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

Treating Psoriasis During Pregnancy: Safety and Efficacy of Treatments

Psoriasis is a chronic inflammatory disease with a well-documented negative effect on the quality of life of affected patients. Psoriasis often occurs in the reproductive years, during which the issue of pregnancy needs to be addressed. The course of psoriasis during pregnancy is unpredictable, and many patients face the challenge of needing treatment during pregnancy. In this review we provide an overview of the key considerations for managing psoriasis in pregnant women, covering the potential effects of active psoriasis and co-morbid conditions on the health of the mother and fetus, as well as the effects of psoriasis treatment options on the developing fetus. Although there are no robust data on the safety of systemic treatment of pregnant women, increasing evidence regarding the safety of cyclosporine (ciclosporin) treatment as well as anti-tumor necrosis factor-α is available and should be considered in pregnant women with moderate to severe psoriasis unresponsive to local corticosteroids and UVB light treatment.

Polycyclic Aromatic Hydrocarbons: Part I. Exposure

Polycyclic aromatic hydrocarbons (PAH) comprise the largest class of cancer-causing chemicals and are ranked ninth among chemical compounds threatening to humans. Although interest in PAH has been mainly due to their carcinogenic property, many of these compounds are genotoxic, mutagenic, teratogenic, and carcinogenic. They tend to bioaccumulate in the soft tissues of living organisms. Interestingly, many are not directly carcinogenic, but act like synergists. PAH carcinogenicity is related to their ability to bind DNA thereby causing a series of disruptive effects that can result in tumor initiation. Thus, any structural attribute or modification of a PAH molecule that enhances DNA cross linking can cause carcinogenicity. In part I, we review exposure to these dangerous chemicals across a spectrum of use in the community and industry.

Biological monitoring of environmental exposure to polycyclic aromatic hydrocarbons in subjects living in the area of recycling electronic garbage, in Southern China

The study was undertaken to evaluate the environmental exposure to polycyclic aromatic hydrocarbons in subjects living in the area of recycling electronic garbage in Southern China and research the influence of environment smoke tobacco (EST) to people through active and passive smoking. Urinary concentrations of 2-hydroxynaphthalene, 2-hydoxyfluorene, 9-hydroxyphenanthrene, and 1-hydroxypyrene were determined in 141 randomly selected voluntary residents aged 13 to 81 years in two polycyclic aromatic hydrocarbon (PAH)-exposed groups, two control groups, and an EST research group. The concentrations of 2-hydroxynaphthalene, 2-hydoxyfluorene, 9-hydroxyphenanthrene, and 1-hydroxypyrene in PAH-exposed groups are significantly higher (p<0.05) than those of control groups. Mean value of 1-hydroxypyrene in the residents living in the area of recycling electronic garbage (1.1 μmol/mol creatinine) is a little higher than those of iron foundry workers, automobile repair workers, and firefighters. Mean value of 2-hydroxynaphthalene (11.3 μmol/mol creatinine) is much higher than that of shipyard and aircraft maintenance and much lower than some occupational exposure, such as coking batteries, sorting department, and distillation department in coking plant. Some metabolites of PAHs (PAHm) are significantly elevated through active and passive smoking, while the influence of EST to other PAHm is not statistically significant. 2-Hydroxynaphthalene, 2-hydoxyfluorene, 9-hydroxyphenanthrene, and 1-hydroxypyrene in the urine of smokers are, respectively, 3.9, 1.9, 1.4, and 1.9 times to those of nonsmokers. In nonsmokers, passive smokers excreted 1.1, 1.5, 1.9, and 1.5 times of 2-hydroxynaphthalene, 2-hydoxyfluorene, 9-hydroxyphenanthrene, and 1-hydroxypyrene compared to nonpassive smokers.

Profile of urinary phenanthrene metabolites in smokers and non-smokers

Phenanthrene metabolites (phenols and dihydrodiols) and 1-hydroxypyrene excreted in the 24-h urine of smokers, non-smokers and lung cancer patients, who after heavy smoking became light smokers, were determined and compared. In contrast to 1- hydroxypyrene, no significant differences of the absolute amounts of phenanthrene metabolites were found between smokers and non-smokers. A ratio phenanthrene metabolites/l-hydroxypyrene of 10.4 was observed for non-smokers and 9.9 for lung cancer patients, but 4.2 for smokers. Significantly different ratios for the regiospecific oxidation of phenanthrene were found for smokers when compared with non-smokers (1,2-oxidation vs 3,4-oxidation was 1.45 in the case of smokers, but 2.34 in the case of non-smokers) indicating a cigarette smoke - but not PAH - caused induction of CYP 1A2 in smokers. As a consequence of the degree of PAH exposure the ratio dihydrodiols/phenols depends on the total amount of metabolites excreted. Phenols predominate, equally in smokers and non-smokers after low exposure, while dihydrodiols become more prominent in highly exposed persons (coke plant workers). Both (i) the regiospecific oxidation of PAH and (ii) the ratio of dihydrodiol vs phenol formation may be recognized from the urinary phenanthrene metabolite profile. This pattern mirrors the enzymatic status (balance of the CYP isoforms and epoxide hydrolase) in individuals. Accordingly, more detailed information may be obtained from the urinary metabolite pattern than from 1- hydroxypyrene, commonly used in PAH biomonitoring.

