Re: question about paint
It is true that for most carcinogens, it's prolonged or repeated exposure to them that causes cancer, so I don't think you have to worry too much about painting one car.
However, even one sunburn can cause enough damage to the skin to cause mutations of the skin cells and, eventually, cancer. And there's no way to test for who is most susceptible to developing skin cancer (except that we know that the skin of infants is more susceptible to damage), so the best course of action regarding sun exposure is...the less, the better. NEVER go out in the sun without protection.