Chapter 3 - Risk Assessment of Borates in Occupational Settings

Abstract

Boric acid and sodium borates have been considered as being toxic to reproduction and development, following results of animal experiments with high doses. Experimentally, an NOAEL (no-observed-adverse-effect level) of 17.5mgB/kg-bw/day has been identified for the male reproductive effects of boron in a multigenerational study of rats, and an NOAEL for the developmental effects in rats was identified at 9.6mgB/kg-bw/day. However, these unfavorable effects of boron exposure have not been proven in humans. The recently published epidemiological studies provide valuable data from workers highly exposed to boron in China and Turkey. However, boron-mediated unfavorable effects on the reproductive toxicity biomarkers in male workers have not been identified. The available epidemiological study results indicated that human boron exposure, even in the highest exposure cohorts, is too low to reach the blood concentrations that would be required to exert adverse effects on reproduction. Consequently, the boron-mediated reprotoxic effects identified in animal experiments with high doses may not be relevant to humans.