Urinary 1-hydroxypyrene as a biomarker of exposure to polycyclic aromatic hydrocarbons: biological monitoring strategies and methodology for determining biological exposure indices for various work environments

This article reviews the published studies on urinary 1-hydroxypyrene (1-OHP) as a biomarker of exposure to polycyclic aromatic hydrocarbons (PAHs) in work environments. Sampling and analysis strategies as well as a methodology for determining biological exposure indices (BEIs) of 1-OHP in urine for different work environments are proposed for the biological monitoring of occupational exposure to PAHs. Owing to the kinetics of absorption of pyrene by different exposure routes and excretion of 1-OHP in urine, in general, 1-OHP urinary excretion levels increase during the course of a workday, reaching maximum values 3-9 h after the end of work. When the contribution of dermal exposure is important, post-shift 1-OHP excretion can however be lower than pre-shift levels in the case where a worker has been exposed occupationally to PAHs on the day prior to sampling. In addition, 1-OHP excretion levels in either pre-shift, post-shift or evening samples increase during the course of a work-week, levelling off after three consecutive days of work. Consequently, ideally, for a first characterization of a work environment and for an indication of the major exposure route, considering a 5-day work-week (Monday to Friday), the best sampling strategy would be to collect all micturitions over 24 h starting on Monday morning. Alternatively, collection of pre-shift, post-shift and evening urine samples on the first day of the work-week and at the end of the work-week is recommended. For routine monitoring, pre-shift samples on Monday and post-shift samples on Friday should be collected when pulmonary exposure is the main route of exposure. On the other hand, pre-shift samples on Monday and Friday should be collected when the contribution of skin uptake is important. The difference between beginning and end of work-week excretion will give an indication of the average exposure over the workweek. Pre-shift samples on the first day of the work-week will indicate background values, and, hence, reflect general environment exposure and body burden of pyrene and/or its metabolites. On the other hand, since PAH profile can vary substantially in different work sites, a single BEI cannot apply to all workplaces. A simple equation was therefore developed to establish BEIs for workers exposed to PAHs in different work environments by using a BEI already established for a given work environment and by introducing a correction factor corresponding to the ratio of the airborne concentration of the sum of benzo(a)pyrene (BaP) equivalent to that of pyrene. The sum of BaP equivalent concentrations represents the sum of carcinogenic PAH concentrations expressed as BaP using toxic equivalent factors. Based on a previously estimated BEI of 2.3 μmol 1-OHP mol(-1) creatinine for coke-oven workers, BEIs of 4.4, 8.0 and 9.8 μmol 1-OHP mol(-1) creatinine were respectively calculated for vertical pin Söderberg workers, anode workers and pre-bake workers of aluminium plants and a BEI of 1.2 μmol 1-OHP mol(-1) creatinine was estimated for iron foundry workers. This approach will allow the potential risk of cancer in individuals occupationally exposed to PAHs to be assessed better.

DNA adducts in skin biopsies and 1-hydroxypyrene in urine of psoriasis patients and healthy volunteers following treatment with coal tar

Coal tar ointments (CTO) are frequently used in the treatment of psoriasis and eczema, but CTO contain carcinogenic polycyclic aromatic hydrocarbons (PAH). PAH are absorbed and metabolized in the skin. In psoriasis, the skin barrier is altered and therefore, absorption and metabolism of PAH may differ from healthy skin. In this study, levels of urinary 1-hydroxypyrene and PAH-DNA adducts in the skin were studied in psoriatic patients and healthy volunteers. Three punch biopsies were taken from the lower back of 10 male volunteers and from a psoriatic plaque in 10 male patients. A surface of 6.25 cm(2) was treated with CTO. After 96 h CTO was removed and another three skin biopsies were collected from the treated area. DNA was isolated from skin biopsies and urine was collected during and after the exposure period. After 24h, a twofold lower 1-hydroxypyrene urinary excretion was observed in patients compared to healthy volunteers and after 48 h, this difference reached statistical significance (p<0.05). Over 96 h the median level of the sum of PAH-DNA adducts, analyzed by (32)P-post-labeling, increased from 3.5 before CTO administration to 21.1 adducts per 10(8) nucleotides in volunteers, and from 1.0 to 3.6 adducts per 10(8) nucleotides in patients. At 96 h, PAH-DNA levels were higher in healthy volunteers than in patients (p<0.05). Biomarkers for uptake, bioavailability and bioactivation of PAH were lower in patients compared to volunteers. These data suggest a lower risk of carcinogenic effects of CTO in psoriatic skin compared to healthy skin.

Coal tar in dermatology

Coal tar is one of the oldest treatments for psoriasis and eczema. It has anti-inflammatory, antibacterial, antipruritic and antimitotic effects. The short-term side effects are folliculitis, irritation and contact allergy. Coal tar contains carcinogens. The carcinogenicity of coal tar has been shown in animal studies and studies in occupational settings. There is no clear evidence of an increased risk of skin tumors or internal tumors. Until now, most studies have been fairly small and they did not investigate the risk of coal tar alone, but the risk of coal tar combined with other therapies. New, well-designed, epidemiological studies are necessary to assess the risk of skin tumors and other malignancies after dermatological use of coal tar.

