Quantitative Risk Assessment of Trichloroethylene for a Former Chemical Works in Shanghai, China

ABSTRACT

Assessment of the potential risks posed by chlorinated solvents in groundwater is the key to establish the extent of the contamination and derive achievable remedial targets should remediation deems necessary. This article first presents the application of the American Society for Testing and Materials (ASTM) Risk Based Corrective Actions (RBCA) Guidance to quantitatively evaluate human health and environmental risk for a former chemical works in Shanghai, China. The observed maximum trichloroethylene (TCE) concentration in groundwater at the site reached 1220 mg/l that exceeded its solubility of 1070 mg/l at 10°C (Soil annual average temperature is 10°C in Shanghai). The maximum concentration for cis-1, 2-DCE (DCE) was also found to be elevated at 264 mg/l. A critical exposure pathway was considered to be indoor vapor intrusion of TCE into the buildings with excess lifetime cancer risk for children being 1.7 × 10⁻³. This cancer risk exceeded regulatory limits of 1 × 10⁻⁴ to 1 × 10⁻⁶ for The Netherlands, the United Kingdom, and the United States. The calculated groundwater remedial targets for TCE and DCE are 7 mg/l and 904 mg/l, respectively, in order to protect child residents from inhalation of indoor vapors within the close proximity of the source area.

Key Words:

• Risk-Based Corrective Action (RBCA)
• Dense Non-Aqueous Phase Liquids (DNAPL)
• Conceptual Site Model (CSM)
• Fate and Contaminant Transport Modelling
• Site Specific Target Level (SSTL)

ACKNOWLEDGMENTS

The authors thank the National Hi-Tech Research and Development Program of China (Grant No. 2007AA06A401), the Shanghai Environmental Protection Bureau (Grant No, 208321), and the National Natural Science Foundation of China (No. 20607019) for the financial support of this work.