHs). Pyrene was used as a marker compound for both dermal and respiratory exposure to PAHs. The biological measure for the internal exposure to PAHs was urinary 1-OH-pyrene concentration. Measurements on exposure pads at six skin sites showed that mean total skin contamination of the 12 workers ranged between 21 and 166 micrograms pyrene a day. The dermal uptake of pyrene ranged between 4 and 34 micrograms/day, which was about 20% of the pyrene contamination on skin. The mean concentration of total pyrene in the breathing zone air of the 12 coke oven workers ranged from 0.1 to 5.4 micrograms/m3. The mean respiratory uptake of pyrene varied between 0.5 and 32.2 micrograms/day. Based on the estimates of the dermal and respiratory pyrene uptake it is concluded that an average 75% (range 28%-95%, n = 12) of the total absorbed amount of pyrene enters the body through the skin. Because of the difference in the pyrene:benzo(a)pyrene ratio between the air samples and the skin contamination samples, the dermal uptake of benzo(a)pyrene was also estimated. This was about 51% of the total absorbed amount (range 8%-92%, n = 12). The total excreted amount of urinary 1-OH-pyrene as a result of exposure to PAHs during the five consecutive workshifts varied between 36 and 239 nmol. A multiple regression model of the mass balance between pyrene dose (both dermal and respiratory) and 1-OH-pyrene excretion confirmed the relevance of the dermal exposure route. The variation in urinary 1-OH-pyrene excretion was determined more by the dermal pyrene dose than by the respiratory dose. The model showed an estimate of the percentage of the absorbed amount of pyrene that is metabolised and excreted as 1-OH-pyrene in urine. For the 12 workers this percentage varied between 13% and 49% depending on smoking habits and consumption of alcohol. The results of this study indicate that among coke oven workers, the skin is the main route of uptake of PAHs. Preventive measures to reduce exposure to PAHs should be focused more on the reduction of dermal contamination by PAHs than on the reduction of inhaled dose.

Effects of the peroxisome proliferator mono(2-ethylhexyl)phthalate in primary hepatocyte cultures derived from rat, guinea pig, rabbit and monkey. Relationship between interspecies differences in biotransformation and peroxisome proliferating potencies

Primary hepatocyte cultures derived from rat, rabbit, guinea pig and monkey have been treated in vitro with metabolites of di(2-ethylhexyl)phthalate, i.e. mono(2-ethylhexyl)phthalate (MEHP), mono(5-carboxy-2-ethylpentyl)phthalate (metabolite V) and mono(2-ethyl-5-oxohexyl)phthalate (metabolite VI). In rat hepatocyte cultures MEHP and metabolite VI were equally potent in inducing peroxisome proliferation, while metabolite V was much less potent. In rat hepatocytes a 50% increase in both peroxisomal palmitoyl-CoA oxidase activity and microsomal lauric acid omega-hydroxylation activity was found after treatment with 5-15 microM MEHP. In guinea pig, rabbit and monkey hepatocyte cultures, a 50% increase in peroxisomal palmitoyl-CoA oxidase activity was found after treatment with 408-485 microM MEHP. No induction of lauric acid omega-hydroxylation activity was found. These results indicate that peroxisome proliferation can be induced by MEHP in rabbit, guinea pig and monkey hepatocytes, but that these species are at least 30-fold less sensitive to peroxisome proliferation induction than rats. The proposed mechanistic inter-relationship between induction of lauric acid omega-hydroxylation activity and peroxisome proliferation is found in rat hepatocytes, but not in hepatocytes of the other three species. Treatment of guinea pig hepatocyte cultures with MEHP resulted in an increase in triglyceride concentrations in the hepatocytes. In rat and rabbit hepatocyte cultures, triglyceride concentrations were much less altered by MEHP. In monkey hepatocytes a decrease in hepatic triglyceride concentration was found after treatment with MEHP. These effects are in agreement with in vivo effects observed before. After treatment of primary hepatocyte cultures with MEHP, high concentrations of omega- and (omega-1)-hydroxylated metabolites of MEHP were found in media from rat, rabbit and guinea pig cultures. The formation of these metabolites did not decline in time. During treatment the metabolite profile in media from rat hepatocyte cultures moved towards omega-hydroxy metabolites of MEHP. In media from monkey hepatocyte cultures the lowest concentrations of hydroxylated metabolites were determined. No major species differences were found in the potency to form oxidized MEHP metabolites, and thus no unique metabolite differences were found, which could explain the species differences in sensitivity for peroxisome proliferation.

