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

The micronucleus assay in exfoliated buccal cells: application to occupational exposure to polycyclic aromatic hydrocarbons

Many polycyclic aromatic hydrocarbons (PAHs) have been identified as cancer-inducing chemicals for animals and/or humans. Also, there is sufficient evidence that exposures in the occupational settings are carcinogenic or probably carcinogenic to human. Engine exhaust and used engine oils are major PAH sources in engine repair workshops and traffic. Analysis of micronucleus (MN) in exfoliated buccal cells is a sensitive method for monitoring genetic damage in human populations. In our study, we used three different occupational groups (Group 1; engine repair workers, Group 2; taxi drivers, Group 3; traffic police) and two controls (Control I for Group 1 and Control II for Group 2 and Group 3) for the exposed groups. We analysed MN frequencies in exfoliated buccal cells and compared the exposed groups (Group 1; n=34, Group 2; n=17, Group 3; n=15) and subjects not occupationally exposed to PAH (Control I; n=28, Control II; n=20). The mean (+/-S.D.) MN (%) frequencies in exfoliated buccal cells from Group 1 and Control I were 0.07+/-0.05 and 0. 05+/-0.04, respectively (p>0.05; Table 2). The mean (+/-S.D.) MN (%) frequencies in exfoliated buccal cells from Group 2, 3 and Control II were 0.12+/-0.05, 0.10+/-0.05 and 0.03+/-0.03, respectively (p<0. 0001, p<0.05; Table 2) Smokers and nonsmokers do not differ with respect to the incidence of MN in all groups.

Biological monitoring exposure of workers from plant producing carbon electrodes: quantification of benzo[a]pyrene DNA-adducts in leukocytes, by a 32P-postlabelling method and an immunoassay

The levels of benzo[a]pyrene were monitored for blood DNA-benzo[a]pyrene adducts in 17 workers from a plant producing carbon electrodes, with high exposure to benzo[a]pyrene (575-902-1149 ng m(-3)). Two different techniques, a 32P-postlabelling method and a competitive immunoassay using polyclonal antibodies obtained from rabbits immunised with DNA modified by benzo[a]pyrene-trans-7,8-dihydrodiol-9,10-epoxide were used. For each worker, urinary 1-hydroxypyrene, a potential indicator of exposure to polycyclic aromatic hydrocarbons, was measured. The effect of tobacco by urinary cotinine measurement was also considered. The postlabelling and immunoassay detection limits for DNA-benzo[a]pyrene adducts were respectively 0.15 and 10 fmol 50 microg(-1) of DNA. The results obtained by the two methods demonstrated a good detection of DNA-benzo[a]pyrene adducts, but no direct relationship between the quantity of adducts and the concentration of benzo[a]pyrene in air-borne was noted in the studied plant. The levels of DNA-benzo[a]pyrene adducts obtained by immunoassay were significantly higher than those obtained by the 32P-postlabelling (P < 0.001). For several workers, variations due to professional or non professional factors must be taken into account in interpreting the results. In conclusion, the two methods used proved very efficient in determining DNA-benzo[a]pyrene adducts, and may be useful in monitoring human exposure to known and previously unidentified environmental genotoxic agents.

Urinary 1-hydroxypyrene concentrations in coke oven workers

OBJECTIVES

To investigate the relation of individual occupational exposure to total particulates benzene soluble fraction (BSF) of ambient air with urinary 1-hydroxypyrene (1-OHP) concentrations among coke oven workers in Taiwan.

METHODS

80 coke oven workers and 50 referents were monitored individually for the BSF of breathing zone air over three consecutive days. Exposures were categorised as high, medium, or low among coke oven workers based on exposure situations. The high exposure group (n = 18) worked over the oven. The medium and low exposure groups (n = 41 and n = 21) worked at the side of the oven for > 4 hours and < 4 hours a day, respectively. Urine was collected before the shift on the morning of day 1 and after the shift on the afternoon of day 3 to find the change of 1-OHP concentrations across the shift.

RESULTS

The median (range) changes of urinary 1-OHP concentrations across the shift for various exposure situations (microgram/g creatinine) were as follows: high 182 (7 to 3168); medium 9 (-8 to 511); low 7 (-6 to 28); and referents 0.2 (-2 to 72). This change of urinary 1-OHP was highly associated with individual occupational exposure to the BSF in air (r = 0.74 and 0.64, p < 0.001). The regression model showed significant effects of individual exposures to the BSF and alcohol consumption on urinary postshift 1-OHP after adjusting for preshift 1-OHP in the total population (n = 130). More exposure to the BSF led to higher postshift 1-OHP (p < 0.001); current drinkers of > 120 g/week had lower urinary postshift 1-OHP than never and former drinkers (p = 0.01). A 10-fold increase in the average BSF in air resulted in about a 2.5-fold increase in postshift 1-OHP among the 80 coke oven workers.

