2.1 Review of the Adverse Health Effects of Lead Exposure, with a Focus on Neurological Effects, as Observed in Animal Studies

Chapter 2 of the §403 risk analysis report presented information on the toxicity of lead, through a discussion of how body-lead burden is measured, how lead works in the body, the resulting adverse health effects, and populations at risk. This chapter introduced the endpoints used in the risk analysis to represent the adverse health effects resulting from lead exposure and to estimate the benefits of the §403 rule. These endpoints included the likelihood of exceeding a specified blood-lead concentration threshold (10 or 20 μg/dL), the likelihood of achieving a specified IQ score decrement as a result of lead exposure (1, 2, or 3 points on average across the population), the likelihood of achieving an IQ score in the population of less than 70 points due to lead exposure, and the average IQ score decrement in the population that results from lead exposure. The blood-lead concentration thresholds were among those established by the Centers for Disease Control and Prevention (CDC) as levels of concern. The IQ-related endpoints represented measures of the neurological effects of lead exposure. The representative population upon which the §403 risk analysis focused was children aged 1-2 years, as it was considered the most appropriate age range for the estimation of health effects.