Immunotoxicity: Impacts and Research Approaches

The immune system is vulnerable to toxicant exposures during early development, but environmental chemicals have only recently been considered as possible immunotoxicants. So far, immunotoxicity is not routinely considered in the risk assessment of industrial chemicals, even less so developmental exposures, despite evidence on dioxins and related compounds, certain metals, and recent information on the perfluorinated alkylate substances (PFASs). The mouse is an especially useful experimental model. Recent epidemiological studies have employed the antibody response to childhood immunizations as a clinically relevant outcome that reflects major immune system functions. Lowered antibody responses occur along with increased frequency of infectious disease in children at elevated PFAS exposure, including early postnatal exposure that may affect B cell maturation. In addition, autoimmune disease, such as ulcerous colitis, is a possible outcome that requires further study, as does immune suppression in regard to possible carcinogenicity. Beyond the PFASs and other known immunotoxicants, most environmental chemicals have not been properly tested and may well represent immunotoxic potentials. Given the public health impact from existing and emerging infectious diseases and other potential consequences, developmental immunotoxicity should no longer be ignored as an important adverse effect of environmental chemicals.