Miscellaneous chemical carcinogens

Chemical carcinogenesis can come in a variety of forms which are not directly related to occupation or medical treatment:

• natural result of presence of organism or its product:
  • some strains of Aspergillus flavus stored on grains or peanuts produce a toxin for hepatocytes - aflatoxin B1; in Africa and the Far East, the concentration of aflatoxin in the diet correlates with the incidence of hepatocellular carcinoma
  • Helicobacter pylori produces a chronic gastritis that has been linked to the eventual development of gastric carcinoma
• dietary influence:
  • provide substrates for the formation of carcinogens, e.g. nitrites and nitrates
  • increasing the duration of carcinogen contact with stem cells by changing the dietary composition, e.g. low-residue diets which prolong transit
  • varying the proportion of selenium and vitamins C and E in the diet, so influencing the amount of free radical production and hence gene damage
• pollution:
  • air: when air pollution was more severe at the turn of the century, lung cancer was concentrated in urban areas
  • water: weak relationship between the presence of halogenated hydrocarbons and pesticides and bladder cancer