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.

He then calculated the concentration of pyrethroids that would have made it to the brain, and introduced a solution with that concentration into a dish containing nerve cells; he found that the cells lost neurites—little extensions that help them communicate with each other. The same thing happens in Alzheimer's disease, which means pyrethroids might have something to do with that disease as well as cancer.

Van Schaik entered his experiments in the 2008 Intel Science Talent Search and was named a finalist. His parents were thrilled—especially his mom, who'd spent long hours sitting in the University of South Carolina, Columbia, labs where Van Schaik had done much of his work, waiting for him to finish up his experiments. "I think she has her Christmas cards done up to 2012," he says.

The effect on his career: Boosted by his own experience working in the lab, several years ago Van Schaik developed a science curriculum for second through fifth graders called "science captivates minds". This past summer, for two hours a day, three days a week, he'd help preteens at local Boys and Girls Clubs do hands-on experiments to test various concepts: Can you make a battery out of a lemon? How many pennies can various shapes of tinfoil boats hold before they sink? His major breakthrough, he says, was initiating pre- and post-testing to see exactly what his young charges learned. He could then retool to make the lessons hit home. "I've actually seen as much as a 600 percent improvement in certain subject areas," he says.

This, in turn, caused a 600 percent rise in happiness among the Boys and Girls Club staff. "The kids loved him," says Susan Key, vice president for operations of the Boys and Girls Club of the Midlands in Columbia. Many came in to the program thinking that science was about textbooks. Van Schaik showed that, in fact, it could be about pig lungs and tomatoes. "Kids came out of it really loving and embracing science," Key says. "A teacher couldn't have done anything better."

What he's doing now: Van Schaik enrolled at the Massachusetts Institute of Technology this fall.