Evaluation of genotoxicity in a group of workers from a petroleum refinery aromatics plant

The Comet Assay as a Tool in Human Biomonitoring Studies of Environmental and Occupational Exposure to Chemicals-A Systematic Scoping Review

Biomonitoring of human populations exposed to chemical substances that can act as potential mutagens or carcinogens, may enable the detection of damage and early disease prevention. In recent years, the comet assay has become an important tool for assessing DNA damage, both in environmental and occupational exposure contexts. To evidence the role of the comet assay in human biomonitoring, we have analysed original research studies of environmental or occupational exposure that used the comet assay in their assessments, following the PRISMA-ScR method (preferred reporting items for systematic reviews and meta-analyses extension for scoping reviews). Groups of chemicals were designated according to a broad classification, and the results obtained from over 300 original studies (n = 123 on air pollutants, n = 14 on anaesthetics, n = 18 on antineoplastic drugs, n = 57 on heavy metals, n = 59 on pesticides, and n = 49 on solvents) showed overall higher values of DNA strand breaks in the exposed subjects in comparison with the unexposed. In summary, our systematic scoping review strengthens the relevance of the use of the comet assay in assessing DNA damage in human biomonitoring studies.

Effect of Ligand Aromaticity on Cyclohexane and Benzene Sorption in IRMOFs: A Computational Study

A series of four isoreticular MOFs (IRMOF-1, -10, -14, and -16) were selected for a computational investigation of the effect of ligand aromaticity on the adsorption capacity of an aromatic VOC (benzene) compared to its nonaromatic analog (cyclohexane). The affinity of the adsorbates was evaluated by calculating Henry's constants and adsorption enthalpies. It has been evidenced that while KH values decrease with ligand elongation (IRMOF-10 and -16), inserting a pyrene core into the MOF structure (IRMOF-14) increases both the cyclohexane and benzene adsorption efficiency by ∼290 and 54%, respectively. To elucidate host-guest interactions, we sought to locate preferential adsorption sites in MOF structures for the two VOCs studied by using the GCMC method. It appears that benzene interacts with the metal center (Zn4O clusters) and most of the ligand while cyclohexane tends to localize preferentially only near the Zn4O clusters. Coadsorption isotherms (equimolar mixture of benzene and cyclohexane) demonstrated the preferential adsorption of cyclohexane due to the stronger affinity for the MOF structure. On the other hand, for other isoreticular structures, the ligand elongation leads to a shift of the adsorption curve of cyclohexane caused by pore size increase and therefore less interactions with the walls. This phenomenon is counterbalanced in the case of IRMOF-14 due to stronger interactions between the cyclohexane and pyrene groups. The present results thus open perspectives in the design of promising MOF candidates for high-performing separation and sorption/detection of hydrocarbon VOCs.

A Palladium-Based MOF for the Preferential Sorption of Benzene

Selective sorption of volatile aromatic compounds is a challenging issue for their total abatement. Despite the well-known affinity of palladium toward rich π systems, studies dedicated to volatile organic compound (VOC) capture with Pd(II)-based metal-organic frameworks (MOFs) are still very scarce. Intending to shed more light on this complex topic, this work compares the adsorption properties of two isostructural MOFs [Cu(2-pymo)₂]_n and [Pd(2-pymo)₂]_n and their selectivity for the sorption of linear, cyclic, or aromatic VOCs. The combination of both experimental and computational investigations highlights an increasing aromatic affinity over saturated hydrocarbons when palladium is chosen as a metal center (n_Benzene/n_n-hexane = 1.8 at 0.5 p/p₀) in the MOF instead of copper (n_Benzene/n_n-hexane = 0.7 at 0.5 p/p₀). Furthermore, [Pd(2-pymo)₂]_n clearly exhibits preferential adsorption of benzene over toluene (n_Benzene/n_Toluene = 1.7 at 0.5 p/p₀), due to the steric hindrance effects of the latter. The present results clearly underline the attractiveness of Pd-based MOFs for the design of selective aromatic adsorbents. Moreover, they also highlight the [Pd(2-pymo)₂]_n MOF as a relevant candidate for the selective capture of benzene, by a synergistic combination of both charge interactions and steric hindrance effects.

[Cancer risk evaluation in individuals occupationally exposed to organic solvents]

OBJECTIVE

To evaluate the frequency of micronuclei (MNs) and influence of GSTM1 and GSTT1 gene polymorphisms as biomarkers of cancer risk in car painters (n=152) compared to unexposed individuals (n=152).

METHODS

Molecular epidemiology study, cross-sectional analysis of gen and environment interaction. The evaluation of MN and genetic polymorphisms was determined by molecular tests in lymphocytes from subjects involved in the study.

RESULTS

It was determined that the frequency of MNs is 1.6 higher in the exposed group compared to the reference group (1.39 ± 0.92 versus 0.87 ± 0.78, p<0.0001). There was no increase in the frequency of MNs associated with the polymorphisms in GSTM1 and GSTT1.

CONCLUSIONS

The increase of MNs in car painters serves to alert the increased risk of cancer in this population exposed to organic solvents. These results can be used in Occupational Epidemiological Surveillance Programs, as a prevention strategy and policies to regulate and control the use of solvents at a national level and in other countries with a large informal sector of individuals exposed to these chemicals to reduce the risk of cancer.

A Scoping Review of Technologies and Their Applicability for Exposome-Based Risk Assessment in the Oil and Gas Industry

INTRODUCTION

Oil and gas workers have been shown to be at increased risk of chronic diseases including cancer, asthma, chronic obstructive pulmonary disease, and hearing loss, among others. Technological advances may be used to assess the external (e.g. personal sensors, smartphone apps and online platforms, exposure models) and internal exposome (e.g. physiologically based kinetic modeling (PBK), biomonitoring, omics), offering numerous possibilities for chronic disease prevention strategies and risk management measures. The objective of this study was to review the literature on these technologies, by focusing on: (i) evaluating their applicability for exposome research in the oil and gas industry, and (ii) identifying key challenges that may hamper the successful application of such technologies in the oil and gas industry.

METHOD

A scoping review was conducted by identifying peer-reviewed literature with searches in MEDLINE/PubMed and SciVerse Scopus. Two assessors trained on the search strategy screened retrieved articles on title and abstract. The inclusion criteria used for this review were: application of the aforementioned technologies at a workplace in the oil and gas industry or, application of these technologies for an exposure relevant to the oil and gas industry but in another occupational sector, English language and publication period 2005-end of 2019.

RESULTS

In total, 72 articles were included in this scoping review with most articles focused on omics and bioinformatics (N = 22), followed by biomonitoring and biomarkers (N = 20), external exposure modeling (N = 11), PBK modeling (N = 10), and personal sensors (N = 9). Several studies were identified in the oil and gas industry on the application of PBK models and biomarkers, mainly focusing on workers exposed to benzene. The application of personal sensors, new types of exposure models, and omics technology are still in their infancy with respect to the oil and gas industry. Nevertheless, applications of these technologies in other occupational sectors showed the potential for application in this sector.

DISCUSSION AND CONCLUSION

New exposome technologies offer great promise for personal monitoring of workers in the oil and gas industry, but more applied research is needed in collaboration with the industry. Current challenges hindering a successful application of such technologies include (i) the technological readiness of sensors, (ii) the availability of data, (iii) the absence of standardized and validated methods, and (iv) the need for new study designs to study the development of disease during working life.

