Changes in lymphocyte single strand breakage and liver function of workers exposed to vinyl chloride monomer

doi:10.1016/0378-4274(95)03321-1

Toxicology Letters

Volume 77, Issues 1–3, May 1995, Pages 379-385

https://doi.org/10.1016/0378-4274(95)03321-1 Get rights and content

Abstract

Vinyl chloride monomer (VCM) is a suspected human carcinogen. Its metabolite, chloroethylene epoxide, is able to alkylate the DNA molecule and to produce single strand breakage (SSB). A total of 244 workers from 4 polyvinyl chloride (PVC) manufacturing factories were recruited to assess the SSB of their peripheral lymphocyte DNA. The method of alkaline unwinding and hydroxyapatite chromatography was used to detect and calculate frequencies of SSB. In addition, hepatitis B and C markers and the liver function of the workers were also examined. The worker's cumulative exposures to VCM were retrospectively constructed from the current monitoring data and each worker's job history. Multiple linear regression models were constructed to predict the worker's level of SSB and liver functions based on various exposure indices and variables, such as age, sex, smoking, drinking, and hepatitis markers. The results showed that current smoking and drinking status, and the presence of VCM exposures on the previous day were 3 major determinants of the level of SSB. Among the liver function tests, only γ-glutamyi transpeptidase (GGT) was associated with current VCM exposures. In contrast, aspartate aminotransferase (AST), alkaline phosphatase (ALP) and alanine aminotransferase (ALT) were mainly affected by the presence of hepatitis B surface antigen (HBsAg) or anti-hepatitis C vins (anti-HCV). We conclude that GGT should be considered to be included in the regular health screening of VCM workers, and that the SSB method may not be suitable for long-term monitoring of cumulative exposure because of the quick DNA repair mechanism in humans.

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Cited by (22)

