Geyer et al. 2004, undeclared steroids in nutritional supplements

The landmark IOC-funded prevalence study of anabolic-androgenic steroid contamination in non-hormonal supplements, published in the International Journal of Sports Medicine. Researchers bought 634 supplements from 215 suppliers across 13 countries and analysed them. Ninety-four of the 634 (14.8%) contained anabolic-androgenic steroids, mainly undeclared prohormones of testosterone and nandrolone, that were not listed on the label, at concentrations from 0.01 to 190 µg/g. Prevalence varied by country of purchase (highest in the Netherlands at 25.8%, then Austria, the UK and the USA) and was more than twice as high among products from companies that also sold prohormones (21.1%) as from other suppliers (9.6%). Still the most-cited figure for supplement contamination, though it is now around two decades old and pre-dates the wave of novel stimulants, so it understates today’s stimulant picture.