Derivation of an occupational exposure limit for benzene using epidemiological study quality assessment tools

This paper derives an occupational exposure limit for benzene using quality assessed data. Seventy-seven genotoxicity and 36 haematotoxicity studies in workers were scored for study quality with an adapted tool based on that of Vlaanderen et al., 2008 (Environ Health. Perspect. 116 1700-5). These endpoints were selected as they are the most sensitive and relevant to the proposed mode of action (MOA) and protecting against these will protect against benzene carcinogenicity. Lowest and No- Adverse Effect Concentrations (LOAECs and NOAECs) were derived from the highest quality studies (i.e. those ranked in the top tertile or top half) and further assessed as being "more certain" or "less certain". Several sensitivity analyses were conducted to assess whether alternative "high quality" constructs affected conclusions. The lowest haematotoxicity LOAECs showed effects near 2 ppm (8 h TWA), and no effects at 0.59 ppm. For genotoxicity, studies also showed effects near 2 ppm and showed no effects at about 0.69 ppm. Several sensitivity analyses supported these observations. These data define a benzene LOAEC of 2 ppm (8 h TWA) and a NOAEC of 0.5 ppm (8 h TWA). Allowing for possible subclinical effects in bone marrow not apparent in studies of peripheral blood endpoints, an OEL of 0.25 ppm (8 h TWA) is proposed.

Bone Marrow Oxidative Stress and Acquired Lineage-Specific Genotoxicity in Hematopoietic Stem/Progenitor Cells Exposed to 1,4-Benzoquinone

Hematopoietic stem/progenitor cells (HSPCs) are susceptible to benzene-induced genotoxicity. However, little is known about the mechanism of DNA damage response affecting lineage-committed progenitors for myeloid, erythroid, and lymphoid. Here, we investigated the genotoxicity of a benzene metabolite, 1,4-benzoquinone (1,4-BQ), in HSPCs using oxidative stress and lineage-directed approaches. Mouse bone marrow cells (BMCs) were exposed to 1,4-BQ (1.25–12 μM) for 24 h, followed by oxidative stress and genotoxicity assessments. Then, the genotoxicity of 1,4-BQ in lineage-committed progenitors was evaluated using colony forming cell assay following 7–14 days of culture. 1,4-BQ exposure causes significant decreases (p < 0.05) in glutathione level and superoxide dismutase activity, along with significant increases (p < 0.05) in levels of malondialdehyde and protein carbonyls. 1,4-BQ exposure induces DNA damage in BMCs by significantly (p < 0.05) increased percentages of DNA in tail at 7 and 12 μM and tail moment at 12 μM. We found crucial differences in genotoxic susceptibility based on percentages of DNA in tail between lineage-committed progenitors. Myeloid and pre-B lymphoid progenitors appeared to acquire significant DNA damage as compared with the control starting from a low concentration of 1,4-BQ exposure (2.5 µM). In contrast, the erythroid progenitor showed significant damage as compared with the control starting at 5 µM 1,4-BQ. Meanwhile, a significant (p < 0.05) increase in tail moment was only notable at 7 µM and 12 µM 1,4-BQ exposure for all progenitors. Benzene could mediate hematological disorders by promoting bone marrow oxidative stress and lineage-specific genotoxicity targeting HSPCs.

A Quantitative Meta-Analysis of the Relation between Occupational Benzene Exposure and Biomarkers of Cytogenetic Damage

BACKGROUND

The genotoxicity of benzene has been investigated in dozens of biomonitoring studies, mainly by studying (classical) chromosomal aberrations (CAs) or micronuclei (MN) as markers of DNA damage. Both have been shown to be predictive of future cancer risk in cohort studies and could, therefore, potentially be used for risk assessment of genotoxicity-mediated cancers.

OBJECTIVES

We sought to estimate an exposure-response curve (ERC) and quantify between-study heterogeneity using all available quantitative evidence on the cytogenetic effects of benzene exposure on CAs and MN respectively.

METHODS

We carried out a systematic literature review and summarized all available data of sufficient quality using meta-analyses. We assessed the heterogeneity in slope estimates between studies and conducted additional sensitivity analyses to assess how various study characteristics impacted the estimated ERC.

RESULTS

Sixteen CA (1,356 individuals) and 13 MN studies (2,097 individuals) were found to be eligible for inclusion in a meta-analysis. Studies where benzene was the primary genotoxic exposure and that had adequate assessment of both exposure and outcomes were used for the primary analysis. Estimated slope estimates were an increase of 0.27% CA [(95% CI: 0.08%, 0.47%); based on the results from 4 studies] and 0.27% MN [(95% CI: -0.23%, 0.76%); based on the results from 7 studies] per parts-per-million benzene exposure. We observed considerable between-study heterogeneity for both end points (I2>90%).

DISCUSSION

Our study provides a systematic, transparent, and quantitative summary of the literature describing the strong association between benzene exposure and accepted markers of genotoxicity in humans. The derived consensus slope can be used as a best estimate of the quantitative relationship between real-life benzene exposure and genetic damage in future risk assessment. We also quantitate the large between-study heterogeneity that exists in this literature, a factor which is crucial for the interpretation of single-study or consensus slopes. https://doi.org/10.1289/EHP6404.

Occupational benzene exposure and the risk of genetic damage: a systematic review and meta-analysis

Background

Benzene, an important component of organic solvents, is commonly used in industry. Meanwhile, benzene is a human carcinogen leading to leukemia. Although the links between benzene and various types of genetic damage indicators have been evaluated in several studies, but their results remain inconsistent. So we conducted a meta-analysis, and to explore the influence of low concentration benzene exposure on workers’ genetic damage indicators using 3.25 mg/m³ as the boundary value, in order to provide a basis for improved prevention and control of the harm from benzene exposure to the occupational population.

Methods

We conducted a search of five databases, including Pub Med, Web of Science, China National Knowledge Infrastructure (CNKI), Wan Fang Data and Chongqing VIP, to identify relevant articles up to December 25, 2018. Two researchers independently extracted and evaluated the data according to the inclusion and exclusion criteria of the literature. The imported articles were managed by Endnote X7, and the data were extracted and sorted by Excel 2013. We utilized Stata 12.0 software to perform the meta-analysis in the present study.

Results

A total of 68 eligible articles were finally included for the synthetic analyses. The meta-analysis results showed that occupational benzene exposure led to significantly increased Micronucleus (MN) frequency, Sister chromatid exchange (SCE) frequency, Chromosome aberration (CA) frequency, Olive Tail moment (OTM), Tail moment (TM), Tail length (TL), and Tail DNA% (T DNA%) compared to the control group (P < 0.05), and the pooled effect value estimates were 1.36, 0.98, 0.76, 1.06, 0.96, 1.78, and 1.42, respectively. Subsequent analysis of the effect of low concentration benzene exposure on genetic damage found significantly increased MN frequency increased compared with the control group (P < 0.05).

Conclusions

Occupational benzene exposure can affect multiple genetic damage indicators. Even at an exposure concentration lower than 3.25 mg/m³, benzene exposure has genotoxicity. These data provide an important scientific basis for the further revision of occupational disease prevention strategies. At the same time, increased attention should be focused on the health monitoring of the occupational population exposed to benzene, and health management should be strengthened to improve the health of the occupational population.

