Multipronged evaluation of genotoxicity in Indian petrol-pump workers

Assessment of genotoxicity biomarkers in gasoline station attendants due to occupational exposure

Gasoline station attendants are exposed to numerous chemicals that might have genotoxic and carcinogenic potential, such as benzene in fuel vapor and particulate matter and polycyclic aromatic hydrocarbons in vehicle exhaust emission. According to IARC, benzene and diesel particulates are Group 1 human carcinogens, and gasoline has been classified as Group 2A "possibly carcinogenic to humans." At gas stations, self-service is not implemented in Turkey; fuel-filling service is provided entirely by employees, and therefore they are exposed to those chemicals in the workplace during all working hours. Genetic monitoring of workers with occupational exposure to possible genotoxic agents allows early detection of cancer. We aimed to investigate the genotoxic damage due to exposures in gasoline station attendants in Turkey. Genotoxicity was evaluated by the Comet, chromosomal aberration, and cytokinesis-block micronucleus assays in peripheral blood lymphocytes. Gasoline station attendants (n = 53) had higher tail length, tail intensity, and tail moment values than controls (n = 61). In gasoline station attendants (n = 46), the frequencies of chromatid gaps, chromosome gaps, and total aberrations were higher compared with controls (n = 59). Increased frequencies of micronuclei and nucleoplasmic bridges were determined in gasoline station attendants (n = 47) compared with controls (n = 40). Factors such as age, duration of working, and smoking did not have any significant impact on genotoxic endpoints. Only exposure increased genotoxic damage in gasoline station attendants independently from demographic and clinical characteristics. Occupational exposure-related genotoxicity risk may increase in gasoline station attendants who are chronically exposed to gasoline and various chemicals in vehicle exhaust emissions.

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.

Linking Benzene, in Utero Carcinogenicity and Fetal Hematopoietic Stem Cell Niches: A Mechanistic Review

Previous research reported that prolonged benzene exposure during in utero fetal development causes greater fetal abnormalities than in adult-stage exposure. This phenomenon increases the risk for disease development at the fetal stage, particularly carcinogenesis, which is mainly associated with hematological malignancies. Benzene has been reported to potentially act via multiple modes of action that target the hematopoietic stem cell (HSCs) niche, a complex microenvironment in which HSCs and multilineage hematopoietic stem and progenitor cells (HSPCs) reside. Oxidative stress, chromosomal aberration and epigenetic modification are among the known mechanisms mediating benzene-induced genetic and epigenetic modification in fetal stem cells leading to in utero carcinogenesis. Hence, it is crucial to monitor exposure to carcinogenic benzene via environmental, occupational or lifestyle factors among pregnant women. Benzene is a well-known cause of adult leukemia. However, proof of benzene involvement with childhood leukemia remains scarce despite previously reported research linking incidences of hematological disorders and maternal benzene exposure. Furthermore, accumulating evidence has shown that maternal benzene exposure is able to alter the developmental and functional properties of HSPCs, leading to hematological disorders in fetus and children. Since HSPCs are parental blood cells that regulate hematopoiesis during the fetal and adult stages, benzene exposure that targets HSPCs may induce damage to the population and trigger the development of hematological diseases. Therefore, the mechanism of in utero carcinogenicity by benzene in targeting fetal HSPCs is the primary focus of this review.

Occupational health hazards and wide spectrum of genetic damage by the organic solvent fumes at the workplace: A critical appraisal

Long-term exposure to organic solvents is known to affect human health posing serious occupational hazards. Organic solvents are genotoxic, and they can cause genetic changes in the exposed employees' somatic or germ cells. Chemicals such as benzene, toluene, and gasoline induce an excessive amount of genotoxicity results either in genetic polymorphism or culminates in deleterious mutations when concentration crosses the threshold limits. The impact of genotoxicity is directly related to the time of exposure, types, and quantum of solvent. Genotoxicity affects almost all the physiological systems, but the most vulnerable ones are the nervous system, reproductive system, and blood circulatory system. Based on the available literature report, we propose to evaluate the outcomes of such chemicals on the exposed humans at the workplace. Attempts would be made to ascertain if the long-term exposure makes a person resistant to such chemicals. This may seem to be a far-fetched idea but has not been studied. The health prospect of this study is envisaged to complement the already existing data facilitating a deeper understanding of the genotoxicity across the population. This would also demonstrate if it correlates with the demographic profile of the population and contributes to comorbidity and epidemiology.

