T7 PM Metals and Bioaccumulation
Tuesday, 15 November 2005: 1:50 PM - 5:30 PM in 327-329

(MCB-1117-844174) Pb Bioaccumulation in Deer Mice: Competition and Antagonism by Co-Occurring Essential Metals in Lab and Field Studies.

McBride, T¹, Reynolds, K², McFarland, C¹, McMurry, S¹, Hooper, M¹, ¹ Texas Tech Universtiy, Lubbock, TX, USA² USFWS, Phoenix, AZ, USA

ABSTRACT- Our studies of mixed metal and metalloid (As, Cd, Cu, Pb, Zn) exposure in deer mice (Peromyscus maniculatus) at the Anaconda Smelter Site indicated that metal bioavailability of soils contaminated by aerial deposition occurred as a simple linear function of the levels of metals in the soils, though the slope and intercept of the functions were notably lower than anticipated in preliminary risk assessments. Alternatively, metals from former industrial site soils were up to 10 times more available, as evidenced by deer mice carcass concentrations. Further, Pb-induced ALAD inhibition in Anaconda deer mice was reduced compared to similarly exposed laboratory rodents. The co-occurrence of biologically interactive metals in the soil (notably Zn and Cu) potentially influenced these unanticipated findings. To investigate these unexpected findings, we initiated an assortment of regimes with deer mice using both highly bioavailable metals, as well as site-specific soils. Findings from mixed-metal dosing studies are compared and contrasted with those from deer mice dosed with soils collected from specific subsites on the Anaconda Smelter Superfund site, and deer mice captured directly on the studied subsites, to assess the utility of laboratory methods for estimating bioaccumulation and biomarker effects detected in field collected animals. Adult, lab-reared deer mice, exposed to increasing Cu and Zn concentrations, concurrent with effect-inducing Pb exposures, had significantly reduced Pb accumulation in a variety of tissues, suggesting they compete in the uptake mechanisms for Pb. Further, increased Zn, but not Cu, in the diet antagonized Pb's inhibitory effect on ALAD (delta-aminolevulinic acid dehydratase) activity. An initial soil feeding study (3% in food of adult deer mice) indicated that Pb bioaccumulation was approximately 30% compared to Pb-Acetate dosed food at similar concentrations. Further, no differential bioavailability was detected between aerial and industrial sites soils in this initial investigation.

Key words: deer mouse, metals, soils, bioaccumulation