Dr. Ivan Rusyn is a professor of environmental sciences and engineering at UNC-Chapel Hill. Here, he explains how the new field of toxicogenetics is studying the safety of chemicals found in our surroundings. Questions and answers have been edited.
Q: What do we know about the safety of the chemicals we are exposed to in our daily lives?
Drugs are thoroughly tested before they are approved for use. However, the situation is quite different for environmental chemicals that humans may be exposed to through the workplace, consumer products, or their natural environments.
Only pesticides and related compounds are tested before they are approved. Chemicals in use before the Toxic Substances Control Act became the law in the 1970s were all “grandfathered” in, meaning they were assumed to be safe.
New chemicals require registration, not approval, by the Environmental Protection Agency, and the burden is on the U.S. government to prove the compounds may be hazardous to humans. Of the estimated 100,000 chemicals that may have been released into the environment, only a small fraction has been evaluated for posing potential health risks.
Q: If we know so little about the safety of these environmental chemicals, what is being done to bridge that gap?
The European Union has moved to reverse the burden of proof for environmental chemicals – meaning manufacturers must provide certain information to governmental agencies that their products are safe. TSCA reform is also gaining momentum in Congress. But we still don’t know what the best way is to address the enormous number of chemicals that have little to no information to assess their safety hazard.
Q: Will there ever be a way to predict who will have a poor response to a specific chemical exposure, even before they are exposed?
A strong link between exposure and human diseases like cancer has been established for a few chemicals. For some, unique genetic variants have been identified that may render certain individuals more susceptible. We and our colleagues at the National Institute of Environmental Health Sciences and the National Center for Advancing Translational Sciences recently compiled the largest publicly available set of cytotoxicity data to explore how genetics plays a role in susceptibility.
The NIEHS-NCATS-UNC DREAM Toxicogenetics Challenge invites the greater scientific community to use this information to develop computer models that may predict what individuals may be at risk, or what chemicals may have the greatest potential hazard.