Residues chemical contaminants in milk may be introduced throughout the food chain and they must be tackled, noted Michael Hickey of Cork-based Dairy and Food Consultancy in Charleville, Co Cork.

Hickey was speaking at this week’s Teagasc Milk Quality Conference in Tipperary.

The diary consultant in his presentation noted in the case of milk products residues may come from feed and forage, in milk production, milking, transport, processing and packaging.

“These residues may come from the environment, additive use, industrial pollution (including emissions, accidents and waste), mycotoxins, pesticides, veterinary drugs, radionuclides, cleaning chemicals, by-products of heat treatment and migration from packaging materials,” Hickey outlined.

“There are many examples of such food contamination over the years. These include examples of deliberate contamination for fraudulent purposes, for example melamine. For convenience the subject of residues in food, including milk, can be addressed under three main headings, chemical contaminants, the approved use and potential resultant residues of pesticides used in agriculture and the approval and potential resultant residues of veterinary drugs in animals. The use of substances prohibited for use in food production has also to be considered.

To address the potential of residues causing risks to human health, risk analysis  at international, regional and national levels are key, he said.

“Standards and legislation have been enforced, including specified maximum residue limits, to minimise the risks to human health and to manage and monitor the effectiveness of controls put in place,” he outlined.

Consequently many countries, including Ireland, have specific national residue monitoring programmes in place for animal products, including milk.

According to the consultant, laboratories play a key role in this risk-management framework.

“Among the challenges for laboratories are that many maximum residue limits are at, or near, the limits of detection of current methodology. Current monitoring strategies rely mainly on targeted approaches but there is an emerging trend towards using untargeted strategies, which rely on finding and using biomarkers of treatment or contamination residues,” he concluded.