title: Screening for estrogen residues in calf urine: comparison of a validated yeast estrogen bioassay and gas chromatography-tandem mass spectrometry.
abstract: Within the European Union, the control for residues of illegal hormones in food-producing animals is based on urine analysis for a few target analytes using gas chromatography/mass spectrometry and/or liquid chromatography-tandem mass spectrometry. Recently, we developed a robust yeast bioassay screening tool for estrogens, which was validated as a qualitative screening method in accordance with EC decision 2002/657/EC. In this study, we present long-term performance data and a comparison of urine data obtained with this bioassay, and data from an established gas chromatography-tandem mass spectrometry (GC/MS/MS) confirmatory analysis method. More than 120 calf urine samples from a controlled reference experiment were analysed using both protocols. According to the GC/MS/MS method, only the natural estrogens 17alpha-estradiol and estrone were present in the non-compliant samples. The bioassay was less sensitive than GC/MS/MS for the relatively weak estrogenic compound 17alpha-estradiol, in accordance with expectations. Assuming that application of the mass spectrometric method is considered beyond reasonable doubt, the bioassay performed very well: only 5.6% of the calf urine samples found compliant in GC/MS/MS were screened false suspect in the bioassay screening method. The bioassay results of non-compliant urine samples under routine conditions were as predicted, taking into account the relative estrogenicity of the natural estrogens 17alpha-estradiol and estrone vs. 17beta-estradiol. Only one sample was screened false negative for 17alpha-estradiol and estrone. Application of this fast and simple estrogen bioassay in routine surveillance and control can significantly reduce GC/MS/MS sample workload and allow higher percentages of animals to be screened for potential hormone abuse.
authors.affiliation: RIKILT Institute of Food Safety, P.O. Box 230, 6700 AE Wageningen, The Netherlands. michel.nielen@wur.nl
authors.forename: M W F
authors.initials: MW
authors.lastname: Nielen
authors.forename: T F H
authors.initials: TF
authors.lastname: Bovee
authors.forename: H H
authors.initials: HH
authors.lastname: Heskamp
authors.forename: J J P
authors.initials: JJ
authors.lastname: Lasaroms
authors.forename: M B
authors.initials: MB
authors.lastname: Sanders
authors.forename: J A
authors.initials: JA
authors.lastname: Van Rhijn
authors.forename: M J
authors.initials: MJ
authors.lastname: Groot
authors.forename: L A P
authors.initials: LA
authors.lastname: Hoogenboom
mesh_terms: D000818:Animals; D001681:Biological Assay / Q000379:methods*; D002417:Cattle; D004350:Drug Residues / Q000032:analysis*; D004967:Estrogens / Q000652:urine*; D005260:Female; D005506:Food Contamination / Q000032:analysis* / Q000517:prevention & control; D008401:Gas Chromatography-Mass Spectrometry; D008297:Male; D012680:Sensitivity and Specificity; D015003:Yeasts / Q000378:metabolism
chemical_list: D004967:Estrogens