Executive Summary

This is a draft position statement for discussion. This does not represent the views of the Committee and should not be cited.

Statement on the derivation of a health-based guidance value for antimony First draft statement

Secretariat

April 2025

Executive Summary

1.               Post European Union (EU) exit, the Drinking Water Inspectorate (DWI) is reviewing the regulatory standards for some chemicals in drinking water, including antimony. The UK Health Security Agency (UKHSA) sought advice of the Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) with respect to an appropriate health-based guidance value (HBGV) for antimony.

2.               The World Health Organization (WHO), the US Agency for Toxic Substances and Disease Registry (ATSDR) and Health Canada have used the same study (Poon et al., 1998) to derive different HBGVs. The differences are primarily due to variations in the interpretation of the study findings, particularly in the choice of the No Observed Adverse Effect Level (NOAEL).

3.               The COT agreed that the Poon et al. (1998) study was the most appropriate study to use to derive a HBGV for antimony. The COT determined that the NOAEL of 6,000 micrograms per kilogram of body weight per day (µg/kg bw/day), based on decreased body weight gain and reduced food and water consumption in adult rats, was the point of departure. An uncertainty factor (UF) of 300 was recommended, resulting in a tolerable daily intake (TDI) of 20 µg Sb/kg bw/day as a HBGV for antimony.