"Risk assessment of lead for Japanese infants and children based on blood-lead concentrations" 

Norihiro Kobayashi, Kikuo Yoshida 

National Institute of Advanced Industrial Science and Technology

SETAC Asis/Pacific 2006 Abstract, Vol.1  pp.E5-3-E5-3 (2006) 

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Abstract

In this study, health risks of lead for Japanese infants and children were estimated based on blood lead concentrations acquired by biomonitoring and IEUBK (Integrated Exposure Uptake BioKinetics) model calculations.
In the biomonitoring, 294 children (0-15 years old) who live in Shizuoka prefecture in Japan were targeted. Blood lead concentrations were measured by using ICP-MS. Geometric average and geometric standard deviation of blood lead concentrations for the population were 1.4 μg/dL and 1.6, respectively.
Based on the available toxicity data, we concluded that blood lead concentration of 10 μg/dL is the critical level for infants and children. The probability of a child’s blood lead concentrations exceeding the critical level based on the distribution of blood lead concentration was estimated to be 6×10-5 for the population.
Using IEUBK model, average distributions of blood lead concentrations for Japanese infants and children (0-6 years old) were estimated. Concentrations of lead in environmental media (lead in air, soil, dust, food, and water) in Japan and exposure factors for Japanese infants and children were used as the model inputs. Geometric average of blood lead concentrations and the probability of a child’s blood lead concentrations exceeding the critical level estimated by the model were 2.3 μg/dL and 1.0×10-3, respectively.
In the U.S.EPA and WHO, the probability of a child’s blood lead concentration exceeding 10μg/dL to 1-5% is the basis for the regulation of lead for environmental media. The probabilities acquired by the biomonitoring and the IEUBK model calculations were 1 order of magnitude lower than these standards.
From these results, we concluded that the health risks of lead for Japanese infants and children are very low and urgent countermeasures to reduce environmental lead are not required in Japan.

Keywords

lead, risk assessment, blood concentration, IEUBK model