The widely used phenolic preservatives ethylparaben, propylparaben, butylpa
raben and their common metabolite p-hydroxybenzoic acid were tested for the
ir ability to evoke an oestrogenic response in vivo. Yolk protein induction
in sexually immature rainbow trout was used as an oestrogen-specific endpo
int after repeated injections of the compounds. All tested parabens were oe
strogenic in doses between 100 and 300 mg/kg, while the metabolite showed n
o activity. Ethylparaben was found to be approximately sixty times weaker t
han propyl- and butylparaben which had oestrogenic potencies comparable to
those previously found for bisphenol A.