Determining a BMDL of Blood Lead Based on ADHD Scores Using a Semiparametric Regression

• Activity Number: 506
• Type: Contributed
• Date/Time: Wednesday, August 1, 2012 : 10:30 AM to 12:20 PM
• Sponsor: Section on Risk Analysis
• Author(s): Byung-Soo Kim*+ and Ah Hyun Kim
• Companies: Yonsei University and Yonsei University
• Keywords: attention deficit hyperactivity disorder ; benchmark dose lower limit ; reference point ; semi-parametric regression

Abstract

The primary purpose of this paper is to derive a benchmark dose (BMD) and its 95 percent lower confidence limit (BMDL) using a semi-parametric regression model for a small change on the attention-deficit hyperactivity disorder (ADHD) score due to lead based on the first wave of Children's Health and Environment Research (CHEER) survey data, which have been regularly collected in S. Korea since 2005. Ha et al. (2009, NeuroToxicology) showed that the appearance of ADHD symptoms had a borderline trend of increasing with the blood lead concentration. Budtz-Jørgensen (EFSA, 2010a) derived the BMDL of lead corresponding to a benchmark region of 1 full intelligent quotient (IQ) score using the raw data in Lanphear et al. (2005, EHP). European Food Safety Authority (EFSA, 2010b) determined the BMDL of 1.2µg/dl as a reference point for the characterization of lead when assessing the risk of intellectual deficit measured by the IQ score. Kim et al. (2011) indicated that even lower BMDL could be obtained based on the ADHD score. But, their BMDL's heavily depended upon the model assumptions. We show in this paper that a semi-parametric approach resolves the model dependence of BMDL's.