Human urinary mutagenicity after wood smoke exposure during traditional temazcal use

Abstract

In Central America, the traditional temazcales or wood-fired steam baths, commonly used by many Native American populations, are often heated by wood fires with little ventilation, and this use results in high wood smoke exposure. Urinary mutagenicity has been previously employed as a non-invasive biomarker of human exposure to combustion emissions. This study examined the urinary mutagenicity in 19 indigenous Mayan families from the highlands of Guatemala who regularly use temazcales (N = 32), as well as control (unexposed) individuals from the same population (N = 9). Urine samples collected before and after temazcal exposure were enzymatically deconjugated and extracted using solid-phase extraction. The creatinine-adjusted mutagenic potency of urine extracts was assessed using the plate-incorporation version of the Salmonella mutagenicity assay with strain YG1041 in the presence of exogenous metabolic activation. The post-exposure mutagenic potency of urine extracts were, on average, 1.7-fold higher than pre-exposure samples (P < 0.005) and also significantly more mutagenic than the control samples (P < 0.05). Exhaled carbon monoxide (CO) was ~10 times higher following temazcal use (P < 0.0001), and both CO level and time spent in temazcal were positively associated with urinary mutagenic potency (i.e. P < 0.0001 and P = 0.01, respectively). Thus, the wood smoke exposure associated with temazcal use contributes to increased excretion of conjugated mutagenic metabolites. Moreover, urinary mutagenic potency is correlated with other metrics of exposure (i.e. exhaled CO, duration of exposure). Since urinary mutagenicity is a biomarker associated with genetic damage, temazcal use may therefore be expected to contribute to an increased risk of DNA damage and mutation, effects associated with the initiation of cancer.

Mutagenicity and Lung Toxicity of Smoldering vs. Flaming Emissions from Various Biomass Fuels: Implications for Health Effects from Wildland Fires

“…For example, the smoldering mutagenicity EF was found to be approximately 5, and 16 times higher than those of oak combusted in cookstoves ( Mutlu et al 2016 ), and of municipal waste combustion ( Watts et al 1992 ) or diesel exhaust ( Mutlu et al 2015 ), respectively. Thus, in this context, the smoldering emissions from wildland fires are highly mutagenic and support the notion that smoldering wood smoke is genotoxic and ultimately carcinogenic in humans ( IARC 2010 ; Kato et al 2004 ; Long et al 2014 ).…”

Household Fuel Use and the Risk of Gastrointestinal Cancers: The Golestan Cohort Study

“…Burning biomass fuels produces many harmful pollutants, some of which are recognized as carcinogens, including polycyclic aromatic hydrocarbons (PAH), benzene, and formaldehyde (IARC 2013), and these compounds can be absorbed through the skin, respiratory system, and GI tract (IARC 2013). Higher exposure to combustion of biomass fuels may increase the systemic absorption of these carcinogenic compounds, as documented in studies that have demonstrated high urinary levels of PAH metabolites, benzene, and carbon monoxide (CO) in individuals who were using biomass fuels (Fan et al 2014;Long et al 2014;Riojas-Rodriguez et al 2011;Viau et al 2000). In one study, an intervention with improved chimney-equipped stoves resulted in reduced urinary levels of PAH metabolites (Riojas-Rodriguez et al 2011).…”

Mutagenicity and Pollutant Emission Factors of Solid-Fuel Cookstoves: Comparison with Other Combustion Sources

“…Urinary mutagenicity was elevated in 49 Brazilian charcoal workers with high exposure to woodsmoke outdoors compared with 34 workers with no exposure, and this correlated with urinary concentrations of 2-naphthol and 1-pyrenol, of which the parent compounds (naphthalene and pyrene) have been found in woodsmoke ( Kato et al 2004 ). A study by Long et al (2014) of Mayan individuals that used traditional wood-fired steam baths reported that urinary mutagenicity and exhaled CO both increased after use of the steam bath and were significantly correlated ( r 2 = 0.53, p < 0.001).…”