Health Risk Assessment For The Soil Of A Brownfield Contaminated By POPs And Study On Screening Of Remediation Technique

The characteristics of persistent organic pollutants(POPs) such as toxicity, persistence , bioaccumulation, the potential for their long-range transport, and their ubiquitous presence throughout the world in ecosystems and in humans were the impetus for the creation of the Stockholm Convention. To implement the Convention, the Chinese government would take measures to eliminate or reduce the release of POPs into the environment. Several brownfields contaminated by POPs would emerge during the process of implementing, which may cause damage or potential risk to human health and ecosystem.Methodologies for human health risk assessment (HRA) were applied on the abandoned industrial site contaminated by POPs at Changzhou, east China. For the purposes of this risk assessment, chlordane and mirex were proposed as indicator chemicals of this site, which was based on archive data collection, sampling and analysis. For the defined future land use patterns, the industrial exposure scenario was assumed and evaluated. Considering the particularity of the site, some parameters were modified during the process of assessment. Due to the potential risks which may pose to humans, the HRA focused on 3 typical exposure pathways by soil. The results of the baseline risk assessment indicated that the combined hazard index for chlordane and mirex was less than 1, but the potential cancer risk of contaminated soil at this site had exceed the acceptable cancer risk, which was greater than 10^-5 in some high exposure spot. It was also indicated that the high risk spots were near the workshop and warehouse. The risk from exposure via ingestion contributed most, which far outweighed the risk via inhalation. The risk-based remedial goals calculated for chlordane and mirex on this site were both 50mg/kg . The contaminated soil with the volume of 915 m³ had to be remediated at high exposure spot.In the paper, an attempt was made to compare different remediation alternatives for soil contaminated by POPs on this site. Analytical Hierarchy Process as a multiple criteria decision-making tool was firstly applied in order to screen the optimal remediation technique. The emphasis was on comparing their general impacts in terms of technical factors, environmental consequences, economic feasibility and social requests in current conditions. An integrated evaluation system was constructed with four levels and nineteen indexes. Ten experts with professional backgrounds were asked to fill in the comparison matrices in order to reduce bias in the evaluation. The final result indicated that the technique of security landfill could be adopted as an optimum alternative for soil remediation on the site contaminated by chlordane and mirex at Changzhou.