3-Hydroxybenzo(a)pyrene as a biomarker of dermal exposure to benzo(a)pyrene

The aim of this study was to determine the percutaneous absorption flux of BaP (20 microg/cm(2) in ethanol) and the usefulness of urinary 3-OHBaP as a bio-indicator of dermal exposure to BaP. The percutaneous absorbed dose and absorption flux were estimated by comparison with intravenous administration of BaP (0.01 and 0.05 mg/kg in Cremophor) as reference way. A percutaneous absorption flux of 0.37 microg/cm(2)/h was determined by killing groups of rats, following exposure time of 4.5 and 24 h. [(14)C] skin content was 3.1 microg/cm(2), after 24 h exposure to BaP. Total urinary 3-OHBaP accounted for 0.4% of the real absorbed dose, which was fourfold higher than the percentage of an intravenous dose excreted as 3-OHBaP. This finding reveals that percutaneous absorption of BaP, based on the ratio of urinary excretion of 3-OHBaP following percutaneous exposure compared to percutaneous absorption following intravenous administration of BaP, is overestimated in the rat. In vitro, BaP was intensively metabolised by rat skin. Unchanged BaP and 3-OHBaP in receptor fluid accounted for 50 and 30% of the total radioactivity. This percutaneous first past effect of BaP in rats could, in part, explain the higher urinary excretion ratio of 3-OHBaP compared to the value based on intravenous administration of BaP. Conversely, BaP was largely lower metabolised as 3-OHBaP during percutaneous absorption by humans, so BaP absorption flux should be overestimated to a lesser extent in humans than in rats.

Final safety assessment of Coal Tar as used in cosmetics

Coal Tar is a semisolid by-product obtained in the destructive distillation of bituminous coal, which functions in cosmetic products as a cosmetic biocide and denaturant--antidandruff agent is also listed as a function, but this is considered an over-the-counter (OTC) drug use. Coal Tar is a nearly black, viscous liquid, heavier than water, with a naphthalene-like odor and a sharp burning taste, produced in cooking ovens as a by-product in the manufacture of coke. Crude Coal Tar is composed of 48% hydrocarbons, 42% carbon, and 10% water. In 2002, Coal Tar was reported to the Food and Drug Administration (FDA) to be used in four formulations, all of which appear to be OTC drug products. Coal Tar is monographed by the FDA as Category I (safe and effective) OTC drug ingredient for use in the treatment of dandruff, seborrhoea, and psoriasis. Coal Tar is absorbed through the skin of animals and humans and is systemically distributed. In short-term studies, mice fed a diet containing Coal Tar found it unpalatable, but no adverse effects were reported other than weight loss; rats injected with Coal Tar experienced malaise in one study and decreased water intake and increased liver weights in another; rabbits injected with Coal Tar residue experienced eating avoidance, respiratory difficulty, sneezing, and weight loss. In a subchronic neurotoxicity study using mice, a mixture of phenols, cresols, and xylenols at concentrations approximately equal to those expected in Coal Tar extracts produced regionally selective effects, with a rank order of corpus striatum > cerebellum > cerebral cortex. Coal Tar applied to the backs of guinea pigs increases epidermal thickness. Painting female rabbits with tar decreases the absolute and relative weights of the ovaries and decreased the number of interstitial cells in the ovary. Four therapeutic Coal Tar preparations used in the treatment of psoriasis were mutagenic in the Ames assay. Urine and blood from patients treated with Coal Tar were genotoxic in bacterial assays. Coal Tar was genotoxic in a mammalian genotoxicity assay and induced DNA adducts in various tissue types. Chronic exposure of mice to Coal Tar significantly decreased survival and liver neoplasms were seen in a significant dose-related trend; in other studies using mice lung tumors and perianal skin cancers were found. Coal Tar was comedogenic in three small clinical studies. Folliculitis is associated with the prolonged use of some tars. Several published reports describe cases of contact sensitivity to Coal Tar. Polycyclic aromatic hydrocarbons, which make up Coal Tar, are photosensitizers and cause phototoxicity by an oxygen-dependent mechanism. A retrospective study of the reproductive toxicity of Coal Tar in humans compared exposed women to controls and found little difference in spontaneous abortion and congenital disorders. Cancer epidemiology studies of patients who have received Coal Tar therapy of one form or other have failed to link treatment with an increase in the risk of cancer. Although the Cosmetic Ingredient Review (CIR) Expert Panel believes that Coal Tar use as an antidandruff ingredient in OTC drug preparations is adequately addressed by the FDA regulations, the Panel also believes that the appropriate concentration of use of Coal Tar in cosmetic formulations should be that level that does not have a biological effect in the user. Additional data needed to make a safety assessment include product types in which Coal Tar is used (other than as an OTC drug ingredient), use concentrations, and the maximum concentration that does not induce a biological effect in users.

Biological monitoring of exposure: trends and key developments

The concept of biological monitoring (BM) has gained the special interest of individual scientists and international organizations. Today, when analytical problems have almost ceased due to new laboratory techniques and quality assurance systems, the methods for interpretation of results have become the most important issue. There are important discrepancies regarding the role of biological monitoring of occupational exposure between Europe and the United States. BM has been an important tool of medical health surveillance in the European countries. In the United States it belongs rather to the field of occupational hygiene. It seems that both the approaches can be accepted. More attention should be paid to the development of the truly health-based biomarkers of exposure based on the dose-effect and dose-response relationships. New areas of application of BM of occupational exposure include determination of DNA and protein adducts, unchanged volatile organic compounds in urine, monitoring of exposure to pesticides, antineoplastic drugs, hard metals, and polycyclic aromatic hydrocarbons. In the general environment BM is the most valuable tool for acquiring knowledge of current levels of internal exposure to xenobiotics, identifying the hot spots and developments in trends of exposure. BM can provide policy makers with more accurate information on the control measures undertaken. At present, the main areas include heavy metals, persistent organic pollutants and pesticides. BM of chemical exposure has become increasingly important in the assessment of the health risk in occupational and environmental medicine. Therefore it would be worthwhile to include BM in the curricula for the training of occupational hygienists.

