Lead Poisoning Effects on Children's Academic Performance

Introduction

Although it is a preventable disease, lead exposure in general and lead poisoning among children in particular remains a serious problem in the United States today. Lead poisoning is caused by the consumption of lead in some form, including dust particles and lead-based paint chips (Lead poisoning still leads in environmental risk issues, 2009). Lead poisoning can affect individuals of any age from virtually any walk of life, but minority young people from lower socioeconomic families tend to suffer disproportionately, in spite of aggressive efforts by the federal government to reduce the use of lead in occupational settings as well as in household paints, gasoline products (Lead poisoning, 2009), and even the lead solder used in household and commercial plumbing (Miranda & Anthopolos, 2011).

Current estimates indicate that at least 4 million young people in America are at risk (Children and lead poisoning, 2017), and between half a million (McGill, 2013) and one million children in the U.S. already have dangerously high blood lead levels above 5 micrograms per deciliter—the level at which the U.S. Centers for Disease Control and Prevention recommends the commencement of public health actions (Lead poisoning, 2009). To determine the facts about this troubling issue, this paper reviews and discusses the relevant literature to provide an overview of lead and lead poisoning and to determine the effect of lead poisoning on children's performance at school. A discussion concerning the implications of lead poisoning's adverse effect on children's academic performance is followed by a summary of the research and important findings in the conclusion.

Overview of Lead, Lead Exposure, and Lead Poisoning

Although the element has a number of valuable commercial uses (Learn about lead, 2017), lead is enormously toxic to humans, and no safe blood lead level for children has been identified in the research to date (Lead, 2017). Lead poisoning is currently the most common environmental health problem affecting children in the United States (Endres & Montgomery, 2009). Although adults are also at risk, children face greater danger from lead exposure because the substance is more readily absorbed by them compared to adults and their body tissues are especially sensitive to its harmful effects (Currie, 2010). The high level of toxicity means that exposure to lead can adversely impact almost all bodily systems (Lead, 2017).

Exposure to lead may go unnoticed in children because there may not be any clearly discernible symptoms (Lead, 2017). Some of the more common symptoms and signs of lead poisoning in children include developmental delay, learning difficulties, irritability, loss of appetite, weight loss, sluggishness and fatigue, abdominal pain, vomiting, constipation, hearing loss, seizures, and pica (i.e., eating paint chips) (Overview of lead poisoning, 2017). Moreover, these symptoms can persist well into adolescence and adulthood (Endres & Montgomery, 2009).

Although the majority of American homes constructed prior to 1960 contain paint with large concentrations of lead, the practice of using these durable paints persisted into the late 1970s (Overview of lead poisoning, 2017). Current estimates indicate that approximately 64 million housing units in the United States contain lead paint, and the overwhelming majority of these units are occupied by urban-dwelling, lower-income families (Overview of lead poisoning, 2017). American children who live in housing units constructed prior to 1978 are at far greater risk of experiencing lead exposure as a result of lead-based household paints (McGill, 2013).

Likewise, schools and daycare facilities built prior to 1978 may also represent a source of lead poisoning (Overview of lead poisoning, 2017). Soil, cookware, toys, and playground equipment with lead-based paint can also cause lead poisoning in children (Overview of lead poisoning, 2017). In addition, children living within 500 miles of airports where aircraft use leaded aviation fuel suffer higher blood lead levels compared to other children (Miranda & Anthopolos, 2011). Miranda and Anthopolos emphasize that "lead emitted from aircraft using leaded aviation gasoline (avgas) is currently the largest source of lead in air in the United States, constituting about 50% of lead emissions in the 2005 National Emissions Inventory" (p. 1514). Because many lower-income residences are located in geographic proximity to airports, children from lower socioeconomic families face a heightened risk of lead exposure and poisoning.

Despite these troubling issues, blood lead concentrations in American children have experienced significant and sustained decreases over the past four decades due to legislation and stricter standards for lead-based products. Notwithstanding this progress, however, hundreds of thousands—and perhaps millions—of poor American young people are already suffering from elevated blood lead levels, and many remain exposed to sources of lead not typically encountered by their more affluent counterparts. Many children from lower-income families continue to live in housing units with aging lead paint and elevated lead dust levels, placing them at greater risk of lead exposure and the corresponding academic deficits this can cause (Prevention of childhood lead toxicity, 2017).

