Lead Poisoning

DESCRIPTION

Lead poisoning is one of the most common pediatric environmental health problems. Severity of lead poisoning is based on actual blood lead level (BLL) and systemic symptoms.
The Centers for Disease Control and Prevention (CDC) states that there is no safe BLL and considers an elevated BLL to be ≥3.5 mcg/dL.
- This “reference value” is based on the 97.5th percentile for lead levels of children aged 1 to 5 years collected for the National Health and Nutrition Examination Surveys (NHANES).
- This replaced the previous “level of concern” terminology for levels ≥10 mcg/dL based on the Advisory Committee on Childhood Lead Poisoning Prevention (ACCLPP) recommendations in light of many studies demonstrating cognitive and behavioral effects at BLL <10 mcg/dL.

There are >500,000 U.S. children 1 to 5 years of age with BLLs >5 micrograms per deciliter (mcg/dL).

24 million housing units have hazards from lead-based paint.
In 2015, the water supply in Flint, Michigan was found to have significantly elevated lead levels. Due to the change in water source, the percentage of Flint children with elevated blood-lead levels may have risen from about 2.5% in 2013 to as much as 5% in 2015.
Racial and income disparities persist due to gap in housing quality, nutrition, and access to health care.

Young children who are crawling and/or have hand-to-mouth behaviors
Children with developmental delays
Children with pica behavior
Children with iron, calcium, or zinc deficiency
Residence in older homes with flaking or deteriorating lead-based paint or older homes without lead hazard controls during remodeling process
Recent immigrants or refugees from countries where ambient lead contamination is high
Use of lead-glazed ceramics, potteries, and crystals
Use of traditional therapies containing lead (e.g., azarcon, some Ayurvedic and Chinese medicines)
Ingestion of lead-containing spices or candies imported from India, China, or Mexico
Children living or who have lived in industrial plant areas known for lead emissions.
Children living with parents who have occupations or hobbies known for lead contaminations

Primary prevention: removal of potential environmental lead hazards prior to exposure
- The ACCLPP focuses on primary prevention as it emphasizes that there is no “safe” level of lead and the effects of lead are likely irreversible.
- Clinicians should provide anticipatory guidance to all parents about lead exposure pathways and the prevention of exposures
Secondary prevention: screening for elevated BLLs.
- Minimum screening recommendations: BLL test for children at 1 and 2 years and for those 36 to 72 months old who have not had previous screening
- Screening children immigrating from other countries and screening pregnant and lactating women and their neonates and infants for lead exposure prior to or during pregnancy and lactation
Tertiary prevention: chelation therapy to prevent or reduce lead toxicity for children meeting specific BLL criteria
Control measures
- Abatement of building-based (residential) lead hazards by removal, encapsulation, or enclosure of lead-containing structures
- Control of environmental lead dust exposure and ingestion by good housekeeping (wet dusting and mopping of household dust), personal hygiene (cleaning of child’s hands, toys, personal items; wiping feet on mats prior to entering the home), and hiring certified renovators who are United States Environmental Protection Agency (EPA)-approved to perform renovations that may disrupt lead-based paint
- Removal of any other known lead source from the child’s environment.

Lead adversely affects many organ systems including neurologic, hematologic, gastrointestinal (GI), renal, and reproductive.
- Many toxic effects result from inhibition of enzymes involved in heme biosynthesis, as lead binds to sulfhydryl groups on active sites of δ-aminolevulinic acid dehydratase (ALAD), ferrochelatase, porphobilinogen synthase, coproporphyrinogen oxidase, and other enzymes.
- Lead acts competitively with calcium and also interacts with other voltage-gated cation channels in various biologic systems.
Children absorb lead more efficiently from the GI tract, and absorption is enhanced by concurrent iron, calcium, and/or zinc deficiencies.
Because the developing, immature central nervous system (CNS) is susceptible to toxic effects of lead, the neuropsychologic effects of lead poisoning on fetuses/young children are of particular concern. Even relatively low BLLs are associated with IQ deficits, attention-related behaviors, and poor academic achievement.