Aflatoxin

Chemical structure of aflatoxin B1

Aflatoxins are various poisonous carcinogens and mutagens that are produced by certain molds, particularly Aspergillus species mainly by Aspergillus flavus and Aspergillus parasiticus. According to the USDA, "They are probably the best known and most intensively researched mycotoxins in the world."[1] The fungi grow in soil, decaying vegetation and various staple foodstuffs and commodities such as hay, maize, peanuts, coffee, wheat, millet, sorghum, cassava, rice, chili peppers, cottonseed, tree nuts, sesame seeds, sunflower seeds, and various cereal grains and oil seeds. In short, the relevant fungi grow on almost any crop or food. When such contaminated food is processed or consumed, the aflatoxins enter the general food supply. They have been found in both pet and human foods, as well as in feedstocks for agricultural animals. Animals fed contaminated food can pass aflatoxin transformation products into milk, milk products, and meat.[2] For example, contaminated poultry feed is the suspected source of aflatoxin-contaminated chicken meat and eggs in Pakistan.[3]

Children are particularly vulnerable to aflatoxin exposure, which is linked to immune suppression, stunted growth,[4] delayed development,[5] aflatoxicosis,[6] food spoilage and liver cancer. Some studies have reported an association between childhood stunting and aflatoxin exposure, although this link has not been consistently detected in all studies.[7][8][9][10] Furthermore, a causal relationship between childhood stunting and aflatoxin exposure has yet to be conclusively shown by epidemiological studies, though such investigations are underway.[11][12][13] Adults have a higher tolerance to exposure, but are also at risk. No animal species is known to be immune. Aflatoxins are among the most carcinogenic substances known.[14] After entering the body, aflatoxins may be metabolized by the liver to a reactive epoxide intermediate or hydroxylated to become the less harmful aflatoxin M1.

Aflatoxin poisoning most commonly results from ingestion, but the most toxic aflatoxin compound, B1, can permeate through the skin.[15]

The United States Food and Drug Administration (FDA) action levels for aflatoxin present in food or feed is 20 to 300 ppb.[16] The FDA has had occasion to declare both human and pet food recalls as a precautionary measure to prevent exposure.

The term "aflatoxin" is derived from the name of the species Aspergillus flavus, in which some of the compounds first were discovered. A new disease was identified with unknown characteristics in England during the 1950s and 1960s, which increased turkey mortality. Later, aflatoxin was recognized in 1960 in England as a causative agent of the mysterious Turkey ‘X’ disease that causes excessive mortality in turkey poults.[17] Aflatoxins form one of the major groupings of mycotoxins, and apart from Aspergillus flavus various members of the group of compounds occur in species such as Aspergillus parasiticus, Aspergillus pseudocaelatus, Aspergillus pseudonomius, and Aspergillus nomius.[18]

  1. ^ "Molds on Food: Are They Dangerous?". www.fsis.usda.gov.
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  4. ^ Khlangwiset P, Shephard GS, Wu F (October 2011). "Aflatoxins and growth impairment: a review". Critical Reviews in Toxicology. 41 (9): 740–55. doi:10.3109/10408444.2011.575766. PMID 21711088. S2CID 19262759.
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  6. ^ "Aflatoxicosis". 30 September 2014.
  7. ^ Voth-Gaeddert LE, Stoker M, Torres O, Oerther DB (April 2018). "Association of aflatoxin exposure and height-for-age among young children in Guatemala". International Journal of Environmental Health Research. 28 (3): 280–292. Bibcode:2018IJEHR..28..280V. doi:10.1080/09603123.2018.1468424. PMID 29706087. S2CID 23510545.
  8. ^ Turner PC, Collinson AC, Cheung YB, Gong Y, Hall AJ, Prentice AM, Wild CP (October 2007). "Aflatoxin exposure in utero causes growth faltering in Gambian infants". International Journal of Epidemiology. 36 (5): 1119–25. doi:10.1093/ije/dym122. PMID 17576701.
  9. ^ Mitchell NJ, Hsu HH, Chandyo RK, Shrestha B, Bodhidatta L, Tu YK, Gong YY, Egner PA, Ulak M, Groopman JD, Wu F (2017). "Aflatoxin exposure during the first 36 months of life was not associated with impaired growth in Nepalese children: An extension of the MAL-ED study". PLOS ONE. 12 (2): e0172124. Bibcode:2017PLoSO..1272124M. doi:10.1371/journal.pone.0172124. PMC 5315312. PMID 28212415.
  10. ^ Chen C, Mitchell NJ, Gratz J, Houpt ER, Gong Y, Egner PA, Groopman JD, Riley RT, Showker JL, Svensen E, Mduma ER, Patil CL, Wu F (March 2018). "Exposure to aflatoxin and fumonisin in children at risk for growth impairment in rural Tanzania". Environment International. 115: 29–37. Bibcode:2018EnInt.115...29C. doi:10.1016/j.envint.2018.03.001. PMC 5989662. PMID 29544138.
  11. ^ Smith LE, Prendergast AJ, Turner PC, Mbuya MN, Mutasa K, Kembo G, Stoltzfus RJ (December 2015). "The Potential Role of Mycotoxins as a Contributor to Stunting in the SHINE Trial". Clinical Infectious Diseases. 61 (Suppl 7): S733–7. doi:10.1093/cid/civ849. PMC 4657594. PMID 26602301.
  12. ^ Hoffmann, V.; Jones, K.; Leroy, J. L. (2018). "The impact of reducing dietary aflatoxin exposure on child linear growth: a cluster randomised controlled trial in Kenya". BMJ Global Health. 3 (6): e000983. doi:10.1136/bmjgh-2018-000983. PMC 6278920. PMID 30588341.
  13. ^ Hoffmann V, Jones K, Leroy J (December 2015). "Mitigating aflatoxin exposure to improve child growth in Eastern Kenya: study protocol for a randomized controlled trial". Trials. 16: 552. doi:10.1186/s13063-015-1064-8. PMC 4669614. PMID 26634701.
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  17. ^ Cite error: The named reference wannop was invoked but never defined (see the help page).
  18. ^ J. Varga, J.C. Frisvad, R.A. Samson: "Two new aflatoxin producing species, and an overview of Aspergillus section Flavi", Stud Mycol. 2011 Jun 30; 69(1): 57–80. doi: 10.3114/sim.2011.69.05