Effect of the reduction of skin contamination on the internal dose of creosote workers exposed to polycyclic aromatic hydrocarbons

Ten creosote-exposed workers of a wood impregnation plant participated in this study, which took place in two consecutive weeks on a Monday, after a weekend off. On one of the two days each worker wore Tyvek coveralls underneath his normal workclothes. Dermal contamination measurements (pyrene on exposure pads) and biological monitoring (urinary 1-OH-pyrene) were performed to measure the reduction of both the skin contamination and the internal dose. The total pyrene skin contamination of workers not wearing coveralls ranged between 47 and 1510 micrograms.d-1 (0.2-7.5 mumol.d-1). On the average, the coveralls reduced the pyrene contamination on the workers' skin by about 35 (SD 63)%. The excreted amount of 1-OH-pyrene in urine decreased significantly from 6.6 to 3.2 micrograms (30.2 to 14.7 nmol). Multiple regression analysis showed that skin contamination by polycyclic aromatic hydrocarbons is the main determinant of the internal exposure dose of creosote workers.

Absorption of polycyclic aromatic hydrocarbons through human skin: differences between anatomical sites and individuals

In order to determine differences in absorption of polycyclic aromatic hydrocarbons (PAH) between anatomical sites and individuals, coal-tar ointment was applied to skin of volunteers at various sites. The surface disappearance of PAH and the excretion of urinary 1-OH-pyrene after skin application of coal-tar ointment were used as parameters for dermal PAH absorption. The surface disappearance was determined by the measurement of the fluorescence of PAH on skin. Surface disappearance measurements show low but significant differences in dermal PAH absorption between anatomical sites: shoulder > forehead, forearm, groin, > ankle, hand (palmar site). The average PAH absorption rate constant at different skin sites ranges from 0.036/h to 0.135/h (overall mean: 0.066/h). This indicates that after 6 h of exposure, 20-56% of a low dermal dose of PAH (e.g., about 1.0 ng pyrene/cm2) will be absorbed. The interindividual differences in PAH absorption are small (7%) in comparison with differences between anatomical sites (69%). Results based on the urinary excretion of 1-OH-pyrene are less clear. The site of application of the coal-tar ointment (dose: 2.5 mg/cm2 during 6 h) has no significant effect on the excreted amount of 1-OH-pyrene in urine. It is estimated that after coal-tar ointment application on skin, 0.3-1.4% of the pyrene dose (about 2 micrograms pyrene/cm2) becomes systemically available. For the accurate estimation of PAH uptake through skin of workers, it seems relevant to distinguish different body regions, not only because of the regional variation in percutaneous PAH absorption, but also because of the high dispersal of PAH contamination on skin of workers.

Metabolites of the plasticizer di(2-ethylhexyl)phthalate in urine samples of workers in polyvinylchloride processing industries

Little is known about occupational exposure to the plasticizer di(2-ethylhexyl)phthalate (CAS number 117-81-7), a compound widely used in polyvinylchloride (PVC) plastics. We have studied the uptake of DEHP in workers by determining the concentrations of four metabolites of DEHP in urine samples, i.e., mono(2-ethylhexyl)phthalate (MEHP), mono(5-carboxy-2-ethylpentyl)phthalate, mono(2-ethyl-5-oxohexyl)phthalate, and mono(2-ethyl-5-hydroxyhexyl)phthalate. In addition DEHP concentrations in the air were determined by personal air sampling. Nine workers in a PVC boot factory exposed to a maximum of 1.2 mg/m3 DEHP showed an increase in the urinary concentrations of all four metabolites over the workshift. These results were obtained on both the first and the last day of the workweek. With the exception of MEHP, the increases in the concentrations of the metabolites during a workday were statistically significant. Six workers from a PVC cable factory exposed to a maximum of 1.2 mg/m3 DEHP showed a one- to fourfold increase in the concentrations of the four metabolites over the workshift, but these increases were not statistically significant. These results indicate that measurement of DEHP metabolites in urine samples may be of use for monitoring the occupational exposure to DEHP.

