Thioether excretion of workers exposed to bitumen fumes

Assessment of primary, oxidative and excision repaired DNA damage in hospital personnel handling antineoplastic drugs

The International Agency for Research on Cancer has classified several antineoplastic drugs in Group 1 (human carcinogens), among which chlorambucil, cyclophosphamide (CP) and tamoxifen, Group 2A (probable human carcinogens), among which cisplatin, etoposide, N-ethyl- and N-methyl-N-nitrosourea, and Group 2B (possible human carcinogens), among which bleomycins, merphalan and mitomycin C. The widespread use of these mutagenic/carcinogenic drugs in the treatment of cancer has led to anxiety about possible genotoxic hazards to medical personnel handling these drugs. The aim of the present study was to evaluate work environment contamination by antineoplastic drugs in a hospital in Central Italy and to assess the genotoxic risks associated with antineoplastic drug handling. The study group comprised 52 exposed subjects and 52 controls. Environmental contamination was assessed by taking wipe samples from different surfaces in preparation and administration rooms and nonwoven swabs were used as pads for the surrogate evaluation of dermal exposure, 5-fluorouracil and cytarabine were chosen as markers of exposure to antineoplastic drugs in the working environment. The actual exposure to antineoplastic drugs was evaluated by determining the urinary excretion of CP. The extent of primary, oxidative and excision repaired DNA damage was measured in peripheral blood leukocytes with the alkaline comet assay. To evaluate the role, if any, of genetic variants in the extent of genotoxic effects related to antineoplastic drug occupational exposure, the study subjects were genotyped for GSTM1, GSTT1, GSTP1 and TP53 polymorphisms. Primary DNA damage significantly increased in leukocytes of exposed nurses compared to controls. The use of personal protective equipment (i.e. gloves and/mask) was associated with a decrease in the extent of primary DNA damage.

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.

Evaluation of micronuclei in exfoliated urothelial cells and urinary thioether excretion of smokers

Mutagens are present in large quantities in the urine of cigarette smokers, thus, their urothelial cells may represent a possible target for absorbed and excreted mutagens. Our aim is to validate the micronucleus (MN) test in exfoliated urothelial cells obtained from urine samples of cigarette smokers. The urinary thioether (UT) test is also carried out on the same individuals in order to find out whether there is any correlation between these two end-points. The mean (+/- SE) MN frequency and UT determination is 1.93 (+/- 0.11)% and 9.71 (+/- 1.61) mmol SH/mol creatinine for 23 smokers, and 0.66 (+/- 0.05)% and 4.20 (+/- 0.56) mmol SH/mol creatinine for 20 nonsmokers. Our results show a higher frequency of micronucleated cells (p < 0.001) and higher excretion of UTs (p < 0.05) in smokers as compared to nonsmokers. Concentrations of UTs and MN frequencies increased with tobacco consumption. The MN frequencies showed only a marginal increase, not significant (p > 0.05), after passive smoking compared to nonsmoking values. There was no significant correlation between MN frequencies and UTs, either in smokers (r = 0.164, p > 0.05) or in nonsmokers (r = -0.018, p > 0.05). Our data demonstrate tobacco-induced chromosome damage in bladder tissue consistent with increased risk of cancer at this site among smokers.

Chromosomal aberrations and micronuclei in reinforced plastics workers exposed to styrene

The aim of this study was to investigate the cytogenetic changes induced in humans exposed to styrene in a reinforced plastics plant. Blood and urine samples were collected from 18 styrene exposed workers and 18 age and sex matched control subjects from the administrative department of the same factory. Chromosome aberrations (CAs) and micronuclei (MN) (cytokinesis block method) were analyzed in blood lymphocytes. All of the subjects included in the study were male non-smokers. The duration of employment ranged from 10 to 22 years (14.3 +/- 4.4). In order to monitor exposure to styrene, urinary mandelic acid (MA) levels were measured using a standard colorimetric method. The level of thioethers in the urine was also determined colorimetrically. The mean level of mandelic acid was significantly higher in the exposed workers (328.44 +/- 266.21 mg/g creatinine) compared with that of the controls (50.09 +/- 16.84 mg/g creatinine) (p < 0.05). The level of urinary thioethers was found to be higher among the exposed workers. The number of cells with chromosomal aberrations was significantly higher in the workers (6.06 +/- 4.41) compared with the controls (3.44 +/- 2.28) (p < 0.05). There was no significant increase in the frequency of micronuclei in the exposed workers compared to controls. Our results support earlier findings on increased rates of chromosomal aberrations in reinforced plastics workers.