The genotoxicity of an organic solvent mixture: A human biomonitoring study and translation of a real-scenario exposure to in vitro

This study aimed to evaluate occupational exposure to a styrene and xylene mixture through environmental exposure assessment and identify the potential genotoxic effects through biological monitoring. Secondly, we also exposed human peripheral blood cells in vitro to both xylene and styrene either alone or in mixture at concentrations found in occupational settings in order to understand their mechanism of action. The results obtained by air monitoring were below the occupational exposure limits for both substances. All biomarkers of effect, except for nucleoplasmic bridges, had higher mean values in workers (N = 17) compared to the corresponding controls (N = 17). There were statistically significant associations between exposed individuals and the presence of nuclear buds and oxidative damage. As for in vitro results, there was no significant influence on primary DNA damage in blood cells as evaluated by the comet assay. On the contrary, we did observe a significant increase of micronuclei and nuclear buds, but not nucleoplasmic bridges upon in vitro exposure. Taken together, both styrene and xylene have the potential to induce genomic instability either alone or in combination, showing higher effects when combined. The obtained data suggested that thresholds for individual chemicals might be insufficient for ensuring the protection of human health.

DNA damage analysis concerning GSTM1 and GSTT1 gene polymorphism in gold jewellery workers from Peshawar Pakistan

PURPOSE

To evaluate the genotoxic effects of gold jewellery fumes and its association with GSTM1 and GSTT1 genetic polymorphisms.

MATERIALS AND METHODS

We examined 94 subjects including 54 gold jewellery workers and 40 controls. The DNA damage was evaluated by alkaline comet assay and genotyping by PCR.

RESULTS

The mean total comet score (TCS) in gold jewellery workers was significantly higher as compared to the control subjects (128.0 ± 60.6 versus 47.7 ± 21.4; p = 0.0001). Duration of occupational exposure had positive correlation (r = 0.453, p < 0.01) with DNA damage. Age and tobacco use had significant effects on the TCS of the exposed group as compared to the control group (p < 0.05). The frequency of the GSTM1-null genotype in the exposed group was significant (p = 0.004) as compared to the control group. No significant association (p > 0.05) between the GSTM1 and GSTT1 genotypes and DNA damage was found.

CONCLUSIONS

Our results suggest that there is increased DNA damage in gold jewellery workers due to their occupational surroundings. Hence there is a strong need to educate the workers about the adverse health effects of potentially hazardous chemicals and highlight the importance of using protective measures.

Biomarkers of susceptibility and effect in car painters exposed to organic solvents

Introduction

Car painters are routinely exposed to organic solvents classified as carcinogenic and mutagenic substances.

Objective

To characterize the population susceptibility and evaluate the genotoxic effects of exposure to organic solvents.

Methods

A cross-sectional study comparing a group of car painters exposed to organic solvents with a non-exposed group. CYP2E1 polymorphisms and the presence of micronuclei in lymphocytes were determined.

Results

One hundred twenty-two workers participated in the study: 62 who worked in car paint shops and were exposed to solvents, and 60 who were not exposed. There were statistically significant differences between the two groups regarding micronucleated cells and nucleoplasmic bridges frequencies (p= 0.042 and p= 0.046, respectively; exact likelihood ratio). Significant differences were found at the interaction between the CYP2E1 genotype c1c1 and occupational exposure to solvents, with higher frequencies of micronuclei (p= 0.013) and micronucleated cells (p= 0.015). However, when the frequencies of micronuclei, micronucleated cells and nucleoplasmic bridges in the exposure group were compared between the c1c1 and c2c2/c1c2 allele groups of the CYP2E1 polymorphism, statistically significant differences were found.

Conclusions

This study confirms that when workers with CYP2E1 polymorphisms, specifically the c1c1 genotype, are exposed to organic solvents, they are more likely to have somatic cell mutations, a condition associated with increased susceptibility to diseases such as cancer.

Catalytic pyrolysis of biomass wastes over Org-CaO/Nano-ZSM-5 to produce aromatics: Influence of catalyst properties

Catalytic pyrolysis of biomass wastes is a promising way to produce aromatics. Based on the conventional CaO/ZSM-5 system, this study aims to improve the aromatics yields by developing an upgraded system which combined nanosized ZSM-5 with CaO from organic calcium precursors (Org-CaO/NZSM-5). The results showed that the aromatics proportion in bio-oil from pyrolysis of Jatropha de-oiled cake with Org-CaO/NZSM-5 increased to 93%. The corresponding yield of BTX (benzene, toluene and xylene) and naphthalene was around 70% which was almost twice than that with conventional CaO/ZSM-5. Org-CaO showed better thermal cracking ability and deoxygenation with more hydrocarbons intermediates and higher H/C_eff of vapors, contributing to enhanced formation of BTX over NZSM-5. NZSM-5 contained much more mesopores and acid sites on external surface, promoting higher conversion of bulky molecules into naphthalenes. Compared with peanut shell, corncob and bagasse pyrolysis, Jatropha de-oiled cake pyrolysis produced much higher aromatics with Org-CaO/NZSM-5.

Evaluation of oxidative and methylating DNA damage in painters occupationally exposed to organic solvents and paints

Introduction: The exposure to organic solvents and paints has been associated with genotoxicity and a greater risk of neoplasms. However, the type of DNA damage induced in humans by the exposure to these compounds, which would help explain the mechanisms of their genotoxicity, is still not fully characterized. Due to inadequate practices of occupational safety, car painters in the informal sector are a highly exposed group to organic solvents and paints. Objective: To identify the oxidative and methylating damage in the DNA of lymphocytes of car painters exposed to organic solvents and paints. Materials and methods: Isolated peripheral blood lymphocytes from 62 painters and 62 unexposed subjects were analyzed by the modified high-throughput comet assay with the Fpg and AlkA enzymes. The categories used for the evaluation of the DNA damage were basal damage (without enzymes), oxidative and methylating damage. The measurement parameter used to establish the damage was the percentage of DNA in the tail. Results: The percentage of DNA in the tail was higher in the exposed group compared to the unexposed group (p<0.05). In the exposed group, this percentage was higher in the oxidative damage category than the baseline (16.50 vs. 12.87; p<0.001), whereas methylating damage did not show significant differences (14.00 vs. 12.87; p>0.05). Conclusion: In this study, exposure to organic solvents and paints was associated with an increase in oxidative lesions in the DNA of car painters’ lymphocytes, such as the production of 8-oxodG and other formamidopyrimidine products which are considered highly mutagenic.

Integrative study of cell damage and cancer risk in gas station attendants

Gas station attendants are potentially exposed to carcinogenic substances. This study aimed to evaluate chronic occupational exposed gas station attendant's according to genetic parameters and its relationship with cancer predisposition. Forty gas station attendants were recruited and paired with 40 control subjects. Thousand cells from each subject were analyzed counting the number of pyknotic (PYC), karyolitic (KYL), karyorrhetic (KHC), condensed chromatin (CC), binucleated (BN), basal cells (BC), Nuclear buds (Nbud), and differentiated cells (DIFF). More 2.000 differentiated cells were analyzed counting micronucleated (MNi) and nuclear buds (NBud). We observed a statistical increase in BC and decrease in DIFF (p < 0.05). PYC, CC, KYL, MN, NBud were statistically increased (p < 0.05). All in all, our data showed elevated DNA damage, chromosomal instability, and cell cycle disturbing in our group of gas station attendants. It is a clear risk for their health in future and could be classified as a cancer predisposition.

