International programme on chemical safety (IPCS) environmental health criteria on boron human health risk assessment

The International Program on Chemical Safety (IPCS), a collaborative program of the United Nations Environment Program, the International Labour Organization (ILO), and the World Health Organization (WHO), includes the Environmental Health Criteria (EHC) Program inaugurated in 1973 by WHO. These EHC are integrated evaluations of the human health and environmental risks from exposure to specific chemicals carried out by a group of international scientists. Boron (B) was evaluated at an IPCS Task Group (TG) convened in November 1996. All TGs are convened under WHO rules and procedures. These procedures relate the overall process used to prepare an EHC including transparency of the process, conflict of interest, the roles of Members and Observers, and the conduct of the TG. The scope and purpose of an EHC, for an element such as B, and its possible role in national and international chemical safety programs will be discussed. In the early 1990s, countries asked that IPCS request TGs to prepare, where data permit, health-based guidance values (GVs) (both total daily intake and to recommend health-based guidelines for various environmental media). This final evaluation in an EHC reflects the collective consensus view of the TG Members. To foster the use of consistent methodology by TGs, IPCS prepared in 1994 an EHC on the methodology for the preparation of GVs for human exposure limits (EHC 170). In developing their final evaluation, TGs have been asked to consider using this methodology. This was done by the TG on B, and a total daily intake for humans of 0.4 mg/kg body wt was derived from animal studies of reproductive and developmental effects in rodents and pharmacokinetic data from both animals and humans. The application of the methodology described in EHC 170 regarding choice of critical effect and uncertainty factors will be discussed.