Effects of Detergent Formula Chelating Agents on the Metabolism and Toxicity of Cadmium in Mice

Abstract

Chelating agents, like NTA (nitrilotriacetic acid), STPP (sodium tripolyphosphate, Na5P3010) and EDTA, are used as components of detergents. An increased toxicity of some metal compounds when combined with NTA led to decreased use of this chelating agent in relation to STPP. Short and long-term effects of these chelating agents on Cd toxicity in mice were investigated. In the short-term study, mice s.c. exposed to CdCl2 (3.2 mg Cd/kg body wt) in combination with STPP (32 mg/kg body wt) demonstrated a markedly higher mortality compared to animals given CdCl2 alone. This increase in mortality was similar to the one encountered when CdCl2 (3.2 mg Cd/kg body wt) and NTA (32 mg/kg body wt) were combined. Animals exposed s.c. to CdCl2 + STPP or CdCl2 + NTA showed histological evidence of liver necrosis 24 h after exposure not seen in animals given the same dose of CdCl2 alone; animals had markedly lower Cd concentrations in the livers compared to only Cd-exposed animals. In the long-term study, mice were exposed orally to CdS04 (50 ppm Cd) alone or in combination with STPP (500 ppm), NTA (500 ppm or EDTA (50 ppm)) or EDTA (50 ppm by continuous administration by way of the drinking water for 18 mo. A decreased total excretion of urine proteins was seen in all Cd-treated animals irrespectively of the combination with various chelating agents. NTA and STPP given by s.c. injection to mice increased the toxicity of Cd but neither NTA, STPP nor EDTA given orally altered the toxicity of Cd during a period of long-term exposure of 18 mo.