Environmental and occupational exposure to benzene from fuels is a major cause for concern for national and international authorities, as benzene is a known carcinogen in humans and there is no safe limit for exposure to carcinogens. The objective of this study was to evaluate the genotoxic effects of chronic occupational exposure to benzene among two groups of workers: filling station workers (Group I) and security guards working at vehicles entrances (Group II), both on the same busy highway in Rio de Janeiro, Brazil. Sociodemographic data on the workers were evaluated; the concentration of benzene/toluene (B/T) in atmospheric air and individual trans,trans-muconic acid (ttMA) and S-phenylmercapturic acid (S-PMA) were measured; oxidative stress was analyzed by catalase (CAT), glutathione S-transferase (GST), superoxide dismutase (SOD), thiol groups (THIOL) and malondialdehyde (MDA); genotoxicity was measured by metaphases with chromosomal abnormalities (MCA) and nuclear abnormalities, comet assay using the enzyme formamidopyrimidine DNA glycosylase (C-FPG), and methylation of repetitive element LINE-1, CDKN2B and KLF6 genes. Eighty-six workers participated: 51 from Group I and 35 from Group II. The B/T ratio was similar for both groups, but Group I had greater oscillation of benzene concentrations because of their work activities. No differences in ttMA and S-PMA, and no clinical changes were found between both groups, but linearity was observed between leukocyte count and ttMA; and 15% of workers had leukocyte counts less than 4.5 × 10⁹ cells L⁻¹, demanding close worker’s attention. No differences were observed between the two groups for THIOL, MDA, MCA, or nuclear abnormalities. A multiple linear relationship was obtained for the biomarkers MCA and C-FPG. A significant correlation was found between length of time in current job and the biomarkers C-FPG, MCA, GST, and MDA. Although both populations had chronic exposure to benzene, the filling station workers were exposed to higher concentrations of benzene during their work activities, indicating an increased risk of DNA damage.

Oxidative stress can be induced by mercury (Hg) exposure, including through fish consumption (diet), leading to health risks. The objective of this study was to evaluate the association between oxidative stress biomarkers and dietary Hg exposure levels in riverine children and adolescents at Madeira River (RO/Brazil). Population from three riverine local communities presenting different fish consumption frequencies was sampled. Hg was determined in blood (ICP-MS) and glutathione (GSH); glutathione S-transferases (GST) and malondialdehyde (MDA) were determined in serum (spectrophotometry). Statistical analyses were performed using parametric and non-parametric tests. Multiple linear regression models and generalized additives models were also used to estimate the relationships between oxidative stress biomarkers and blood Hg. The juvenile riverine population from Cuniã RESEX presented the highest levels of oxidative stress and Hg levels in blood (GST = 27.2 (4.93) U/L, MDA = 1.69 (0.27) µmol/L, Hg = 20.6 (18.0) µg/L). This population also presented the highest frequency of fish consumption. The positive relation between Hg and GST and MDA, adjusted for individual characteristics, suggests an oxidative effect. This study shows the importance of oxidative stress biomarkers in the evaluation of dietary Hg exposure since initial and reversible metabolic changes were observed, enriching health risk assessments.

Resumo Introdução: a avaliação de uma exposição mensura sua intensidade, frequência e duração, podendo detectar danos precoces que, se ignorados, podem evoluir para um quadro nocivo. Nos campos da saúde ambiental e ocupacional, os biomarcadores de genotoxicidade tem sido largamente utilizados para essa avaliação. Objetivo: identificar, descrever e discutir os principais bioindicadores de genotoxicidade e seu uso conjunto com técnicas de avaliação de expressão gênica em estudos de exposição ocupacional ao benzeno em postos de revenda de combustíveis (PRC). Métodos: revisão bibliográfica de trabalhos publicados entre 1995 e 2015. Resultados: as técnicas identificadas foram: ensaio cometa, estresse oxidativo, micronúcleos, aberrações cromossômicas, polimorfismos, adutos de DNA e proteínas, fatores epigenéticos e expressão gênica. Foi observado que testes de danos genéticos e epigenéticos são utilizados em frentistas de PRC que participam de programas de saúde do trabalhador ou de pesquisas, embora um baixo número de publicações sobre o tema tenha sido identificado. Esse fato talvez possa ser explicado pelos poucos países onde a profissão persiste e pelas limitações para o desenvolvimento de pesquisas nesses países. Conclusão: os bioindicadores de genotoxicidade e as técnicas de expressão gênica são úteis na detecção de dano precoce desta exposição ocupacional e devem ser avaliados em conjunto.

Objective: To evaluate the association between environmental exposure to the following chemical substances: cadmium (Cd), lead (Pb), nickel (Ni), manganese (Mn), benzene (BZN), and toluene (TLN), and Period Circadian Regulator 3 (PER3) gene variable number of tandem repeats (VNTR) polymorphisms, according to chronotype in a population living in a steel residue-contaminated area. Methods: This assessment comprises a study conducted from 2017 to 2019 with 159 participants who completed health, work, and Pittsburgh sleep scale questionnaires. Cd, Pb, Ni, Mn, BZN, and TLN concentrations in blood and urine were determined by Graphite Furnace Atomic Absorption Spectrometry (GFAAS) and Headspace Gas Chromatography (GC), and genotyping was carried out using Polymerase Chain Reaction (PCR). Results: A total of 47% of the participants were afternoon chronotype, 42% were indifferent, and 11% were morning chronotype. Insomnia and excessive sleepiness were associated with the indifferent chronotype, while higher urinary manganese levels were associated with the morning chronotype (Kruskal–Wallis chi-square = 9.16; p < 0.01). In turn, the evening chronotype was associated with poorer sleep quality, higher lead levels in blood, and BZN and TLN levels in urine (χ² = 11.20; p < 0.01) in non-occupationally exposed individuals (χ² = 6.98; p < 0.01) as well as the highest BZN (χ² = 9.66; p < 0.01) and TLN (χ² = 5.71; p < 0.01) levels detected in residents from the influence zone 2 (far from the slag). Conclusion: Mn, Pb, benzene, and toluene contaminants may have influenced the different chronotypes found in the steel residue-exposed population.