Aflatoxin Detoxification in Humans Laboratory, Field and Clinical Perspectives

Abstract

Studies to identify human aflatoxin metabolites provide essential information for understanding the clinical manifestations of these toxicants. Although there have been very few of these studies a total of 10 aflatoxins have been isolated from human tissues; 4 mold products and 6 human metabolites including an aflatoxin B₁-guanine adduct. These metabolites appear in urine, blood and tissues in the pg to ng/ml range. The metabolites have occured at a high frequency in some study populations. Questions remain regarding the metabolism and bio-reactivity of these metabolites. For example, aflatoxin Q₁ might represent a detoxification pathway yet there is uncertainty concerning its toxicity. It is produced by liver metabolism in vitro but has not been found in human urine. There is evidence that it forms a glucuronide, hence, it should be sought in this form. The mutagenicity of aflatoxicol, a toxic metabolite produced by reduction of aflatoxin B₁, varies depending upon stereochemical form. Glutathione antimutagenicity is selective among these metabolites. Thus, the search for aflatoxin metabolites will become critical to clinical interpretation. Toxicological differences between metabolites must be elucidated and sensitive multi-derivative assays universally applied in field epidemiology.