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.

GSTM1 null genotype as a risk factor for anti-BPDE-DNA adduct formation in mononuclear white blood cells of coke-oven workers

The influence of the genetic deletion polymorphism of glutathione S-transferase micro 1 (GSTM1 *0/*0) on levels of anti (+/-)-r-7,t-8-dihydroxy-t-9,10-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene (anti-BPDE-DNA) adduct in the peripheral blood lymphocyte plus monocyte fraction (LMF) of coke-oven workers was investigated. A total of 95 male Polish coke-oven workers (60% current smokers) from two different plants comprised the sample population. Polycyclic aromatic hydrocarbons (PAH) exposure was assessed by means of the individual post-shift urinary excretion of 1-pyrenol (mean +/- S.D.: 6.93 +/- 7.20 micromol/mol creatinine; 70% of the subjects exceeded the proposed biological exposure index (BEI) 2.28 micromol/mol creatinine). Anti-BPDE-DNA adduct levels were detected by high performance liquid chromatography (HPLC)/fluorescence analysis of the anti-BPDE tetrol I-1 released after acid hydrolysis of DNA samples. Genotypes were determined by polymerase chain reaction (PCR) on the genomic DNA of each subject. Coke-oven workers without active GSTM1 (GSTM1 *0/*0, 33%) had significantly higher adduct levels than those with active GSTM1 (GSTM1*1/*1 and *1/*0) (5.90 +/- 5.59 versus 3.25 +/- 2.01 adducts/10(8) bases, Mann-Whitney U-test, z = 2.53, P = 0.011), PAH exposure in the two subgroups being similar (7.06 +/- 6.83 versus 6.67 +/- 8.00 1-pyrenol micromol/mol creatinine). The highest number of GSTM1 null subjects (12/23, 39%) belonged to the quartile with the highest adduct levels (i.e., >4.67 adducts/10(8) nucleotides). That is, coke-oven workers with GSTM1 *0/*0 genotype had a significantly higher risk of having high adduct levels than individuals with active GSTM1 genotype (Fisher exact test P = 0.0355; odds ratio (OR) = 4.145, 95% CI 1.0-18.8). Multiple linear regression analysis showed that the increase in anti-BPDE-DNA adduct levels in LMF was significantly related to the high occupational exposure to PAHs (benzo[a]pyrene (BaP)) of coke-oven workers (t = 3.087, P < 0.01) and to the lack of GSTM1 activity (t = 3.512, P < 0.001), rather than to the two other confounding factors of PAH intake, i.e. charcoal-broiled meat consumption and smoking habits. In conclusion, our results indicate the clear influence of the GSTM1 detoxifying genotype on anti-BPDE-DNA adduct formation in the LMF of coke-oven workers. This is invaluable for future environmental-occupational studies using this biomarker of PAH exposure.

Biomonitoring of polycyclic aromatic hydrocarbons in human urine

Measurement of polycyclic aromatic hydrocarbons (PAH) metabolites in human urine is the method of choice to determine occupational and/or environmental exposure of an individual to PAH, in particular, when multiple routes of exposure have to be taken into account. Requirements for methods of biomonitoring PAH metabolites in urine are presented. Studies using 1-hydroxypyrene or phenanthrene metabolites including its phenols and dihydrodiols are summarized. The role of these PAH metabolites as established biomarkers and also more recent developments of PAH biomonitoring are discussed.

Urinary 1-hydroxypyrene levels in workers exposed to coke oven emissions at various locations in a coke oven plant

Polycyclic aromatic hydrocarbons, which are carcinogenic and mutagenic to humans, are primary compounds in coke oven emissions generated by the coking process. The authors examined the relationship between coke oven workers' urinary 1-hydroxypyrene levels and their exposure to polycyclic aromatic hydrocarbons, as determined on the basis of work category and pre- and postshift effects in a steel plant in Taiwan. Eighty-eight coke oven workers constituted the exposed group, and 61 office workers in a steel plant located 1.5 km from the coke plant constituted the control group. The benzene-soluble fraction in personal air samples, and 1-hydroxypyrene in urine samples, were measured for 3 consecutive days. The 3-day urinary 1-hydroxypyrene sampling results for topside workers (i.e., those most heavily exposed to emissions) in the coke oven group, and for the control group, as determined from postshift geometric means, were 23.8 microg/gm creatinine and 0.3 microg/gm creatinine, respectively. These values increased to 13.4 and 0.1 microg/gm creatinine, respectively, after an 8-hr work period. The major source of polycyclic aromatic hydrocarbons for the exposed group was occupational; therefore, the closer workers were to the coke oven, the greater their exposure, and, consequently, the greater their metabolite level. Urinary 1-hydroxypyrene levels of the exposed group were 80 times higher than those of the control group. Smoking had no significant effect on the excretion of urinary 1-hydroxypyrene. 1-hydroxypyrene levels in the workers' urine during an 8-day period was cumulative (half-life = 18.6 hr). The authors concluded that it would be desirable to switch highly exposed workers to a low-exposure work area, after a period of rest. In addition, urinary 1-hydroxypyrene was a confirmed, useful biological indicator for exposure to polycyclic aromatic hydrocarbons.

