Abstract
Health based guidelines for environmental concentrations of chemicals are designed to prevent harmful chemical exposures. However, none exists for indoor settled dust, despite its ingestion being a documented pathway of exposure, for certain chemicals. The objective of this paper is to present the derivation of a health-based indoor settled dust guideline (ISDG) for lead. The guideline was developed to protect a specific fraction of the most vulnerable population against the most sensitive effect, taking into account other exposure pathways. It is calculated from a toxicological reference value, body weight, and the mass of ingested dust. The most vulnerable population is young children, and the corresponding critical effect is a loss of IQ points, with a toxicity reference value of 0.5 µg.kgbw-1.d-1. Assuming that 80% of the exposure for the most affected individuals comes from dust ingestion, the ISDG for protecting 90, 95 or 95% of young children are 43, 33 and 20 µg.gdust-1, respectively. These values are consistently lower than the concentrations that would trigger lead poisoning screening. The main uncertainties lie in the estimations of the amount of ingested dust. This ISDG could contribute to environmental management efforts to prevent or reduce lead exposures.