Graham Van Schaik
courtesy Graham Van Schaik

His finalist year: 2008

His finalist project: Figuring out whether an ingredient in pesticides and bug repellent is toxic

What led to the project: As a boy, whenever Graham Van Schaik visited his grandmother in Florida, he helped her out in the garden. He'd weed and dig, but she wouldn't let him near her pesticides. "She said it made her feel ill," he says.

He was curious why, and thought he'd found an answer when he looked at the ingredient list. There, he found a chemical called permethrin, a member of a family of chemicals known as pyrethroids that are often used in home and farm pesticides, bug repellents, lice creams and the like. Pyrethroids are known to be highly toxic to some animals, including cats.

Van Schaik, now 18, wanted to know what they did in humans. So, while in high school in Columbia, S.C., he designed several experiments to mimic how the human body would encounter pyrethroids. Van Schaik grew tomato plants at home and applied the dose of pyrethroids used in regular garden pesticides. After picking and washing the tomatoes, he analyzed them at a South Carolina Department of Agriculture laboratory, and found that traces of the chemical had seeped deep into their flesh.

He then applied amounts similar to what a person would ingest over time to cells in a dish, and found that pyrethroids were associated with a jump in cell growth. That suggests they may potentially increase the risk of cancer, although more studies would be needed to determine a clear link.

Van Schaik—after reading about previous research suggesting that pyrethroids might affect the central nervous system—wondered whether pyrethroids might quicken the progression of Alzheimer's disease and other neurodegenerative disorders. Because this research noted that as much as half of pyrethroids we breathe in end up in the central nervous system, he wanted to see just how much someone might inhale in the course of a normal day. When he pumped air containing small amounts of pyrethroids into a pig lung, he found that in fact the chemicals did stick to lung tissue.