Urinary 1-hydroxypyrene and other PAH metabolites as biomarkers of exposure to environmental PAH in air particulate matter

Humans are exposed to polycyclic aromatic hydrocarbons (PAHs) from occupational, environmental, medicinal and dietary sources. PAH metabolites in human urine can be used as biomarkers of internal dose to assess recent exposure to PAHs. The most widely used urinary PAH metabolites are 1-hydroxypyrene (1-OHP) or 1-hydroxypyrene-O-glucuronide (1-OHP-gluc), the major form of 1-OHP in human urine, because of their relatively high concentration and prevalence in urine and their relative ease of measurement. Elevated levels of 1-OHP or 1-OHP-gluc have been demonstrated in smokers, in patients receiving coal tar treatment (vs. pre-treatment), in postshift road pavers or coke oven workers, and in subjects ingesting charbroiled meat. This metabolite is found (at low levels) in most human urine samples, even in persons without apparent occupational or smoking exposure. Recent studies suggest that environmental exposure to PAHs (and air particles) is associated with increased excretion of 1-OHP-gluc or 1-OHP. These findings raise the possibility of using urinary concentration of 1-OHP-gluc, or another PAH metabolite, as a surrogate biomarker of exposure to airborne fine (sooty) particulate matter--the major source of PAHs in polluted air. Reported associations between ambient particulate matter concentrations and health effects among adults and children, including respiratory disease and mortality, indicate the need for biomarkers of fine particle exposure. If validated, such biomarkers would be useful in supplementing and refining exposure information obtained by ambient monitoring.

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.

Cytogenetic biomonitoring of workers exposed to bitumen fumes

Bitumen samples and fumes consist essentially of polycyclic hydrocarbons (PAH) and their derivatives, some of which are known to be carcinogenic or co-carcinogenic in animals. The level of total PAH is low when compared with coal-tar products. There is very limited data on possible health risk from exposure to bitumen fumes in workers. In this study, sister-chromatid exchange (SCE), micronuclei (MN) and high frequency of SCE cells (HFCs) were determined for 28 workers exposed to bitumen fumes and 28 control subjects. Urinary 1-hydroxypyrene (1-OHP) excretion was used as a biomarker of occupational exposure to PAH. The mean value of 1-OHP excretion of workers was 0.78+/-0.46 micromol/mol creatinine and for controls 0.52+/-0.44 micromol/mol creatinine (p<0.05). The mean values of SCE per cell and the frequency ( per thousand) of MN in peripheral lymphocytes from the workers and controls were 5.13+/-0. 64, 4.71+/-0.67, and 2.25+/-0.42, 1.79+/-0.32 respectively (p<0.05, p<0.0001). The mean value of HFCs for workers and controls were 7. 85+/-2.3 and 7.05+/-3.16, respectively (p>0.05). Our data reveal that bitumen fumes during road paving operations are absorbed by workers and that bitumen fume exposure is able to significantly induce cytogenetic damage in peripheral lymphocytes of workers after controlling some possible confounding factors, such as age, sex and smoking habits.

Biological monitoring of young workers exposed to polycyclic aromatic hydrocarbons in engine repair workshops

Several polycyclic aromatic hydrocarbons (PAHs) are carcinogenic in rodents, while exposure to these compounds has been associated with various types of human cancer. Engine exhaust and used engine oils are major PAH sources in engine repair workshops. Urinary 1-hydroxypyrene (1-OHP) levels and some genotoxicity parameters (sister-chromatid exchange, SCE; micronucleus, MN) have been compared among engine repair workers (n = 61, age: between 13 and 18) and workers not occupationally exposed to PAH (n = 30, age: between 13 and 19). The mean value (+/- S.E.) of urinary 1-OHP excretions of workers was 4.71 +/- 0.53 micromol/mol creatinine and also mean urinary 1-OHP for controls was found to be as 1.55 +/- 0.28 micromol/mol creatinine. The mean values (+/- S.E.) of SCE frequency per cell in peripheral lymphocytes from the workers and controls were 4.47 +/- 0.09 and 4.06 +/- 0.16, respectively (p < 0.05). The mean (+/- S.E.) MN (per thousand) frequencies in peripheral lymphocytes from the workers and controls were 1.87 +/- 0.04 and 1.56 +/- 0.06, respectively (p < 0.0001). The effect of smoking for the above parameters were also evaluated.

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.

Association of exposure to polycyclic aromatic hydrocarbons (estimated from job category) with concentration of 1-hydroxypyrene glucuronide in urine from workers at a steel plant

OBJECTIVES

Increased risk of lung cancer has been associated with employment in the steel industry. This association is thought to be due in part to increased concentrations of polycyclic aromatic hydrocarbons (PAHs) in air found in this work environment. Measurement of PAH metabolites in human urine provides a means of assessing individual internal dose of PAHs. This study examined the relative contribution of occupation and smoking to urinary concentration of 1-hydroxypyrene glucuronide (1-OHPG) among a group of workers at a steel plant.

METHODS

Concentrations of 1-OHPG in urine from 44 workers with jobs associated with increased air concentrations of PAHs and 40 workers with jobs with low or no exposure to PAHs were measured. 20 workers in each group were not current smokers. Urinary 1-OHPG was measured by synchronous fluorescence spectroscopy after immunoaffinity chromatography specific for PAH metabolites.

