Presence of unreported carcinogens, Aflatoxins and their hydroxylated metabolites, in industrialized Oaxaca cheese from Mexico City

Abstract

Aflatoxins (AFs) are toxic secondary metabolites of the fungi Aspergillus flavus, A. parasiticus and A. nomius. The fungi produce these AFs in cereals, oilseeds and spices. AFs have damaging effects on all organisms, including humans, and their symptoms can be classified as acute (vomiting, hemorrhage and death) or chronic (immunodepression, Reye syndrome, Kwashiorkor, teratogenesis, hepatitis, cirrhosis, and various cancers). Basic AFs (AFB1, AFB2, AFG1, and AFG2) are metabolized in the liver or by microbes that produce hydroxylated metabolites (AFM1, AFM2, and AFP1) and aflatoxicol (AFL), soluble in water and easy to dispose. Thus, AFs can be excreted in fluids, such as milk. AFs are not destroyed in the process of making cheese.The purpose of this study was to identify and quantify the AFs present in 30 samples of industrialized Oaxaca-type cheese sold in Mexico City. The average concentrations of AFs detected in the 30 samples of industrialized cheese were as follows: AFB1 (0.1 μg kg−1) in 20% (6/30); a trace amount of AFB2 (0.01 < LOD) in only 3% (1/30); AFG1 (0.14 μg kg−1) in 10% (3/30); AFG2 (0.6 μg kg−1) in 30% (9/30); AFM1 (1.7 μg kg−1) in 57% (17/30); AFP1 (0.03% μg kg−1) in 3% (1/30); and AFL (13.1 μg kg−1) in 97% (29/30). AFB1 and AFL were the most abundant aflatoxins in Oaxaca-type cheese. However, eight aflatoxins were present, contributing an average of 15.7 μg kg−1 AFs distributed among the 30 samples. The risk assessment analysis showed that there was no substantial risk for cancer due to AFs in industrialized Oaxaca cheese from Mexico City.