Determination of four metabolites of the plasticizer di(2-ethylhexyl)phthalate in human urine samples

A method for biological monitoring of exposure to the plasticizer di(2-ethylhexyl)phthalate (DEHP) is described. In this method the four main metabolites of DEHP [i.e., mono(2-ethylhexyl)phthalate (MEHP), mono(5-carboxy-2-ethylpentyl)phthalate, mono(2-ethyl-5-oxohexyl)phthalate, and mono(2-ethyl-5-hydroxyhexyl)-phthalate] are determined in urine samples. The procedure includes enzymatic hydrolysis, ether extraction, and derivatization with triethyloxonium tetrafluoroborate. Analysis is performed by gas chromatography-electron impact mass spectrometry. The detection limit for all four metabolites is less than 25 micrograms/l urine. The coefficient of variation based on duplicate determinations of urine samples of workers occupationally exposed to DEHP was 16% for MEHP (mean concentration 0.157 mg/l) and 6%-9% for the other three metabolites (mean concentrations 0.130-0.175 mg/l). The method described here was used to study DEHP metabolism in man. Most persons excrete mono(2-ethyl-5-oxohexyl)-phthalate and mono(2-ethyl-5-hydroxyhexyl)phthalate as a (glucuronide) conjugate. Mono(5-carboxy-2-ethylpentyl)phthalate is mainly excreted in free form, while for MEHP a large interindividual variation in conjugation status was observed. Of the four metabolites quantified, 52% are products of a (omega-1)-hydroxylation reaction of MEHP [i.e., mono(2-ethyl-5-oxohexyl)phthalate and mono(2-ethyl-5-hydroxylation reaction of MEHP [i.e., mono(5-carboxy-2-ethylpentyl)phthalate], and 26% is not oxidized further (i.e., MEHP). A good correlation is obtained when the amount of MEHP omega-hydroxylation products is compared with the amount of MEHP (omega-1)-hydroxylation products in urine samples. When the internal dose of DEHP has to be established we recommend that the levels of all four metabolites of DEHP be studied in urine samples.

Dermal exposure to polycyclic aromatic hydrocarbons among primary aluminium workers

Large amounts of PAH's are released in the electrode production departments of pre-bake cell aluminium reduction plants. Emission sources are mixing, shaping and baking of the anode (paste plant and bake oven) and pot relining operations. A study was performed to quantify the importance of dermal uptake of PAH's among exposed workers. Twenty workers in the anode production departments (paste plant (N = 8) and bake oven (N = 5)) and the pot relining department (N = 7) volunteered for the study. Monitoring was performed over a period of 5 consecutive days using personal air sampling, dermal contamination sampling and biological monitoring. Pyrene concentrations measured in the respirable air samples, ranged up to 320 micrograms/m3. Dermal contamination of pyrene was monitored at three skin sites (wrist, jaw/neck and groin) using exposure pads as pseudo-skin. The skin contamination with pyrene ranged up to 375 ng/cm2. Contamination of the groin skin site, although covered by work clothes ranged up to 106 ng/cm2. The concentration of 1-hydroxypyrene in pre and post-shift urine ranged up to 27 mumol/mol creatinine and showed an increase during the day and a decrease during the night. Pyrene in air and pyrene on the skin were tested for significance of correlation with urinary 1-hydroxypyrene in samples taken at several moments: end-of-shift, pre-shift next morning and weekly increase. The correlation coefficients between dermal contamination and urinary 1-hydroxypyrene were equal or higher than the correlation coefficient between pyrene air concentration and urinary 1-hydroxypyrene. The total skin contamination in exposed workers is estimated to be more than three times higher than the intake via the respiratory tract. The contribution of dermal exposure to the total PAH body burden of exposed workers therefore appears to be significant.