Urinary trans-trans muconic acid (exposure biomarker to benzene) and hippuric acid (exposure biomarker to toluene) concentrations in Mexican women living in high-risk scenarios of air pollution

This study aimed to determine t,t-muconic acid (t,t-MA; exposure biomarker for benzene) and hippuric acid (HA; exposure biomarker for toluene) concentrations in the urine of women living in Mexico. In a cross-sectional study, apparently healthy women (n = 104) were voluntarily recruited from localities with a high risk of air pollution; t,t-MA and HA in urine were quantified using a high-performance liquid chromatography (HPLC) technique. Mean urinary levels of t,t-MA ranged from 680 to 1,310 μg/g creatinine. Mean values of HA ranged from 0.38 to 0.87 g/g creatinine. In conclusion, compared to data recently reported in literature, we found high urinary levels of t,t-MA and HA in assessed women participating in this study. We therefore deem the implementation of a strategy aimed at the reduction of exposure as a necessary measure for the evaluated communities.

Assessment of DNA damage in blood lymphocytes of bakery workers by comet assay

The comet assay is widely used in screening and identification of genotoxic effects of different substances on people in either their working or living environment. Exposure to fuel smoke leads to DNA damage and ultimately different types of cancer. Using a comet assay, the present study aimed to assess peripheral blood lymphocyte DNA damage in people working in bakeries using natural gas, kerosene, diesel, or firewood for fuel compared to those in the control group. The subjects of this study were 55 people in total who were divided into four experimental groups, each of which comprised of 11 members (based on the type of fuel used), and one control group comprised of 11 members. Using CometScore, the subjects' peripheral blood lymphocytes were examined for DNA damage. All bakers, that is, experimental subjects, showed significantly greater peripheral blood lymphocyte DNA damage compared to the individuals in the control group. There was greater peripheral blood lymphocyte DNA damage in bakers who had been using firewood for fuel compared to those using other types of fuel to such an extent that tail moments (µm) for firewood-burning bakers was 4.40 ± 1.98 versus 1.35 ± 0.84 for natural gas, 1.85 ± 1.33 for diesel, and 2.19 ± 2.20 for kerosene. The results indicated that burning firewood is the greatest inducer of peripheral blood lymphocytes DNA damage in bakers. Nonetheless, there was no significant difference in peripheral blood lymphocyte DNA damage among diesel and kerosene burning bakers.

Avaliação da exposição ocupacional ao benzeno em trabalhadores frentistas e analistas de combustíveis utilizando o Teste Cometa como biomarcador de genotoxicidade

Resumo Introdução: frentistas e analistas de combustíveis estão expostos a vários compostos orgânicos voláteis presentes na gasolina, incluindo benzeno, que se destaca por sua importância toxicológica. Objetivo: avaliar a exposição ocupacional ao benzeno na gasolina, utilizando o Teste Cometa como biomarcador de genotoxicidade em comparação ao ácido trans,trans-mucônico urinário (AttM) como biomarcador de exposição ao benzeno. Métodos: estudo de corte transversal com análises de biomarcadores de exposição e de genotoxicidade em grupo de expostos ocupacionalmente ao benzeno através da gasolina e grupo controle. Resultados: o Teste Cometa mostrou uma média (desvio padrão) de índice de dano, expresso em unidades arbitrárias, no grupo exposto de 28,4 (10,1) significativamente mais elevado do que no grupo não-exposto, 18,4 (10,1). O AttM urinário, em mg/g de creatinina, foi significativamente maior no grupo exposto, 1,13 (0,45), em relação ao grupo não exposto, 0,44 (0,33). Os dois biomarcadores apresentaram boa correlação linear (r=0,81; p<0,05), indicando uma forte associação entre o biomarcador de exposição e o biomarcador de efeito. Conclusão: os resultados sugerem que uma maior exposição ocupacional ao benzeno está associada a um risco aumentado de dano genotóxico entre indivíduos expostos à gasolina.

Induced cytotoxic damage by exposure to gasoline vapors: a study in Sinaloa, Mexico

Gasoline is a blend of organic compounds used in internal combustion engines. Gasoline-station attendants are exposed to gasoline vapors, which pose a potentially mutagenic risk. According to the International Agency for Research on Cancer, exposure to gasoline and engine exhaust is possibly carcinogenic to humans. We determined the frequency of micronucleus and other nuclear abnormalities, such as pyknotic nuclei, chromatin condensation, cells with nuclear buds, karyolytic cells, karyorrhexis, and binucleated cells in buccal mucosal smears of 60 gasoline-station attendants and 60 unexposed controls. In addition, we explored if factors such as smoking habits, alcohol consumption, and worked years exert an additional synergistic cytotoxic effect. There were statistically significant higher frequencies (p < 0.05) of nuclear abnormalities among exposed attendants compared to the controls. No statistical significant (p > 0.05) additional effect of lifestyle habits such as smoking and alcohol consumption or worked years on the cytotoxicity was observed. The results showed that from the beginning exposure to gasoline vapors increased the frequency of nuclear abnormalities in buccal epithelial cells. Our results provide valuable information on cytotoxic damage for an early pre-symptomatic diagnosis.

High chromosomal instability in workers occupationally exposed to solvents and paint removers

BACKGROUND

Painters are exposed to an extensive variety of harmful substances like aromatic hydrocarbons used as solvents and paint removers, some of which have shown clastogenic activity. These substances constitute a complex mixture of chemicals which contain well-known genotoxicants, such as Benzene, Toluene and Xylene. Thus, chronic occupational exposure to such substances may be considered to possess genotoxic risk. In Colombia the information available around the genotoxic damage (Chromosomal and DNA damage) in car paint shop workers is limited and the knowledge of this damage could contribute not only to a better understanding of the carcinogenic effect of this kind of substances but also could be used as biomarkers of occupational exposure to genotoxic agents.

RESULTS

In this study, the genotoxic effect of aromatic hydrocarbons was assessed in peripheral blood lymphocytes of 24 workers occupationally exposed and 24 unexposed donors, by using Cytogenetic analysis and comet assay. A high frequency of Chromosomal alterations was found in the exposed group in comparison with those observed in the unexposed group. Among the total of CAs observed in the exposed group, fragilities were most frequently found (100 %), followed by chromosomal breaks (58 %), structural (41.2 %) and numerical chromosomal alterations (21 %). Numerical chromosomal alterations, fragilities and chromosomal breaks showed significant differences between exposed and unexposed groups. Among the fragilities, fra(9)(q12) was the most frequently observed. DNA damage index was also significantly higher in the exposed group compared to the unexposed group (p < 0.000).

CONCLUSIONS

Our results revealed that occupational exposure to aromatic hydrocarbons is significantly associated with Chromosomal and DNA damage in car paint shops workers and are also indicative of high chromosomal instability. The high frequency of both Chromosomal Alterations and DNA Damage Index observed in this study indicates an urgent need of intervention not only to prevent the increased risk of developing cancer but also to the application of strict health control and motivation to the use of appropriate protecting devices during work.

