[The toxicology and prevention of the risks of occupational exposure to aromatic polycyclic hydrocarbons. III. The effects: epidemiological evidence, early effects. Individual hypersusceptibility. Health surveillance]

Adverse effects following occupational exposure to polycyclic aromatic hydrocarbons (PAH) are mainly carcinogenic. The available epidemiological data suggest that some substances and industrial processes, in which PAH exposure is frequent, are classified as carcinogenic to humans: primary aluminium industry, cola gasification, coke production, iron and steel foundry, coal tar, pitch, creosote, untreated mineral oils, asphalt, soot. The target organs are mainly lung, bladder, skin. Other relevant effects are skin lesions such as folliculitis. The studies on early biological effects (chromosomal aberrations, sister chromatid exchanges, micronuclei) have shown contradictory results, mainly because of differences in exposure intensity. The metabolic polymorphism may account for a higher susceptibility to lung and bladder cancer following exposure to risk factors; the role of PAH occupational exposure is however to be examined, and the use of indicators of genetic susceptibility is currently limited to research programs. Health surveillance for PAH exposed workers is funded on the Italian laws (DPR 303/56 and D.Lgs. 626/94) and it is mainly dedicated to prevention of carcinogenic effects. Preventive examinations should consider PAH target organs (skin, lung, bladder, larynx) and look for early signs and symptoms. Particular attention will be paid to life habits such as tobacco smoking or diseases which could represent condition of susceptibility. Periodical examinations (every six months) will similarly evaluate PAH target organs. Health surveillance is also programmed for formerly exposed workers and the institution of exposure and cancer registries is mandatory. On the basis of the current scientific data, it is not advisable the use of tumor markers or cytogenetic tests at the individual level as well as the screening of asymptomatic PAH exposed workers for early diagnosis of lung or bladder cancer. Information and formation activities will be part of medical examinations and will be included in specific programs in cooperation with other company functions.

In vitro percutaneous penetration of methyl-parathion from a commercial formulation through the human skin

OBJECTIVE

To compare in vitro percutaneous absorption of methyl-parathion dissolved in an acetone vehicle and in the form of a commercial formulation.

METHODS

Penetration through the human skin was measured in Franz diffusion cells with full thickness skin from a human cadaver as the membrane. The two tailed non-parametric Mann-Whitney U test was used to compare the cumulative diffusion of methyl-parathion in the receptor fluid of the cells at various time intervals.

RESULTS

In vitro skin penetration of methyl-parathion was significantly higher with the commercial formulation. The percentage of the applied dose absorbed after 24 hours was 5.20% v 1.35%. The mean lag time was < 8 hours.

CONCLUSION

Assessments of uptake and internal dose after exposure to pesticides should be based on the commercial products rather than active ingredients, because of the crucial role of the vehicle, as shown in this study.

Solubilization of lead from crystal dust in protein solution (pseudointerstitial fluid) and gastric juice

Since several workers engaged in polishing and engraving crystal articles were found to have higher than average blood levels of lead (560 micrograms/liter, range 80-560 micrograms/liter), we investigated the hypothesis that crystal dust releases lead in the human body. To test the hypothesis, two types of crystal polishing dusts, having different lead contents, were mixed with human serum diluted 1:3 (pseudointerstitial fluid), gastric juice, and phosphate buffer at pH 9. After 14 days of contact, the diluted serum had extracted 0.620% of the lead in the crystal dust (particle size < 20 microns) containing 25.2% lead and 0.425% of that containing 19.9% lead. After 48 hr in gastric juice, 0.235 and 0.556% of the lead was extracted from crystal dusts (unsieved crystal dusts) containing 25.2 and 19.9% lead, respectively. After 28 days in alkaline solution, 0.358 and 0.304% of the lead was extracted respectively from the same two crystal dusts (unsieved crystal dusts).

