Endocrine modulators in the food chain and environment

Recently, considerable attention has been focused on certain environmental contaminants-"endocrine disruptors"-of industrial origin that may mimic the action of sex hormones. Natural compounds and their effects on other types of hormonal activity leg. on adrenal or thyroid function) have for some re ason not provoked similar attention. As exemplified by tributyltin and cert ain bioaccumulating chlorinated compounds. available evidence indicates tha t "endocrine disruption" caused by xenobiotics is primarily an ecotoxicolog ic problem. In mammals, certain phenylmethyl-substituted siloxanes have bee n found to be by far the most potent endocrine disrupters among various syn thetic xenobiotics. Oh the other hand, it has not been possible to scientif ically substantiate either certain alarming reports of powerful synergistic effects between chlorinated pesticides or the alleged adverse effects on t he male reproductive tract in rodents (induced by alkylphenols and plastici zers at extremely low exposures). Whereas there is compelling evidence that estrogens in certain foods and herbal medicines can induce hormonal change s in women as well as oven toxicity in men, existing data are insufficient to support a causal relationship between exposure of the general human popu lation to nonpharmaceutical industrial chemicals and adverse effects operat ing via the endocrine system. Moreover, in terms of magnitude and extent, a ll such exposures to so-called endocrine disruptors are dwarfed by the exte nsive use of oral contraceptives and estrogens for treatment of menopausal and postmenopausal disorders. Also, the exposure to hormonally active xenob iotics is virtually insignificant when compared with the intake of the phyt oestrogens that are present in food and beverages, and it is even more insi gnificant when compared with certain herbal potions used in "alternative me dicine." Furthermore, while there has been much concern about negligible ex posures to xenobiotics with weak hormonelike activities, the potent endocri ne disrupter licorice is freely given to children. Long-term exposure to th is substance induces severe toxic symptoms of mineral corticoid hormone imb alance. Although exposures to xenobiotics: and many natural compounds occur by identical routes of administration and may contribute to the same toxic ological end point, they are, regrettably, judged by completely different s tandards. As is the case with all other chemicals, rational risk assessment and risk management of man-made and natural endocrine modulators must be b ased on rbe mode of action and dose-response relationships. Such end points as the induction of reproductive developmental effects, cancer, etc, relat ing to actual exposures must also be taken into consideration.