RESULTS

Mean (SEM) urinary 1-OHPG concentration was 2.16 (0.42) pmol/ml urine among the 44 occupationally exposed workers compared with 0.38 (0.05) among the 40 workers with no or low exposure (P < 0.0001). Mean urinary 1-OHPG concentration was 1.82 (0.41) pmol/ml urine among the 44 current smokers compared with 0.75 (0.20) among the 40 non-smokers (P < 0.005). Mean 1-OHPG concentrations in non-smokers were 0.26 (n = 20), 0.70 (n = 15), and 2.84 pmol/ml urine (n = 5) for strata of exposure to PAHs (no or low, mid, and high) based on job category; the corresponding values in smokers were 0.55 (n = 20), 0.94 (n = 12), and 4.91 pmol/ml (n = 12), respectively. Multiple linear regression showed significant differences between subjects in different PAH exposure with increased concentrations of 1-OHPG in urine. Amounts of foods containing PAHs ingested by this group of workers were relatively low and did not contribute significantly to urinary 1-OHPG concentrations.

CONCLUSIONS

These results indicate that 1-OHPG is a common urinary metabolite in people with recent occupational exposure to PAHs and is associated with both job category and estimated stratum of PAH exposure.

Levels of pollutants and their metabolites: exposures to organic substances

The measurement of levels of organic pollutants and/or their metabolites in body tissues or fluids are specific markers of internal dose and, provided that the pharmacokinetic properties of the compounds in question are known, these levels may also be used as predictors of effects. Although historical data still remain to be very useful in environmental studies, more reliable exposure measures than combination of environmental levels and such estimators as residential history, job titles, life-style habits, individual perceptions, etc., are highly desirable. This has been clearly demonstrated in studies with 2,3,7,8-tetrachlorndibenzo-p-dioxin (TCDD), where more recent measurements of serum concentrations in persons earlier classified as belonging to exposed groups have indicated that severe misclassifications may have occurred in previously epidemiological studies. This also demonstrates that, in retrospective studies, levels of persistent organic compounds are useful as markers of exposure, as their tissue levels mainly reflect previous exposures. However, most organic compounds are readily metabolized and excreted from the human body, and in many instances it will not be possible with current methodology and instrumentation to detect transient organic pollutants at low levels in the blood. In most cases, the use of urine samples offers a better opportunity to provide samples containing detectable levels. Therefore, the measurement of non-persistent organic substances and/or their metabolites may find potential use in prospective environmental health studies, but the predictive value highly depends on proper timing and frequency of sampling according to their toxicokinetic behaviour. A few examples on the use of organic compounds and/or metabolites as biomarkers are given, e.g., polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs), ochratoxin A, polycyclic aromatic hydrocarbons (PAHs) and cooked food mutagens.

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 and protein adducts in coal tar treated patients and controls and their relationship to glutathione S-transferase genotype

Coal tar treated psoriasis patients were used as a model population to evaluate a panel of immunoassays for monitoring exposure to benzo[a]pyrene (BP) and related polycyclic aromatic hydrocarbons (PAH). The assays included measurement of PAH diol epoxide-DNA adducts in white blood cells by competitive enzyme-linked immunosorbent assay (ELISA) with fluorescence endpoint detection, PAH-albumin adducts by competitive ELISA with color endpoint detection and serum levels of antibodies recognizing BP diol epoxide-DNA adducts by noncompetitive color ELISA. PAH-DNA adducts by ELISA were elevated in patients (mean 6.77 +/- 12.05/10(8)) compared to controls (4.90 +/- 8.81/10(8), p = 0.12). There was no difference in PAH-albumin adducts between patients (mean 0.61 +/- 0.31 fmol/micrograms) and controls (0.63 +/- 0.30 fmol/micrograms). Glutathione S-transferase M1 genotype was also determined but no relationship was found between presence of the gene and either DNA or protein adduct levels. About 30% of both patients and controls had measurable titer of antibodies recognizing BPDE-I-DNA adducts. Measurement of white blood cell DNA adducts by ELISA was the most sensitive method for detecting PAH exposure in coal tar-treated psoriasis patients.

Significance of dermal and respiratory uptake in creosote workers: exposure to polycyclic aromatic hydrocarbons and urinary excretion of 1-hydroxypyrene

OBJECTIVES

To evaluate workers' exposure in a creosote impregnation plant by means of ambient and biological monitoring.

METHODS

Naphthalene (vapour phase) and 10 large molecular polycyclic aromatic hydrocarbons (PAHs) (particulate phase) were measured in the breathing zone air during an entire working week. 1-Hydroxypyrene (1-HP) was measured in 24 hour urine as a metabolite of the pyrene found in neat (dermal exposure) and airborne creosote.

RESULTS

Naphthalene (0.4-4.2 mg/m3) showed 1000 times higher concentrations in air than did the particulate PAHs. In total, the geometric mean (range) of three to six ring PAHs was 4.8 (1.2-13.7) micrograms/m3; pyrene 0.86 (0.23-2.1) micrograms/m3, and benzo(a)pyrene 0.012 (0.01-0.05) micrograms/m3. There was no correlation between pyrene and gaseous naphthalene. The correlations between pyrene and the other nine particulate PAHs were strong, and gave a PAH profile that was similar in all air samples: r = 0.83 (three to six ring PAHs); r = 0.81 (three ring PAHs); r = 0.78 (four to six ring PAHs). Dermal exposure was probably very high in all workers, because the daily output of urinary 1-HP exceeded the daily uptake of inhaled pyrene by < or = 50-fold. Urinary 1-HP concentrations were very high, even on Monday mornings, when they were at their lowest (4-22 mumol/mol creatinine). 1-HP seldom showed any net increase over a workshift (except on Monday) due to its high concentrations (16 to 120 mumol/mol creatinine) in the morning samples. 1-HP was always lower at the end of the shift (19 to 85 mumol/mol creatinine) than in the evening (27 to 122), and the mean (SD) change over the working week (47 (18)) was greater than the change over Monday (35 (32)). The timing of 1-HP sampling is therefore very important.

