Review of subchronic/chronic toxicity of antimony potassium tartrate

Subchronic/chronic toxicity studies on antimony potassium tartrate (APT) have been reviewed. One of the older studies (H. A. Schroeder et al., 1970, J. Nutr. 100 (1), 59-68), on which are based the EPA reference dose value and a number of state, national, and international drinking water criteria for antimony, has severe inadequacies in study conduct making it uninterpretable and inappropriate for characterization of APT toxicity. In particular, the manner in which control data were generated and utilized in this study is considered invalid. More recent drinking water studies conducted by the NTP (1992, "NTP Technical Report on Toxicity Studies of Antimony Potassium Tartrate in F344/N Rats and B6C3F(1) Mice (Drinking Water and Intraperitoneal Injection Studies)," NTP Toxicity Report Series, No. 11) and Poon et al. (1998, Food Chem. Toxicol. 36, 20-35) showed antimony to be of low toxicity. The NOAEL in the 14-day NTP study was 2500 ppm by the oral route in both rats and mice, while Poon et al. (1998) suggested a NOAEL of 0.5 ppm in their 90-day study. However, upon close examination, it was determined that this value was based on subtle histological changes in the thyroid gland that were physiological, not toxicological, in nature. This conclusion is supported further by an absence of these changes in a well-conducted 13-week intraperitoneal exposure study in rats that utilized APT at much higher doses (NTP, 1992). Thus, the NOAEL by Poon et al. (1998) should more appropriately be 50 ppm. When regulatory criteria for antimony are established and/or reviewed, the findings in the NTP study and this critical reevaluation of the Poon et al. (1998) study should be considered when establishing a NOAEL for subchronic exposure to antimony in the future.