We don't use DDT in the US any more, but residues will remain for a long time. Ethylene dibromide has been used as fumigant to get rid of pests in agricultural soils, as well as an insecticide. Some of the chemical carcinogens naturally occur in our environment. Nitrosamines are found in bacon and dried squid, for example. Processed meat of all sorts tend to be bad.
Urethane is part of sake.
Aflatoxins and part of the spoilage process with peanuts and grains. These are monitored pretty carefully in the US, but be careful when you travel in developing countries. Don't eat peanuts unless you are pretty sure that they are fresh. Ethyl alcohol, the alcohol found in beer, wine and distilled spirits also has carcinogenic properties. There are some physical agents that are carcinogenic.