Evaluation of the potential immunotoxicity of bromodichloromethane in ratsand mice

In the past two decades, concern has been expressed over the potential carc inogenicity of disinfection by-products (DBPs) found in chlorinated drinkin g water. More recently, research efforts have expanded to include noncancer endpoints as well. The objective of the present studies war to evaluate th e potential of bromodichloromethane (BDCM), one of the most prevalent DBPs, to adversely affect immune function in mice and rats following drinking wa ter or gavage exposure. Antigen-specific immunity was assessed as the antib ody response to sheep erythrocytes; responses to T- and B-cell mitogens wer e evaluated as a non-antigen-specific measure of the proliferative potentia l of splenic and mesenteric lymph node lymphocytes. In consideration of an exposure route relevant to humans, C57BL/6 mice received 0.05, 0.25, or 0.5 g BDCM/L and F344 rats received 0.07 or 0.7 g BDCM/L via drinking water. I n order to evaluate the effects of higher doses, animals were administered 50, 125, or 250 mg BDCM/kg/d (mice) or 75, 150, or 300 mg BDCM/kg/d (rats) via gavage. Under the conditions of these studies, no significant adverse e ffects on immune function were observed in mice. Despite some changes that were observed in non-antigen-specific immunity in rats, these experiments s uggest that the immune system is not a sensitive target organ for BDCM toxi city.