Validation and application of a reporter gene assay for the determination of estrogenic endocrine disruptor activity in milk

•Milk was investigated for estrogenic endocrine disruptor activity.•A novel estrogenic reporter gene assay was developed for quantifying total estrogenic load in milk.•The validated method is suitable for screening a range of milk samples, except soy.•Testing real samples revealed various levels of estrogenic activity.

Endocrine disruptors (EDs) are compounds known to interfere with the endocrine system by disturbing the action or pathways of natural hormones which may lead to infertility or cancer.Our diet is considered to be one of the main exposure routes to EDs. Since milk and dairy products are major components of our diet they should be monitored for ED contamination. Most assays developed to date utilise targeted, chromatography based methods which lack information on the biological activity and mixture effects of the monitored compounds.A biological reporter gene assay (RGA) was developed to assess the total estrogen hormonal load in milk. It has been validated according to EU decision 2002/657/EC. Analytes were extracted by liquid-liquid extraction with acetonitrile followed by clean up on a HLB column which yielded good recovery and small matrix effects. The method has been shown to be estrogen specific, repeatable and reproducible, with covariance values below 20%. In conclusion, this method enables the detection of low levels of estrogen hormonal activity in milk with a detection capability of 36 pg g−1 EEQ and has been successfully applied in testing a range of milk samples.