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EFFECTS OF SELENIUM ON MALLARD DUCK REPRODUCTION AND IMMUNE FUNCTION
Citation:
Whiteley, P. AND T. Yuill. EFFECTS OF SELENIUM ON MALLARD DUCK REPRODUCTION AND IMMUNE FUNCTION. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/3-89/078 (NTIS PB90120692).
Description:
Selenium from irrigation drain water and coal-fired power stations is a significant environmental contaminant in some regions of the USA. Our objectives were to examine whether selenium-exposed waterfowl had altered immune function, disease resistance, or reproduction. Pairs of adult mallards were exposed for 95-99 days on streams with sodium selenite-treated water at 10 and 30 ppb. r on untreated streams. Selenium biomagnified through the food chain to the ducks. Disease resistance was decreased in ducklings hatched on the streams and challenged with duck hepatitis virus 1 (DHV1) when 15-days old. Liver selenium concentrations for these ducklings on the 10 and 30 ppb streams was 3.6 and 7.6 ppm dry weight respectively. Mortality of ducklings purchased when 7-days old, exposed to selenium for 14 days, and challenged when 22-days old was not affected. However, their selenium exposure was lower (liver selenium 4.1 ppm dry weight for the 30 ppb stream). Five parameters of immune function were measured in adult ducks. Phagocytosis of killed Pasteurella multocida by blood heterophils and monocytes, and blood monocyte concentrations were higher in adult males following 84 days exposure to 30 ppb selenium. Their liver selenium concentrations were 11.1 ppm dry weight after 95-99 days exposure. The direct spleen plaque-forming cell assay and titers of hemagglutinating antibodies to sheep red blood cells of adult male and female mallards were not affected by selenium treatment. The delayed-type hypersensitivity assay was uninformative. Reproductive parameters were monitored by predation reduced sample sizes and no significant differences were found. Egg selenium concentrations for the 30 ppb stream were 3.9 ppm dry weight, much lower than that reported from field sites in California. Disease resistance was decreased and immune function increased in mallards exposed to streams with water selenium concentrations of at least 10 and 30 ppb, respectively.