Association between methylation of DNA damage response-related genes and DNA damage in hepatocytes of rats following subchronic exposure to vinyl chloride
2019, Chemosphere
Citation Excerpt :
Chemically induced epigenetic alterations can also serve as biomarkers of carcinogen exposure (Chappell et al., 2016). Occupational VC exposure has been shown to increase the DNA breakage rate of peripheral blood lymphocytes (Du et al., 1995; Awara et al., 1998; Lei et al., 2004). We found that DNA strand breakage in hepatocytes increased with VC dose and exposure time, suggesting that DNA damage in hepatocyte can be a useful marker for VC exposure and DNA damage.
In the present study, we investigated the association between methylation of DNA damage response-related genes such as cyclin-dependent kinase inhibitor (CDKN)2A, Ras association (RalGDS/AF-6) domain family member (RASSF)1A, O6-methylguanine DNA methyltransferase (MGMT), Kirsten rat sarcoma viral oncogene homolog (KRAS), and spleen-associated tyrosine kinase (SYK) and DNA damage in hepatocytes of rats following subchronic exposure to vinyl chloride (VC). Sixty-four healthy rats were randomly divided into three VC exposure groups (5, 25, and 125 mg/kg) and an untreated negative control group (n = 16 each). VC was administered by intraperitoneal injection every other day for a total of three times a week. Eight randomly selected rats from each group were sacrificed at the end of 6 and 12 weeks, and liver tissue was harvested for the comet assay and for assessment of DNA methylation level and mRNA expression of related genes by PCR. Overall methylation levels in the genome of hepatocytes in VC-exposed rats were higher than those in the control group at 6 and 12 weeks (P < 0.05), although no differences were observed with regarding to dose (P > 0.05). After 12 weeks of exposure, differences in the methylation of RASSF1A and MGMT promoter regions were observed between the high-dose group and other groups (P < 0.05), whereas no differences were observed for the KRAS, SYK, and CDKN2A promoters (P > 0.05). These results suggest that DNA damage and increased genome-wide methylation are biomarkers for VC exposure and that RASSF1A and MGMT promoter methylation is related to the carcinogenic mechanism of VC.
Estimation of benchmark dose for micronucleus occurrence in Chinese vinyl chloride-exposed workers
2013, International Journal of Hygiene and Environmental Health
Citation Excerpt :
Another two (p21 and p53) positive worker had an estimated cumulative exposure of 1.07 ppm-years (mg/m3). Du et al. (1995) found that serum levels of gamma-glutamyl transferase (GGT), but not other indicators of liver function, correlated with exposure in a group of 224 VC workers with time-weighted average (TWA) exposure ranging from 0.36 to 74 ppm (0.92–189 mg/m3). Note that our estimated value is an smaller than these value even smaller than 0.56 mg/m3 based on the cancer risk estimated by Li et al. (1998) This difference may imply that genotoxicity is a more sensitive endpoint than the cancers and our estimated TLV-TWA value may serve as a point of departure when additional safety factors are applied to adjust for uncertainties.
In this study, we estimated the possibility of using benchmark dose (BMD) to assess the dose–response relationship between vinyl chloride monomer (VCM) exposure and chromosome damage. A group of 317 workers occupationally exposed to vinyl chloride monomer and 166 normal, unexposed control in Shandong Province northern China were examined for chromosomal damage in peripheral blood lymphocytes (PBL) using the cytokinesis-blocked micronucleus (CB-MN) assay of DNA damage. The exposed group (3.47 ± 2.65)‰ showed higher micronucleus frequency than the control (1.60 ± 1.30)‰ (P < 0.01). Occupational exposure level based on micronucleus occurrence in all individuals was analyzed with benchmark dose (BMD) methods. The benchmark dose lower limit of a one-sided 95% confidence interval (BMDL) for 10% excess risk was also determined. Results showed a dose–response relationship between cumulative exposure and MN frequency, and a BMDL of 0.54 mg/m³ and 0.23 mg/m³ for males and females, respectively. Female workers were more susceptible to MN damage than male workers.
DNA repair gene polymorphisms and micronucleus frequencies in Chinese workers exposed to vinyl chloride monomer
2011, International Journal of Hygiene and Environmental Health
Citation Excerpt :
VCM is a known animal and human carcinogen capable of damaging DNA and producing many kinds of tumors especially angiosarcoma of the liver (ASL) and hepatocellular cancer (Mundt et al., 2000; Wong et al., 2002). Previous population studies have shown that VCM exposure is associated with increased genotoxicity in humans such as chromosome aberrations, micronuclei (MN) and DNA strand breaks (Fucic et al., 1990, 1996; Du et al., 1995; Zhu et al., 2005). Expression of MN has been reported to be predictive of the development of cancer (Bonassi et al., 2007).
Vinyl chloride monomer (VCM) is genotoxic and cancerogen agent. Individual variations in response to the exposure have been noticed and the variations may be due to genetic differences in the removal of VCM–DNA adducts, such as polymorphism in genes NER pathway and BER pathway. This study explores the relationship between genetic polymorphism of seven genes within the NER pathway (XPA, XPD, XPC, XPG, XPF, and ERCC1) and BER pathway (APE1), and susceptibility to chromosomal damage after exposure to VCM. One hundred and eighty workers occupationally exposed to VCM and 43 unexposed controls were investigated. Chromosome damage in peripheral lymphocytes was measured by the cytokinesis-blocked micronucleus assay. PCR-RFLP technique was applied to detect polymorphisms of the seven genes. The influence of genotype, age, gender, cumulative exposure dose, alcohol consumption, and smoking status on the frequencies of MN was determined using univariate and multiple Poisson regression analyses. We found XPA A23G variant workers had significantly higher MN frequencies than those from the wild-type homozygous counterparts (P = 0.01). Those with the variant XPD Lys751Gln genotype had marginally higher MN frequencies (P = 0.07). On the other hand, XPC PAT and XPF 5′-UTR T2063A variant workers had significantly lower MN frequencies compared with those from their wild-type homozygous counterparts (P = 0.04 and P = 0.004, respectively). Our findings suggest that XPC PAT, XPD Lys751Gln, XPA A23G and XPF 5′-UTR T2063A contribute to the level of chromosome damage in occupational exposure to VCM in Chinese population.
Polymorphisms and haplotypes of DNA repair and xenobiotic metabolism genes and risk of DNA damage in Chinese vinyl chloride monomer (VCM)-exposed workers
2008, Toxicology Letters
In this case–control study, we investigated the association between DNA damage and genetic susceptibility among vinyl chloride monomer (VCM)-exposed workers. The cumulative exposure dose of VCM was calculated based on the workers’ duration of exposure and the geometric mean concentration of VCM in the workplace. DNA damage to peripheral blood lymphocytes was measured by single cell gel electrophoresis (SCGE) assay, and single nucleotide-polymorphisms (SNPs) in xenobiotic metabolism and DNA repair genes were detected by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods. Univariate analysis showed that the CYP2E1 c1c2/c2c2 and XPD751 Lys/Gln and Gln/Gln genotypes were significantly associated with the levels of DNA damage (P < 0.01 and 0.05, respectively). Further logistic regression analysis showed a significant association between CYP2E1 c1c2/c2c2 and DNA damage, and risk of having increased levels of DNA damage was more pronounced in those individuals having XRCC1 194 mutant genotypes and/or XPD751 Lys/Gln and Gln/Gln genotypes. Although most of the XPD and XRCC1 haplotypes did not show any significant difference, the XRCC1 haplotype Trp194–Arg280 was significantly over-represented in the case group (P < 0.05; OR 2.09; 95% CI: 1.07–4.06) than in controls. Overall, our data suggest that the genotypes of CYP2E1, XRCC1 194, and XPD 751 were associated with the level of DNA damage and may contribute to individual sensitivity to DNA damage induced by VCM in the workplace.
Polymorphisms of DNA repair gene XPD and DNA damage of workers exposed to vinylchloride monomer
2005, International Journal of Hygiene and Environmental Health
Vinyl chloride monomer (VCM) is a human carcinogen. However, the exact mechanism of carcinogenesis remains unclear. 2-Chloroethylene oxide (CEO) and 2-chloroacetaldehyde (CAA), the metabolic intermediates of VCM, induce DNA damage which is mainly repaired by the nucleotide excision repair (NER) pathway. The XPD gene product and the related XPB protein are DNA helicases that are involved in transcription and NER. Polymorphisms of XPD have been implicated in chemical exposure-related health effects. In order to explore the mechanism of VCM-related health effects, a special matched case-control design (exposed workers with DNA damage and without damage) was used to investigate the association between the gene polymorphisms of XPD and DNA damage in 106 male and 44 female workers occupationally exposed to VCM. Exposure and anthropometrics information was collected through in-person interview. Such information was then used to calculate cumulative exposure doses of the workers. DNA damage in peripheral lymphocytes was measured by the single cell gel electrophoresis (SCGE) assay that identified DNA strand breaks. Genomic DNA from lymphocytes was used in genotyping assays. Genotypes of XPD Ile199Met, XPD Asp312Asn, and XPD Lys751Gln were identified by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) procedure. The results indicate that the genotypes of XPD 751Lys/Gln and Gln/Gln were significantly associated with the expression of DNA damages (OR 2.21, $P < 0.05$ , 95% CI 1.01–5.13). An interesting observation is the reduction of DNA damage for workers with high VCM exposure and possessing the XPD Asp/Asn and Asn/Asn genotypes (OR 0.33, 95% CI 0.11–0.95). Polymorphisms of XPD may therefore be a major reason of genetic susceptibility in VCM-induced DNA damage and health consequences.
DNA single strand breaks in peripheral lymphocytes associated with urinary thiodiglycolic acid levels in polyvinyl chloride workers
2004, Mutation Research - Genetic Toxicology and Environmental Mutagenesis
The association between vinyl chloride monomer (VCM) exposure and DNA damage has been established. However, the relationship between individual exposure and DNA single strand breaks was limited. Since environmental monitoring may not reflect the actual exposure, a useful marker of exposure is needed to assess the individual exposure. In our previous study, we have found a high correlation between air VCM level and urinary thiodiglycolic acid (TdGA) at the commencement of the next shift. Here, we further used comet assay to evaluate the relationship between urinary TdGA levels and DNA single strand breaks in polyvinyl chloride monomer (PVC) workers. Urinary TdGA levels (n = 26) at the commencement of the following shift were analyzed. Ten of the 26 workers also had personal air sampling for air VCM exposure. Questionnaires were administered to obtain epidemiological information including detailed history of occupation and lifestyles. Workers experiencing air VCM level greater than 5 ppm had higher tail moment and tail intensity (%) than those experiencing VCM exposure between 1 and 5, or <1 ppm, respectively (P < 0.05). The results also revealed that level of DNA single strand breaks, including tail moment and tail intensity, were increased with urinary TdGA level. The dose–response relationship of urinary TdGA level and DNA single strand breaks was particularly significant among the workers with 4 mg/g Cr of urinary TdGA level, which is equivalent to 5 ppm air VCM level. We concluded that air VCM exposure greater than 5 ppm could induce DNA damage. Further sensitive assay should be developed for the diction of DNA damage when air VCM exposure below 5 ppm.

