Analyses of selected heavy metals and aflatoxin M1 in milk for human consumption in Jhang City, Pakistan

A screening survey was conducted during 2012-2013 to determine concen-trations of Copper (Cu), Lead (Pb), Cadmium (Cd), Chromium (Cr), and Aflatoxin M1 (AFM1) in unprocessed, non-branded liquid milk available at conventional milk shops in Jhang city of Punjab. For the heavy metals men-tioned above, samples were also collected directly from dairy herds near a wastewater drain in suburbs of the city. Concentrations of the studied contaminants were compared between winter and summer samples. Median concentra-tions of Cu, Pb, and Cd were significantly higher than the standards of the International Dairy Federation and levels in a very high percentage of the samples exceeded these standards, however, there was no permissible level available for Cr to make a comparable analysis with. Within each season, levels of Cu, Pb, and Cr differed signifi-cantly in milk collected from shops and dairy farms. For each type of milk source, there was a statistically signifi-cant difference in mean concentrations of Cu, Pb, and Cr between summer and winter. The AFM1 levels in 17% of samples were higher than the maximum tolerance limit accepted by the United States (0.50 ìg/L). AFM1 levels were significantly high in the samples with median concentrations of 0.333 and 0.416 in summer and winter, respectively. The findings, i.e. detection of heavy metal contaminant levels above permissible limits in most samples, warrant continuous monitoring of those contaminants and a policy for their control. The levels of AFM1 in samples indicate that feed for animals was contaminated with aflatoxin B1- the precursor of AFM1. The sampling methodology adopted in this study can be a template for executing similar surveys is urban areas of developing countries (and informal markets) where a sampling frame of shops is generally not available. We recommend surveillance of aflatoxin B1 in commercial concentrate feeds and industrial waste management. (Author abstract)