The Health Impacts of Hazardous Chemical Exposures among Child Labourers in Low- and Middle-Income Countries

Of 218 million working children worldwide, many are suspected to be exposed to hazardous chemicals. This review aims to synthesize reported evidence over the last two decades on chemical exposure and adverse health consequences in children labourers in low- and middle-income Countries (LMIC). Included studies investigated health outcomes related to chemical exposures among child labourers aged 5-18 in LMIC. Twenty-three papers were selected for review, focusing on pesticides (n = 5), solvents (n = 3), metals (n = 13) and persistent organic pollutants (POPs) (n = 2). Adverse health effects identified among child labourers included abnormal biomarkers, for example elevated blood and urine chemical concentrations, neurobehavioural deficits and neurological symptoms, mental health issues, oxidative stress and DNA damage, poor growth, asthma, and hypothyroidism. Workplace exposure to chemicals has pernicious health effects on child labourers. Large research gaps exist, in particular for long-term health impacts through chronic conditions and diseases with long latencies. A sizeable disease burden in later life is likely to be directly attributable to chemicals exposures. We urge national and international agencies concerned with child labour and occupational health, to prioritize research and interventions aiming to reduce noxious chemical exposures in workplaces where children are likely to be present.

Biomarkers of Low-Level Environmental Exposure to Benzene and Oxidative DNA Damage in Primary School Children in Sardinia, Italy

Background: The main anthropic sources of exposure to airborne benzene include vehicular traffic, cigarette smoke, and industrial emissions. Methods: To detect early genotoxic effects of environmental exposure to benzene, we monitored environmental, personal, and indoor airborne benzene in children living in an urban area and an area near a petrochemical plant. We also used urinary benzene and S-phenylmercapturic acid (S-PMA) as biomarkers of benzene exposure and urinary 8-hydroxydeoxyguanosine (8-OHdG) as a biomarker of early genotoxic effects. Results: Although always below the European Union limit of 5 μg/m³, airborne benzene levels were more elevated in the indoor, outdoor, and personal samples from the industrial surroundings compared to the urban area (p = 0.026, p = 0.005, and p = 0.001, respectively). Children living in the surroundings of the petrochemical plant had urinary benzene values significantly higher than those from the urban area in both the morning and evening samples (p = 0.01 and p = 0.02, respectively). Results of multiple regression modelling showed that age was a significant predictor of 8-OHdG excretion, independent of the sampling hour. Moreover, at the low exposure level experienced by the children participating in this study, neither personal or indoor airborne benzene level, nor personal monitoring data, affected 8-OHdG excretion. Conclusions: Our results suggest the importance of biological monitoring of low-level environmental exposure and its relation to risk of genotoxic effects among children.

Assessment of BTX Concentration around Fuel Station in Eastern Province Kingdom of Saudi Arabia

Aim:

The aim of this study is to determine the benzene, toluene, and xylenes (BTX) concentration levels in and around fuel station and its expected health risks in the City of Dammam and Al-Khobar, Saudi Arabia.

Method:

Forty fuel dispensing facilities were randomly selected on the basis of three different areas, residential, traffic intersection, and petrol pump locations (refueling stations). coconut shell charcoal cartridges were used for samples collection and portable Ambient Analyzer was used for measuring BTX (benzene, toluene, and xylenes) concentration.

Results:

Results show that the average concentration of benzene, toluene, and xylenes level around fuel stations was 10.30, 4.09, and 2.47 ppm, respectively. All means of concentration values of BTX around residential, traffic intersection, and fuel stations are exceeding the limits of air quality standards values (P < 0.01). The mean concentration of BTX around residential area, side street, and direct street was benzene 8, 12.2, and 11.5 ppm, toluene 2.5, 5.95, and 3.37 ppm, and xylenes 2, 2.13, and 2.7 ppm. Hazard Quotient (HQ) was more than >1 which showed that carcinogenic probability has increased those exposed to this toxic chemical.

