No data are available on adverse health effects from ingestion of large amounts of boron from food and water. According to case reports of poisoning incidents and accidental ingestions of boric acid and borax, these compounds exhibit low toxicity. Stokinger (1981) reported that the minimal lethal dose of boric acid from ingestion is 640 mg/kg/day. The potential lethal dose has been reported to be 15 to 20 g/day for adults and 3 to 6 g/day for infants; however, in an examination of 784 cases of boric acid ingestion, Litovitz and coworkers (1988) found minimal or no toxicity at these or higher intake levels. Initial symptoms include nausea, gastric discomfort, vomiting, and diarrhea. At higher doses, skin flushing, excitation, convulsions, depression, and vascular collapse have been reported.
Human Data. Most of the toxicity data on repeated administration of boron (as boric acid or borax) comes from studies in laboratory animals. However, from reports on the use of borates to treat epilepsy where doses between 1,000 mg/day of boric acid (2.5 mg/kg/ day) to 25 g/day of boric tartrate (24.8 mg/kg/day) were administered chronically, toxicity was expressed as dermatitis, alopecia, anorexia, and indigestion (Culver and Hubbard, 1996). On the basis of their review of the human data in adults, Culver and Hubbard (1996) reported no adverse effects at chronic intakes of 2.5 mg/ kg/day (about 1 g of boric acid). On the basis of nine cases involving infants (Gordon et al., 1973; O’Sullivan and Taylor, 1983), there does not appear to be an increased sensitivity of response to chronic exposure of boron compounds.
Genotoxicity. On the basis of existing data, genotoxicity is not an area of concern after exposure of humans to boron compounds (ATSDR, 1992; Dieter, 1994).
Reproductive and Developmental Effects in Animals. Although not observed in humans, animal studies have shown that high doses of borax or boric acid produce adverse effects in the testis and affect male fertility (IPCS, 1998). Also, adverse effects have been found in the developing fetus (Heindel et al., 1992; IPCS, 1998; Price et al., 1996a). Effects on the testis have been observed in three species—rats, mice, and dogs—after supplementation with boric acid or borates in feed or drinking water (Fail et al., 1990, 1991; Green et al., 1973; Ku et al., 1993; Lee et al., 1978; Weir and Fisher, 1972). The effects