Children as young as five years old are working on tobacco farms and being exposed to toxic levels of nicotine, CNN reported Sept. 25.

A new report from the charity Plan International found that hundreds of thousands of children are working on tobacco farms worldwide, and that on wet days they can be exposed to the amount of nicotine found in 50 cigarettes. “Nicotine is water soluble and can enter via the skin, so if it has recently rained, or there is heavy dew, the nicotine migrates into the water on the leaf,” said Henry Spiller of the Kentucky Regional Poison Center. “If that water gets on to your shirt it essentially becomes a giant nicotine patch.”

Many children suffer chronically from Green Tobacco Disease, a result of nicotine exposure. “Sometimes it feels like you don't have enough breath,” said one child worker. “You reach a point where you cannot breathe because of the pain in your chest. Then the blood comes when you vomit. At the end, most of this dies and then you remain with a headache.”

Experts see the proliferation of child labor as a result of globalization, with tobacco companies shifting production away from wealthy nations like the U.S. to developing countries where labor is cheaper and regulation more lax.