Teenagers from the United States and Taiwan won the top honors Friday at the world's largest science competition for high-school students. Mike Cooper talked to winners of the international science fair held in the southeastern U.S. city of Atlanta.

Students from 51 countries competed in this year's International Science and Engineering Fair. And, for the first time in the history of the awards, all of the top three winners are young women. Each of the three teenagers received the Intel Young Scientist Award, which comes with a $50,000 college scholarship.

Yi-Han Su of Taipei, Taiwan, did research to help the environment. She identified a catalyst that could generate hydrogen more efficiently for fuel cells, which are considered an environmentally friendly fuel source. "Using my catalyst, the hydrogen produced in the reaction can efficiently supply hydrogen for a fuel cell, which may give a chance for effective alternative energy."

Natalie Omattage, from the southern state of Mississippi, developed a more efficient and less expensive way to find food additives that may be contaminated. Miss Omattage, who was born in the United States but whose parents are Sri Lankan, said her research was prompted by the deaths of household pets last year from an ingredient in pet food that had been imported into the United States.

"So, basically, I made a way to identify hazardous chemicals in solutions and this can be applied in the mainstream world through food screening as well as the identification of other chemicals and compounds at border patrol as well as homeland security," Omattage said.

Another winner, Sana Raouff of New York City, was honored for her sophisticated research involving mathematical theories about how knots are tied that may help biochemists classify molecules.

Exhibits at the science fair were highly technical. Many of them looked at ways to protect the environment or produce energy more efficiently.

Omattage, the high school senior from Mississippi, said the weeklong event gave her a chance to meet other young scientists from around the world. "It's been a really good experience. Last year, I came to Intel and I didn't win anything so I didn't really come here thinking I was going to win anything. I just came for the experience. I missed all my senior events and I was kind of upset about it at first because I was missing graduation practice and everything. And I was pretty upset. But then just being here with everybody from all over the world has been a really great experience and just bonding with people, it's been wonderful."

There were more than 1,200 projects in this year's competition, the largest event since the science fair was first held in 1950.