Determinants of urinary thioethers, D-glucaric acid and mutagenicity after exposure to polycyclic aromatic hydrocarbons assessed by air monitoring and measurement of 1-hydroxypyrene in urine: a cross-sectional study in workers of coke and graphite-electrode-producing plants

A cross-sectional epidemiological study was performed on 286 workers from two coke oven and one graphite electrode plants. The aim was to evaluate the usefulness of monitoring 1-hydroxypyrene (1-HOP) in urine for assessing exposure to polycyclic aromatic hydrocarbons (PAHs), and that of the urinary excretion of thioethers and D-glucaric acid, and the mutagenic activity of urine as indicators or biological effects of PAHs. The results confirm that 1-HOP determination in urine probably reflects exposure to PAHs by all routes and is not significantly influenced by the smoking habit. In comparison with the total PAHs in the air and 1-hydroxypyrene in urine, taken as reference exposure parameters, the results indicate that urinary D-glucaric acid excretion is not positively influenced by PAHs exposure; thioethers determination in urine is of poor value, since the smoking habit is a strong confounding factor. The determination of urinary mutagenicity might contribute to the detection of groups of workers exposed to potentially genotoxic PAHs.

Thioethers in urine of sterilization personnel exposed to ethylene oxide

Biological monitoring of exposure to ethylene oxide (EO) was carried out in 31 hospital workers in the sterilization facilities of five hospitals. The excretion of total thioethers was determined in the urine of sterilization workers. An occupational nonexposed group served as a control (n = 31). The air EO level was not monitored routinely, however, peak concentrations of EO up to 200 p.p.m. were detected mainly when the sterilization chambers were open. Our results show a significant difference in urinary thioether excretion between the exposed and control groups (P less than 0.001). Sterilization workers seem to absorb significant quantities of EO. We feel that other alternative and more sensitive methods for detecting thioether metabolites of EO should be carried out to confirm our results.

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.

The applicability of the measurement of urinary thioethers. A study of humans exposed to styrene during diet standardization

The excretion of thioethers was measured in the urine of 6 volunteers, who were experimentally exposed to styrene, and 18 styrene workers. In addition, 12 clerks (non-smokers) and 12 sheet-metal workers (smokers) served as control groups. Diet was standardized during the experiments. Thioethers were measured by a spectrophotometric method. The volunteers were exposed to styrene, 210 mg/m3, for 2h at a 50-W workload. An increase in thioether excretion was observed; the largest was in the urine samples collected between 0.5 and 5 h after the end of the exposure. After 43 h the excretion of thioethers was close to the pre-exposure level (3.5 mmol/mol creatinine). About 1% of the styrene absorbed was detected as thioethers in urine, which is only about 1/10 of the conversion reported for rats. From excretion rate curves a half-life of about 11 h was calculated for styrene thioethers. The styrene workers were employed at two plants. The average exposure to styrene (time-weighted average 8 h) was estimated to be about 115 mg/m3 (smokers in plant A), 55 mg/m3 (non-smokers in plant A) and less than or equal to 10 mg/m3 (non-smokers in plant B). The excretion of thioethers in exposed workers at plant A was higher by 2-4 mmol/mol creatinine than that in non-exposed controls. In plant B, where exposure was lower, an increase in that amount of thioethers excreted in the urine by exposed workers was less pronounced, and was statistically significant only when post-shift samples were compared with pre-shift samples.(ABSTRACT TRUNCATED AT 250 WORDS)