Microsomal lauric acid hydroxylase activities after treatment of rats with three classical cytochrome P450 inducers and peroxisome proliferating compounds

In order to investigate a proposed relationship between induction of hepatic microsomal lauric acid hydroxylase activity and peroxisome proliferation in the liver, male Wistar rats were treated with peroxisome proliferating compounds, and the lauric acid hydroxylase activity, the immunochemical detectable levels of cytochrome P450 4A1 and the activities of peroxisomal enzymes were determined. In addition, the levels of cytochrome P450 4A1 and lauric acid hydroxylase activities were studied after treatment of rats with three cytochrome P450 inducers. After treatment with aroclor-1254, phenobarbital or 3-methylcholanthrene total cytochrome P450 was 1.7-2.7 times induced. However, no induction of lauric acid omega-hydroxylase activities or P450 4A1 levels were found. After treatment of rats with di(2-ethylhexyl)phthalate (DEHP) a dose-dependent induction of lauric acid omega-hydroxylase activities, levels of cytochrome P450 4A1 and peroxisomal fatty acid beta-oxidation was found. Even at a dose-level of 100 mg DEPH/kg body weight per day a significant induction of these activities was observed. The main metabolites of DEHP, mono(2-ethylhexyl)phthalate and 2-ethyl-1-hexanol, also caused an induction of levels of P450 4A1, lauric acid omega-hydroxylase activities and the activity of peroxisomal palmitoyl-CoA oxidase. 2-Ethyl-1-hexanoic acid did not influence lauric acid omega-hydroxylase activities, but did induce levels of P450 4A1 and palmitoyl-CoA oxidase activities. Three other compounds (perfluoro-octanoic acid, valproate and nafenopin) induced both lauric acid omega-hydroxylase activity and peroxisomal palmitoyl-CoA oxidase activity. The plasticizer, di(2-ethylhexyl)adipate, did not induce levels of P450 4A1, lauric acid omega-hydroxylase activities or palmitoyl-CoA oxidase activities. With the compounds tested a close association between the induction of lauric acid omega-hydroxylase activities and peroxisomal palmitoyl-CoA oxidase activity was found. These data support the theory that peroxisome proliferating compounds do induce lauric acid omega-hydroxylase activities and that there might be a mechanistic inter-relationship between peroxisome proliferation and induction of lauric acid omega-hydroxylase activities.

Biological exposure limit for occupational exposure to coal tar pitch volatiles at cokeovens

Biological monitoring is an efficient tool in the evaluation of exposure to chemical agents. However, the dose-response of adverse health effects using biological exposure indices and biological limit values are rarely available. This paper presents an estimation of the occupational exposure limit value of 1-hydroxypyrene in urine, a biological exposure indicator of polycyclic aromatic hydrocarbons (PAH). A large-scale study of the exposure of cokeoven workers to PAH, in which both air sampling (benzene soluble matter and individual PAH including benzo(a)pyrene) and biological monitoring (1-hydroxypyrene in urine) were applied, made it possible to establish an empirical mathematical relationship between the air sampling data and biological monitoring data. It was calculated that cokeoven workers with a urinary concentration of 1-hydroxypyrene of 2.3 mumol/mol creatinine after a 3-day working period equals the airborne threshold limit value (TLV) of coal tar pitch volatiles (CTPV). Epidemiological studies have quantified the relative risk of lung cancer for topside and non-topside cokeoven workers. The published environmental exposure data of topside and non-topside cokeoven workers were used to determine the time-average exposure. The data of 1-hydroxypyrene in the urine of cokeoven workers and data of epidemiological studies from different coke plants were combined according to the concentrations of PAH in the air. Thus, it was possible to establish an indirect relationship between lung cancer mortality risk and the biological exposure indicator for cokeoven workers. Exposure at the level of the suggested tentative biological exposure limit (BEL) of 2.3 mumol/mol creatinine is estimated to be equal to a relative risk of lung cancer of approximately 1.3.

Interaction of smoking, uptake of polycyclic aromatic hydrocarbons, and cytochrome P450IA2 activity among foundry workers