Role of inosine in prevention of methaemoglobinaemia in the pig: in vitro studies

Methaemoglobin reductase activity was studied in pig, human and cattle erythrocytes incubated in a medium containing glucose or inosine as NADH generator. With glucose, methaemoglobin reduction was very fast in human, less so in cattle and slowest in pig erythrocytes. With inosine, pig red cells reduced methaemoglobin more rapidly than human red cells and in bovine erythrocytes the enzyme activity was undetectable. In intact red cells the ability to reduce methaemoglobin depends on the amount of NADH the cell can produce with glucose or inosine utilization. The results show that pig red blood cells utilize inosine as the NADH generator for enzymatic reduction of methaemoglobin. The greater efficiency of pig red cells could be due to several factors: better inosine transport, more active metabolic pathway for inosine utilization (so that more NADH is produced), or greater MR activity when NADH is in excess. In any case, the high rate of methaemoglobin reduction could explain the lower prevalence of methaemoglobinaemia in pigs than in cattle.

Urinary excretion of alkylphosphates in the general population (Italy)

Xenobiotic residues and their metabolites in biological fluids of the general population are an important indicator of exposure to toxic substances dispersed in the environment. Urine samples collected from 124 subjects living in SW Tuscany, Italy were analyzed for alkylphosphates (dimethylphosphate, dimethylthiophosphate, dimethyldithiophosphate, diethylphosphate, diethylthiophosphate, diethyldithiophosphate), aspecific metabolites of organophosphorus insecticides. The compound most frequently found was dimethylthiophosphate which was detectable in 99% of the subjects analyzed, with a geometric mean of 70.7 nmol/g creatinine. The other substances were found in the following percentages of our population, at the following mean concentrations: dimethylphosphate, 87%, 62.8 nmol/g creat.; dimethyldithiophosphate, 48%, 21.1 nmol/g creat.; diethylphosphate, 81%, 27.4 nmol/g creat.; diethylthiophosphate, 73%, 22.8 nmol/g creat.; diethyldithiophosphate, 7%, 13.7 nmol/g creatinine. Subjects eating food (fruit, meat, vegetables) that was not their own produce showed higher urinary concentrations of nearly all the compounds. The other variables considered (sex, age, residence, alcohol, smoking, sampling period) seem to affect the percentages of positive values of the various substances but to different degrees. Age and source of foods were the most important variables for dimethylthiophosphate excretion when mean values were analyzed by Student's t-test and analysis of variance (ANOVA).

Serum erythropoietin and blood lead concentrations

The aim of the study was to test the hypothesis that high blood lead levels are associated with depressed serum erythropoietin concentrations in workers occupationally exposed to lead. The results in exposed workers and in a control group of unexposed subjects were compared. Blood lead values were < or = 20 micrograms/dl in unexposed subjects and > or = 30 micrograms/dl in exposed subjects. The two groups of exposed workers and the control population were matched for sex and age. Hemoglobin levels were not affected by blood lead values and did not differ significantly between the three groups. The two-tailed, nonparametric Mann-Whitney U-test was used to compare unpaired groups. The Spearman rank correlation test was used to evaluate the dose-effect relationship between Pb and EPO. The analysis of the data indicate that erythropoietin values are significantly lower in exposed subjects than a controls. However no correlation was demonstrated between blood lead concentrations and erythropoietin in any group.

[A syndrome caused by separating rags in textile industry: a new clinical entity?]

A group of 104 workers were examined. They were employed in selecting rags and separating the lining from wollen fabrics to be used again as thread waste in the textile industry. The aim of the study was to point out tendon and joint related disorders of the upper limb due to repetitive and forced movements. Twenty-eight (26.9%) workers complained of hand and wrist echography and thermography. In 19 patients (67.8%) clinical carpal tunnel syndrome was diagnosed. Eight workers (28.5%) had Dupuytren's contracture. Swelling of the fingers was found in 23 (82.1%). 14.2% and 28.5% of the workers showed respectively acro-osteolysis and acrosclerosis. The textile industry of Prato shows peculiar characters: the workers employed in selecting rags out a manual job which causes soft tissues and skeletal disorders in a great number of them. The acro-osteolytic and acrosclerotic changes of the fingers seem alike the bone disorders of chronic inflammatory rheumatic diseases as seronegative spondyloarthritis.