CONCLUSIONS

Urinary 1-HP proved to be a good biomarker of exposure to three to six ring PAHs but not to airborne naphthalene. Hence, biomonitoring based on 1-HP has to be completed with exposure assessment for naphthalene as a marker for creosote volatiles that mainly enter the body through the lungs.

Patterns of 1-hydroxypyrene excretion in volunteers exposed to pyrene by the dermal route

The urinary excretion profiles following exposure to pyrene were established in one psoriasic patient under treatment with a coal tar-based shampoo and in two other volunteers exposed to a single dose of 100 microliters creosote and, in a separate experiment, to five consecutive daily dermal applications of 500 micrograms pyrene on 200 cm2 of the inner face of the forearms. Timed micturitions were collected for up to 48 h following exposure. Both in the psoriasic patient and in the volunteers exposed to creosote, the excretion peaks between 10 and 15 h after application and first-order apparent half lives of 11.5-15 h can be calculated for the elimination phase. Compatible with these observations, repeated exposure to pyrene in the volunteers causes an increase in peak and trough urinary 1-hydroxypyrene (1-OHP) values for the first few days following the first exposure. These results suggest that the difference between beginning-of-shift/beginning of work week and beginning-of-shift/end of work week 1-OHP excretions should reflect the average exposure of the week in workers having a constant exposure to pyrene. The difference between the beginning- and end-of-shift excretion values of a given day should reflect the exposure of that day but the maximum excretion would be attained a few hours after termination of exposure.

Background urinary 1-hydroxypyrene levels in non-occupationally exposed individuals in the Province of Québec, Canada, and comparison with its excretion in workers exposed to PAH mixtures

The urinary excretion of 1-hydroxypyrene (1-OHP) was measured in two reference groups of non-occupationally exposed individuals and in four groups of workers. Two of these groups were exposed to what were considered to be low levels of polycyclic aromatic hydrocarbons (PAH) on the basis that even post-shift 1-OHP excretion values were low (< 2 mumol/mol creatinine). Therefore, urine samples were collected from these workers after a period of > 60 h without occupational exposure which should yield values approaching background levels. Pooling these results with those of the reference groups yielded a total of 140 individuals having a mean (geometric) excretion of 0.08 mumol/mol creatinine and 5th, 50th and 95th percentiles of 0.02, 0.09 and 0.32 mumol/mol creatinine. The mean (geometric) excretion in the 95 nonsmokers and 45 smokers of this pool was 0.07 and 0.12 mumol/mol creatinine, respectively (one-tailed Student t-test, P < 0.001). Both this background excretion and the contribution of smoking appeared small in comparison with the excretion levels observed in some groups of exposed workers. Indeed, creosote workers described in this report had a geometric mean (range) excretion of 1.63 (0.18-10.47) mumol/mol creatinine during their working week. It is concluded that, for the biological monitoring of workers exposed to PAH, urinary 1-OHP appears to be a useful bioindicator for which background environmental contamination or smoking habits can be neglected in most cases.

Coupled-column high-performance liquid chromatographic method for the determination of four metabolites of polycyclic aromatic hydrocarbons, 1-, 4- and 9-hydroxyphenanthrene and 1-hydroxypyrene, in urine

A coupled-column high-performance liquid chromatographic method applying system-integrated sample processing on a copper phthalocyanine modified solid-phase material, gradient elution and fluorescence detection for the quantification of 1-, 4- and 9-hydroxyphenanthrene as well as for 1-hydroxypyrene in urine is described. The automated chromatographic system tolerates direct and repeated injection of urine samples. Validation results presented indicate quantitative and matrix-independent recoveries, low imprecisions in within-series and between-series analysis in combination with broad linear working ranges (2-400 nmol/l) and low detection limits (< 0.1 nmol/l).

Biochemical effects of manufactured gas plant residue following ingestion by B6C3F1 mice

