Inorganic boron health effects in humans: An aid to risk assessment and clinical judgment

This is a review of human response to elevated levels of boron containing compounds with emphasis on studies containing sufficient detail for evaluation of dose-response relationships. Qualitative information is also included where it will assist assessment of risk or contribute to clinical judgment. Skin absorption and dermatitis is also reviewed. Quantitative data are sparse, especially for infants and children. For acute oral doses in children, there are only two data points where dose and temporal relationships have been estimated with some care and where recovery was uneventful; these come from a single paper. Doses were 94.7 mg B/kg in a 24-day infant and 30.4 mg B/kg in a 14-month infant. Effects were irritability, mild diarrhea with vomiting, marked erythema in the diaper area at 94.7 mg, and sparse, mildly erythematous macular rashes on the face and neck at 30.4 mg. Adults given intravenous doses averaging 25 mg B-10/kg (range 19-46 mg B-10/kg) over a 75-second period responded within 2 minutes with nausea followed by vomiting, excitation, and subsequent mild depression. No-effect levels for humans can be established at about 1 g of boric acid per day (2.5 mg B/kg/day). The chronic adverse effect level is 5.0 mg B/kg/day. Infant response al high levels is similar enough to adult responses that it is reasonable to assume that the infant is not more sensitive than the human adult. Non-systemic effects of boron are minor. Respiratory exposure in industry has not caused chronic pulmonary effects. Skin exposure does not cause dermatitis. (C) 1997 Wiley-Liss, Inc.