Immunotoxic lesions

Holladay, S.D., S.A. Smith, R.M. Gogal, E.G. Besteman, T. Hrubec, A.S.M.I. Deyab, and S.A. Ahmed. 1996. Morphologic lesions and acute immunotoxic effects in tilapia (Oreochromis niloticus) exposed to benzo[a]pyrene. IAAAM Proc. 27 59. 

Immunotoxicity. No data are available on the immunotoxicity of hexachlorobutadiene in humans following inhalation, oral, or dermal exposure. Data in animals are limited to intermediate and chronic oral studies which examined histological lesions of lymphoid tissue (spleen or thymus) in mice and rats. These studies did not reveal treatment-related lesions except at lethal doses (Harleman and Seinen 1979 Kociba et al. 1971, 1977a NTP 1991 Schwetz et al. 1977 Yang et al. 1989). Additional studies to evaluate immune function via the oral route would be useful to determine whether this system is susceptible to hexachlorobutadiene toxicity. 

Toxic responses can be divided into six types direct tissue lesions pharmacological, physiological, and biochemical effects teratogenesis immunotoxicity genetic toxicity and carcinogenesis. 

Immunotoxicity. No studies were located relating to immunotoxic effects in humans or animals exposed to nitrobenzene via any route. However, splenic lesions have been reported in mice and rats exposed to nitrobenzene via inhalation in both acute-and intermediate-duration studies. These results suggest that a battery of immune function tests in animals exposed via inhalation and orally would provide useful information. The results of the CUT bioassay, however, may provide some information on this end point. 

No increase in the occurrence of non-neoplastic lesions was found in organs and tissues of the immune system following 78 weeks of oral 1,1,2-trichloroethane administration in corn oil at doses of 46 or 92 mg/kg/day in rats and 195 or 390 mg/kg/day in mice (NCI 1978). This study involved histopathological examination of the spleen, thymus, and lymph nodes using light microscopy, but because specific tests for immunotoxicity were not performed, NOAEL values were not derived. 

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