The toxic potential of manufactured gas plant residue (MGP) given in the diet to male and female B6C3F1 mice was evaluated. In addition, the bioavailability of chemical components of MGP were also investigated by monitoring polycyclic aromatic hydrocarbon (PAH) metabolites in urine and DNA adduct formation in forestomach and lung tissue. Basal gel diets containing 0.05, 0.25, 0.50% MGP or 0.005% benzo[a]pyrene (BaP) were fed to animals for 94 and 185 d. Mice readily consumed adulterated diets without any evidence of acute toxicity. The total amount of MGP and BaP consumed by mice ranged from 118 to 2604 mg and from 12 to 29 mg, respectively. Male mice fed a control or BaP diet and female mice fed a 0.05% MGP diet had the highest body weight gains. Male and female mice fed a 0.50% MGP diet had the lowest body weight gains. The bioavailability of chemical components of MGP was evaluated by monitoring the urinary excretion of PAH metabolites by male mice fed a 0.25% MGP diet. 1-Hydroxypyrene was determined by high-performance liquid chromatography analysis to be the major fluorescent metabolite excreted by mice throughout the 185 d of diet administration. At necropsy, no chemical-related gross lesions were detected. In addition, no treatment-related microscopic lesions were evident in tissues obtained from animals fed a 0.50% MGP- or BaP-adulterated diet. The 32P-postlabeling assay was used to evaluate MGP- and BaP-induced DNA adduct formation in lung and forestomach tissue. The level of DNA adducts formed from the chemical components of MGP paralleled the amount of material ingested by animals. Lung DNA adduct levels were considerably higher than forestomach levels when mice ingested a 0.25% or 0.50% MGP diet. These studies demonstrate that the continuous ingestion of MGP or BaP for 185 d does not result in acute toxicity or chemical-related lesions at doses up to 0.50% MGP or 0.005% BaP.

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.

Exposure to polycyclic aromatic hydrocarbons in petrochemical industries by measurement of urinary 1-hydroxypyrene

Biological monitoring of exposure of workers to polycyclic aromatic hydrocarbons (PAHs) in petrochemical industries was performed by the measurement of urinary excretion of 1-hydroxypyrene. In 121 of the 462 workers studied (both smokers and non-smokers) who had had no recent occupational exposure to PAHs a median 1-hydroxypyrene concentration of 0.21 micrograms/g creatinine was found. The upper limit of the 95% confidence interval in these workers of 0.99 micrograms/g creatinine was used as the upper normal value for industrial workers. Urinary 1-hydroxypyrene concentrations were measured in workers involved in manufacture and maintenance operations in oil refineries (13 studies in eight different settings), in workers manufacturing or handling products containing PAHs in chemical plants (five studies in three settings) and laboratories (four studies), and in workers digging soil contaminated with PAHs (three studies). In most studies in oil refineries 1-hydroxypyrene concentrations were only marginally greater than the values measured in the 121 workers with no recent occupational exposure to PAHs. This was also the case in maintenance operations with higher potential exposure to PAHs, indicating that personal protection equipment was generally adequate to prevent excessive exposure. The studies in chemical plants also showed that exposure to PAHs is low. An exception was the workers engaged in the production of needle coke from ethylene cracker residue, where increased urinary 1-hydroxypyrene concentrations were measured. The excretion of 1-hydroxypyrene by the operators and maintenance workers of this plant was investigated in relation to potential methods of exposure to PAHs. Dermal and inhalatory exposure were both significant determinants of exposure to PAHs.

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)

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.

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.

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.

Mercapturic acids, protein adducts, and DNA adducts as biomarkers of electrophilic chemicals

The possibilities and limitations of using mercapturic acids and protein and DNA adducts for the assessment of internal and effective doses of electrophilic chemicals are reviewed. Electrophilic chemicals may be considered as potential mutagens and/or carcinogens. Mercapturic acids and protein and DNA adducts are considered as selective biomarkers because they reflect the chemical structure of the parent compounds or the reactive electrophilic metabolites formed during biotransformation. In general, mercapturic acids are used for the assessment of recent exposure, whereas protein and DNA adducts are used for the assessment of semichronic or chronic exposure. 2-Hydroxyethyl mercapturic acid has been shown to be the urinary excretion product of five different reactive electrophilic intermediates. Classification of these electrophiles according to their acid-base properties might provide a tool to predict their preference to conjugate with either glutathione and proteins or with DNA. Constant relationships appear to exist in the cases of 1,2-dibromoethane and ethylene oxide between urinary mercapturic acid excretion and DNA and protein adduct concentrations. This suggests that mercapturic acids in some cases may also play a role as a biomarker of effective dose. It is concluded that simultaneous determination of mercapturic acids, protein and DNA adducts, and other metabolites can greatly increase our knowledge of the specific roles these biomarkers play in internal and effective dose assessment. If the relationship between exposure and effect is known, similar to protein and DNA adducts, mercapturic acids might also be helpful in (individual) health risk assessment.

Biological monitoring of foundry workers exposed to polycyclic aromatic hydrocarbons

This investigation describes benzo(a)pyrene (BP) serum protein adduct concentrations in 45 foundry workers and 45 matched non-occupationally exposed controls. High and low BP exposure groups were defined using breathing zone hygienic samples for both quartz and BP exposures. A newly developed enzyme linked immunosorbent assay detected benzo(a)pyrenediolepoxide-I binding to serum protein. Mean BP protein adduct concentrations (SD) for non-smoking (24.0 BP equivalents/100 micrograms protein (21.0] and smoking (28.0 (18.2] foundry workers were significantly higher than mean values for non-smoking (7.23 (8.72] and smoking (14.2 (24.4] controls. Foundry workers with high exposures to either quartz (28.4 (15.5] or BP (30.7 (19.3] had slightly raised mean adduct concentrations compared with foundry workers with low exposure for quartz (23.9 (23.1] or BP (24.5 (19.4). Highest mean adduct concentrations were found among a small group of workers with simultaneous high exposures to both quartz and BP (39.2 (6.5] suggesting an additive effect. These data support the ideas of a possible aetiological connection between an increased risk of lung cancer and BP exposure among foundry workers, and an additive effect between BP and quartz. Measurement of BP serum protein adduct concentrations appears to be a useful method by which groups exposed to BP may be biologically monitored.