Chemical Testing: Are We There Yet?
Federal regulators conduct safety evaluations on different kinds of chemicals---pharmaceuticals, industrial compounds, pesticides, food additives, etc. Regulations require toxicity testing, where animals are exposed to an unrealistically high dose of a chemical to elicit an adverse effect. This approach is costly, time-consuming, and controversial. There is also considerable scientific uncertainty, especially when extrapolating data from high dose to low dose, and from whole animals to humans.
In 2007, the National Research Council (NRC) called for a shift to a new paradigm, one where human cells are exposed to an environmentally relevant dose of a chemical. The cellular response from such in vitro assays, coupled with selective use of whole animal testing, can be used to evaluate chemicals more quickly, at less cost, and with fewer animals. Major scientific uncertainties are also reduced.
Since the NRC report, the federal government has taken steps toward the vision.
---Under a collaborative research effort called Tox21, participating federal agencies have developed and/or utilized hundreds of in vitro assays, coupled with high-throughput testing (i.e., involving robotics), to evaluate thousands of chemicals. Researchers are using the resulting data to identify valid, reliable, and relevant test methods to replace the traditional methods.
---After the BP oil spill incident in 2010, questions arose about the safety of the chemicals used to disperse the oil in the water. EPA utilized high-throughput testing methods to quickly screen eight dispersants for cytotoxicity and endocrine activity using 80 different assays. EPA completed this screening in six weeks.
---EPA’s Office of Chemical Safety is planning to use new screening methods to prioritize (starting in 2016) thousands of chemicals for Phase III of its endocrine disruptor screening program (EDSP).
---EPA’s pesticides office is working with external stakeholders to phase in new methods of testing into its registration process There appears to be plenty of opportunity for increased efficiency: regulatory approval for a new pesticide can take a decade and cost ten million dollars. Yet EPA typically uses only a small subset of the required tests to derive the reference dose (safe dose level) for humans.
When these promising new methods are deemed ready, it is unclear if regulatory agencies will remove existing requirements based on traditional methods. Inertia is a mainstay of regulatory programs, and it often takes more than science to motivate political action.
In its 2007 report, NRC predicted a decades-long effort to shift from the old paradigm to the new one. In a few short years, EPA and other federal agencies have taken important first steps, but the journey ahead remains long and arduous.