Oestrone benzoate increased the incidence of mammary tumours in mice following its subcutaneous injection.
Oestrone is embryolethal for preimplantation embryos in some species.
No case reports or epidemiological studies on oestrone alone were available to the Working Group. Epidemiological studies on steroid hormones used in oestrogen-progestin oral contraceptive preparations have been summarized in the section, 'Oestrogens and Progestins in Relation to Human Cancer'. There is sufficient evidence for the carcinogenicity of oestrone in experimental animals. In the absence of adequate data in humans, it is reasonable, for practical purposes, to regard oestrone as if it presented a carcinogenic risk to humans. For definition of the italicized terms, see Preamble Evaluation .