Survey of the occurrence of Aflatoxin M1 in ovine milk by HPLC and its confirmation by MS.

During the period of October-July 2000, 240 samples of dairy ewes milk, obtained from farms of Enna (Sicily, Italy), were checked for Aflatoxin M(1) (AFM(1)) by HPLC using a fluorimetric detector. The limit of detection and the limit of quantification were 250 ng/L for AFM(1). All the positive milk samples for AFM(1) were confirmed by LC-MS. AFM(1) was detected in 81% of milk samples, ranging from 2 to 108 ng/L. Three samples were over the legal limits (50 ng/L). Mean contamination of samples obtained from stabulated ewes was higher than that from grazing ewes (35.27 vs. 12.47 ng/L). Furthermore, samples collected in the period September-October showed higher contamination than samples collected during the other months (42.68 vs. 10.55 ng/L). Both differences are related to the administration of compound feed. Based on current toxicological knowledge we concluded that the AFM(1) contamination levels recorded in ewe milk did not present a serious human health hazard. However, as ewe milk is exclusively used to produce cheese due to its higher protein content, and also considering the preferential binding of AFM(1) to casein during coagulation of milk, a potentially high concentration effect could occur, thus the surveillance of contamination levels should be more continuous and widespread.