Assessment of DNA damage in car spray painters exposed to organic solvents by the high-throughput comet assay

Occupational exposure as a painter is associated with DNA damage and development of cancer. Comet assay has been widely adopted as a sensitive and quantitative tool for DNA damage assessment at the individual cell level in populations exposed to genotoxics. The aim of this study was to assess the application of the high-throughput comet assay, to determine the DNA damage in car spray painters. The study population included 52 car spray painters and 52 unexposed subjects. A significant increase in the %TDNA median (p <  0.001) was observed in the exposed group in comparison to the unexposed group. Neither age (%TDNA: p =  0.913) nor time of exposure (%TDNA: p = 0.398) were significantly correlated with DNA damage. The car spray painters who consumed alcohol did not show a significant increase in DNA damage compared to nonalcohol consumers (p  > 0.05). The results showed an increase in DNA breaks in car spray painters exposed to organic solvents and paints; furthermore, they demonstrated the application of high-throughput comet assay in an occupational exposure study to genotoxic agents.

Follow-Up Genotoxic Study: Chromosome Damage Two and Six Years after Exposure to the Prestige Oil Spill

BACKGROUND

The north-west coast of Spain was heavily contaminated by the Prestige oil spill, in 2002. Individuals who participated in the clean-up tasks showed increased chromosome damage two years after exposure. Long-term clinical implications of chromosome damage are still unknown.

OBJECTIVE

To realize a follow-up genotoxic study to detect whether the chromosome damage persisted six years after exposure to the oil.

DESIGN

Follow-up study.

SETTING

Fishermen cooperatives in coastal villages.

PARTICIPANTS

Local fishermen who were highly exposed (n = 52) and non-exposed (n = 23) to oil seven years after the spill.

MEASUREMENTS

Chromosome damage in circulating lymphocytes.

RESULTS

Chromosome damage in exposed individuals persists six years after oil exposure, with a similar incidence than those previously detected four years before. A surprising increase in chromosome damage in non-exposed individual was found six years after Prestige spill vs. those detected two years after the exposure.

LIMITATIONS

The sample size and the possibility of some kind of selection bias should be considered. Genotoxic results cannot be extrapolated to the approximately 300,000 individuals who participated occasionally in clean-up tasks.

CONCLUSION

The persistence of chromosome damage detected in exposed individuals six years after oil exposure seems to indicate that the cells of the bone marrow are affected. A surprising increase in chromosome damage in non-exposed individuals detected in the follow-up study suggests an indirect exposition of these individuals to some oil compounds or to other toxic agents during the last four years. More long-term studies are needed to confirm the presence of chromosome damage in exposed and non-exposed fishermen due to the association between increased chromosomal damage and increased risk of cancer. Understanding and detecting chromosome damage is important for detecting cancer in its early stages. The present work is the first follow-up cytogenetic study carried out in lymphocytes to determine genotoxic damage evolution between two and six years after oil exposure in same individuals.

Increased levels of chromosomal aberrations and DNA damage in a group of workers exposed to formaldehyde

Formaldehyde (FA) is a commonly used chemical in anatomy and pathology laboratories as a tissue preservative and fixative. Because of its sensitising properties, irritating effects and cancer implication, FA accounts probably for the most important chemical-exposure hazard concerning this professional group. Evidence for genotoxic effects and carcinogenic properties in humans is insufficient and conflicting, particularly in regard to the ability of inhaled FA to induce toxicity on other cells besides first contact tissues, such as buccal and nasal cells. To evaluate the effects of exposure to FA in human peripheral blood lymphocytes, a group of 84 anatomy pathology laboratory workers exposed occupationally to FA and 87 control subjects were tested for chromosomal aberrations (CAs) and DNA damage (comet assay). The level of exposure to FA in the workplace air was evaluated. The association between genotoxicity biomarkers and polymorphic genes of xenobiotic-metabolising and DNA repair enzymes were also assessed. The estimated mean level of FA exposure was 0.38±0.03 ppm. All cytogenetic endpoints assessed by CAs test and comet assay % tail DNA (%TDNA) were significantly higher in FA-exposed workers compared with controls. Regarding the effect of susceptibility biomarkers, results suggest that polymorphisms in CYP2E1 and GSTP1 metabolic genes, as well as, XRCC1 and PARP1 polymorphic genes involved in DNA repair pathways are associated with higher genetic damage in FA-exposed subjects. Data obtained in this study show a potential health risk situation of anatomy pathology laboratory workers exposed to FA (0.38 ppm). Implementation of security and hygiene measures may be crucial to decrease risk. The obtained information may also provide new important data to be used by health care programs and by governmental agencies responsible for occupational health and safety.

Early hematological and immunological alterations in gasoline station attendants exposed to benzene

INTRODUCTION

Elucidation of effective biomarkers may provide tools for the early detection of biological alterations caused by benzene exposure and may contribute to the reduction of occupational diseases. This study aimed to assess early alterations on hematological and immunological systems of workers exposed to benzene.

METHODS

Sixty gasoline station attendants (GSA group) and 28 control subjects were evaluated. Environmental and biological monitoring of benzene exposure was performed in blood and urine. The potential effect biomarkers evaluated were δ-aminolevulinate dehydratase (ALA-D) activity, CD80 and CD86 expression in lymphocytes and monocytes, and serum interleukin-8 (IL-8). The influence of confounding factors and toluene co-exposure were considered.

RESULTS

Although exposures were below ACGIH (American Conference of Governmental Industrial Hygienists) limits, reduced ALA-D activity, decreased CD80 and CD86 expression in monocytes and increased IL-8 levels were found in the GSA group compared to the control subjects. Furthermore, according to multiple linear regression analysis, benzene exposure was associated to a decrease in CD80 and CD86 expression in monocytes.

CONCLUSIONS

These findings suggest, for the first time, a potential effect of benzene exposure on ALA-D activity, CD80 and CD86 expression, IL-8 levels, which could be suggested as potential markers for the early detection of benzene-induced alterations.

Genotoxic and hematological effects in children exposed to a chemical mixture in a petrochemical area in Mexico

Children living in Coatzacoalcos, Veracruz, and in nearby surrounding areas are exposed to a mixture of pollutants from different sources. Previous studies in the area have reported genotoxic and haematotoxic compounds, such as lead (Pb), benzene, toluene, and polycyclic aromatic hydrocarbons (PAHs), in environmental and biological samples. The final toxic effects of these compounds are unknown because the toxic behaviour of each compound is modified when in a complex mixture. This is the first study on the exposure and effect of chemical mixtures on children who live near a petrochemical area. The aim of this study was to evaluate genotoxicity and haematological effects in children environmentally exposed to such mixtures and to determine whether the final effect was modified by the composition of the mixture composition. Biomarkers of exposure to Pb, benzene, toluene, and PAHs were quantified in urine and blood samples of 102 children. DNA damage was evaluated using comet assay, and haematological parameters were determined. Our results show that Pb and toluene did not surpass the exposure guidelines; the exposure was similar in all three localities (Allenede, Mundo Nuevo, and López Mateos). In contrast, exposure to PAHs was observed at three levels of exposure: low, medium, and high. The most severe effects of these mixtures were strictly related to coexposure to high levels of PAHs.

In vitro analysis of the phytotoxic and genotoxic potential of Aligarh wastewater and Mathura refinery wastewater

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Phytotoxicity and genotoxicity suggests highly toxic nature of test wastewaters i.e. Aligarh wastewater and Mathura refinery wastewater.

