Evaluation of the potential immunotoxicity of bromodichloromethane in rats and mice.

In the past two decades, concern has been expressed over the potential carcinogenicity of disinfection by-products (DBPs) found in chlorinated drinking water. More recently, research efforts have expanded to include noncancer endpoints as well. The objective of the present studies was to evaluate the potential of bromodichloromethane (BDCM), one of the most prevalent DBPs, to adversely affect immune function in mice and rats following drinking water or gavage exposure. Antigen-specific immunity was assessed as the antibody response to sheep erythrocytes; responses to T- and B-cell mitogens were evaluated as a non-antigen-specific measure of the proliferative potential 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. In 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 effects on immune function were observed in mice. Despite some changes that were observed in non-antigen-specific immunity in rats, these experiments suggest that the immune system is not a sensitive target organ for BDCM toxicity.

Evaluation of the potential immunotoxicity of chlorinated drinking water in mice.

Recent epidemiological studies have reported associations between the consumption of chlorinated drinking water and various types of human cancer; in addition, exposure to chlorine (Cl-) in drinking water has been reported to suppress certain immune functions in laboratory animals. The current studies were conducted to extend our knowledge of the effects of drinking water exposure to Cl-. Female C57BL/6 mice were administered hyperchlorinated drinking water (7.5, 15, or 30 ppm Cl-) for 2 weeks prior to sacrifice for evaluation of spleen and thymus weights, the plaque-forming cell (PFC) response, hemagglutination (HA) titer, and lymphocyte proliferation (LP). Significant reductions in organ weights and immune response were observed in the positive control groups (i.e. dexamethasone- or cyclophosphamide-exposed mice). No consistent differences were observed between the Cl--exposed animals and vehicle control mice for the evaluated parameters. Thus, under the conditions of these experiments, 2 weeks of exposure to hyperchlorinated drinking water had no apparent adverse effects on immune function.