I'll research that further. The carcinogens in charred meat come from the meat itself--substances degrade in the high heat. So that wouldn't be a vegetable issue. However, there may be issues with burning charcoal, lighter fluid, etc.
I'm definitely making a greater effort to marinate everything, too. That article had a list of about a dozen things you can do to increase the safety of meat grilling. Unfortunately, its not online.
Nutrition Newsletter Information Page Here is some older data; we know even more, now.
Article from 1989