Abstract
We examined a risk assessment method of lead solder in Tokyo Bay using a numerical model. Three kinds of metal (Pb. Ag and Cu) contained in solders were evaluated. The ambient concentration of the metals was estimated by the model AIST-RAMTB (Aist - The Risk Assessment Model for Tokyo Bay) considering the atmosphere and seven major rivers as the supplying sources of metals. The Giant Pacific Oyster {Crassostrea gigas) was selected to evaluate the extinction risk. The growth inhibition concentration for 50% (EC50) was used for Pb as 380 μg・L^-1. Ag and Cu were evaluated based on the lethal concentration for 50% (LQ50); 100 μg・L^-1 for Agand 560 μg • L^-1 for Cu. Uncertainty factor (UF) was defined as 10. The result shows the maximum risk values of 5.57 x 10^-6 for Pb, 1.40 x 10^-6 for Ag and 4.09x 10^-8 for Cu. It suggested that the risk of solder lead was reduced by changing the lead solder to lead-free solder in Tokyo Bay.
