Meet EPA Scientist Tim Shafer, Ph.D.
New Generation of Chemical Testing
Tim Shafer earned his bachelor’s degree in biology and chemistry from Hope College in Holland, MI, in 1986 and his Ph.D. in pharmacology and environmental toxicology from Michigan State University in 1991. Tim started working as a postdoctoral fellow at EPA in August 1991 and has been with the Agency for 29 years. Tim currently is developing high-throughput screening methods for neurotoxicity and developmental neurotoxicity.
What research are you doing at EPA?
The overarching goal of my research is to protect the developing brain from adverse effects of chemicals. In humans, there is evidence that the nervous system is not completely developed until you’re 25 years old, so the effects chemicals might have on its development are important. If the structure or function of the brain is altered during development, this can have life-long consequences for the individual and can also have societal impacts.
For many years, animal-based testing has been the primary way that chemical hazard to the developing nervous system is assessed. Unfortunately, these tests cost about $1 Million for every chemical tested, take 1-2 years to complete and thus have only been conducted for a few hundred compounds. By contrast, there are thousands of chemicals in the environment to which humans are exposed as the brain develops. So we need better ways to test more chemicals for developmental neurotoxicity hazard.
I have a background in neurophysiology, so, I focus on how the nervous system’s cells communicate with one another. We have developed an in vitro assay that allows us to measure the electrical communications between networks of neurons as they develop. It only takes 12 days to evaluate the effects of a chemical in this assay and we can test about 25 chemicals in a month. This is a very sensitive way of looking at how a chemical can disrupt the development of brain function. Together with a now retired colleague, we also developed a series of assays that examine how chemicals can alter brain structure as it develops. Together, these assays comprise a battery of assays that show great promise for detecting chemical effects on the developing brain and are faster and cheaper than the animal study. That means many more chemicals can be tested more quickly than in the animal study.
Can you tell us more about the importance of high-throughput toxicology?
High-throughput toxicology and other New Approach Methodologies (NAMs) are changing the way that we approach assessing the risks associated with chemicals. In the past, toxicology has relied heavily upon animal-based testing approaches which are slow and expensive, and don’t always predict the risks to humans. Human cells are now readily available due to the advent of Inducible Pluripotent (human) Stem cells, which are ethically derived and can be used to generate almost any type of human cell, including brain cells. Now we can use human cells in NAMs and get a much better idea of how chemicals can disrupt human physiology and lead to adverse outcomes. Combined with high-throughput approaches, we can now assess the hazard of many more chemicals in systems that are directly relevant to humans.
What do you like most about your research?
I like the everyday challenges the most, and I’m working with a very cool and exciting technology. I also enjoy the people who I work with; that’s one of my biggest job satisfactions. I work with a really good group of people and with students who are very enthusiastic.
How did you get started in science?
I was always interested in science, even in fifth and sixth grades. By the time I was a senior in high school, I knew I wanted to get a Ph.D. I grew up in Midland, MI, where the headquarters of the Dow Chemical Company is located. It’s the main employer in town, and, as I was growing up, dioxin became a very big issue. It was especially a big issue in Midland because there was dioxin contamination, so the science around dioxin was in the news, as were several controversies involving dioxin. Because I grew up in an environment where issues of toxicology were prevalent, the field of toxicology appealed to me early on.
If you could have dinner with any scientist, past or present, who would it be?
I think right now I’d have to say Albert Einstein. I think he’d be a very interesting person to meet. He was obviously extremely intelligent and had some really neat ideas about physics.
Do you have any advice for students considering a career in science?
I have talked to a lot of different students who I’ve worked with about their career development. I think, if you really want to be in science, you have to be willing to work hard and have a passion for the work. Being passionate about science makes all of the hard work worthwhile.
You also have to have a high tolerance for frustration because there are times when things don’t work, so you need to be persistent. Don’t give up the first time something fails because, when you’re working hard on something, spending time trying to get it to work, and it finally does work, that’s part of the reward.
Editor's Note: The opinions expressed herein are those of the researcher alone. EPA does not endorse the opinions or positions expressed.