T10 PM Advances in Bioaccumulation Assessment
Tuesday, 15 November 2005: 1:50 PM - 5:30 PM in 341-342

(TOR-1117-856586) Bioaccumulation in Small Mammals.

Torres, K¹, Johnson, M², ¹ Tetra Tech, Inc., Lafayette, CA, United States² John Muir Institute of the Environment, UC Davis, Davis, CA, United States

ABSTRACT- Accurate predictions of chemical concentrations in tissues of small mammals are important for reducing uncertainty in ecological risk assessments. Small mammals are a key pathway for the trophic transfer of contaminants to predators. Bioaccumulation modeling can also be useful to improve our understanding of mechanisms involved in bioaccumulation, including absorption, distribution, metabolism, and excretion. Two general types of bioaccumulation models will be reviewed, statistic-based empirical models (e.g., bioaccumulation factors and regressions) and mechanistic models. The relative prevalence, advantages, and shortcomings of available modeling tools will be discussed. Direct measurements of tissue concentrations for risk assessments and monitoring are preferred over modeling in certain situations. Model testing with empirical measurements will be reviewed in the context of a study of bioaccumulation of arsenic, cadmium, copper, lead, and nickel body in house mice (Mus musculus) inhabiting a seasonal wetland in California. Published soil-to-small mammal bioaccumulation regression models produced accurate estimates of arsenic and lead body burdens, but failed to adequately predict copper and nickel levels in mice. A simple mechanistic model for cumulative assimilation of ingested metals overpredicted lead levels in mice generally by less than one order of magnitude, but greatly overpredicted concentrations of arsenic, copper, and nickel. Recommendations for further research and applications of bioaccumulation advancements in ecological risk assessments will be proposed.

Key words: bioaccumulation model, metals, small mammals, ecological risk assessment