No evidence of developmental III effects of low-level lead exposure in a developing country.

Despite substantial controversy regarding the blood levels at which lead adversely affects neurobehavioral development, public health policy in some industrialized countries is prescribing ever more stringent screening criteria for all ages. This study addressed the question of ill effects of lead exposure at the new lower levels, specifically during the late infancy period, which has been targeted for maximum surveillance in pediatric practice. The sample of 184 participants consisted of 12- to 23-month-old healthy infants and toddlers who participated in a community-based study in a developing Central American country (Costa Rica) where extensive family and developmental information was collected. The mean infant blood lead level was 11.0 micrograms/dL, ranging from 5.4 to 37.0 micrograms/dL. Lead levels were not related to the Mental or Psychomotor Developmental Index of the Bayley Scales of Infant Development. When the children were 5 years old, they were reevaluated with complete physical and psychological testing. Blood lead levels in infancy did not predict any of the developmental outcome measures. Thus, among a group of healthy toddlers in a developing country, no ill effects on development of low blood lead levels were observed.