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  1. Delgado, Christine F. PhD
  2. Ullery, Mary Anne EdD
  3. Jordan, Melissa MS
  4. Duclos, Chris MS
  5. Rajagopalan, Sudha MPH
  6. Scott, Keith PhD


Context: Lead is a preventable environmental toxin that has been previously associated with deficits in cognition, academic performance, attention, and behavior in children. Very few studies, however, have examined the relationship between exposure to lead and documented developmental disabilities.


Objective: This study examined the relative risk of lead exposure on developmental disabilities in preschool-aged children.


Design: A statewide lead surveillance data set containing blood lead level (BLL) was integrated with another statewide data set containing developmental disability classifications for special education placement for preschool-aged children.


Participants: The participants were the 85 178 children (average age 2.6 years) whose records in both data sets were able to be linked. Forty-six percent of the participants had an identified developmental disability.


Main Outcome Measure: Developmental disability classification served as the main outcome measure.


Results: A high BLL, defined as 5 [mu]g/dL or more, was associated with significantly increased risk for developmental disabilities (risk ratio [RR] = 1.04; 95% CI = 1.01-1.08), particularly intellectual disability (RR = 1.58, 95% CI = 1.10-2.25) and developmental delay (DD; RR = 1.11, 95% CI = 1.06-1.17).


Conclusions: The results of this study are consistent with previous research identifying an association between lead exposure and numerous intellectual and educational outcomes and demonstrate that high BLL is associated with meeting eligibility criteria for developmental disabilities in young children. Continued research, surveillance, and prevention efforts are needed to further reduce the negative impacts of lead on individuals and society. Reducing or eliminating lead exposure would improve outcomes for individual children (eg, better academic performance) and reduce the burden to society (eg, lower enrollments in special education systems).