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Quantifying Toxicity for the Deepwater Horizon NRDA


Highlights

  • Quantifying the toxicity of substances to marine and aquatic organisms requires expertise.
  • Abt brings impressive statistical modeling expertise to our work.
  • We've used that expertise extensively to assess the aftermath of Deepwater Horizon.
The Challenge

Abt Associates’ staff have extensive experience in designing, conducting, and managing field and laboratory bioassays, which measure the toxicity of a substance by its effect on living cells or tissues. We have used them to quantify the toxicity of various hazardous substances to marine and aquatic organisms.

The majority of such studies require statistical modeling methods to estimate dose-response relationships and to quantify specific features of those relationships. This includes, for example, estimating the LC50 which is the exposure concentration causing 50 percent mortality among exposed organisms.

    The Approach

    Historically, ecotoxicologists have relied on a small number of traditional computer algorithms to describe dose-response relationships, but we apply our statistical modeling expertise to develop customized techniques that provide greater flexibility and statistical rigor to the research effort. We develop applications primarily in the R statistical programming language to provide meaningful estimates of dose-response relationships and refined estimates of uncertainty associated with their key features. Implementing models in the R language also ensures that our techniques are transparent and easily shared with clients and colleagues.

      The Results

      We used these techniques extensively in support of the Deepwater Horizon Natural Resource Damage Assessment that included more than 200 toxicity assays designed to assess mortality, developmental abnormalities, growth retardation, and other toxic impacts to a variety of fish, birds, turtles, and invertebrate species.