Using bioaccessibility testing in health risk assessment as a decision support tool for appropriate redevelopment of former mining sites: a French case study

Ingrid Girardeau (1) , Aline Coftier (1) , Thibauld Conte (1)

1 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)

In many countries, remediation is required when a site poses a risk to human health and/or the environment. In this context, risk assessment methodologies usually rely on the total contaminant concentrations measured on site without considering chemicals bioavailability. Such approach is actually irrelevant when considering former or abandoned mining sites characterised with high concentrations of heavy metals in soils as it often results in an overestimation of risks, leading to heavy, lengthy and costly remediation works. The case study was the site of a cassiterite mining exploitation that ended in 1957. At the present time, 3.7 million cubic meter of tailings and waste rocks, with rather high arsenic and other heavy metals concentrations, remain on the site. Beside these residues, and issues associated with the acid mining drainage, there is still great concern with the frequentation by the public of this site. Effectively, because of its astonishing shape, it is highly visited by a wide range of population (local and national). It offers a unique opportunity for sport and leisure activities (e.g.: mountain bike, walking, trail, horse riding) in a relatively flat region. Therefore, this site represents an opportunity of tourism and economic development for the municipality. The aim of this study was to assess the compatibility of these uses with the soils quality, given that they are especially highly concentrated in arsenic. Ingestion is one of the major routes of soil exposure, by children especially. However, data from literature indicate that the bioaccessible fraction of arsenic for human soil ingestion can vary from 2 to 90%. Therefore, it is relevant to carry out site specific tests. Bioaccessibility tests were carried out on 10 soil samples collected on site, following the Unified BARGE (BioAccessibility Research Groupe of Europe) Method (UBM). This in vitro method simulates the human digestive procedure using synthetic digestive fluids. Results indicate that the bioaccessibility of arsenic on this site ranges between 5 and 50 %, averaging out at 17%. The human health risk assessment at this specific site integrated these bioacessibility results so that health risk quantifications are more relevant, accurate and closer to reality. In this case study, we show that using standard highly conservative approach and more accurate approaches lead to rather different results in terms of possible uses. Using this approach, appropriate solution for redeveloping the site balancing health and environment protection requirements with tourism and economic issues will be available.

Mots clés: arsenic; bioaccessibility; human health risk assessment; cassiterite; redevelopment

Domaines: Ingénierie de l'environnement; Chimie analytique; Environnement et Société

Ingrid Girardeau, Aline Coftier, Thibauld Conte. Using bioaccessibility testing in health risk assessment as a decision support tool for appropriate redevelopment of former mining sites: a French case study. Mine Closure 2018, Sep 2018, Leipzig, Germany. ⟨hal-01855318⟩