Conclusion:

Ambient concentration of BTX was high compare to neighboring residential area and 100 m from the fuel station which can negatively affect on health of several residences. The Environmental contamination associated with BTX in petrol fuel stations impulses the necessity of preventive programs to reduce further air quality deterioration and reduce the expected health risks.

Gasoline-station workers in Brazil: Benzene exposure; Genotoxic and immunotoxic effects

Chronic exposure to benzene is a risk factor for hematological malignancies. Gasoline-station workers are exposed to benzene in gasoline, via both inhalation and dermal contact (attendants and managers) or inhalation (workers in the on-site convenience stores and offices). We have studied the exposure of these workers to benzene and the resulting genotoxic and immunotoxic effects. Levels of urinary trans, trans-muconic acid were higher among gasoline-station workers than among office workers with no known exposure to benzene (comparison group). Among the exposed workers, we observed statistically significant biological effects, including elevated DNA damage (comet assay); higher frequencies of micronuclei and nuclear buds (CBMN assay); lower levels of T-helper lymphocytes and naive Th lymphocytes; lower CD4 / CD8 ratio; and higher levels of NK cells and memory Th lymphocytes. Both groups of exposed workers (inhalation and inhalation + dermal routes) showed similar genotoxic and immunotoxic effects.

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.

The Comet Assay: Assessment of In Vitro and In Vivo DNA Damage

Anthropogenic activities, indiscriminate and rapid industrialization as well as pursuance of a better life has led to an increase in the concentration of chemicals, like pesticides, automobile exhausts, and new chemical entities, in the environment, which have an adverse effect on all living organisms including humans. Sensitive and robust test systems are thus required for accurate hazard identification and risk assessment. The Comet assay has been used widely as a simple, rapid, and sensitive tool for assessment of DNA damage in single cell from both in vitro and in vivo sources as well as in humans. The advantages of the in vivo Comet assay are its ability to detect DNA damage in any tissues, despite having non-proliferating cells, and its sensitivity to detect genotoxicity. The recommendations from the international workshops held for the Comet assay have resulted in establishment of guidelines, and the OECD has adopted a guideline for the in vivo Comet assay as a test for assessing DNA damage in animals. The in vitro Comet assay conducted in cultured cells can be used for screening large number of compounds and at very low concentrations. The in vitro assay has also been automated to provide a high throughput screening method for new chemical entities, as well as in environmental samples. This chapter details the in vitro Comet assay using the 96-well plate and in vivo Comet assay in multiple organs of the mouse.

Genotoxic effects of occupational exposure to benzene in gasoline station workers

Benzene, a hazardous component of gasoline, is a genotoxic class I human carcinogen. This study evaluated the genotoxic effects of occupational exposure to benzene in gasoline stations. Genotoxicity of exposure to benzene was assessed in peripheral blood leucocytes of 62 gasoline station workers and compared with an equal numbers of matched controls using total genomic DNA fragmentation, micronucleus test and cell viability test. An ambient air samples were collected and analyzed for Monitoring of benzene, toluene, ethyl benzene and xylene (BTEX) in work environment and control areas. DNA fragmentation, micronucleus and dead cells percent were significantly higher in exposed workers than controls. Level of benzene, Toluene, Ethyl benzene and xylene in the work environment were higher than the control areas and the permissible limits. Gasoline station workers occupationally exposed to benzene are susceptible to genotoxic effects indicated by increased DNA fragmentation, higher frequency of micronucleus and decreased leukocytes viability.

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.

