Estimation of Risk from EDs

Edgren carried out a number of studies in which bioassays were used to compare the widely differing potencies of a number of analogues of 17/i-oestradiol that were modified in the 18-position. Commenting on the use of potency ratios, Edgren concluded that they were only valid for specific substances and test systems and useless for product safety testing . These problems could have important consequences for any attempt to establish the potency of specific environmental EDs or environmentally relevant mixtures. 

Edgren, in Pharmacology of the Contraceptive Steroids, ed. J. W. Goldzieher, Raven Press, 

Many groups throughout the world tried to repeat the experiments using similar in vitro assays and other test systems, but without success. Current experimental data suggest additive interactions do occur between EDs, but the issue of interactive effects, and synergism in particular, will undoubtedly remain a topic of intense debate for some time to come. 

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