[Percutaneous absorption of phenanthrene: an in vitro study of the monkey skin]

It is well known that polycyclic aromatic hydrocarbons (PAHs) are absorbed through the skin of experimental animals and humans. However dermal uptake of PAHs is difficult to assess due to the lack of specific studies. The aim of this study was to obtain in vitro percutaneous absorption data for phenanthrene. In vitro penetration was measured with excised monkey (Cercopithecus Aethiops) skin in Franz diffusion cells, using a saline solution with 4% bovine serum albumin and gentamicin sulfate as receptor fluid. In two different groups of 7 and 2 cells, 38.1 and 95.3 nmol/cm2 respectively of phenanthrene were applied in an acetone vehicle. The absorption rate in the first group of 7 cells was 0.025 nmol/cm2/h (S.D. = 0.012), the lag time 11.7 (S.D. = 7.0) h and the breakthrough time 70 m (S.D. = 55 m). In the second group of 2 cells, the average absorption rate was 0.066 nmol/cm2/h and the average lag time 11.8 h. The percutaneous absorption at 24, 48 and 72 hours in the 7 cell group was 0.72% (S.D. = 0.52), 2.51% (S.D. = 1.76) and 3.9% (S.D. = 2.0) of the applied dose respectively. In the 2-cell group 1.1%, 2.78% and 4.5% of the applied dose was absorbed at 24, 48 and 72 hours. The results of the present study confirm the extent of percutaneous absorption of phenanthrene. The data can be compared with dermal absorption values of other PAHs obtained under the same experimental conditions.

Biological monitoring of exposure to organophosphorus insecticides by assay of urinary alkylphosphates: influence of protective measures during manual operations with treated plants

Biological monitoring was carried out by assaying urinary dimethylated alkylphosphates [dimethyldithiophosphate (DMDTP), dimethylthio-phosphate (DMTP), and dimethylphosphate (DMP)] in 11 workers exposed to chlorpyrifos-methyl and azinphosmethyl during operations in a previously sprayed peach orchard. The subjects were divided into groups on the basis of the protective clothing worn. The results were compared with those of a reference group of 99 subjects not occupationally exposed to organophosphorus insecticides. The hand-wash liquid of the workers was also analyzed to evaluate skin contamination. Significantly higher levels of urinary excretion of alkylphosphates were found in all groups than in unexposed controls (Student's t test). A good correlation was found between quantities of the active ingredients on the hands and urinary excretion of total dimethylated alkylphosphates (r = 0.788) and of DMTP (r = 0.749) and DMP (r = 0.790) alone. The correlation between azinphos-methyl on the hands and urinary excretion of DMDTP was poor (r = 0.069). Under the working conditions investigated, the main route of absorption seems to be via the skin. Respiratory absorption, however, also appears significant in view of the difference in urinary excretion of dimethylated alkylphosphates found between subjects with and without face masks.

Evolution of hard metal pulmonary fibrosis in two artisan grinders of woodworking tools

The present study describes the medical history of two cases of pulmonary fibrosis in hard metal grinders. The poor chance of foreseeing the prognosis of this disease is particularly underlined. The two workers examined have been studied for about 6 years since the diagnosis. The disease was more severe in the subject who worked a shorter time and who left work because of the disease. In the other subject, who had worked longer and never left the job, the disease was less severe and has never deteriorated with time. Therefore, removing the affected subject from work is of major importance in preventing the progression of the disease, but this is in part connected to individual susceptibility, and the cessation of work and corticosteroid therapy are not always able to provide a cure.

[Urinary 1-hydroxypyrene in full-term pregnant women and their newborn babies as an index of biological exposure to polycyclic aromatic hydrocarbons]

"Trans-placental" exposure to polycyclic aromatic hydrocarbons (PAHs) in newborn babies of mothers smoking during pregnancy was investigated and compared with that in newborn babies of non smoking mothers. PAHs intake was evaluated by measuring urinary levels of 1-hydroxypyrene, a pyrene metabolita and a biological index of exposure. 42 mothers-babies couples (31 smoking and 11 non smoking mothers) were examined. Urinary concentrations of 1-hydroxypyrene in 42 controls, 18 non smoking and 24 smoking women, were determined at the same time. Mean values of 1-hydroxypyrene in non smoking women in labour and their babies were 0.15 (SD 0.11) and 0.15 (SD 0.10) micrograms/g creatinine respectively. In controls the mean was 0.15 (SD 0.09) micrograms/g creat. Mean values of 0.23 (SD 0.17) and 0.20 (SD 0.15) micrograms/g creatinine were determined in smoking mothers and their newborn babies, whereas in smoking controls 1-hydroxypyrene was 0.42 (SD 0.45) micrograms/g creatinine. The highest levels of 1-hydroxypyrene were detected in smokers (both controls and women in labour). Babies of smoking mothers also showed a higher mean value of 1-hydroxypyrene than babies of non smokers. However the only statistically significant difference found was between smoking and non smoking controls.

