In addition to their acute neurotoxic effects, some organophosphorus compounds have been shown to have immunotoxic properties. Alterations in the immune system may lead to chronic morbidity and/or mortality that is not readily apparent at the time of initial exposure. Because it often inhabits land that is intensely farmed, the ring‐necked pheasant (Phasianus colchicus) may be a suitable biomonitor of agroecosystems, especially those used in the production of corn. We examined immunopathologic effects of a widely used organophosphate insecticide, malathion, on 8‐week‐old, cage‐reared ring‐necked pheasants 3 d after a single oral dose. No differences were seen in hematologic parameters, body weight, or weight of the bursa of Fabricius. Birds given a high dose of malathion (230 mg/kg) displayed significant decreases in absolute and relative thymic and splenic weights (p ± 0.05). Significant changes were also seen in thymic and splenic histomorphometry (p ± 0.05). The high‐dose group and, in some cases, the low‐dose group (92 mg/kg) displayed significant histologic lesions. These findings indicate that a single dose of malathion, at the LD50 level (230 mg/kg) and occasionally at 40% of the LD50 level (92 mg/kg), is capable of inducing quantitative and qualitative changes in the lymphoid organs of the ring‐necked pheasant that may affect immune function.
- Ring‐necked pheasant
ASJC Scopus subject areas
- Environmental Chemistry
- Health, Toxicology and Mutagenesis