Effects of low level lead and cadmium on reproduction in Peromyscus leucopus and a study of lead concentration in small mammals from old orchards
Yocum, Susan Marie
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Lead and cadmium frequently occur together as contaminants in polluted environments such as roadsides, urban areas, mines, and smelters. Few studies have been conducted to examine the possible interactive effects these metals may have on reproduction of wild species. The first part of this study was directed toward examining the effects of low level dietary lead and cadmium on reproduction in Peromyscus Jeucopus. Two laboratory studies were conducted. Treatment with combinations of 0, 1 or 4 Î¼/g lead acetate and/or cadmium chloride was found to have no effect on overall health or reproductive ability of white-footed mice. In a second, experiment mice were treated with combinations of 0 or 10 Î¼g/g lead acetate and/or cadmium' chloride. Treatment was continued through three generations of mice (P1, Fl, F2); progeny of the P1 were paired with nonrelatives in the same group and continued on the same treatment. Percentage-of pairs producing at least one litter in a ten week period was reduced in mice receiving both lead and cadmium. By the F2 generation only one of ten pairs produced offspring. There were minor variations in litter parameters (# pups/litter, birth weight, weanling weight and viability of litters) measured for the three generations; however, treatment did not appear to greatly affect litters in those pairs which had litters. In the P1 generation kidney weights were lower in mice receiving lead and epididymidis weight was higher in mice receiving cadmium. Mice (P1) receiving cadmium and lead had lower numbers of spermatozoa/mg testis. Lead content of carcass, liver and kidneys was analyzed in mice from the P1 generation. The second part of this study examined the persistence of lead in the environment after the source of contamination has been removed. Short-tailed shrews (Blarina brevicauda) trapped in an orchard with a history of lead arsenate use had higher whole body lead concentrations than individuals of the same species trapped in a control orchard. Within the treated orchard lead concentrations in pine voles (Microtus pinetorum) were significantly higher than concentrations in short-tailed shrews.
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