CONCLUSION

Urinary 1-OHP concentrations can be used as a good biomarker to assess individual exposure to the BSF in air. Alcohol drinking may modify the toxicokinetic pathway of the BSF; the effects of alcohol should be investigated further in occupational studies.

Comprehensive evaluation of long-term trends in occupational exposure: Part 1. Description of the database

OBJECTIVES

To conduct a comprehensive evaluation of long term changes in occupational exposure among a broad cross section of industries worldwide.

METHODS

A review of the scientific literature identified studies that reported historical changes in exposure. About 700 sets of data from 119 published and several unpublished sources were compiled. Data were published over a 30 year period in 25 journals that spanned a range of disciplines. For each data set, the average exposure level was compiled for each period and details on the contaminant, the industry and location, changes in the threshold limit value (TLV), as well as the type of sampling method were recorded. Spearman rank correlation coefficients were used to identify monotonic changes in exposure over time and simple linear regression analyses were used to characterise trends in exposure.

RESULTS

About 78% of the natural log transformed data showed linear trends towards lower exposure levels whereas 22% indicated increasing trends. (The Spearman rank correlation analyses produced a similar breakdown between exposures monotonically increasing or decreasing over time.) Although the rates of reduction for the data showing downward trends ranged from -1% to -62% per year, most exposures declined at rates between -4% and -14% per year (the interquartile range), with a median value of -8% per year. Exposures seemed to increase at rates that were slightly lower than those of exposures which have declined over time. Data sets that showed downward (versus upward) trends were influenced by several factors including type and carcinogenicity of the contaminant, type of monitoring, historical changes in the threshold limit values (TLVs), and period of sampling.

CONCLUSIONS

This review supports the notion that occupational exposures are generally lower today than they were years or decades ago. However, such trends seem to have been affected by factors related to the contaminant, as well as to the period and type of sampling.

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.

Assessment of exposure to polycyclic aromatic hydrocarbons during firefighting by measurement of urinary 1-hydroxypyrene

Firefighters may be exposed to carcinogenic agents in the smoke from fires, and there has been some concern regarding firefighters' risk of developing occupational-related cancer. Polycyclic aromatic hydrocarbons (PAHs) are present in most fires, posing a cancer risk. The objective of this study was to evaluate the PAH exposure among firefighters. Students (n = 9) and teachers (n = 4) at a firefighter training school delivered urine samples before and 6 to 7 hours after extinguishing burning diesel fuel. The urine samples were analyzed by high-performance liquid chromatography for 1-hydroxypyrene. A small but significant increase in 1-hydroxypyrene levels in the urine was found after the firefighting. This means that firefighting may cause exposure to PAHs. Although the exposure levels were low in this study, they may be different during other types of fires.

Assessment of exposure to polycyclic aromatic hydrocarbons in engine rooms by measurement of urinary 1-hydroxypyrene

OBJECTIVE

Machinists have an increased risk of lung cancer and bladder cancer, and this may be caused by exposure to carcinogenic compounds such as asbestos and polycyclic aromatic hydrocarbons (PAHs) in the engine room. The aim of this study was to investigate the exposure of engine room personnel to PAHs, with 1-hydroxypyrene in urine as a biomarker.

METHODS

Urine samples from engine room personnel (n = 51) on 10 ships arriving in different harbours were collected, as well as urine samples from a similar number of unexposed controls (n = 47) on the same ships. Urinary 1-hydroxypyrene was quantitatively measured by high performance liquid chromatography. The exposure to PAHs was estimated by a questionnaire answered by the engine room personnel. On two ships, air monitoring of PAHs in the engine room was performed at sea. Both personal monitoring and area monitoring were performed. The compounds were analysed by gas chromatography of two types (with a flame ionisation detector and with a mass spectrometer).

RESULTS

Significantly more 1-hydroxypyrene was found in urine of personnel who had been working in the engine room for the past 24 hours, than in that of the unexposed seamen. The highest concentrations of 1-hydroxypyrene were found among engine room personnel who had experienced oil contamination of the skin during their work in the engine room. Stepwise logistic regression analysis showed a significant relation between the concentrations of 1-hydroxypyrene, smoking, and estimated exposure to PAHs. No PAHs were detected in the air samples.

CONCLUSION

Engine room personnel who experience skin exposure to oil and oil products are exposed to PAHs during their work. This indicates that dermal uptake of PAHs is the major route of exposure.

Exposure to polycyclic aromatic hydrocarbons in coal liquefaction workers: impact of a workwear policy on excretion of urinary 1-hydroxypyrene

OBJECTIVE

This study was undertaken to assess whether contaminated personal clothing worn beneath a coverall (normal workwear) is a source of potentially significant dermal exposure to polycyclic aromatic hydrocarbons (PAHs) in coal liquefaction workers.

