New method used to detect 20 drugs in cow, goat and human milk

Up to 20 kinds of antibiotics, anti-inflammatories, antiseptics, lipid regulators, beta-blockers and hormones can be detected simultaneously in various kinds of milk, thanks to a new method developed by researchers at the universities of Jaén and Córdoba in Spain and the Abdelmalek Essaadi University in Morocco.

"We used this methodology to analyse 20 samples of cows' milk (fresh, whole, semi-skimmed, skimmed and powdered), goats' milk (whole and semi-skimmed) and breast milk from human volunteers, and we found that the drug content differs according to the type of milk," Evaristo Ballesteros, a researcher at the University of Jaén and the study director, said.

The highest number of pharmacological substances was found in whole cows' milk, particularly niflumic acid, mefenamic acid and ketoprofen (three anti-inflammatory drugs) and the hormone 17-beta-estradiol. Niflumic acid was also found in goats' milk, along with flunixin.

The human milk analysed, meanwhile, also contained anti-inflammatory drugs (such as ibuprofen and naproxen), as well as the antiseptic triclosan and some hormones, such as 17-alfa-ethinyl estradiol, 17-beta-estradiol and estrone.

The researchers acknowledge that the results of the study, published in the Journal of Agricultural and Food Chemistry, cannot be extrapolated to all kinds of milk in general due to the small number of samples analysed, but they say it does confirm the validity of the method. The technique uses a "system of continuous extraction of substances in solid phase" and classifies them using "gas chromatography-mass spectrometry."

"The validation results clearly show that this method is the most sensitive and one of the most selective described to date in the scientific literature," explains Ballesteros. "It is also highly precise and exact, with short analysis times (around 30 minutes)."

The scientists 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, aside from its good organoleptic properties and good value, is also harmless, pure, genuine, beneficial to health and free of toxic residues," the researcher concludes.