ICCVAM Biennial Report 2014-2015

Ecotoxicity testing refers both to the assessment of chemical effects on fish, birds, or other wild organisms and the testing of soil, sediment, or effluents for the presence of toxic compounds. To fulfill their mandates to protect the environment, several ICCVAM member agencies, including the Department of the Interior (DOI) and the U.S. Environmental Protection Agency, require manufacturers of pesticides and other chemical products to conduct ecotoxicity testing.

Ecotoxicity testing can require animal testing using either the species of interest or animal models of the species of interest. ICCVAM member agencies are exploring ways to reduce or replace animal use for ecotoxicity studies.

ICCVAM Agency Activities

• DOI: USGS scientists are using a variety of in vitro assay systems for environmental monitoring.
  • USGS scientists are utilizing yeast and mammalian cell assays to monitor endocrine active chemicals in environmental waters. These data along with data from geographic information system analyses are used to identify land uses associated with increased endocrine activity.
  • A suite of yeast, bacterial, and eukaryotic cell culture assays are used to screen environmental waters within National Park Service lands to assess biological activity of chemical mixtures in these waters. This work is done in parallel with comprehensive chemical analysis as a means of assigning possible biological significance.
  • In vitro reporter gene assays and transgenic zebrafish strains are used to screen water samples for endocrine activity. These include samples from sites near hydraulic fracturing operations, wastewater treatment facilities, and agricultural lands.
  • Omics approaches that measure the expression of genes (genomics) or metabolites (metabolomics) are being used in fish to analyze whole organ or individual animal responses to toxicants. For example, studies in carp determined that upregulation of genes involved in uncoupling cellular respiration to energy production is associated with resistance to rotenone. Additionally, metabolomic profiling has been applied to elucidating potential biological pathways influenced by exposure to toxicants. A library of metabolites associated with toxicity to specific toxicants is being developed.
• DOI: USGS is developing an approach that reduces animal use for identification of potential fish toxicants by using a more efficient initial screening process. The three integrated phases of the screening process include identifying physical properties of compounds that affect bioavailability in fish, prescreening of a chemical databank to prioritize candidate compounds, and screening of selected compounds for cytotoxicity using in vitro biological assays and fish cell lines. Compounds that demonstrate potent cytotoxic effects are then selected for in vivo biological assays for toxicity screening. Although in vivo testing continues to be utilized, primary investigations using prioritization and in vitro testing reduce the use of whole fish.
  The chemical databank to be used for this purpose is in the final stages of internal review and approval. The databank is expected to be publicly available on the USGS website in the near future.
• DOI: Anticoagulant rodenticides, used worldwide for vertebrate pest control in urban and suburban settings, agriculture, and island restoration projects, pose risks to children, companion animals, and nontarget wildlife. As a result, restrictions have been placed on the use of some anticoagulant rodenticide baits.
  Scientists with the U.S. Geological Survey (USGS) and international collaborators have developed an adverse outcome pathway for anticoagulant rodenticides. This effort demonstrated that, while the mechanism of action of anticoagulant rodenticides at the molecular and cellular levels is well understood, future research in specific areas is needed to better characterize the effect of these rodenticides on nontarget species at the individual and population levels.
• DOI: Anticoagulant rodenticides are used for rat eradication to protect breeding colonies of birds on remote island refuges in the Pacific Ocean. USGS is using the up-and-down procedure, as described in EPA guideline OPPTS 870.1100, to reduce animal use for testing the sensitivity of triggerfish to three anticoagulant rodenticides. These studies will help fish and wildlife management biologists determine the relative risks of anticoagulant rodenticide use to nontarget fish species in coral reef areas.