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Contributed paperChanges in lymphocyte single strand breakage and liver function of workers exposed to vinyl chloride monomer

Abstract

Toxicol. Appl. Pharmacol.

Mutat. Res.

Mutat. Res, DNA Repair

Adv. Clin. Chem.

Occupational acroosteolysis. A report of 31 cases

J. Am. Med. Assoc.

Acro-osteolysis occurring in men engaged in the polymerization of vinyl chloride

Br. Med. J.

On the so called Vinyl Chloride disease

Dutsch. Med. Weschr.

Occupational acroosteolysis. I. An epidemiological study

Arch. Environ. Health

Occupational acroosteolysis. II. An industrial hygiene study

Arch. Environ. Health

Occupational acroosteolysis. III. A clinical study

Arch. Environ. Health

An industry-wide epidemiologic study of vinyl chloride workers, 1942–1982

Am. J. Ind. Med.

Cohort and case-control analyses of workers exposed to vinyl chloride: an update

J. Occup. Med.

Incidence of cancer among vinyl chloride and polyvinyl chloride workers

Br. J. Ind. Med.

Covalent binding of haloethylenes

Fundamentals of genetic toxicity

Single-strand breaks, chromosome aberrations, sister-chromatid exchanges, and micronuclei in blood lymphocytes of workers exposed to styrene during the production of reinforced plastics

Environ. Mol. Mutagen.

Contributed paper
Changes in lymphocyte single strand breakage and liver function of workers exposed to vinyl chloride monomer