Why do we screen for lead?
The goal of lead screening is to minimize the neurodevelopmental effects of lead poisoning through source control and early detection.
Lead is absorbed from the GI tract more efficiently in younger children, so they are at higher risk of symptoms owing to lead poisoning. Similarly, kids <6yo are more susceptible to the toxic effects of lead because they have an incomplete blood-brain barrier that permits the entry of lead into the developing nervous system.
- The relationship between iron deficiency and elevated lead levels remains inadequately understood. Iron deficiency increases the rate of absorption of some divalent metals, including lead. Furthermore, children with iron deficiency anemia tend to present with higher lead levels.
When the neurologic system is affected, children can experience multiple effects:
- Behavioral changes
- Lower IQ scores
- Loss of language and developmental milestones
- Hearing loss
- Seizures and encephalopathy (in presence of severe toxicity)
- Abdominal pain
- Impaired vitamin D metabolism
Key point: There is no safe lead level. Children are especially at risk from lead because of their small size and developing brains. Lead exposure can affect nearly every system in the body. Even low levels of lead in blood have been shown to negatively affect a child’s intelligence, ability to pay attention, and academic achievement.
Universal childhood lead screening is required by law in multiple states, especially in the northeast US, including Rhode Island!
Who’s at risk?
There are many sources of lead:
- Plumbing / drinking water
- Consumer products (e.g., plastics, older toys, jewelry)
- Certain foods/supplements (e.g., certain imported candies and herbs)
- Certain occupations/activities (e.g., battery manufacturing, metal work, older home renovation)
As such, there are many populations at high risk for lead exposure: children <6yo, children with developmental delays (increased mouthing behaviors), houses built before 1978 (especially low-income), immigrants and refugees, international adoptees, pregnancy, and certain occupations, as above.
Wait… What happened in 1978?
- In 1978, the federal government banned consumer use of lead-based paint. Despite this legislation, lead paint is still present in millions of homes, sometimes under layers of newer paint. If the newer paint is in good shape, then underlying lead paint is usually not a problem. Deteriorating lead-based paint (peeling, chipping, chalking, cracking, damaged, or damp) is a hazard and needs immediate attention.
You may have noticed that many states that require universal lead screening are located in New England, which has some of the country’s oldest homes. In fact, 80% of homes in Rhode Island were built before 1978.
The number of children with elevated blood lead levels has been steadily declining in all areas of Rhode Island over the past 20 years:
Nevertheless, the COVID-19 pandemic has exacerbated lead poisoning for multiple reasons, including children spending more time at home, less access to routine lead testing, delays in lead remediation, and shortages of chelation agents.
Another troublesome fact is that, compared to the remainder of the state, the core cities in RI (Central Falls, Pawtucket, Providence, Woonsocket) have twice the rate of children with elevated blood levels:
Rhode Island children with a history of lead exposure, even at low levels, have been shown to have decreased reading readiness at kindergarten entry and diminished reading and math proficiency in the third grade. The most significant declines in academic performance occurred among children with the highest blood lead levels living in the four core cities.
Starting in 2015, an environmental inspection of a child’s home was offered whenever a single venous lead test was ≥15 µg/dL. The Rhode Island Department of Health sends certified lead inspectors to determine whether lead hazards are present and works with owners to make the properties lead-safe.
Primary & Secondary Prevention
Primary prevention is the removal of lead hazards from the environment before a child is lead exposed. It is the most effective way to ensure that children do not experience harmful long-term effects of lead exposure.
- Certificates are required with lease agreements showing documentation of de-leading and inspection
- A 2016 Rhode Island law requires testing of drinking water in all RI schools
- Regulations for gasoline, paint, plastic, cookware, and manufacturing
Secondary prevention includes blood lead testing, follow-up care, and referral. It remains an essential safety net for children who may already be exposed to lead.
- Universal screening in Rhode Island with blood lead levels at the 1- and 2-year-old well child checks
- Questionnaire screening after age 2yo:
The AAP/Bright Futures’ recommendations for preventive healthcare suggest that the risk for lead poisoning be assessed at 6, 9, 12, 18, and 24 months of age, and annually thereafter through 6 years of age. Screening is performed with a blood lead level (BLL), which may be capillary or venous. Patients who have elevated capillary sampling should have confirmatory venous blood testing.
- In Rhode Island, for a child between 9-36 months of age, screen once between 9-15 months of age and again 12 months later, between 21-36 months of age.
Management depends on the lead level:
- <5 mcg/dL:
- Repeat the BLL in 6-12 months if the child is at high risk or risk changes during the time frame. Ensure levels are done at 1 and 2 years of age.
- For children screened at age <12 months, consider retesting in 3-6 months because lead exposure may increase as mobility increases.
- Perform routine health maintenance including assessment of nutrition, physical and mental development, as well as iron deficiency risk factors.
- Provide anticipatory guidance on common sources of environmental lead exposure: paint in homes built prior to 1978, soil near roadways or other sources of lead, take-home exposures related to adult occupations, imported spices, cosmetics, folk remedies, and cookware.
- 5-14 mcg/dL:
- Perform steps as described above for levels <5
- Re-test venous BLL within 1-3 months to ensure the lead level is not rising. If it is stable or decreasing, retest the BLL in 3 months. Refer patient to local health authorities.
- Take a careful environmental history to identify potential sources of exposures (see above) and provide preliminary advice about reducing/eliminating exposures. Take care to consider other children who may be exposed.
- Provide nutritional counseling related to calcium and iron. In addition, recommend having a fruit at every meal as iron absorption quadruples when taken with vitamin C-containing foods. Encourage the consumption of iron-enriched foods (e.g., cereals, meats).
- Ensure iron sufficiency with adequate laboratory testing and treatment per AAP guidelines.
- Perform structured developmental screening evaluations at child health maintenance visits, as lead’s effect on development may manifest over years.
- 15-44 mcg/dL:
- Perform steps as described above for levels 5-14 mcg/dL.
- Confirm the BLL with repeat venous sample within 1-4 weeks.
- Additional, specific evaluation of the child, such as a plain abdominal XR should be considered based on the environmental investigation and history (e.g., pica for paint chips, mouthing behaviors). Gut decontamination using whole bowel irrigation is suggested if leaded foreign bodies are visualized. Any treatment for BLLs in this range should be done in consultation with an expert.
- >45 mcg/dL:
- Follow guidance for BLL 15-44 mcg/dL, as above.
- Confirm the BLL with repeat venous lead level. Timing of repeat BLL is determined by whether symptoms of lead poisoning are present and the height of the initial BLL.
- Perform chelation therapy (managed with the assistance of an experienced provider). Hospitalize patients in whom lead safe housing cannot be assured and all patients with BLL >69 mcg/dL. Safety of the home with respect to lead hazards, isolation of the lead source, family social situation, and chronicity of the exposure are factors that may influence management.
Blog post based on Med-Peds Forum talk by Laura Schwartz, PGY1