White phosphorus burns inside the body as long as it also has access to oxygen, but what does it do to the soil and water? I don't know of any studies, so it seems that we have alot of research to do on our own to get any answers.
I know nothing about Chemistry and have no medical knowledge, so I don't know what information would be helpful, but at this point, any research has to start somewhere. http://www.absoluteastronomy.com/topics/Phosphorus