A glass of milk can contain a cocktail of up to 20 painkillers, antibiotics and growth hormones, scientists have shown.
Using a highly sensitive test, they found a host of chemicals used to treat illnesses in animals and people in samples of cow, goat and human breast milk.
The results highlight how man-made chemicals are now found throughout the food chain.
The highest quantities of medicines were found in cow’s milk.
Researchers believe some of the drugs and growth promoters were given to the cattle, or got into milk through cattle feed or contamination on the farm.
The Spanish-Moroccan team analysed 20 samples of cow’s milk bought in Spain and Morocco, along with samples of goat and breast milk.
Their breakdown, published in the Journal of Agricultural and Food Chemistry, revealed that cow’s milk contained traces of anti-inflammatory drugs commonly used as painkillers in animals and people.
The University of Jaen, Spain listed seven anti-inflammatories (including mefenamic acid, niflumic acid, ketoprofen, diclofenac, phenylbutazone, naproxen and flunixin), three hormones (including the sex hormone 14 Beta-estradiol, steroid hormone 17a-ethinylestradiol and estrone), three drugs (including pyrimethamine, triclosan and florfenicol).
The University scientists, led by Dr Evaristo Ballesteros, ty of Jaen in Spain, say their technique could be used to check the safety of other types of food.
Dr Ballesteros said: ‘We believe the new methodology will help to provide a more effective way of determining the presence of these kinds of contaminants in milk or other products.
‘Food quality control laboratories could use this new tool to detect these drugs before they enter the food chain. This would raise consumers’ awareness and give them the knowledge that food is… harmless, pure, genuine, beneficial to health and free of toxic residues,’ he added.
The tests also found niflumic acid in goat’s milk, while breast milk contained traces of painkillers ibuprofen and naproxen, along with the antibiotic triclosan and some hormones.
The researchers say their new 30-minute test is the most sensitive of its kind. If the findings are true for Spanish and Moroccan milk, they could equally be true for milk produced in Britain and northern Europe.
Last year Portsmouth University scientists found that fish were being contaminated with the anti-depressant Prozac.
The drug enters rivers from the sewer system and tinkers with the brain chemistry of fish, the researchers claimed.
Previous studies have shown that caffeine is released into our waterways after surviving the sewage treatment process.
The hormones from the contraceptive pill and HRT have been blamed for feminising fish, leading to male fish producing eggs.
The effects of antibiotics, blood pressure drugs and cholesterol-lowering drugs on wildlife are also being studied around the world.