Table 1.

Sources of detectable carcinogens in food.

Source	Examples a
1. Naturally occurring
Plant:	alkenylbenzene derivatives aristolochic acid cycasin ptaquiloside d-limonene	psoralen pyrrolizidine alkaloids pulegone β-myrcene
Microbial/Fungal:	various mycotoxins
2. Contaminants
Introduced before processing:	daminozide dioxins	DDT flumequine
Introduced during processing:	trichloroethylene	methylene chloride
Food contact materials:	plastics (polyolefins, polyesters, polystyrene, polyamides, etc.) polymeric coatings	monomers (vinyl chloride, styrene, acrylonitrile)
3. Additives
Anthropogenic:	α,β-aldehydes butylated hydroxyanisole and butylated hydroxytoluene	hexenal saccharin
4. Formed from food components
During processing:	acrylamide chloropropanols ethyl carbamate (urethane)	furan various nitrosamines alkylated imidazoles
During packaging:	bisphenol A furan	phthalates
During storage:	benzene
During cooking:	acrylamide benzo[a]pyrene	various heterocyclic amines
In the body:	nitrosamines and nitrosamides α,β-aldehydes	ethylene oxide

^a Many of the agents listed are detectable only at minute levels by highly sensitive analytical techniques.