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The IC₅₀ value in Allium cepa root growth inhibition test was recorded to be 0.14X and 0.10X for Mathura refinery and Aligarh industrial wastewaters, respectively.

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Significant decline in the survival of various E. coli K12 DNA repair defective mutants was observed when the tester strains were exposed to the test wastewaters.

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Chromosomal aberration test suggested considerable amount of chromosomal abnormalities brought about by test wastewaters.

Present report deals with the phytotoxicity and genotoxicity of Mathura refinery wastewater and Aligarh wastewater of Northern India. The IC₅₀ value in Allium cepa root growth inhibition test was recorded to be 0.14X and 0.10X for Mathura refinery and Aligarh industrial wastewaters, respectively. Significant decline in the survival of various Escherichia coli K12 DNA repair defective mutants was observed when the tester strains were exposed to the aforementioned samples. The order of sensitivity was invariably as: AB1157 (wild type) < AB2494 (lexA mutant) < AB2463 (recA mutant) < AB2480 (uvrA recA double mutant). These results suggested a significant amount of DNA damage within the bacterial cells exposed to test wastewaters. A. cepa genotoxicity test also demonstrated a considerable amount of chromosomal damage of A. cepa brought about by the test samples. The aberration index (A.I.) for Aligarh wastewater and refinery wastewater was recorded to be 11.2% and 14.7%, respectively, whereas the aquaguard mineral water serving as negative control displayed the A.I. value to be 2.6%. Interestingly, genotoxicity of both industrial wastewaters was reduced to a remarkable extent in presence of mannitol, the hydroxyl radical scavenger. Present study clearly indicated a distinct pattern of the chromosomal aberrations showing predominantly stickiness and stray chromosomes in case of AWW while clumping and stickiness in case of RWW, thereby affirming the genotoxicity of both test waters.

Evaluation of genotoxic effects of benzene and its derivatives in workers of gas stations

The search for reliable biomarkers of human exposure to benzene and its derivatives is still subject of research. Many of the proposed biomarkers have limitations ranging from the low sensitivity to the wide variability of results. Thus, the aim of our study was to assess the frequencies of chromosomal abnormalities (CA) and sister chromatid exchanges (SCE) in workers of gas stations, with (cases, n = 19) and without (local controls, n = 6) risk of exposure to benzene and its derivatives, comparing them with the results from the general population (external controls, n = 38). The blood dosages of benzene, toluene, and xylenes were measured in all participants. Blood solvent levels were compared with the findings obtained in cytogenetic evaluation and a research protocol which included data of the workplace, lifestyle, and health of the individuals. We did not detect the presence of benzene and its derivatives and did not find chromosomal damage that may be associated with the gas station activity in cases. Moreover, although we found an association of increased SCE and the working time in the local controls, the values found for SCE are within normal limits. Thus, our evaluation of SCE and CA reflected the levels of benzene and its derivatives observed in the blood. We believe, therefore, that SCE and CA may actually constitute possible tests for the evaluation of these exposures. However, we believe that further studies, including individuals at risk, are important to confirm this assertion.

Is organic farming safer to farmers' health? A comparison between organic and traditional farming

Exposure to pesticides is a major public health concern, because of the widespread distribution of these compounds and their possible long term effects. Recently, organic farming has been introduced as a consumer and environmental friendly agricultural system, although little is known about the effects on workers' health. The aim of this work was to evaluate genetic damage and immunological alterations in workers of both traditional and organic farming. Eighty-five farmers exposed to several pesticides, thirty-six organic farmers and sixty-one controls took part in the study. Biomarkers of exposure (pyrethroids, organophosphates, carbamates, and thioethers in urine and butyrylcholinesterase activity in plasma), early effect (micronuclei in lymphocytes and reticulocytes, T-cell receptor mutation assay, chromosomal aberrations, comet assay and lymphocytes subpopulations) and susceptibility (genetic polymorphisms related to metabolism - EPHX1, GSTM1, GSTT1 and GSTP1 - and DNA repair-XRCC1 and XRCC2) were evaluated. When compared to controls and organic farmers, pesticide farmers presented a significant increase of micronuclei in lymphocytes (frequency ratio, FR=2.80) and reticulocytes (FR=1.89), chromosomal aberrations (FR=2.19), DNA damage assessed by comet assay (mean ratio, MR=1.71), and a significant decrease in the proportion of B lymphocytes (MR=0.88). Results were not consistent for organic farmers when compared to controls, with a 48% increase of micronuclei in lumphocytes frequency (p=0.016) contrasted by the significant decreases of TCR-Mf (p=0.001) and %T (p=0.001). Our data confirm the increased presence of DNA damage in farmers exposed to pesticides, and show as exposure conditions may influence observed effects. These results must be interpreted with caution due to the small size of the sample and the unbalanced distribution of individuals in the three study groups.

Modeling of human exposure to benzene in urban environments

Urban areas characterized by high spatial and temporal variability in air pollution levels require implementation of comprehensive approaches to address exposure of individuals. The main objective of this study was to implement a quantitative assessment of individual exposure to benzene in urban environments. For this purpose, ExPOSITION model based on a global positioning system (GPS) tracking approach was applied to estimate individual exposure in different microenvironments. The current investigation provides an application example and validation of the modeling approach against personal and biological exposure measurements collected during the measurements campaign. The probabilistic approach using the Johnson system of distributions was implemented to characterize variability of indoor concentrations. The results obtained for daily average individual exposure to benzene corresponded to mean levels of 1.6 and 0.8-2.7 μg/m(3) in terms of 5th-95th percentiles. Validation of the model results against several personal exposure samples collected for the selected individuals revealed a Pearson's correlation coefficient of .66. This modeling approach explicitly addressed the temporal and spatial variability in the exposure and established a source-receptor relationship.

Genotoxic effect of exposure to metal(loid)s. A molecular epidemiology survey of populations living and working in Panasqueira mine area, Portugal

Previous studies investigating the exposure to metal(loid)s of populations living in the Panasqueira mine area of central Portugal found a higher internal dose of elements such as arsenic, chromium, lead, manganese, molybdenum and zinc in exposed individuals. The aims of the present study were to evaluate the extent of genotoxic damage caused by environmental and occupational exposure in individuals previously tested for metal(loid) levels in different biological matrices, and the possible modulating role of genetic polymorphisms involved in metabolism and DNA repair. T-cell receptor mutation assay, comet assay, micronucleus (MN) test and chromosomal aberrations (CA) were performed in a group of 122 subjects working in the Panasqueira mine or living in the same region. The modifying effect of polymorphisms in GSTA2, GSTM1, GSTP1, GSTT1, XRCC1, APEX1, MPG, MUTYH, OGG1, PARP1, PARP4, ERCC1, ERCC4, and ERCC5 genes was investigated. Significant increases in the frequency of all biomarkers investigated were found in exposed groups, however those environmentally exposed were generally higher. Significant influences of polymorphisms were observed for GSTM1 deletion and OGG1 rs1052133 on CA frequencies, APEX1 rs1130409 on DNA damage, ERCC1 rs3212986 on DNA damage and CA frequency, and ERCC4 rs1800067 on MN and CA frequencies. Our results show that the metal(loid) contamination in the Panasqueira mine area induced genotoxic damage both in individuals working in the mine or living in the area. The observed effects are closely associated to the internal exposure dose, and are more evident in susceptible genotypes. The urgent intervention of authorities is required to protect exposed populations.

