Aflatoxins are a known carcinogen that first appeared in the First Annual Report on Carcinogens published in 1980 by the National Toxicology Program/U.S. Department of Health and Human Services. At the time there were 26 chemicals listed as known human carcinogens.
Aflatoxins are a type of mycotoxin that grow in decaying vegetation when ideal conditions of high moisture content and temperature exist. Aflatoxins grow naturally and can be found in cereals, oilseeds, spices, tree nuts, and the milk of animals that are fed contaminated feed. A small amount (100 grams per year) is produced for research purposes.
The effects of aflatoxins are either acute or chronic. Acute effects are hemorrhage, acute liver damage, edema, and possibly death. Acute effects occur when moderate to high levels of aflatoxins are consumed. Chronic effects occur due to low to moderate levels of consumption of aflatoxins and the effects are more difficult to recognize. Some effects are impaired food conversion and slower growth rates.
All animals (including humans) are susceptible to the effects of aflatoxins, though mortality in developed countries is rare. In fact, a laboratory worker attempted suicide by ingesting 12 ug/kg of body weight of aflatoxin per day for 2 days, and 6 months later ingested 11 ug/kg for 14 days. The worker only suffered rash, nausea, and headache, and 12 months later a physical exam showed all body functions were normal.
In 1974 an outbreak of aflatoxicosis due to contaminated corn occurred in India that affected 397 people, 108 of which died. The daily amount ingested was estimated to have been 55 ug/kg of body weight for an unknown number of days.
In 1982 another outbreak of aflatoxicosis occurred in Kenya. 20 people were admitted to the hospital, 12 of whom died. The estimated intake of aflatoxin was 38ug/kg of body weight for an unknown number of days.
Studies and research
In one study, 7% of monkeys given aflatoxin B1 for over 2 years developed liver cancer. Another study showed what could be considered safe levels of aflatoxin by exposing liver tissues to aflatoxins B1 and M1. Using the HPLC method, results showed that at the level of .71 mg/100grams for aflatoxin B1 and 1.1 mg/100 grams of M1, some contamination was present but not at a toxic level.
Statistical research done on aflatoxic rates in areas with high incidences of hepatitis B should take into account possible confounding due to the carcinogenic effect both have on the liver. Many of the underdeveloped areas in which exposure to aflatoxin from contaminated foods is common also have a high rate of hepatitis B. However, even when taking into account the effect of hepatitis B on the liver, there was a high association of aflatoxin and liver cancer.
Chemical structure and properties of aflatoxins
18 different types of aflatoxins have been identified. They are divided into two categories based on their chemical structure – see images for which group some of the more common types fall into.
Aflatoxins are destroyed with bleach or by autoclaving with ammonia. They will not be destroyed by cooking and food preparation. Aflatoxins are slightly soluble in water, soluble in moderately polar organic solvents, and insoluble in nonpolar solvents. They are unstable in UV light, pH below 3 or above 10, and when exposed to oxidizers.
Sources:
http://ntp.niehs.nih.gov/ntp/roc/eleventh/profiles/s006afla.pdf
National Toxicology Program – Department of Health and Human Services Substance Profiles
http://www.cfsan.fda.gov/~mow/chap41.html
US Food and Drug Administration – Center for Food Safety and Applied Nutrition
http://www.ncbi.nlm.nih.gov/pubmed/63557
J Natl Cancer Inst.CARCINOGENICITY OF AFLATOXIN B1 IN RHESUS MONKEYS: TWO ADDITIONAL CASES OF PRIMARY LIVER CANCER.
http://www.jmedcbr.org/archives/CBMTSIII/cbmts3-37.pdf
Journal of Medical Chemical, Biological and Radiological Defense DETERMINATION OF AFLATOXINS BL AND ML IN CHICKEN LIVER BY HPLC
http://www.aflatoxin.info/aflatoxin.asp
PROPERTIES OF AFLATOXIN AND IT PRODUCING FUNGI
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