While the rate of elevated blood lead levels in refugee children arriving in the U.S. decreased over time, it remained 10 times that of the U.S. population for kids ages 1 to 5 years, a multi-state CDC study found.
Of nearly 30,000 refugee children (ages 6 months to 16 years) who received a medical exam upon entering the U.S., the prevalence of elevated blood lead levels (≥5 µg/dL) decreased from 24.4% in 2010 to 14.4% in 2014, reported Clelia Pezzi, MPH, of the CDC’s Division of Global Migration and Quarantine in Atlanta, and colleagues.
Among 1- to 5-year-olds, the rate of elevated blood lead levels in refugees during this time (23.7%) was 10 times the National Health and Nutrition Examination Survey (NHANES)-estimated rate for children in the U.S. from 1999 to 2010 (2.3%).
“Children absorb a higher percentage of ingested lead and suffer ill effects at much lower blood levels than adults,” Pezzi told MedPage Today in an email. “It is essential to intervene right away to lower a child’s lead exposure, and in severe cases, to remove lead from the body to prevent illness or damage.”
CDC guidelines currently recommend blood screening in refugee children ages 6 months to 16 years upon arriving in the U.S., rescreening kids ages 6 years and younger 3 to 6 months after their arrival, and providing these younger children with daily pediatric multivitamins containing iron.
Prior research had indicated the prevalence of lead poisoning in refugee children may be 14 times greater than children in the general U.S. population, with these elevated levels linked to overseas exposure, nutritional deficits, and the use of food and toys that contain lead, according to the guidelines.
Also, refugee families are often placed in affordable, older housing where children may more often be exposed to lead-contaminated soil or pipes, said Andrea Green, MD, and Matthew Saia, MD, both of the University of Vermont in Burlington, in an accompanying editorial.
One challenge in monitoring refugee children for elevated blood lead levels is that these families may not be informed of their initial test results, they explained, or if they are, may not relay the results to their primary care providers after they are screened at a public health clinic.
“Coordination between public health departments, resettlement agencies, and medical homes can be challenging, and the transfer of information may be incomplete and impaired,” wrote Green and Saia, adding that “coordinated system-level communication strategies are necessary.”
Pezzi and her team collected data from 27,284 resettled children from 2010 to 2014, representing about a quarter of all refugee arrivals across this time frame. Mean age was 8 years, and girls made up 49% of the sample. Other demographic variables in this group were similar to the total U.S. refugee population.
Data was obtained from 11 state medical examination sites and one Indiana county health department. About 3 of 4 blood screening tests were venous, which was the preferred method since capillary tests risk contamination from lead-traced fingers, the authors reported. Results from any follow-up blood screens performed 3 to 6 months after the initial tests were also collected.
Among 1,121 children that received a valid follow-up test, 10% had blood lead levels that increased by ≥2 µg/dL, “indicating that they may have been exposed to lead in the U.S.,” Pezzi said.
She added that many sites were unable to obtain children’s follow-up screening results, which suggests children are not receiving this follow-up as the CDC recommends, and that perhaps some physicians are not aware these guidelines are in place.
Of the five countries with the most refugee children arriving to the U.S., Nepal had the highest rate of children with elevated blood lead levels (27.5%), followed by Thailand (21%) and Iraq (20.7%); the rate was highest among refugees from India (57.9%) and Afghanistan (55.1%), although a relatively small number of children arrived from these countries.
Boys had a higher prevalence of elevated blood lead levels than girls overall (22.8% vs 15.7%), a difference that increased with age and was significant across all age groups, except children under age 2 years, Pezzi and colleagues reported.
Finally, of 8,951 children who had complete hemoglobin results, elevated blood lead levels were associated with the presence of moderate or severe anemia (hemoglobin <10 g/dL), though this outcome did not remain significant after adjusting for age, sex, and time of year.
Still, this finding might be particularly concerning because anemia “can enhance lead absorption such that even minimal lead exposures pose high risk,” Green and Saia said.
Pezzi noted that she and her team were unable to determine the means by which children were exposed to lead, as well as the average blood lead levels for children with results <5 µg/dL. Another important limitation is that about 90% of follow-up data was collected from just two sites, and it was unclear whether data obtained from these sites were collected before or after refugees had settled into their permanent housing. Lastly, it’s possible that some sites may have used screening methods that underestimated the presence of blood lead levels, since at times researchers weren’t able to determine which screening method was used at various locations.
Nine of the sites involved in this study were supported by the Strengthening Surveillance for Diseases Among Newly-Arrived Immigrants and Refugees agreement from the CDC.
Pezzi reported no disclosures. One co-author disclosed consulting fees from Meridian Bioscience.
The editorialists reported no relevant disclosures.