[Evaluation of omethoate and fenitrothion absorption in greenhouse workers using protective equipment in confined areas]

Sprayers and workers engaged in manual operations in a greenhouse were monitored for exposure to omethoate and fenitrothion. Urinary dialkyl phosphates (dimethyl thiophosphate and dimethyl phosphate) were used as biological index of exposure to the two chemicals. Residues of fenitrothion on foliage were measured as well as levels of fenitrothion and omethoate in air samples collected in the breathing zone (personal sampling) and in the work-place near the entrance and the end of the greenhouse (static sampling). Skin exposure was estimated from pads placed on the thorax under overalls and from hand washing liquid at the end of the workshift. Sprayers wore respiratory and skin protection during the workshift. Workers engaged in manual operations did not wear respiratory protection. Re-entry to the greenhouse was permitted 48 h after spraying. Levels of omethoate and fenitrothion in air samples, on pads and on the hands, during manual operations on ornamental plants, were very low. Urine analysis shoved no significant difference between the pre- and post-exposure samples. No significant difference was found between levels of urinary dialkyl phosphates in the control group and exposed workers. Cholinesterase activity (acetyl and butyryl) showed no significant reduction at the end of the workshift compared with baseline values.

[Evaluation of urinary excretion of ethylenethiourea in subjects occupationally and non-occupationally exposed to ethylenebis(dithiocarbamates)]

Ethylenebisdithiorcabamate (EBDC) fungicides are broken down metabolically and in the environment to ethylenethiourea (ETU), a suspected carcinogen. Urinary ETU was assayed in control groups and subjects occupationaly exposed to EBDC and was found to be an excellent indicator of exposure both to ETU and EBDC. Correct use of protective clothing greatly reduced exposure and urinary excretion of ETU. ETU was excreted, albeit in low concentrations, in a high percentage (91% and 30%) of subjects in both control groups, demonstrating its utility as an indicator of widespread EBDC contamination.

Ionized calcium in calf serum: relation to total serum calcium, albumin, total protein and pH

Serum ionized calcium, total calcium, albumin, total protein and pH were determined in 340 female Italian Friesian calves, aged from 1 day to 6 months. Analyses of data from calves divided into 7 age groups showed only occasional correlations between Ca++ and the other parameters. For pooled values for the calves aged 1-6 months, there were significant positive correlations between ionized and total calcium and between total calcium and albumin, and a negative correlation between ionized calcium and serum pH. However, the correlation coefficients were too low to be usable for prediction of the levels of ionized calcium from the levels of total calcium or from the other parameters. When it is essential to evaluate the calcium status of a calf, direct measurement of ionized calcium must be done.

Environmental and biological monitoring of polycyclic aromatic hydrocarbons (PAHs) in coke plants and other workplaces

The authors report the results obtained from environmental and biological monitoring of PAHs at different workplaces. Pyrene and benzo(a)pyrene were chosen as indicators of PAHs pollution and their concentrations were determined in the working environments. Two urinary metabolites of these hydrocarbons: 1-hydroxypyrene and 3-hydroxybenzo(a)pyrene, were also studied. PAHs exposure was studied at the following workplaces: a coke plant, a pyrite mine, a railway tunnel and several earthenware factories. The results obtained at the coke plant showed pyrene and benzo(a)pyrene levels (area samplings) at the battery top in the range 1.42-26.57 micrograms/m3 and 0.39-12.85 micrograms/m3 respectively. At the other workplaces lower concentrations of these two compounds were recorded. In the exposed workers, the trend of urinary 1-hydroxypyrene levels was similar to the results of environmental monitoring. The geometric mean of 1-hydroxypyrene concentrations in the urine of coke plant workers was 5.76 micrograms/g creatinine, whereas in the other exposed subjects no geometric mean values higher than 0.60 microgram/g creatinine were obtained. In the case of occupational exposure to low pyrene and benzo(a)pyrene concentrations (pyrite mine, railway tunnel, earthenware factories) the urinary 1-hydroxypyrene levels were similar to those observed in respectively smoking and non-smoking referents.