Cytogenetic evaluation and the association with polymorphisms of the CPY1A1 and NR1I3 genes in individuals exposed to BTEX

The gas station attendants are exposed daily to chemical agents that compose gasoline, such as BTEX (benzene, toluene, ethylbenzene, and xylene), and the exposure to these agents can cause a variety of effects on the human health. Among the various possible cell alterations associated with these exposures are the formation of micronuclei and of binucleated cells which are used as indicators of clastogenic action. Benzene, the main carcinogenic agent, is metabolized to more soluble forms and easily excreted by isoenzymes of cytochrome P450, such as CYP1A1. The CYP1A1 gene is highly polymorphic and one of its allele variations can be detected by the use of restriction endonucleasis MspI and is originated by the transition of a thymine by a cytosine (3798T>C), resulting in the polymorphic allele CYP1A1*2A. The objective of this study was to evaluate the cytogenetic damage induced by the exposure to BTEX and to associate it with the polymorphisms of the CYP1A1 and NR1I3 genes. Samples of exfoliated cells from the oral mucosa of 27 gas station attendants and from a control group were collected. The results found show that the group exposed to BTEX presents significantly higher alterations than those in the control group for micronuclei (MN; 6.85 ± 1.33 vs. 2.96 ± 1.91, P < 0.001) and for the total of nuclear alterations observed (MN + binucleated cells (BNC); 9.59 ± 4.73 vs. 5.07 ± 2.21, P < 0.001). When comparing the cytological alterations and the genotypes among the exposed individuals for the polymorphism 3798T>C of the CYP1A1 gene, homozygotes TT present MN + BNC significantly higher than carriers of the allele C (10.88 ± 5.36 vs. 5.33 ± 2.52, P = 0.028). No association was observed in the control group or for the NR1I3 gene. These results show that molecular and cytogenetic data can be used in the future as tools to monitor individuals exposed to such compounds.

Application of micronucleus test and comet assay to evaluate BTEX biodegradation

The BTEX (benzene, toluene, ethylbenzene and xylene) mixture is an environmental pollutant that has a high potential to contaminate water resources, especially groundwater. The bioremediation process by microorganisms has often been used as a tool for removing BTEX from contaminated sites. The application of biological assays is useful in evaluating the efficiency of bioremediation processes, besides identifying the toxicity of the original contaminants. It also allows identifying the effects of possible metabolites formed during the biodegradation process on test organisms. In this study, we evaluated the genotoxic and mutagenic potential of five different BTEX concentrations in rat hepatoma tissue culture (HTC) cells, using comet and micronucleus assays, before and after biodegradation. A mutagenic effect was observed for the highest concentration tested and for its respective non-biodegraded concentration. Genotoxicity was significant for all non-biodegraded concentrations and not significant for the biodegraded ones. According to our results, we can state that BTEX is mutagenic at concentrations close to its water solubility, and genotoxic even at lower concentrations, differing from some described results reported for the mixture components, when tested individually. Our results suggest a synergistic effect for the mixture and that the biodegradation process is a safe and efficient methodology to be applied at BTEX-contaminated sites.

Aromatic DNA adducts and number of lung cancer risk alleles in Map-Ta-Phut Industrial Estate workers and nearby residents

The Map-Ta-Phut Industrial Estate (MIE) in Rayong, Thailand, is the location of one of the largest industrial complexes in southeastern Asia. The MIE complex produces a mixture of air pollutants, including polycyclic aromatic hydrocarbons, compounds capable to induce the generation of DNA adducts. DNA adducts are considered to be a biomarker of carcinogen exposure; however, its production can be modulated by genetic susceptibility. Thus, we analysed the influence of EPHX1 His139Arg (A>G, rs2234922) and NQO1 Pro187Ser (C>T, rs1800566) involved in the metabolism of polycyclic aromatic hydrocarbons; MnSOD(2) Val16Ala (C>T, rs1799725) a gene that acts against the free radical generation; APE1/Ref-1 Asp148Glu (T>G, rs3136820) a gene involved in the repair of DNA, and in the control of cell-cycle and apoptosis on leucocyte DNA adducts in 77 MIE workers, 69 Map-Ta-Phut residents, and 50 rural controls, Rayong, Thailand. We searched for associations with the 'sum of at-risk alleles' by combining the variant alleles of EPHX1, NQO1 and MnSOD(2) together with the wild-type allele of APE1, since they appeared to influence lung cancer risk. Although our findings revealed significant associations between DNA adducts and the EPHX1 His139Arg and NQO1 Pro187Ser polymorphisms, the combination of at-risk alleles was found to affect DNA damage much stronger. DNA adducts were significantly increased in the individuals bearing 4 and ≥ 5 at-risk alleles [mean ratio (MR) = 1.55, 95% CI 1.10-2.18, P = 0.012, and MR = 2.11, 95% CI 1.27-3.51, P = 0.004, respectively)]. After correction for residence/employment categorisation, a significant increment was present in the MIE workers with ≥ 5 alleles (MR = 2.88, 95% CI 1.46-5.71, P = 0.003). Our data indicate relationships between the generation of DNA adducts and the enzymatic activities of EPHX and NQO1. The combination of unfavourable genetic variants seems to determine the individuals' susceptibility, rather than a single polymorphism.

DNA-damage response associated with occupational exposure, age and chronic inflammation in workers in the automotive industry

The evaluation of genome integrity in populations occupationally exposed to combine industrial factors is of medical importance. In the present study, the DNA-damage response was estimated by means of the alkaline comet assay in a sizeable cohort of volunteers recruited among workers in the automotive industry. For this purpose, freshly collected lymphocytes were treated with hydrogen peroxide (100μM, 1min, 4°C) in vitro, and the levels of basal and H(2)O(2)-induced DNA damage, and the kinetics and efficiency of DNA repair were measured during a 180-min interval after exposure. The parameters studied in the total cohort of workers were in a range of values prescribed for healthy adult residents of Belarus. Based on the 95th percentiles, individuals possessing enhanced cellular sensitivity to DNA damage were present in different groups, but the frequency was significantly higher among elderly persons and among individuals with chronic inflammatory diseases. The results indicate that the inter-individual variations in DNA-damage response should be taken into account to estimate adequately the environmental genotoxic effects and to identify individuals with an enhanced DNA-damage response due to the influence of some external factors or intrinsic properties of the organism. Underling mechanisms need to be further explored.

Exposure to indoor air pollutants (polycyclic aromatic hydrocarbons, toluene, benzene) in Mexican indigenous women

Indoor air pollution is considered to be a serious public health issue in Mexico; therefore, more studies regarding this topic are necessary. In this context, we assessed exposure to polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds in: (i) women who use firewood combustion (indoor) for cooking and heating using traditional open fire; (ii) women who use firewood combustion (outdoor) for cooking and heating using traditional open fire; and (iii) women who use LP gas as the principal energy source. We studied 96 healthy women in San Luis Potosi, México. Urine samples were collected, and analyses of the following urinary exposure biomarkers were performed by high-performance liquid chromatography: 1-hydroxypyrene (1-OHP), trans, trans-muconic acid, and hippuric acid (HA). The highest levels of 1-OHP, trans, trans-muconic acid, and HA were found in communities where women were exposed to indoor biomass combustion smoke (or products; geometric mean ± s.d., 3.98 ± 5.10 μmol/mol creatinine; 4.81 ± 9.60 μg/l 1-OHP; 0.87 ± 1.78 mg/g creatinine for trans, trans-muconic acid; and 1.14 ± 0.91 g/g creatinine for HA). Our findings indicate higher exposure levels to all urinary exposure biomarkers studied in women who use indoor firewood combustion for cooking and heating (using traditional open fire).