Oxidative Stress and Genotoxicity of Long-Term Occupational Exposure to Low Levels of BTEX in Gas Station Workers

Atmospheric benzene, toluene, ethylbenzene, and xylenes (BTEX) can lead to multiple health injuries. However, what remains uncertain is the effect of long-term exposure to low levels of BTEX. Thus, we determined the BTEX levels in the air from the refueling and office areas in gas stations. Then we collected workers’ (200 refueling vs. 52 office workers) peripheral blood samples to analyze the serum total-superoxide dismutase (T-SOD), glutathione (GSH), malondialdehyde (MDA), and 8-hydroxydeoxyguanosine (8-OHdG) levels. DNA damage was analyzed by the comet assay and micronucleus test in buccal epithelial cells. We found that the levels of BTEX in refueling areas were significantly higher than those in office areas (p < 0.001). The serum T-SOD and GSH of refueling workers were significantly lower than those in office workers (p < 0.001). By contrast, the serum MDA and 8-OHdG of refueling workers were significantly higher than those of office workers (p < 0.001, MDA; p = 0.025, 8-OHdG). Furthermore, tail and Olive tail moments in refueling workers were longer (p = 0.004, tail moment; p = 0.001, Olive tail moment), and the micronucleus rate was higher (p < 0.001) than those in office workers. Taken together, long-term exposure to low levels of BTEX may reduce the antioxidant ability and increase the risk of DNA damage in refueling workers of gas stations.

DNA damage and repair capacity in workers exposed to low concentrations of benzene

DNA damage and cellular repair capacity were studied in 18 male fuel tanker drivers and 13 male filling-station attendants exposed to low and very low concentrations of benzene, respectively, and compared to 20 males with no occupational exposure (controls). Exposure to airborne benzene was measured using passive personal samplers, and internal doses were assayed through the biomarkers t,t-muconic acid, S-phenylmercapturic acid and urinary benzene. DNA damage was evaluated using tail intensity (TI) determined by the comet assay in peripheral lymphocytes. Urinary 7-hydro-8-oxo-2'-deoxyguanosine (8-oxodG) was measured as a biomarker of oxidative damage. DNA repair kinetics were assessed using the comet assay in lymphocytes sampled 20 and 60 min post H2O2 exposure. Benzene exposure differed significantly between the drivers (median 246.3 µg/m(3)), attendants (median 13.8 µg/m(3)), and controls (median 4.1 µg/m(3)). There were no differences in TI and 8-oxodG among the three groups, or between smokers and non-smokers. DNA repair kinetics were similar among the drivers, attendants and controls, although the comet assay on H2 O2 -damaged lymphocytes after 60 min revealed significantly lower levels of TI only in drivers. The DNA repair process in smokers was similar to that observed in drivers. In conclusion, this study found no relationship between low levels of benzene exposure and DNA damage, although there was evidence that exposure interferes with DNA repair kinetics. The biological impact of this finding on the onset of genotoxic effects in exposed workers has still to be ascertained.

Comet assay based DNA evaluation of fuel filling stations and automobile workshops workers from Khyber Pakhtunkhwa province, Pakistan

BACKGROUND

Fuel filling stations workers and automobile workshops mechanics are consistently exposed to gasoline hydrocarbons during their occupation, this may cause DNA damage. Objective of this study was to evaluate the level of DNA damage in subjects occupationally exposed to these hydrocarbons.

METHODS

Comet assay was performed on blood lymphocytes of exposed subjects to assess the probable DNA damage. 100 cells per individual were scored and graded by comet tail length. Exposed group consisted of 98 subjects (age 25.4 ± 7.2 years), of which 68 were CNG/Petrol filling men and 30 were automobile workshop workers, selected randomly from different service stations and automobile workshops of populated and adjacent cities of Peshawar, Mardan and Nowshera of Khyber Pakhtunkhwa province, while control group included 92 subjects (age 26.7 ± 11.8 years) were also from the same areas.

RESULTS

Significantly high level of DNA damage was found in the subjects exposed to gasoline hydrocarbons as compared to control subjects (173.2 ± 50.1 and 61.0 ± 25.0, P = 0.001, respectively). Period of exposure and use of tobacco also showed considerable effects (P < 0.05) on DNA damage, while effect of age and daily working hours on total comet score (TCS) were non-significant (P > 0.05).

CONCLUSIONS

The results of our study concluded that petroleum hydrocarbons have the potential to cause DNA damage in the exposed subjects. The study also suggested that protective strategies should be implemented by the concerned authorities to minimize exposure to fuel hydrocarbons.