According to the American Academy of Pediatrics, "Evidence continues to accrue that commonly encountered blood lead concentrations, even those below 5 µg/dL (50 ppb), impair cognition [and] there is no identified threshold or safe level of lead in blood" (Prevention of childhood lead toxicity, 2017, p. 1). The most recent research shows that during the period from 2007 through 2010, more than half a million preschool students aged 1 to 5 years (about 2.6%) in the U.S. suffered from elevated blood lead concentrations equal to or greater than 5 µg/dL. In most cases of lead poisoning, these sources of exposure have been shown to inordinately affect lower-income and minority children, but whenever housing units are renovated, the potential for exposure to lead increases for families across all socioeconomic categories (Lead poisoning, 2009).

Effect of Lead Poisoning on Children's Performance at School

There is a growing body of scientific evidence concerning the relationship between higher blood lead levels developed during early childhood and diminished academic performance, cognitive skills, motor skill development, and intellectual functioning (Endres & Montgomery, 2009). While some symptoms of elevated blood lead levels—such as weight loss—may not directly affect academic performance in substantive ways, lead poisoning does have a direct effect. According to Currie (2009), "Health problems can affect a child's school readiness both directly and indirectly. Lead poisoning, for example, directly impairs a child's cognition and causes behavior problems" (p. 118).

These findings are supported by a number of recent studies. A retrospective study by Evens (2015) involved 58,650 Chicago-born children from 1994 and 1998 who had been evaluated for blood lead concentration levels at some point between birth and 2006 and who were enrolled in the third grade in Chicago public schools during the period 2003 through 2006. Drawing on the Chicago Blood Lead Registry, the Chicago birth registry, and Illinois Standard Achievement Test (ISAT) scores for third-grade pupils, the study identified the relationship between academic performance and blood lead concentrations (Evens, 2015). Even after controlling for race/ethnicity, income levels, gender, low birth weight, and premature birth, the findings confirmed that early childhood exposure to lead in any form represented an accurate predictor of subsequent diminished academic performance among this third-grade cohort (Evens, 2015). Specifically, elevated blood lead concentrations in early childhood adversely affected both math and reading performance, with substantially higher failure rates observed (Evens, 2015).

These findings are congruent with the results of several other studies that have identified a relationship between elevated blood lead concentrations and academic performance as measured by standardized tests (Evens, 2015). Research by Miranda and Anthopolos (2011) found that blood lead concentration levels as low as 2 micrograms per deciliter can have significant impacts on academic performance during early childhood as measured by end-of-grade test scores. As a result, the U.S. Centers for Disease Control have concluded that there are no safe blood lead level concentrations for children (Miranda & Anthopolos, 2011).

Although additional research is needed to identify the precise relationship between various blood lead level concentrations and adverse effects on different academic domains, a study of third- and fourth-grade students in Massachusetts found that improved academic performance—as measured by state tests—was achieved following the implementation of initiatives designed to reduce the rate of lead exposure and poisoning (Zubrzycki, 2012). Zubrzycki (2012) reports that "groups of children with higher levels of blood-lead exposure were likely to do worse on the tests, and as blood-lead levels dropped, student achievement improved" (p. 2). These interventions produced an impressive 1% to 2% decrease in the number of students who scored unsatisfactorily on the Massachusetts state tests (Zubrzycki, 2012).

A study by Chandramouli and Steer (2009) similarly identified a direct relationship between diminished academic performance and lead exposure at levels lower than the 5 µg/dL standard currently used as an indicator for clinical concern. In addition, lead poisoning in children can cause a number of other problems that exacerbate learning difficulties, including a reduction in intelligence quotient, higher levels of antisocial and aggressive behaviors, and physical and emotional developmental delays (Morse, 2006). These negative outcomes carry profound implications for American society in general and for educators in particular, as discussed further below.

Conclusion

Throughout history, lead has been a double-edged sword for humankind, providing a number of useful applications on the one hand but eventually poisoning anyone who consumes it over time on the other hand. Because many modern commercial applications—such as plumbing and paint—have included lead, the element continues to represent a significant public health threat that demands evidence-based solutions. While the primary sources of lead contamination have largely been mitigated through federal legislation and stricter standards, even renovation projects can still introduce new lead contaminants into the environment.

As efforts to remediate lead in the environment continue, school systems are faced with providing the highest quality—and therefore most expensive—educational services for children with elevated blood lead concentrations. Some of the steps shown to be effective in addressing this problem include educating parents concerning strategies to reduce and eliminate lead contamination in the home and ensuring that these educational materials are accessible to the broadest segment of the targeted population. Ultimately, protecting children from lead exposure is not only a public health imperative but also a prerequisite for equitable educational opportunity.

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