E-screen and vitellogenin assay for the detection of the estrogenic activity of alkylphenols and trace elements

Abstract

The estrogenic potential of 4-nonylphenol (4-NP), 4-octylphenol (4-OP), p- t-octylphenol ( p-t-OP) and three trace elements, lead (Pb), copper (Cu) and cadmium (Cd(NO 3) 2 and CdCl 2), were compared in two different tests, a proliferation assay with estrogen receptor-positive human MCF-7 breast cancer cells (E-screen) and the induction of vitellogenin (Vtg) in juvenile goldfish ( Carassius auratus). The results showed differences in the bioassays' sensitivity and potency with the following order: E-screen > Vtg. Among alkylphenols, both in vitro and in vivo, 4-NP and 4-OP showed the highest estrogen-like activity while p-t-OP was inferior. For trace elements, Pb and Cu showed estrogenic activity in vitro and they were also active in vivo. A range of estrogenicity was observed for different species of cadmium (Cd(NO 3) 2 and CdCl 2) which showed the highest relative proliferative effect (RPE %) in vitro, when compared with the 17β-estradiol (E 2; RPE = 100%) but, Cd(NO 3) 2 was not estrogenic in vivo. The results suggest that an integrated approach using in vitro and in vivo assays is necessary for a correct risk assessment of the endocrine disrupting activity induced by environmental contaminants.