Urinary Biomarkers in Charcoal Workers Exposed to Wood Smoke in Bahia State, Brazil

Abstract

Charcoal is an important source of energy for domestic and industrial use in many countries. Brazil is the largest producer of charcoal in the world, with ∼350,000 workers linked to the production and transportation of charcoal. To evaluate the occupational exposure to wood smoke and potential genotoxic effects on workers in charcoal production, we studied urinary mutagenicity in Salmonella YG1041 +S9 and urinary levels of 2-naphthol and 1-pyrenol in 154 workers of northeastern Bahia. Workers were classified into three categories according to their working location, and information about socio-demographic data, diet, alcohol consumption, and smoking was obtained using a standard questionnaire. Spot urine samples were collected to evaluate urinary mutagenicity and urinary metabolites. Urinary mutagenicity increased significantly with exposure to wood smoke and was modified by smoking. The prevalence odds ratio was 5.31, and the 95% confidence interval was 1.85; 15.27 for urinary mutagenicity in the highly exposed group relative to the nonexposed group. The levels of urinary metabolites increased monotonically with wood smoke exposure and were associated with the GSTM1 null genotype, which was determined previously. The prevalence odds ratio (95% confidence interval) for higher levels of 2-naphtol among the highly exposed was 17.13 (6.91; 42.44) and for 1-hydroxyprene 11.55 (5.32; 25.08) when compared with nonexposed workers. Urinary 2-naphthol was the most sensitive indicator of wood smoke exposure. This is the first reported measurement of internal exposure to wood smoke among charcoal workers, and the results showed that these workers receive a systemic exposure to genotoxic compounds.

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“…The technique has been employed to assess urinary mutagenicity in subjects exposed to complex combustion emissions of coal and biomass fuels, selected industrial chemicals, and airborne particulate matter at urban and nonurban locations. − More specifically, studies have assessed urinary mutagenicity in benzidine-exposed factory workers in India, wood smoke-exposed charcoal workers in Brazil, and wood-smoke-exposed individuals using traditional Native American saunas. These studies showed positive correlations between exposure metrics (e.g., duration) and urinary mutagenicity. ,, …”

“…Mutagenic potency was calculated as the slope of the initial linear portion of the concentration− response function and expressed as rev/μmol of creatinine. 10,44 Urinary creatinine concentration was used to correct for urinary dilution.…”

“…The mean positive control response was 1371.5 ± 65.5 rev/plate, and the mean negative control was 36.7 ± 1.3 rev/plate. Mutagenic potency was calculated as the slope of the initial linear portion of the concentration–response function and expressed as rev/μmol of creatinine. , Urinary creatinine concentration was used to correct for urinary dilution.…”

“…These studies showed positive correlations between exposure metrics (e.g., duration) and urinary mutagenicity. 10,21,22 In addition to urinary monitoring of chemical metabolites and mutagenicity, urinary biomarkers of physiological condition have also been used for occupational monitoring (e.g., isoprostanes and Clara Cell secretory protein (CC16)). Isoprostanes are products of free-radical fatty acid peroxidation that can be generated and excreted in the urine as 15isoprostane F2t (i.e., 8-iso-PGF 2α ).…”

“…PAH exposure can be assessed in a number of different ways including urinary monitoring, personal air monitoring, and dermal wipe sampling. Urinary monitoring is a convenient, noninvasive PAH exposure assessment technique that involves quantification of the concentrations of specific PAH metabolites that are reported to be indicative of combustion emission exposure. − Numerous studies have employed urinary concentrations of hydroxylated PAH metabolites to assess occupational exposures to combustion emissions and PAHs in facilities or environments associated with charcoal production, road paving, rubber manufacturing, production of coke and refined metals, cooking, and wildland firefighting. − Interestingly, firefighters can be engaged in a variety of occupational activities that can contribute to vastly different combustion emission exposure levels (e.g., active fire suppression, overhaul, vertical ventilation, etc. ). , …”