Exposure assessment of Portuguese infants to Aflatoxin M1 in breast milk and maternal social-demographical and food consumption determinants

Abstract

Mycotoxins are secondary metabolites of fungi that have toxic effects on both humans and animals. Aflatoxin M1 (AFM1) which can be transmitted to newborns via breast milk, is a hydrolyzed metabolite of Aflatoxin B1 (AFB1) that is ingested along with contaminated food. AFM1 is classified as “possibly carcinogenic agent for Human” (group 2B IARC). Despite the potential hazard of AFM1 to breastfed babies, there is a lack of studies of exposure evaluation in Europe and a complete absence of reports in Portugal.The present study aimed to determine the occurrence of AFM1 in maternal milk and the degree of exposure of infants to this toxin. The correlation between the concentration of AFM1 and basic socio-demographic factors and the consumption of certain categories of food was also aimed. Thus 67 milk samples from nursing mothers living in Portugal were collected, between 2015 and 2016, and analyzed using a competitive commercial ELISA kit, in order to determine the presence of AFM1.Twenty-two samples (32.8%) contained levels of AFM1 above the detection limit (5 ng/L), ranging between 5.1 and 10.6 ng/L (7.4 ± 1.9 ng/L). In the observed exposure pattern, AFM1-positive milk samples were associated with summer collection, lower mother's educational level, early lactation phase and the maternal consumption of rice and chocolate. No other studied determinants, whether socio-demographic (age, weight, height, number of children, characteristics of breastfeeding, the infants' weight) or dietary (frequency of food consumption) showed a significant statistical influence. Assessment of AFM1 estimated daily intake (EDI) revealed a higher exposure of younger babies (<7 kg; EDI 1.06 ng/kg b.w./day) in relation to older ones (≥7 kg; 0.86 ng/kg b.w./day), and the proposed value of TDI (0.2 ng/kg b.w.).Thus the results of this study suggest the need to reinforce surveillance of AFB1 occurrence in food, as a protective and control measure, not only for adults, but ultimately for lactating infants exposed through maternal breast milk. Although AFM1 presents an inferior carcinogenic potency, it is noteworthy that when compared with adults, infants feature a lower capacity of carcinogen biotransformation, a fairly restricted diet and a higher consumption in relation to body weight.