An increased lung cancer risk has been described among foundry workers. Polycyclic aromatic hydrocarbons (PAHs) and silica are possible aetiological factors. This study describes a urinary PAH metabolite, 1-hydroxypyrene (hpU), as well as the degree of cytochrome P450IA2 activity/induction as reflected by the urinary caffeine ratio (IA2) in 45 foundry workers and 52 controls; IA2 was defined as the ratio of paraxanthine 7-demethylation products to a paraxanthine 8-hydroxylation product (1,7-dimethyluric acid). Mean exposure concentrations for foundry workers were defined by breathing zone hygienic samples (respirable dust 1.2 to 3.52 mg/m3 (93 samples)) and as total PAH (0.46 micrograms/m3) and pyrene concentrations (0.28 micrograms/m3) (six samples). Non-smoking controls and foundry workers had similar IA2 ratios (5.63, 95% confidence interval (95% CI) 4.56-6.70 and 4.40, 95% CI 3.56-5.24). The same was true for smoking controls and foundry workers (9.10, 95% CI 8.00-10.20 and 8.69, 95% CI 7.37-10.01). Both smoking groups had raised IA2 ratios compared with non-smokers (p less than 0.01). Non-smoking controls and foundry workers had similar hpU concentrations (0.16, 95% CI 0.10-0.22 and 0.11, 95% CI 0.09-0.13 mumol/mol creatinine). Smoking foundry workers had raised hpU concentrations (0.42, 95% CI 0.25-0.59) compared with smoking controls (0.26, 95% CI 0.18-0.34) (p less than 0.01). A small subgroup of smoking foundry workers with the highest exposures to both silica and PAH also had the highest hpU concentrations (0.70, 95% CI - 0.07-1.47 mumol/mol creatinine) (p less than 0.04). Increased hpU concentrations in smoking foundry workers suggest a more than additive effect from smoking and foundry exposures resulting in increased PAH uptake. Increased P450IA2 enzyme activity was only found in smokers and no additional effect of foundry exposures was seen. These data suggest that smoking as well as work related PAH exposure may be casually related to increased risk of lung cancer in foundry workers.

Evaluation of urinary excretion of 1-hydroxypyrene and thioethers in workers exposed to bitumen fumes

Biological monitoring of exposure to bitumen fumes during road-paving operations was carried out. In order to evaluate the biological uptake of the workers, the nonselective urinary thioether assay and a selective method for the determination of urinary 1-hydroxypyrene were used. Urinary thioether data of exposed workers were higher than those of nonexposed subjects. The effect of smoking, however, was stronger than the effect of occupational exposure. Levels of 1-hydroxypyrene in road-paving workers were significantly higher than those in control subjects. The 1-hydroxypyrene level was also influenced by smoking habits, but the effect of occupational exposure was stronger. Our present data suggest that enhanced urine levels of both thioethers and 1-hydroxypyrene in bitumen workers may indicate an increased genotoxic risk. Furthermore, our results demonstrate the applicability of the 1-hydroxypyrene assay after occupational exposure to petroleum-based products.

Non-mutagenicity of 4 metabolites of di(2-ethylhexyl)phthalate (DEHP) and 3 structurally related derivatives of di(2-ethylhexyl)adipate (DEHA) in the Salmonella mutagenicity assay

Four metabolites of the rat liver carcinogen di(2-ethylhexyl)phthalate (DEHP) (mono-(2-ethylhexyl)phthalate, mono-(2-ethyl-5-hydroxyhexyl)phthalate, mono-(2-ethyl-5-oxohexyl)phthalate, and mono-(5-carboxy-2-ethylpentyl)phthalate) and 3 structurally related derivatives of di(2-ethylhexyl)adipate (DEHA) (mono-(2-ethylhexyl)adipate, mono-(2-ethyl-5-hydroxyhexyl)adipate, and mono-(2-ethyl-5-oxohexyl)adipate) were tested for mutagenicity in the Ames assay using Salmonella typhimurium strains TA97, TA98, TA100, and TA102, with and without a metabolic activation preparation. Aroclor 1254-induced rat liver S9 and DEHP-induced rat liver S9 were used. Concentrations of these compounds up to 1000 micrograms/plate were negative with all tester strains in the presence or absence of metabolic activation.

