Poison Ivy Getting Bigger, Stronger

U.S. researchers say increased carbon dioxide is helping poison ivy grow bigger faster.

Even with a small change in CO2, poison ivy increased its biomass, U.S. Department of Agriculture plant physiologist Lewis Ziska told ABC News.

The study, which will be published this summer, said high-CO2 plants produce a more allergenic form of urushiol, which causes the itching.

The study suggests poison ivy will become more abundant and more toxic in the future, potentially affecting global forest dynamics and human health, the USDA Web site said.

The new data reinforces a May 2006 study that also found increasing amounts of carbon dioxide could potentially create bigger, more poisonous plants, ABC said Wednesday.