Urinary 1-nitropyrene metabolites as markers of exposure to diesel exhaust in an underground mine.

摘要

Elevated exposure to diesel exhaust (DE) is widespread and has been linked to adverse health outcomes including respiratory irritation, cardiovascular disease, immune dysfunction and lung cancer. Underground miners experience amongst the highest exposures to DE of any occupation. Thus, miners are at high risk for suffering adverse health effects associated with DE exposure. MSHA currently mandates measurement of elemental carbon (EC) and total carbon (TC) to assess workers exposures to DE in underground metalonmetal mines. However, limitations in the specificity and reliability of these metrics of DE exposure hamper quantitative evaluation of links between DE exposure and adverse health outcomes. The DE-specific chemical 1-nitropyrene (1-NP) has been suggested as a potential alternative marker of exposure to DE, and 1-nitropyrene metabolites in urine may serve as useful biomarkers of exposure to DE. In the current study we measured DE exposures in a cohort of 20 workers at a large underground metal mine. Diesel powered equipment at this mine uses a B70 biodiesel blend fuel. Full shift personal air samples were collected on up to eight occasions from each worker using an MSHA compliant SKC DPM impactor downstream of a GS-1 cyclone pre-filter. 103 of these samples were analyzed for EC and 1-NP. A total of 535 urine samples were collected pre- and post shift from the workers - of which 170 were analyzed for two specific metabolites of 1-NP - 6-hydroxy-1-nitropyrene (6-OHNP) and 8-hydroxy-1-nitropyrene (8-OHNP). The geometric mean (GM) metabolite levels were 0.014 pg/mg creatinine for 6-OHNP and 0.007 pg/mg creatinine for 8-OHNP. Metabolite levels were lowest in the pre-shift sample on the first day of the work week, and increased progressively throughout the work week. Consistent with this observation, metabolite levels did not show a significant association with personal exposure to 1-NP in the single work-shift preceeding collection of the urine sample. However, urinary metabolite concentrations were associated with cumulative 1-NP exposure across the four days prior to collection of the urine sample. These data indicate that in this workplace where DE is anticipated to be the only source of 1-NP, urinary metabolites of 1-NP show promise as a biomarker of occupational exposure to DE.