Determination of the cytochrome P-450 IV marker, omega-hydroxylauric acid, by high-performance liquid chromatography and fluorimetric detection

The formation of omega-hydroxylauric acid from lauric acid is an indicator of the activity of cytochrome P-450 IV family proteins. The two main metabolites of lauric acid, (omega-1)-and omega-hydroxylauric acid, have been completely separated by reversed-phase high-performance liquid chromatography. Measurement of lauric acid hydroxylase activity in microsomal liver samples, based on derivatization of the substrate and metabolites with the fluorescent agent 4-bromomethyl-6,7-dimethoxycoumarin, is a precise method (coefficient of variation = 7.6 and 10% for omega and (omega-1) metabolites, respectively) with good sensitivity (signal-to-noise ratio in microsomal samples of untreated rats greater than 20). In microsomal fractions from livers of rats treated with di-(2-ethylhexyl)phthalate the extent of omega-hydroxylation of lauric acid increased dose-dependently (ca. ten-fold). The (omega-1)-hydroxylase activity was not altered. A strong correlation between immunochemically determined cytochrome P-450 IVA1 and lauric acid omega-hydroxylase activity was found (r = 0.94, n = 30).

Effect of di(2-ethylhexyl)phthalate on enzyme activity levels in liver and serum of rats

In order to identify non-invasive, biochemical indicators of di(2-ethylhexyl)phthalate (DEHP) exposure, we have compared the effects in blood serum with biochemical effects in liver in rats fed a diet containing 0, 0.25, 0.75 and 2% DEHP for 2 weeks. After 3 days of treatment serum arylesterase activity levels and serum triglycerides were decreased to 60% and 20% of control values, respectively. After a 2-week treatment with DEHP the effects were generally stronger. Compared to a control group, serum arylesterase activity levels, serum triglycerides and serum cholesterol were decreased to 40%, 20% and 50%, respectively. Serum cholinesterase activity levels and serum albumin concentrations were increased by the DEHP treatment to 290% and 135% of control values, respectively. In the livers a hepatomegaly, an induction of cytochrome P-450 IVA1 and induction of the activity of palmitoyl-CoA oxidase and carnitine acetyl-CoA transferase was found to be 180%, 1080%, 1300% and 1700% of control values, respectively. The liver is a more sensitive target for DEHP exposure compared to the biochemical effects in serum, but determination of the serum parameters can be used to determine early biological effects of exposure to DEHP.

Ambient and biological monitoring of cokeoven workers: determinants of the internal dose of polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbons (PAH) were measured in the breathing zone air of 56 battery workers at two cokeovens during three consecutive days. The concentration of total PAH ranged up to 186 micrograms/m3. Preshift and end of shift urine samples were collected to determine 1-hydroxypyrene, a metabolite of pyrene. Control urine samples were available from 44 workers in the shipping yard of a hot rolling mill. The median values of 1-hydroxypyrene in urine of smoking and non-smoking controls were 0.51 and 0.17 mumol/mol creatinine, respectively. Concentrations of 1-hydroxypyrene up to 11.2 mumol/mol were found in the urine of the cokeoven workers. At the start of the three day working period after 32 hours off work, the 1-hydroxypyrene concentrations were four times higher and at the end of the working period 10 times higher compared with control concentrations. Excretion of 1-hydroxypyrene occurred with a half life of 6-35 hours. Both the ambient air monitoring data and the biological monitoring data showed that the topside workers were the heaviest exposed workers. The relation between air monitoring data and biological monitoring data was not strong. Multiple regression analysis was performed to identify determinants of the internal dose. The combination of exposure and smoking amplify each other and the use of a protective airstream helmet decreases the internal dose. An effect of alcohol consumption and the use of medication on the toxicokinetics of pyrene was not found.

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.

Airborne concentrations, skin contamination, and urinary metabolite excretion of polycyclic aromatic hydrocarbons among paving workers exposed to coal tar derived road tars

The exposure of surface dressing workers to polycyclic aromatic hydrocarbons (PAH) was studied. Four different paving sites, at which coal tar-containing binders were applied, were selected as work sites with high exposure levels of PAH. Breathing zone airborne particulates, contamination of the skin with PAH, and 1-hydroxypyrene in urine of the workers involved in chip sealing were determined. Substantial concentrations of cyclohexane-soluble airborne particulate matter were found (GM = 0.2 mg/m3, n = 28). Skin contamination was determined using two different methods: with exposure pads and by hand washing. Pads were mounted on several parts of the body: wrist, elbow, neck, shoulder, and ankle. The pads located on the wrist appeared to be the most contaminated (pyrene: GM = 22 ng/1.77 cm2, n = 40). The end-of-shift hand washing showed that the hands of the workers were contaminated with PAH (pyrene: GM = 70 micrograms, n = 35). Preshift hand washing showed far lower, but detectable, quantities of PAH on workers' hands (pyrene: GM = 5 micrograms, n = 35). Enhanced levels of urinary 1-hydroxypyrene among the workers were found. The highest levels were found in the end-of-shift urine samples. Correlations between the pyrene exposure variables were studied. Significant positive correlations were found between pyrene on the wrist pad versus end-of-shift urinary 1-hydroxypyrene; between pyrene on the hands versus end-of-shift urinary 1-hydroxypyrene; and between the two different skin contamination variables.