PRACTICAL IMPLICATIONS

High mean levels of 1-hydroxypyrene, t,t-muconic acid, and hippuric acid were found in women who use firewood combustion (indoor) for cooking and heating using traditional open fire and taking into account that millions of women and children in Mexico are living in scenarios similar to those studied in this report, the assessment of health effects in women and children exposed to polycyclic aromatic hydrocarbons and volatile organic compounds is urgently needed. Moreover, it is immediately necessary an intervention program to reduce exposure.

Evaluation of genotoxicity and oxidative damage in painters exposed to low levels of toluene

Toluene is an organic solvent used in numerous processes and products, including industrial paints. Toluene neurotoxicity and reproductive toxicity are well recognized; however, its genotoxicity is still under discussion, and toluene is not classified as a carcinogenic solvent. Using the comet assay and the micronucleus test for detection of possible genotoxic effects of toluene, we monitored industrial painters from Rio Grande do Sul, Brazil. The putative involvement of oxidative stress in genetic damage and the influences of age, smoking, alcohol consumption, and exposure time were also assessed. Although all biomarkers of toluene exposure were below the biological exposure limits, painters presented significantly higher DNA damage (comet assay) than the control group; however, in the micronucleus assay, no significant difference was observed. Painters also showed alterations in hepatic enzymes and albumin levels, as well as oxidative damage, suggesting the involvement of oxidative stress. According to multiple linear regression analysis, blood toluene levels may account for the increased DNA damage in painters. In summary, this study showed that low levels of toluene exposure can cause genetic damage, and this is related to oxidative stress, age, and time of exposure.

Cellular damages in the Allium cepa test system, caused by BTEX mixture prior and after biodegradation process

Petroleum and derivatives have been considered one of the main environmental contaminants. Among petroleum derivatives, the volatile organic compounds benzene, toluene, ethylbenzene and xylene (BTEX) represent a major concern due to their toxicity and easy accumulation in groundwater. Biodegradation methods seem to be suitable tools for the clean-up of BTEX contaminants from groundwater. Genotoxic and mutagenic potential of BTEX prior and after biodegradation process was evaluated through analyses of chromosomal aberrations and MN test in meristematic and F(1) root cells using the Allium cepa test system. Seeds of A. cepa were germinated into five concentrations of BTEX, non-biodegraded and biodegraded, in ultra-pure water (negative control), in MMS 4×10(-4)M (positive control) and in culture medium used in the biodegradation (blank biodegradation control). Results showed a significant frequency of both chromosomal and nuclear aberrations. The micronucleus (MN) frequency in meristematic cells was significant for most of tested samples. However, MN was not present in significant levels in the F(1) cells, suggesting that there was no permanent damage for the meristematic cell. The BTEX effects were significantly reduced in the biodegraded samples when compared to the respective non-biodegraded concentrations. Therefore, in this study, the biodegradation process showed to be a reliable and effective alternative to treat BTEX-contaminated waters. Based on our results and available data, the BTEX toxicity could also be related to a synergistic effect of its compounds.

Cytogenetic biomonitoring on a group of petroleum refinery workers

Workers employed in petroleum refineries are exposed to a wide range of toxic compounds (benzene, polycyclic aromatic hydrocarbons, heavy metals, etc.) with known mutagenic and carcinogenic potential. In this study, we investigated by using the cytokinesis block micronucleus (CBMN) assay on human peripheral blood lymphocytes (PBL) whether general occupational exposure in petroleum refineries resulted in early biological effects, which would be indicative of adverse health effects in the long term. In this study, out of more 500 workers enrolled in the study, 79 male subjects (46 nonsmokers and 33 smokers), employed in two different Italian petroleum refineries, and a total of 50 male control subjects (34 nonsmokers and 16 smokers) were selected by using very strict selection criteria. The comparison of chromosome damage in PBL between exposed and control populations pointed out a significant increase of micronuclei in the exposed group, correlated with the length of employment. Results confirm that smoking is the principal confounding factor for the responses. In conclusion, our results are indicative of a potential genotoxic risk related to the complex occupational exposure in petroleum refineries, despite the measures adopted in the plants, and corroborate the need to increase safety measures to avoid exposure to chemical agents.

Determination of genetic damage and urinary metabolites in fuel filling station attendants

Fuel (diesel and petrol) constitutes a complex mixture of volatile flammable liquid hydrocarbons among them benzene (BZ), toluene (TOL), and xylene (XYL) are considered to be the most hazardous, predominantly BZ because of its carcinogenic potency. Exposure to these compounds may have an impact on the health of the exposed subjects. Hence, genotoxicity and quantitative analysis of these compounds was performed in blood and urine samples of 200 workers exposed to fuel in filling stations and compared to controls. The level of genetic damage was determined by micronucleus test (MNT) in buccal epithelial cells (BEC) and chromosomal aberrations (CA) assay in peripheral blood lymphocytes (PBL) of fuel filling station attendants (FFSA) and compared to a matched control group. Urine analysis for BZ and its metabolites, phenol (Ph), trans, trans-Muconic Acid (t, t-MA), and S-Phenyl Mercapturic Acid (S-PMA) was done in all the study subjects. The results of our study revealed that exposure to BTX in petrol vapors induced a statistically significant increase in the frequency of micronuclei (MN) and CA in the exposed subjects than in controls (P < 0.05). There was a significant rise in the levels of urinary BZ, Ph, t, t-MA, and S-PMA in the exposed subjects. Our study highlights the significance of MNT, CA, and urinary metabolites as potential biological exposure indices of genetic damage in FFSA. This study suggests the need for regular monitoring of FFSA for possible exposure to BTX as a precautionary and preventive step to minimize exposure and reduce the associated health risks.

Assessment of occupational cytogenetic risk, among petrol station workers

The focal aim of this study was to assess the frequency of chromosomal aberrations (CA) including chromatid type aberrations (CTA) and chromosomal type aberrations (CSA), micronucleus (MN) and XRCC1 399 Arg/Gln polymorphism in the peripheral blood lymphocytes of 27 petrol pump workers and same number of controls to explore the possible cytogenetic risk on occupational exposure to petrol vapors. The exposed subjects and controls were classified into two groups based on their age (group I < 40 years; group II > 40 years) apart from the classification of the exposed subjects based on their exposure duration (> 8 and < 8 years). CTA and MN frequency were significantly higher in petrol pump workers (p < 0.05) with longer work duration. CTA was found to increase with age in the exposed subjects as well as controls, with exposed subjects showing a statistically higher degree. This effect was not observed in MN. A significantly higher frequency of MN was observed in the smoking petrol pump workers than in control smokers (p < 0.05). No association was found between smoking and CA in both subjects. The study on XRCC1 399 Arg/gln polymorphism in petrol pump workers demonstrated very less difference in allele frequency compared to controls. In conclusion, these datas indicate that petrol pump workers under risk group should be monitored for any long-term adverse effects of the exposure.