AGE-RELATED SUSCEPTIBILITY TO IMMUNOTOXICANTS - ANIMAL DATA AND HUMANPARALLELS

There are numerous examples, of both the identical and different effec ts of animals exposure to toxic agents, which can be compared in both, exposed prenatal/neonatal animals and exposed adults. In some instanc es, although the chemical and its metabolites are stored for long peri ods in adipose tissue, adult exposure (short of acute poisoning) has l ittle effect on the immune system (Johnson et al., 1986. An immunotoxi cological evaluation of gamma-chlordane. Fundam. Appl. Toxicol. 6, 317 -326), while exposure during gestation results in immunoteratology (Ba rnett, 1996. Developmental immunotoxicology. In: Smialowicz, R.J., Hol sapple, M.P. (Eds.), Experimental Immunotoxicology, CRC Press, Boca Ra ton, FL, pp.47-62). With the heavily studied dioxins, both prenatal as well as adult exposure causes immunotoxicity, however, the effects ar e not always the same. Attempts to confirm these observations in human s have been hampered by a multitude of problems that are directly rela ted to the exposure paradigm, such as lack of accurate exposure data, varying lengths of exposure, etc. as well as many variables that are s imply related to differences in genetic makeup, lifestyle, socioeconom ic status, etc. that are part of the human populations. A few studies have noted important trends in immune status that are correlated with levels of halogenated aromatic hydrocarbon exposures, however, even th ese fail to provide unequivocal answers regarding the relative risk of prenatal exposure. (C) 1997 Elsevier Science B.V.