Science Wednesday: The Challenges and Rewards of Health Assessment

Each week we write about the science behind environmental protection. Previous Science Wednesdays.

Conducting health assessments for chemicals at EPA involves synthesizing the available scientific literature on a particular chemical and determining the health risks that the chemical poses to humans. Personally, I find it fulfilling to be involved in this type of career because the information is useful to the public.

Being a health assessor is rewarding but there are also several challenges in determining how a chemical might act in the human body. One challenge is determining the effect of a chemical in the body when you don’t know much about the toxicological data. There are sophisticated tools, such as microarray analysis and structure-activity analysis, to study compounds with limited information. In microarray analysis, scientists treat particular genes with a chemical and then monitor the results. So if a data-poor chemical has a similar gene profile to an endocrine disrupting chemical, then we hypothesize that this chemical could be a potential endocrine disruptor. Structure-activity analysis helps classify a compound based on its chemical structure. Both of these types of analyses can be completed quite quickly to understand how these data-poor chemicals could act when humans are exposed.

It is also quite challenging when a chemical has been studied extensively. When there is a lot of research on a chemical, arguments sometimes arise about the validity of the research or if a chemical is actually responsible for a resulting health effect. To add to the confusion, although there could be several studies on a chemical, they might not necessarily indicate a clear health effect. In some cases, chemicals have many studies showing health effects in animals but no evident effects in humans.

As health assessors, we generally assume that humans are more sensitive to health effects than animals. Therefore, if a chemical causes toxic effects in animals, then humans should be more susceptible. To reduce this uncertainty, it is important to understand the difference in a chemical’s effect between animals and humans.

Even though there are challenges in evaluating the health risks of chemicals to humans, it is rewarding to know that this information can be used to help keep people healthy. Overall, my job is to understand the potential health risks that could arise from exposures to chemicals in the environment.

About the author: Ambuja Bale works as a risk assessor in EPA’s National Center for Environmental Assessment. She has a PhD in Pharmacology and Toxicology.