Methylarsenic compounds

MAK Value Documentation – Translation of the German version from 2014

  Andrea Hartwig¹ (Chair of the Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, Deutsche Forschungsgemeinschaft)
  MAK Commission<sup>2

1</sup> Institute of Applied Biosciences, Department of Food Chemistry and Toxicology, Karlsruhe Institute of Technology (KIT), Adenauerring 20a, Building 50.41, 76131 Karlsruhe, Germany
² Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, Deutsche Forschungsgemeinschaft, Kennedyallee 40, 53175 Bonn, Germany

Abstract

The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has evaluated methylarsenic compounds considering all toxicological endpoints. Available publications and unpublished study reports are described in detail.

Methylarsenic compounds are the carcinogenic metabolites of arsenic and its inorganic compounds, which are proven human carcinogens. Methylated arsenic compounds are able to interfere with all important cellular processes. In mice and rats, dimethylarsinic acid was clearly carcinogenic. Trimethylarsine oxide caused liver adenomas in F344 rats and with methylarsenic acid, preneoplastic liver effects were found. If all aspects are considered, methylarsenic compounds are classified in Carcinogen Category 1. Methylarsenic compounds are genotoxic in vitro and in vivo. As they are bioavailable and can reach the germ cells, they are classified in Category 3 A for Germ Cell Mutagens. Methylarsenic compounds are genotoxic carcinogens, for which no safe systemic exposure can be estimated. It must be assumed that even small amounts absorbed percutaneously increase the carcinogenic risk. Therefore, methylarsenic compounds are designated with an “H” (for substances that can be absorbed through the skin in toxicologically relevant amounts). Dimethylarsinic acid induced developmental toxicity in rats. Apart from a well‐documented case report, there are no clear findings available to conclude a skin‐sensitizing potential in humans.

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