Effect of Low-Level Lead Exposure on Intellectual Impairment
Jenna M. O’Connell
Elisabeth B. Winterkorn
Intellectual Impairment in Children With Blood Lead Concentrations Below 10 Micrograms Per Deciliter
Canfield RL, Henderson CR Jr, Cory-Slechta DA, et al. N Engl J Med. 2003;348(16):1517–1526
Background
Numerous studies have demonstrated neurotoxic effects of lead levels above 10 mcg/dL, particularly in young children. Adverse outcomes include impairment in intellectual functioning and social-behavioral conduct. The Centers for Disease Control and Prevention (CDC) and World Health Organization (WHO) had previously designated 10 mcg/dL as a level of concern; however, it remained unclear whether cognitive deficits could occur in children with lower levels.
Objectives
To observe whether impaired performance on intelligence testing occurs at blood lead concentrations <10 mcg/dL.
Methods
Prospective cohort study of children born in 1 US city between 1994 and 1995.
Patients
172 children ages 24 to 30 months. Select exclusion criteria: prematurity, low birth weight, trisomy 21, speech or hearing abnormalities.
Intervention
Blood lead levels measured 7 times from 6 to 60 months of age compared with rates of intellectual impairment on the Stanford–Binet Intelligence Scale (IQ), administered at ages 3 and 5 years.
