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Evaluation of the possible impacts of rodenticides on wildlife must be conducted in the context of risk-benefit considerations. Harmful introduced pests (e.g., commensal rats and mice) historically have required management around human habitation for economic and public health reasons. Disparate views of limited data have accumulated concerning the wildlife impacts resulting from commensal rodent control activities. The founding of the Rodenticide Registrants Task Force (RRTF), a trade association that includes all the major manufacturers and importers of anticoagulant rodenticide products (and bromethalin, a non-anticoagulant rodenticide) in the U.S., is described. The potential for anticoagulant dispersion in wildlife via primary and secondary routes is considered. Toxicology and pharmacokinetic studies are analyzed to obtain a better understanding of the biological and toxicological significance of low levels of rodenticide in animal tissue. A framework to address rodenticide impact to wildlife is presented. It is based upon the example of long-term cooperative efforts in England involving government, environmental, and manufacturer groups.

The toxicity of octamethylcyclotetrasiloxane (OMCTS) to the midge Chironomus tentans was examined in a series of aqueous and sediment exposures. Midge larvae were exposed for 14 days to five concentrations of radiolabeled [14C]OMCTS in each of three sediments (low, medium, and high organic carbon content). Additional tests were conducted with a water-only exposure. Results indicate the lowest 14-day no observed effect concentrations (NOEC) to be 65, 120, and 54 mg/kg for the low, medium, and high organic carbon sediments, respectively. For the water-only exposure, the 14-day NOEC was > 15 micrograms/liter. These results were used in the preparation of a risk assessment for OMCTS which took into consideration the physicochemical and environmental fate properties of the compound, as well as actual field monitoring and worst-case modeling results for assessment of exposure. Available evidence suggests that sediment concentrations of OMCTS do not present a risk to sediment-associated organisms. For 95% of sediment samples, data indicate that the margins of safety would be greater than 400 and potentially over 1000. Worst-case margins of safety were greater than 150.

The toxicity of di-2-ethylhexyl phthalate (DEHP), a ubiquitous environmental pollutant, was measured experimentally as a contaminant in shrimp aquaculture feeds. Diets containing 40 to 50,000 ppm DEHP were fed to Penaeus vannamei for 14 d at 4% body weight/d. DEHP concentrations in shrimp, diet, and water were measured by electron-capture gas chromatography. Whole-body residues in shrimp were 18 ppm at the highest dose, and bioconcentration factors were inversely proportional to dose. DEHP in water was less than or equal to 1.7 ppb for all dose levels. No increased mortality or histopathological alterations were observed at any dose. Absorption of DEHP by P. vannamei was measured in static 24- and 96-h bioassays. Diets enriched with [14C]DEHP to levels of 60, 600, and 6000 ppm were fed at 2% body weight/d. At all dose levels, 3.7% of total radioactivity was measured as body burden in shrimp and 40% as polar species in test water after 96 h. DEHP by oral administration was absorbed, metabolized, and excreted, and this process was linear with dose for the dose range studied.