Blood Lead Levels between 5 and 9 micrograms per deciliter are associated with developmental delay, as measured by the Denver II developmental screening test

Background: Lead poisoning continues to be an enormous problem in the United States. It is estimated that 250,000 children in the United States age 1-5 have blood lead levels (BLL) above 10 micrograms per liter (µg/dl), the level at which intervention is often recommended or mandated. However, clinical studies indicate that children with BLL between 5-9 µg/dl are at higher risk and also require intervention. The Cincinnati Health Department (CHD) evaluates all children less than 6 years old with BLLs from 5-9 µg/dl using the Denver II Developmental Screening Test (Denver II). Methods: Children aged less than 6 years who had BLLs of 5-9 µg/dl were evaluated by CHD public health nurses, and screened for developmental delay using the Denver II. Proportion of patients with an abnormal Denver II was calculated using descriptive statistics. Results: A total of 419 children were identified with BLLs of 5-9 µg/dl. Of these patients, 203 (48.4%) had a Denver II test scored ‘normal', 60 (14.3%) scored ‘normal with one caution', 53 (12.6%) scored ‘suspect without delay', and 103 (24.6%) scored ‘suspect with one or more delays'. However, there was no evidence for a dose-response relationship between BLLs within the range from 5-9 µg/dl, higher levels were not associated with more delay than lower levels. Conclusion: Based on developmental screening using the Denver II, it appears that a significant number of children with BLL of 5-9 micrograms will have evidence of developmental delay. Public health officials may want to lower the BLL that requires intervention.