Mutagenicity of bi-, tri- and tetra-cyclic aromatic hydrocarbons in the "taped-plate assay" and in the conventional salmonella mutagenicity assay

Aromatic hydrocarbons in the range of 1-4 nuclear rings were examined for mutagenicity in the so-called "taped-plate assay". This modification of the Ames assay is particularly equipped for the detection of volatile mutagens. Of the many compounds tested only phenanthrene, pyrene, benzo[c]phenanthrene and benzoacenaphthylene were positive in this assay. The present data underline the exceptional behaviour of fluoranthene by being a rather potent bacterial mutagen with a volatile nature (as found in a previous study).

1-Hydroxypyrene as an indicator of the mutagenicity of coal tar after activation with human liver preparations

Liver S9 fractions were prepared from male Wistar rats, either non-induced or induced with Aroclor 1254 and from 5 human kidney transplant donors. The preparations were compared for their ability to metabolize the premutagens present in coal tar to mutagenic metabolites in the Salmonella mutagenicity assay towards strain TA98. Low levels of mutagenicity of coal tar were seen with human S9 preparations. The differences between the S9 mix of the 5 donors in capacity to activate premutagens were approximately 6-fold. The activation of coal tar by rat liver S9 preparations was higher than by the human S9 preparations. The metabolic conversion of pyrene in coal tar to 1-hydroxypyrene by the same human S9 preparations was determined in a parallel assay. 3 human preparations showed a high correlation between the formation of 1-hydroxypyrene and bioactivation of coal tar to mutagenic metabolites. The slope values of the individual regression lines were equal, suggesting that 1-hydroxypyrene is a good indicator for the activation of premutagens present in coal tar.

S-phenyl-N-acetylcysteine in urine of rats and workers after exposure to benzene

An HPLC method for the determination of S-phenyl-N-acetylcysteine in urine is described. The sensitivity is 6 mumol/L (CV = 9%) urine. Exposure of rats to six different concentrations of benzene, ranging from 0-30 ppm, was highly associated with urinary excretion of S-phenyl-N-acetylcysteine (r = 0.86) and with total phenol (r = 0.81). A background level of phenol was found in urine of both non-exposed rats and of non-exposed referents. However, no background excretion of S-phenyl-N-acetylcysteine was found, either in rats or in humans. In urine of exposed rats, the level of S-phenyl-N-acetylcysteine was approximately five times lower than the phenol level. Workers occupationally exposed to benzene, showing high levels of urinary phenol, revealed low concentrations of urinary S-phenyl-N-acetylcysteine. The biological monitoring of industrial exposure to benzene by determination of S-phenyl-N-acetylcysteine in urine is not better than the determination of phenol in urine.

Fluoranthene, a volatile mutagenic compound, present in creosote and coal tar

Creosote, a coal-tar distillation product, contains mutagens which are volatile at 37 degrees C. After distillation of creosote we found that these volatile mutagens were present in the distillation fraction with the highest boiling range (greater than 360 degrees C). The "volatile mutagenic activity" was connected with the presence of fluoranthene, a polycyclic aromatic hydrocarbon. Commercially available fluoranthene was positive in the so-called "taped-plate assay" (the test system used for the detection of volatile mutagens) towards the strains TA98 and TA100 in the presence of S9 mix. The tested creosote and coal tar contained fluoranthene in concentrations of 5.2 and 2.2%, respectively.

