Even low lead levels linked with decreased reading ability

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1. Childhood lead exposure, even below the CDC’s 10 mg/dL “level of concern,” is associated with lower reading readiness at the beginning of kindergarten; this association remained after adjustment for demographic factors, language, and socioeconomic status.

2. 67% of children studied had at least 1 blood lead level (BLL) > 5 mg/dL. 20% of children studied had at least 1 BLL > 10 mg/dL.

Evidence Rating Level: 2 (Good)

Study Rundown: In 1991, the Centers for Disease Control and Prevention set 10 mg/dL as the “level of concern” for blood lead levels in children, noting that high lead levels are associated with cognitive impairment. This retrospective cohort study examined the potential association between BLL and kindergarten reading readiness of 3406 children in an urban setting. The results were adjusted for gender, age, year enrolled, race, child language, and free/reduced lunch status as a measure of socioeconomic status. After adjustment, BLL showed a negative dose-response relationship with reading readiness. There was no evidence of a threshold. BLL were found to be markedly higher than NHANES estimates. This study is limited by its retrospective nature and its use of free/reduced lunch as a proxy for socioeconomic status. This study suggests the need for further evaluation of BLL and cognitive impairment, particularly in urban settings where lead exposure may be higher than currently estimated. In addition, the study reaffirms the need for continued interventions to aid in preventing cognitive impairment secondary to excessive lead exposure.

Click to read the study published today in Pediatrics

Relevant Reading: Lead Exposure in Children: Prevention, Detection, and Management

Study Author, Pat McLaine, DrPH, MPH, RN, talks to 2 Minute Medicine: Department of Family and Community Health, University of Maryland School of Nursing

“Childhood lead exposure is associated with lower reading readiness at the start of kindergarten. And national estimates may seriously underestimate the effect of childhood lead exposure on urban school systems. Solutions that focus on housing, health and early education are needed. Thought should be given to integrating what we already know about the prevention of childhood lead poisoning, the value of early care and education, including behavioral and developmental screening, and the value of home visiting. These three worlds need to be better aligned so that we can truly make a difference in bringing every child in America to school healthy and ready to learn.” 

In-Depth [retrospective cohort study]: This study linked state Rhode Island Department of Health (RIDH) BLL measurements with reading readiness at the start of kindergarten in 3406 children educated through the Providence Public School District (PPSD). Reading readiness was assessed utilizing the Phonological Awareness Literacy Screening – Kindergarten (PALS-K test). The data was adjusted for demographic factors, language, and socioeconomic status. When compared to children with blood lead levels < 5 mg/dL, children with levels of 5 – 9 mg/dL were 1.21 times more likely to not meet the national benchmark for reading readiness (95% CI: 1.19 – 1.23). Children with levels greater than 10 mg/dL were 1.56 times more likely to not meet national benchmark standards (95% CI: 1.51 – 1.60). 67% percent of children had at least 1 BLL greater than 5 mg/dL. 20% had at least 1 BLL greater than 10 mg/dL.

By Neha Joshi and Leah H. Carr

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