Influence of duration of simulated transport on plasma stress markers in the calf

The effects of simulated transport of calves for 150 min on plasma cortisol, NEFA, glucose, and calcium were evaluated. Both cortisol and NEFA reached maximal values within 30-60 min, with no further increases during the transportation. Changes in glucose and calcium were not significant. The results indicate that in simulated transport, the duration per se is not a crucial factor in transport stress.

Metyrapone and adrenal response in stressed calves

The effects on some hematochemical stress indices of previously administered metyrapone (750 mg given orally six times every 4 hours) were evaluated in calves submitted to simulated transport for 30 min. The plasma cortisol increases were significantly lower than those observed in untreated calves of the same age, sex and breed. Plasma adrenaline and NEFA increased similarly in both groups of calves during simulated transport and were unaffected by metyrapone administration. The results indicate that in cattle, as in other animals, metyrapone inhibits cortisol biosynthesis. Under our experimental conditions, the rise of NEFA, a well known stress index, seems mainly to be related to adrenaline release.

Effect of transport loading or noise on blood biochemical variables in calves

The influence of 2 transport stressors (loading and noise) on several serum and plasma biochemical variables was studied in 4 calves. When calves were loaded and kept for 30 minutes on a motionless transport simulator or were exposed to the noise of the working simulator, increases in plasma epinephrine and serum cortisol and nonesterified fatty acids concentrations were similar to changes observed in calves subjected to simulated transport for 30 minutes. Results indicate that loading and noise have an important role in transport stress.

Adrenal response in the calf to repeated simulated transport

The adrenal responses in calves submitted to simulated transport on three occasions for 30 min were evaluated. Plasma adrenaline, cortisol and NEFA increased significantly during simulated transport but became less marked in successive trials. Haematological stress-related parameters (Hb, PCV) increased to the same extent on repeated exposure to simulated transport. Plasma noradrenaline, glucose and cholesterol values were unchanged throughout the study.

Mortality among pyrite miners with low-level exposure to radon daughters

Mortality among pyrite miners with low-level exposure to radon daughters. Scand J Work Environ Health 14 (1988) 280-285. A cohort mortality study was conducted with regard to a pyrite mine located in central Italy. Exposure to radon ranged from 0.12 to 0.36 working levels (WL) in the work areas; most measurements were around 0.2 WL. The concentration of free silica in the dust was less than 2%. The cohort was determined from company files and included 1,899 subjects. Mortality was studied for the years 1965-1983. The loss to follow-up was less than 2%. The standardized mortality ratio for all causes and all neoplasms was 97 and 107, respectively. That for lung cancer and for nonmalignant respiratory diseases was 131 (95% confidence interval 97-175) and 173 (95% confidence interval 135-231), respectively. It was estimated that the extra cases of lung cancer attributable to radon daughters numbered 13 per 10(6) person-years and working level month in the whole cohort and 21.3 per 10(6) person-years in the subcohort with 10-25 years of exposure.

Fasciola hepatica: increase of glycogen phosphorylase activity due to prostaglandins

Both prostaglandin E1 (PGE1) and prostaglandin F2 alpha (PGF2 alpha) stimulate the glycogen phosphorylase (EC 2.4.1.1.) activity of Fasciola hepatica. Whole or sliced parasites were incubated with PGE1 (2.8 X 10(-7) and 2.8 X 10(-5) M) and PGF2 alpha (2.1 X 10(-7) and 2.1 X 10(-5) M) and enzyme activity was measured in homogenates prepared immediately following the incubation. No substantially different effect was noted between the two assayed doses of prostaglandins. Prostaglandins appeared to be less effective in sliced parasites.

Influence of age and cortisone treatment on two intestinal lysosomal hydrolases in young rats

The effects of cortisone acetate injected i.p. on acid phosphatase and beta-glucuronidase in the small intestine mucosa of two groups of rats aging 12-14 and 20-22 days are reported. The following results are obtained: a) Total and free activities of the two enzymes show age-dependent differences. b) Cortisone acetate causes a very marked decrease of the enzymic activities only in the younger rats while being ineffective on the older ones. c) The kinetics of the enzyme release at 37 degrees C appear independent either of age or of cortisone injection. d) The "in vitro" lysosome labilizing treatments are ineffective.