Ecological Risk Assessment of Copper in Coastal Areas of Japan: How will Bioavailability Considerations Change the Assessment Results?

We conducted ecological risk assessment of copper in coastal areas of Japan. For risk assessment, we used a method in the initial environmental risk assessment conducted by the Ministry of the Environment, Japan, and several methods considering bioavailability, used for setting water quality criteria in Europe and the United States. The hazard quotient （ HQ ） method was used for risk characterization. Risk assessment was conducted using 1,622 copper concentration values from the Japanese coastal areas over the past 31 years that we were able to collect. As a result, the area with HQ exceeding 1 was 70.2% of the total in the screening level evaluation; considering bioavailability, it was 3.6 to 4.0%, and the risk characterization result changed depending on the hazard assessment method. Also, considering bioavailability, it was clear that there is a difference in the risk characterization result because water quality varies depending on the location even within the same bay. These results suggest that it is important to obtain toxicological data of species inhabiting Japan and copper concentrations in Japanese coastal areas and to examine what kind of evaluation method should be used for risk assessment.