Biological monitoring of polycyclic aromatic hydrocarbons. Metabolites in urine

Assays of urinary mutagenicity, urinary 3-hydroxy-benzo(a)pyrene, and urinary 1-hydroxypyrene were used to study their suitability in estimating exposure to polycyclic aromatic hydrocarbons (PAH) in coal tar products. Rats exposed to coal tar solutions applied on the dorsal skin excreted mutagens, 3-hydroxy-benzo(a)pyrene, and 1-hydroxypyrene dose dependently in their urine. The correlation between the three parameters was high. Five dermatologic patients undergoing topical coal tar treatment excreted low concentrations of 3-hydroxy-benzo(a)pyrene and high concentrations of 1-hydroxypyrene. A significant correlation between the excretion of the two metabolites was found. The smoking workers of a coal tar distillation plant showed a significantly enhanced urinary mutagenicity compared with their nonsmoking colleagues, but an increase due to occupational exposure was not found. However, the concentration of 1-hydroxypyrene in the urine of these workers highly exceeded the upper 95 percentile of a reference population. The urinary excretion of 1-hydroxypyrene of smoking referents was not significantly increased compared with that of nonsmoking referents. The data suggest that urinary 1-hydroxypyrene is a sensitive and specific marker for the assessment of occupational exposure to PAH.

1-hydroxypyrene in human urine after exposure to coal tar and a coal tar derived product

A method for isolating 1-hydroxypyrene from urine is described. The presence of 1-hydroxypyrene in urine was identified by fluorescence excitation and emission scanning after HPLC-separation. 1-Hydroxypyrene could be detected in the urine of rats following oral administration of as little as 0.5 microgram pyrene. The dose-dependence of 1-hydroxypyrene in urine was evident after a wide range of pyrene dosing. After therapeutical coal tar treatment of dermatological patients the enhanced excretion of 1-hydroxypyrene was highly significant. Employees of a creosote impregnating plant showed an excretion pattern of 1-hydroxypyrene which could be related to their work. 1-Hydroxypyrene in urine of non-exposed people was very low, but detectable. It is suggested that the method reported is suitable for the assessment of uptake of man to pyrene, a compound that is commonly present in work environments which are associated with pollution of polycyclic aromatic hydrocarbons.

Excretion of 3-hydroxy-benzo(a)pyrene and mutagenicity in rat urine after exposure to benzo(a)pyrene

3-hydroxy-benzo(a)pyrene (3-OH-B(a)P) and mutagenic activity in rat urine were determined after the oral administration of benzo(a)pyrene given in three repeated doses of 10, 20 and 50 mumol kg-1. The procedure for the determination of 3-OH-B(a)P consisted of enzymic hydrolysis, separation and HPLC-analysis. The mutagenic activity of concentrated urine samples was assayed with the Salmonella typhimurium strain TA98 in the presence of S9 mix and beta-glucuronidase. The urinary excretion of 3-OH-B(a)P and mutagens showed a correlation and both increased dose-dependently during the sampling period of 6 days. Data indicated that 3-OH-B(a)P can be regarded as a reliable representative of all urinary (pre)-mutagens derived from benzo(a)pyrene and exposure of rats to benzo(a)pyrene could be detected with greater sensitivity by the HPLC assay of 3-OH-B(a)P than with the non-specific mutagenicity assay.

Detection of volatile mutagens in creosote and coal tar

Creosote and coal tar were examined for the presence of volatile mutagens by use of the so-called "taped plate assay". Application of this method, recently published by Distlerath et al., reveals that vapour escaping from creosote and coal tar at 37 degrees C was able to revert the Salmonella typhimurium strains TA98 and TA100 in the presence of S9 mix. The simplicity of this method makes it useful for routine screening of industrial fluids or solid products for the presence of volatile mutagens.

Urinary excretion of 3-hydroxy-benzo[a]pyrene after percutaneous penetration and oral absorption of benzo[a]pyrene in rats

A method for the monitoring of exposure to benzo[a]pyrene was applied to rat urine samples. Benzo[a]pyrene was administered percutaneously and orally with repeated doses of 10, 20 and 50 mumol/kg body wt. At low dose levels, the urinary excretion of 3-OH-benzo[a]pyrene was higher after percutaneous treatment than after oral administration. The excretion of 4 benzo[a]pyrene metabolites, including 3-OH-benzo[a]pyrene, is faster after oral administration. The percutaneous absorption of small doses of benzo[a]pyrene appears to be greater than the oral absorption.