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To the Editor.—
The response of Dr. Dean C. Fletcher to a question by Dr. Melvin Brody (227:1067, 1974) about safety of estrogens in beef production was somewhat misleading. A statement suggests that all livers contained diethylstilbestrol (DES) and that all meat, likewise, had a DES residue. In actual fact, DES has been detected in only a minute fraction of livers and never in "other meat" when used at levels consistent with commercial practice.The statement, "these levels [2 parts per billion] became detectable because of improvements in analytical techniques," most probably refers to the recently developed radioimmunoassay technique. This method has been reported to have a sensitivity in the parts-per-trillion range. Thus, the 2 ppb statement referred to could possibly have meant 2 ppt, a thousandfold difference.As correctly stated, low levels of DES (ie, 2 ppb) have not caused toxicity or carcinogenicity. Carcinogenicity studies have been conducted with
Rossmeier A. Estrogenic Substances in Beef. JAMA. 1974;229(5):520-521. doi:10.1001/jama.1974.03230430014008