METHODS

An intervention study was conducted over a two week period involving 10 workers that reflected the range of activities performed at the factory. A cross over design was used to examine the influence of normal workwear (personal clothing worn beneath a coverall) and intervention workwear (new coverall, shirt, trousers, underwear, socks, and boots) upon excretion of urinary 1-hydroxypyrene (1-OHP) and skin pad deposition of pyrene.

RESULTS

The impact of intervention was noted in three ways: (1) A notable reduction (55%) in the mass of 1-OHP excreted on the first day of the intervention phase was found. The median reduction in mass excreted (22.7 nmol) was significant from zero at the 5% level; (95% confidence interval (95% CI) 9.5-40.8 nmol). (2) A notable reduction (82%) in skin pad deposition of pyrene on the first day of the intervention phase was found. The median reduction of 13.20 ng.cm-2 was significant from zero at the 5% level; (95% CI 7.3-26.4 ng.cm-2). (3) About a 50% reduction in 1-OHP concentration over the working week occurred during the intervention phase; an increase of 2.07 mumol/mol creatinine was found from the start to the end of the work period during the intervention phase compared with an increase of 4.06 mumol/mol creatinine during the normal phase. This reduction was not significant at the 5% level.

CONCLUSION

The results indicate that on the first day of the working week investigated, significant reductions in absorbtion (as measured by excretion of urinary 1-OHP) and deposition of PAHs (as measured by skin pad deposition of pyrene) can be effected by improvements in workwear policy. The impact of the improved workwear regimen was also detected by reduction in spot urinary 1-OHP concentrations, although this effect was less pronounced. One implication of the findings is that exposure to PAHs may arise from workers' own contaminated personal clothing. As a consequence of this study an improved workwear policy has been implemented at the factory.

Urinary 1-hydroxypyrene as biomarker of exposure to polycyclic aromatic hydrocarbons in workers in petrochemical industries: baseline values and dermal uptake

The suitability of urinary 1-hydroxypyrene as a biomarker for the assessment of exposure to polycyclic aromatic hydrocarbons (PAH) in petrochemical industries was evaluated in 562 workers involved in various operations in petrochemical industries. The median 1-hydroxypyrene concentration in 121 of these workers (both smokers and non-smokers) who had had no recent occupational exposure to PAH was 0.11 mumol/mol creatinine. The upper limit of the 95% confidence interval was 0.51 mumol/mol creatinine. During activities with a low potential exposure to PAH, such as loading bitumen and the handling of clarified slurry oils and furfural extracts, 1-hydroxypyrene concentrations were only marginally increased compared with the values measured in the 121 workers with no recent occupational exposure to PAH. Despite the substantially higher potential exposure to PAH during clean-out operations of various oil refinery installations, the concentrations of 1-hydroxypyrene in the workers involved were in the same range. This suggests that personal protection equipment was generally adequate to prevent excessive exposure. However, in workers digging PAH-contaminated soil and workers engaged in the production of needle coke from ethylene cracker residue, significantly increased urinary 1-hydroxypyrene concentrations were measured. A major decrease in urinary 1-hydroxypyrene following the application of dermal protective equipment in the ground workers suggested that skin absorption plays a major role in occupational exposure to PAH. The excretion of 1-hydroxypyrene by the workers of the needle coke plant was investigated in relation to potential determinants of exposure to PAH. It was indeed found that not only inhalatory but also dermal exposure was a significant determinant of occupational exposure to PAH.

Urinary 1-naphthol and 1-pyrenol as indicators of exposure to coal tar products

Chemical exposure of assemblers handling creosote-impregnated wood and of a single worker chiselling coal tar pitch layer was assessed by measuring airborne naphthalene and various polycyclic aromatic hydrocarbons (PAHs), and by measurement of urinary excretion of 1-naphthol and 1-pyrenol. The sum concentration of PAHs and of 4-6 aromatic ring-containing PAHs were high, 440 micrograms/m3 and 290 micrograms/m3, respectively, when chiselling. In the assembler's workplace, the PAH concentrations were about 1/50 of this value. Regarding airborne naphthalene concentrations the situation was reversed (assemblers, 1000 micrograms/m3; chiseller, 160 micrograms/m3). Correspondingly, the assemblers' urinary 1-napthol concentrations were 15-20 times higher than those of the chiseller. The urinary 1-pyrenol concentration of the chiseller was 2-4 times higher than among the assemblers. As the estimated pyrene inhalation doses among the assemblers could account for only about 2%-25% of the 24-h pyrenol excretion in urine, the skin was presumably the main route of uptake. For an assessment of the exposure to PAHs, air measurements, monitoring of metabolites in urine and preferably also data on the composition of the skin-contaminating product are needed.