Key Elements of a Primary Prevention Program

Percent of Preschool Children Exceeding Selected Blood Lead Levels, NHANES II - III Pirkle JL, et al. Environ Health Perspect 1998;106:

Lead Toxicity - Still A Major Public Health Problem Lead toxicity is epidemic in parts of U.S. Major environmental justice problem. Evidence of adverse effects below 10  g/dl. Systemic toxin associated with numerous adverse conditions and diseases in humans.

Lead-associated Reading Deficits in U.S. Children Blood lead levels (  g/dl) Reading Score Lanphear BP, et al. Public Health Reports 2000;115:

Canfield R, et al. NEJM 2003;348:

Relationship of Lead-IQ Scores among Children for Seven Prospective Lead-Exposed Cohorts Boston Cincinnati Mexico Port Pirie Rochester Yugoslavia Cleveland Concurrent Blood Lead (  g/dl) IQ

Relationship of Concurrent Blood Lead Concentration with Children’s Intellectual Function using a Restricted Cubic Spline Function Concurrent Blood Lead (  g/dL) IQ

Estimated Lead-associated IQ Deficits by Concurrent Blood Lead Concentration, 5 th to 95 th percentile Range of Blood Lead Estimated IQ Deficit (95% CI) 2.4 to 30  g/dL 6.9 (4.2, 9.4) 2.4 to 10  g/dL 3.9 (2.4, 5.3) 10 to 20  g/dL 1.9 (1.2, 2.6) 20 to 30  g/dL 1.1 (0.7, 1.5) Lanphear BP, et al. EHP 2005;113:

Relationship of Concurrent Blood Lead Concentration with Children’s Intellectual Function at Blood Lead Levels Above and Below 7.5  g/dL Peak blood lead <7.5  g/dL Peak blood lead ≥7.5  g/dL Log-linear model Concurrent Blood Lead (  g/dL) IQ p = 0.015

Risk for Spontaneous Abortion by Maternal Blood Lead Concentration Odds Ratio * Borja-Aburto VH, et al. Am J Epidemiol 1999:150: Blood Lead (  g/dL)

Association of Blood Lead Levels and Delinquency in Adolescents Dietrich KN. Neurotox & Teratol 2001;23:

Relationship of Lead Exposure and Murder Rate (/100,000) in the U.S. Nevin R. Environmental Research 2000:83;1-22

Why not change the blood lead level of concern at this time? There are no effective “clinical” interventions to lower blood lead for children with levels < 10 µg/dL Children can’t be classified as having blood lead levels 10 µg/dL because of the inaccuracy inherent in laboratory testing There is no evidence of a threshold; thus, lowering the “level of concern” would be arbitrary and provide uncertain benefits

Types of Prevention Education Enforcement Engineering > Cost> Efficacy

Decline in Children’s Blood Lead Levels due to Regulation Year Source: CDC Lead-Based Paint Poisoning Prevention Act Begin Phase- Out of Leaded Gasoline Residential Lead Paint ban (1978) Lead-Based Paint Hazard Reduction Act (1992) Lead in Plumbing Ban (1986) Ban on Lead Solder in Canned Foods (1995)

Why Primary Prevention? Adverse effects of lead are persistent. Adverse effects of lead are systemic. Chelation does not result in improved neurobehavioral outcomes. No discernable threshold for adverse effects of lead exposure. Prevention is cost-beneficial.

Steps to Prevent Childhood Lead Exposure Identify sources of lead Identify unacceptable levels of lead in contributing sources Test efficacy and safety of interventions to reduce lead exposure Develop and implement regulations and screening programs.

Percent Increase in Blood Lead from Sources of Lead Exposure during Early Childhood Percent Increase Lanphear BP, et al. Journal of Pediatrics 2002;140:40-47.

Frequency of Mouthing Behaviors during Early Childhood Percent Months of Age Lanphear BP, et al. Journal of Pediatrics 2002;140:40-47.

Contribution of Lead-contaminated Floor Dust to Blood Lead Level by Age Correlation Bornschein R. (unpublished data). Age (months) Screening

Effect of Lead Hazard Controls Results of Controlled Trials HazardBPb *AgeChange Control (µg/dl) (µg/dl) CharneyDust Control> FarfelAbatement> StaesStabilization> 25< AschengrauAbatement3 - 22< * Blood lead levels at baseline

Geometric Mean Floor Dust Lead Levels (µg/ft 2 ) by Abatement Status* Pre- Abatement Post- Abatement 6 Months Post-Abatement *Farfel AJPH 1990: 80;

EPA Residential Standards for Lead- Contaminated House Dust Floors 40  g/ft 2 Sills250  g/ft 2 Troughs800  g/ft 2

Contribution of Lead-Contaminated Floor Dust to Children’s Blood Lead Floor Dust Lead (  g/ft 2 ) Lanphear BP, et al. Environmental Research 1998;79:51-68.

Risk of blood lead levels > 10  g/dl by floor dust lead levels (  g/ft 2 ) Floor dust lead levels (  g/ft 2 ) Odds Ratio

Screening Characteristics for Blood Lead > 10  g/dL by Lead-Contaminated Floor Dust Floor Dust Lead (  g/ft 2 ) SensitivitySpecificity Lanphear BP, et al. Public Health Reports 2005;120:

Percent > 10 µg/dL < > 50 Non-residential Blood Lead Levels > 10 µg/dL among Children in Rochester, 1995

Health Outcomes and Measures of the Environment Study 12, 24 and 36-Month Outcomes Exposures and Biomarkers for Pesticides, Lead and Cotinine Behavior, Cognition and Executive Function Hearing and Growth Randomization Enroll Women < 16 weeks gestation (n= 400) 36 - month visit 24 - month visit 12 - month visit Injury Control Group (n = 200) 36 - month visit 24 - month visit 12 - month visit Lead Hazard Group (n = 200) Meconium Collection Collection of Biomarkers and exposure assessment in early childhood Conduct prenatal surveys, collect maternal urine and blood samples for assessing fetal exposure to toxicants

Implications For Prevention Emphasis to shift from screening children to screening houses, yards and water. Empirically-derived health-based standards for lead in house dust, soil and water are needed. Randomized trials to assess if lead hazard controls are effective in preventing exposure. Studies to examine adverse effects of lead exposure at lower blood lead concentrations. Eliminate all non-essential uses of lead and develop regulations to control lead emissions.