Tobacco use, Body Mass Index, and Potentially Malignant Disorders Among petrol fillers in Pimpri-Pune (India): A descriptive study

Background:

Since petrol is combustible and smoking is banned at the petrol pumps, it may be predicted that use of smokeless tobacco is more prevalent among the petrol fillers. Also, smokeless tobacco is a major risk factor for developing oral potentially malignant disorders. The present study was conducted to determine the tobacco use, body mass index (BMI), and potentially malignant disorders among a cohort of petrol fillers and also to evaluate the interaction of tobacco use and BMI with the presence of potentially malignant disorders.

Settings and Design:

The study was conducted at 45 petrol stations located at Pimpri-Pune, India. A descriptive study design was used.

Materials and Method:

Four hundred and ten petrol fillers aged 17-64 years participated in the study. General information and tobacco history was obtained by interview. Height and weight were recorded to obtain BMI. Oral examination was conducted to identify the potentially malignant disorders.

Statistical analysis:

Chi-square test, Z test, and logistic regression were used. The level of significance was fixed at 5%.

Results and Conclusions:

It was found that 242 (59.02%) used tobacco in different forms. 77.68% were tobacco chewers, and 8.26% were smokers. Leukoplakia was prevalent among 68.47%, oral submucous fibrosis among 27.45%, and 5.08% had erythroplakia. Age (χ² = 11.46, P < 0.05), duration (χ² = 17.46, P < 0.05), and frequency of tobacco chewing (χ² = 14.16, P < 0.05) were significantly associated with potentially malignant disorders. Tobacco chewing was more prevalent as compared to smoking. It can be concluded that the petrol fillers are at a high risk for developing oral potentially malignant disorders.

The comet assay: assessment of in vitro and in vivo DNA damage

Rapid industrialization and pursuance of a better life have led to an increase in the amount of chemicals in the environment, which are deleterious to human health. Pesticides, automobile exhausts, and new chemical entities all add to air pollution and have an adverse effect on all living organisms including humans. Sensitive test systems are thus required for accurate hazard identification and risk assessment. The Comet assay has been used widely as a simple, rapid, and sensitive tool for assessment of DNA damage in single cells from both in vitro and in vivo sources as well as in humans. Already, the in vivo comet assay has gained importance as the preferred test for assessing DNA damage in animals for some international regulatory guidelines. The advantages of the in vivo comet assay are its ability to detect DNA damage in any tissue, despite having non-proliferating cells, and its sensitivity to detect genotoxicity. The recommendations from the international workshops held for the comet assay have resulted in establishment of guidelines. The in vitro comet assay conducted in cultured cells and cell lines can be used for screening large number of compounds and at very low concentrations. The in vitro assay has also been automated to provide a high-throughput screening method for new chemical entities, as well as environmental samples. This chapter details the in vitro comet assay using the 96-well plate and in vivo comet assay in multiple organs of the mouse.

Proposal on limits for chemical exposure in saturation divers' working atmosphere: the case of benzene

Saturation diving is performed under extreme environmental conditions. The divers are confined to a limited space for several weeks under high environmental pressure and elevated oxygen partial pressure. At present, divers are protected against chemical exposure by standard exposure limits only adjusted for the increased exposure length, i.e. from 8 to 24 hours a day and from 5 to 7 days a week. The objective of the present study was to indicate a procedure for derivation of occupational exposure limits for saturation diving, termed hyperbaric exposure limits (HEL). Using benzene as an example, a procedure is described that includes identification of the latest key documents, extensive literature search with defined exclusion criteria for the literature retrieved. Hematotoxicity and leukemia were defined as the critical effects, and exposure limits based upon concentration and cumulative exposure data and corresponding risks of leukemia were calculated. Possible interactions of high pressure, elevated pO₂, and continuous exposure have been assessed, and incorporated in a final suggestion of a HEL for benzene. The procedure should be applicable for other relevant chemicals in the divers' breathing atmosphere. It is emphasized that the lack of interactions from pressure and oxygen indicated for benzene may be completely different for other chemicals.

