Do Current Standards of Practice in Canada Measure What is Relevant to Human Exposure at Contaminated Sites? I: A Discussion of Soil Particle Size and Contaminant Partitioning in Soil

• Published in: Human and ecological risk assessment Vol. 12; no. 3; pp. 591 - 605
• Main Authors: Bright, Doug A., Richardson, G. Mark, Dodd, Matt
• Format: Journal Article
• Language: English
• Published: Boca Raton Taylor & Francis Group 01.06.2006; Taylor & Francis Ltd
• Subjects: Atoms & subatomic particles; contaminant; Contaminants; distribution; Estimates; Health risk assessment; Health risks; Human exposure; Human subjects; Ingestion; Inhalation; Organic contaminants; Particle size; Risk assessment; Samples; Skin; soil; Soil contamination; Soil types; Soils; Canada
• ISSN: 1080-7039; 1549-7860
• DOI: 10.1080/10807030600561816

Human health risk estimates for sites with contaminated soils are often based on the assumption that the bulk concentration of substances in outdoor soil samples is a reasonable predictor of exposures via incidental soil ingestion, soil particle inhalation, and dermal absorption. Most underlying conceptual models are grossly simplistic, however, when considered in light of (i) biases in the distribution of contaminants across soil particle sizes, (ii) the size range of particles in soils and dusts that is environmentally available, and (iii) factors that influence desorption from particles and uptake into humans. The available studies indicate that contaminant distribution across soil particle size fractions varies widely between different soil types and contaminant delivery mechanisms, and it cannot be assumed that higher masses of contaminants per unit mass of soil are correlated with smaller particles sizes. Soil data gathered in support of detailed human health risk assessments, therefore, should allow for the examination of distribution across particle sizes of contaminants of concern, and consider those size fractions most critical to human exposure. Soil evaluations for health risk assessments of metals/metalloids should also consider mineralogical characterization.