Mercury and inorganic mercury compounds [MAK Value Documentations, 2011]

Abstract

The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has re‐evaluated the maximum concentration at the work place (MAK value) of mercury and inorganic mercury compounds of 0.1 mg Hg/m3, considering all toxicological endpoints. For mercury and inorganic mercury compounds biological monitoring (biological tolerance or BAT value) is indicated to correlate exposure and inner burden. Based on the reduction of the BAT value to 25 µg mercury/g creatinine in 2007, the MAK value is reduced to 0.02 mg/m 3 (calculated as mercury). Due to the systemic effects and the long half‐life, classification in Peak Limitation Category II with excursion factor 8 is retained. Mercury and inorganic mercury compounds remain classified as possibly carcinogenic to humans as epidemiological studies show no conclusive carcinogenicity of mercury. However, in male rats at high doses squamous cell papillomas develop in the forestomach, and in male mice renal tubular adenomas and carcinomas increase. The mode of action and the relevance of these findings to humans is still unknown. Inorganic mercury compounds are clastogenic in vitro, and the clastogenic effect could be confirmed in one animal study starting at 2 mg/kg body weight, which is at least 500 times above the MAK value of 0.02 mg/m 3 . Therefore mercury and inorganic mercury compounds are not classified in a category for Germ Cell Mutagens. Data in humans are inconsistent and data in animals are insufficient to obtain a reliable statement as to whether the MAK value of 0.02 mg/m 3 protects from prenatal toxicity. Thus, mercury and inorganic mercury compounds are classified in Pregnancy Risk Group D. Skin contact may contribute significantly to systemic toxicity and mercury and inorganic mercury compounds are designated with an “H” notation. Sensitization and contact allergic reactions to mercury or inorganic mercury compounds in humans have been confirmed in other publications. Data on respiratory sensitization are not available. Mercury and its inorganic compounds continue to be designated with “Sh”, but not with “Sa”.