"Multiple-tiered approach to evaluate risk of lead (Pb) on aquatic organisms in Japan"  

Wataru Naito

National Institute of Advanced Industrial Science and Technology

SETAC North America 27th Annual Meeting  ( Montreal 2006/11/6)

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Abstract

Two-tiered ecological risk assessment of lead on aquatic organisms in Japan was conducted using surface water monitoring data and effect threshold values based on a large aquatic toxicity database. Two effect threshold values were used to characterize potential risk of lead on aquatic organisms. One is the screening threshold value (Total lead =5.6μg・l-1) that corresponding to HC5 (hazardous concentration for 5% of the species) for aquatic life determined by the estimated sensitivity species distribution of lead. The other is the level at which the growth rate of fish populations (r’) become 0 (Total lead =68 g・l-1 for the most sensitive species among fish populations of interest). Comparisons between these threshold values and approximately 5000 measured concentrations yearly in surface waters indicate that the measured concentrations of the majority of monitoring sites are below the screening threshold value and only two measured concentrations were above population-level threshold. Considering environmental chemistry such as bioavailable fractions and the form of existence of lead in a water environment, it is concluded that the current levels of lead are of little concern to aquatic life in the majority of Japanese surface waters. 

Keywords

鉛，生態リスク，個体群レベル，水生生物，公共用水域