Aflatoxin M in Nicaraguan and locally made hard white cheeses marketed in El Salvador.

Aflatoxin M is a carcinogenic and genotoxic metabolite of Aflatoxins present in food contaminated by fungi for lactating cattle, it is excreted through milk and when used to make cheese, the toxin will also be transferred to the dairy. The contamination of unripened hard white cheese with AFM seems to vary according to the season of the year, possibly due to the change of foodstuff, from fresh pasture in the rainy season to dried foods in the dry season and vice versa. This research determined both the prevalence and contents of AFM in cheeses of local and Nicaraguan origin marketed in El Salvador, as well as the changes occurred according to the season and the association between levels of AFM with meteorological parameters. The significantly higher prevalence of AFM contamination in both local cheeses and Nicaraguans, was found in the dry season and the lowest in the rainy season (41 % vs. 20 %; 31 % vs. 0%, respectively), the same trend was observed in AFM contents (0.076 vs. 0.036 μg/kg; 0.050 vs. 0.021 μg/kg, respectively). A significant association was demonstrated between levels of AFM with the averages of accumulated rainfall and relative humidity according to the sampled season. The prevalence of AFM in cheeses indicate that El Salvador and Nicaragua are endemic to dairy contamination by that mycotoxin. Seasonal variation may be due to a lack of rainfall, that promotes the growth of aflatoxigenic fungi in the crops of raw materials, which will be used for feedstuff intended for dairy cattle, thus, the consumption of contaminated food will cause the temporary increase of AFM in milk and their derivatives.