Environmental and occupational exposure to manganese: a multimedia assessment

Abstract

Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic additive used in Canada since 1976 as an anti-knock agent in unleaded gasoline. Its combustion leads to the emission of Mn oxides, especially Mn3O4. Since no study has assessed the potential risk of chronic exposure to low concentrations resulting from these emissions, the present investigation was undertaken to assess the level of environmental and occupational exposure of the human population. The multimedia exposure of two groups of workers (garage mechanics and blue-collar workers) potentially exposed to different levels of Mn from the combustion of MMT was assessed using personal air samplers, a dietary compilation, water samples at their places of residence, an epidemiological questionnaire and blood and hair samples. Results show that garage mechanics were exposed on average to higher atmospheric Mn at work (0.42 microgram/m3) than the blue-collar workers (0.04 microgram/m3). However, the contribution of atmospheric Mn to the total absorbed dose was less than 1%, and well below the standards established for occupational or environmental exposure; food contributes more than 95% of the multimedia dose. The average whole blood Mn concentrations were similar for the two groups (0.67-0.76 microgram/100 ml) and fall within the normal adult range. The average hair Mn concentrations were significantly higher for the garage mechanics (0.66 microgram/g) than for the blue-collar workers (0.39 microgram/g). The contribution of exogenous Mn versus endogenous Mn is questioned. As judged by the governmental standards or criteria for occupational and non-occupational environments, the current Mn levels in food, water and air may not cause any problems for the workers.

Hair Manganese and Hyperactive Behaviors: Pilot Study of School-Age Children Exposed Through Tap Water

“…In certain geologic regions, long contact times between ground water and bedrock enriched in Mn can lead to locally high levels in the water [U.S. Environmental Protection Agency (EPA) 2004]. Mn is an essential nutrient, and ingestion from drinking water is assumed to represent a small proportion of total intake, typically contributing < 1% although this can rise to 20% depending on Mn concentration in the water (Loranger and Zayed 1995). The rest of Mn intake occurs through food.…”

Potential Health Effects of Gasoline and Its Constituents: A Review of Current Literature (1990-1997) on Toxicological Data

“…Information is scarce on potential health risk derived from MMT as a gasoline additive (157,166). In a Canadian study (166) (168).…”

Too Easily Lead? Health Effects of Gasoline Additives

“…Canadian studies have shown increased manganese levels in exposed individuals, but airborne exposure accounted for less than 1% of absorption (26,27 (Fig. 1, 2).…”