Chemical residues and contaminants in milk: A review

The presence of chemical residues and contaminants in milk such as pesticides, antibiotics, mycotoxins and heavy metals, is of public health concern and a cause for economic loss to the dairy industry. The sources of contamination are now well traced. Wide spread use of persistent pesticides in agriculture and mosquito eradication had resulted in pollution of the environment and transfer of their residues to milk through feed, fodder and soil. Restrictions imposed on their use have started yielding results in India. The levels of pesticide residues have reduced drastically and are mostly within the MRL fixed by the FAO/WHO. The reports on the incidence of antibiotic residues are not alarming, but call for constant monitoring. Aflatoxin B, in feeds produced due to poor storage and favourable climatic conditions suitable for fungal growth results in the presence of aflatoxin M, in milk. Contamination of the geosphere from industrial wastes and automobile emissions leads to the ingestion of toxic metals by the animals; a small portion of this is transferred to milk. As these toxic substances are generally stable to the normal heat processes of milk, avoiding contamination appears to be the only practical way to ensure safety of milk for human consumption.