Chronic inhalation of biomass smoke is associated with DNA damage in airway cells: involvement of particulate pollutants and benzene

This study examined whether indoor air pollution from biomass fuel burning induces DNA damage in airway cells. For this, sputum cells were collected from 56 premenopausal rural women who cooked with biomass (wood, dung, crop residues) and 49 age-matched controls who cooked with cleaner liquefied petroleum gas. The levels of particulate matters with diameters of less than 10 and 2.5 µm (PM(10) and PM(2.5)) in indoor air were measured using a real-time aerosol monitor. Benzene exposure was monitored by measuring trans,trans-muconic acid (t,t-MA) in urine by HPLC-UV. DNA damage was examined by alkaline comet assay in sputum cells. Generation of reactive oxygen species (ROS) and level of superoxide dismutase (SOD) in sputum cells were measured by flow cytometry and spectrophotometry, respectively. Compared with controls, biomass users had 4 times higher tail percentage DNA, 37% more comet tail length and 5 times more Olive tail moment (p < 0.001) in inflammatory and epithelial cells in sputum, suggesting extensive DNA damage. In addition, women who cooked with biomass had 6 times higher levels of urinary t,t-MA and 2-fold higher levels of ROS generation concomitant with 28% depletion of SOD. Indoor air of biomass-using households had 2-4 times more PM(10) and PM(2.5) than that of controls. After controlling potential confounders, positive association was found between DNA damage parameters, particulate pollution, urinary t,t-MA and ROS. Thus, long-term exposure to biomass smoke induces DNA damage in airway cells and the effect was probably mediated, at least in part, by oxidative stress generated by inhaled particulate matter and benzene.

Assessment of impact on health of children working in the garbage dumping site in Dhaka, Bangladesh

Waste dumping is one of the major causes of environment pollution in Bangladesh. This study was designed to assess the impact on health of children working in one of the garbage dumping sites in Dhaka. Blood samples were collected from exposed (n = 20, aged: 8-15 years, exposed to dumped garbage from 6 months to 6 years) and control subjects (n = 15, age matched and never worked in the garbage dumping site). Oxidative stress markers like lipid hydroperoxides, thiobarbituric acid reactive substances and protein carbonyl content were measured. Alkaline comet assay was performed to assess the possible damage in DNA. To check the consequences of possible toxic exposure, we performed liver function tests of the study subjects. Oxidative stress-mediated damage of macromolecules was found to be significantly increased in the exposed children. Liver function tests were found normal. Thus, the children working in garbage dumping site are in severe health risk.

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.

Chromosome aberrations in workers exposed to organic solvents: Influence of polymorphisms in xenobiotic-metabolism and DNA repair genes

Organic solvents are widely used as diluents or thinners for oil-paints, gasoline and other organic mixtures. We evaluated chromosome aberrations (CAs) in lymphocytes of 200 workers exposed to organic solvents and 200 referents and the influence of polymorphisms in xenobiotic-metabolism (CYP2E1, GSTM1 and GSTT1) and in DNA repair genes (XRCC1(194) Arg/Trp, XRCC1(280) Arg/His, XRCC1(399) Arg/Gln and XRCC3(241) Thr/Met). Polymorphisms were determined by PCR-RFLP. Poisson regression analysis indicates a significant CA frequency increase in exposed workers, representing a higher risk in relation to the matched referent (RR 2.15, 95% CI 1.21-1.53, p<0.001). The CA frequency in exposed workers was influenced by the polymorphic genotypes: GSTM1 null (RR 1.33, 95% CI 1.31-1.69, p<0.001), XRCC1(194) Arg/Trp, Trp/Trp (RR 1.23, 95% CI 1.08-1.40, p<0.001) and by the wild genotypes CYP2E1 C1/C1 (RR 1.20, 95% CI 1.05-1.37, p<0.001), GSTT1 positive (RR 1.49, 95% CI 1.31-1.69, p<0.001), XRCC1(280) Arg/Arg (RR 1.44, 95% CI 1.26-1.64, p<0.001) and XRCC1(241) Thr/Thr (RR 1.54, 95% CI 1.34-1.76, p=0.001). We contribute to the follow-up predictive value of individual susceptibility biomarkers and their CA frequency influence during occupational organic solvent exposure. We provide tools for surveillance and prevention strategies to reduce potential health risks in countries with a large population of car painters not using protection devices and limited organic solvents use control.