Kinner outlined a series of gaps in the current system of testing dispersants. U.S. EPA's analysis of their toxicity focuses on acute effects of exposure in two representative species, but "we do very little chronic toxicity work," she said. That work would evaluate whether dispersants could heighten the mortality of larvae and other sensitive species that may not die off immediately but studies show are absorbing tiny droplets of dispersed oil into their shells.
Dispersant studies have not examined the products' long-term effects and their consequences when applied at high pressure, Kinner added, which BP did by spraying the chemicals subsea near the leaking wellhead. Diaz added another mystery to the list, noting that current studies focus on marine organisms that may not be feeling the brunt of this summer's dispersant assault.
"All the risks we've evaluated have used surface, shallow-water species that are easily maintained" in a laboratory setting, Diaz said. "We haven't been using oceanic species to assess risk, and this is a key issue."
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