Lead

Epidemiology

The average blood lead level (BLL) in children has decreased over the past decades because of lead bans in gasoline and paints. The Centers for Disease Control and Prevention (CDC) has lowered the acceptable threshold for normal BLLs from less than 40 microgram/deciliter (mcg/dL) in 1970 to stating in 2012 that there is no “normal” level and creating an “intervention level” of greater than 5 mcg/dL. In the past thirty years, the percentage of children with BLLs greater than 10 mcg/dL has decreased from 88% to 1.21%.

Despite this improvement, some children remain at greater risk for lead poisoning: Black children, children ages 1 to 5 years (especially children ages 1–2 years because of hand-to-mouth activity typical for this age group), children living in older deteriorated housing, immigrant and internationally adopted children, and children living in poverty. Additionally, children with developmental delays such as autism or pervasive developmental delay are at increased risk for lead poisoning because of prolonged oral exploratory behaviors.

Health Effects of Lead

There is no level of lead in the blood considered to be safe for humans. Children are uniquely sensitive to environmental toxins because their metabolic rates are higher relative to size, they breathe at a faster rate, and they consume more food and water per pound of body weight than adults. Children are at greater risk of lead toxicity than adults because their brains are rapidly developing and younger children display hand-to-mouth behavior that increases their exposure to lead. Children with low levels of lead poisoning generally do not display any acute symptoms, although children with high levels of lead (e.g., greater than 60 mcg/dL) can present with constipation, abdominal pain, headaches, seizures, and even death.

Lead poisoning has been associated with neurodevelopmental problems in children. Epidemiologic studies have found that effects on children's development can be seen at very low BLLs (<5 mcg/dL). Lead [Page 354]poisoning has been associated with school failure, cognitive loss, inattention, distractibility, hyperactivity, aggression, and delinquent behaviors. Studies have also shown that lead poisoning can negatively impact children's IQ scores.

Other populations at greater risk for lead poisoning within the school include pregnant women, whose fetuses' brains are susceptible to the toxic effects of lead, and children with developmental delay who may exhibit more hand-to-mouth behavior.

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