The preservatives ethyl-, propyl- and butylparaben are oestrogenic in an in vivo fish assay

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.