Blood lead levels in a continuity clinic population.

Introduction: Lead toxicity is well recognized as a significant cause of morbidity in children, especially those under the age of six years. While lead toxicity has not been recognized as a public health problem in Houston, it is possible that children in the area suffer from low-level lead effects on the central nervous system.
Objectives: To detect asymptomatic cases of lead toxicity in one population of Houston children and to assess the effectiveness of the lead risk questionnaire.
Design: Venous blood samples for quantitative lead were analyzed utilizing the Anodic Stripping Voltameter. The Centers for Disease Control's lead risk assessment questionnaire was administered to each patient.
Setting: Baylor College of Medicine Continuity Clinic at Texas Children's Hospital.
Subjects: All patients, ages 9-72 months, seen for routine care between December 1992 and June 1994 were screened once.
Results: Blood lead levels were obtained on 801 children; all but 47 completed lead risk questionnaires. The mean age of the study group was 2.37 years (SD 1.84) and they were 54% male. They were 39% Hispanic, 39% Black, and 18% White. Eighty-eight percent reported an annual income of < $20,000. They lived in 127 separate zip codes. Twenty-five (3.1%) patients had elevated blood lead, 21 between 10-14 micrograms/dL and 4 between 15-19 micrograms/dL. No patients had blood lead levels of > or = 20 micrograms/dL. No statistically significant differences were found between patients with blood lead < 10 micrograms/dL and those with > or = 10 micrograms/dL when comparing for age, sex, ethnicity, income, and zip code. Only those children living in or regularly visiting a pre-1960 home with peeling or chipping paint were significantly more likely to have elevated blood lead (p = .045).
Conclusion: Although the majority of children in our setting were poor and urban, the prevalence of blood lead > or = 10 micrograms/dL was 3.1%, well below the estimated 17% quoted by the Centers for Disease Control in recommending stringent screening guidelines. The lead risk assessment questionnaire failed to identify 32% of children with elevated blood lead levels. Since this questionnaire is critical to screening populations at low risk for lead toxicity, it is important to determine whether a revised questionnaire or a more careful elicitation of parental responses will improve identification of those children at risk.