I learned a while back that if you read the full prescribing information for almost any medication a doctor prescribed, you would find some pre-clinical study in which there was some mutation or tumor produced, whether in bacteria or mammals.  I'm talking about medications that received FDA approval.  They'd do test after test to evaluate carcinogenicity, and one of the tests would always come up as at least a possible or equivocal positive.  It used to spook me, and I wondered how the drugs got approved, until it began to strike me that almost anything is associated with tumors, mutations, or other adverse effects in the right dose or context (in massive doses, in female hamsters but not male or female mice, only if put up the nose but not if slathered on the skin, etc).  Rather than being alarming, this was reassuring to me.  It kind of gave me the idea that you should always pause before panicking when you hear of evidence that a chemical (such as a cosmetic ingredient) may cause cancer.
It also helped me to know that we're exposed every day to carcinogens, and that they are unavoidable in our world.  I'm not arguing that you shouldn't minimize exposure to the major players, stuff that comes up positive on every test of carcinogenicity with flying colors or makes geiger counters go berzerk (benzene, high dose radon, tobacco).  But I do think grouchy older people (or younger people) who shrug and say "everything causes cancer" have a point.*
Anyway, monologue over, but I thought I'd share the following article from the American Council on Science and Health.  Here  is a list of all-natural carcinogens in a holiday meal.
http://www.acsh.org/publications/pubID.103/pub_detail.asp
*And here is where it gets interesting.  One thing I learned from the above article is that of chemicals that have been tested in rodents to determine their cancer-causing potential, 57% of the naturally-occurring chemicals, and 59% of the man-made ones tested positive.  That means, if we determined what chemicals we should steer clear of based only on rodent studies, we'd avoid more than half of naturally-occurring AND synthetic substances.  We wouldn't have a lot left that we'd tolerate being put in our cosmetic products (or be willing to eat in our food.)