Revisiting Lead Exposure’s Negative Impact on Test Scores: What Can Neighborhoods Tell Us?

Introduction

Assessments indicate that more than 90% of housing units in Syracuse were constructed prior to the 1978 federal ban on leadbased paint. Due to the city’s aging housing stock, children in Syracuse face an elevated risk of lead exposure, most commonly through deteriorating paint, and dust in older homes. Historically, nearly 10% of children in the city exhibited toxic blood lead levels. This figure has declined by almost half since 2012 due in large part to increased public health outreach and interventions; however, lead exposure remains a persistent and acute public health concern.

These risks disproportionately affect children living in low-income neighborhoods with older housing and significantly more limited resources.

At the same time, academic outcomes among children in Syracuse remain a concern. Only approximately 17% of third-grade students enrolled in the Syracuse City School District (SCSD) meet proficiency standards in English Language Arts (ELA), as measured by New York State standardized assessments. This sharply contrasts with proficiency rates of roughly 45% state-wide and in suburban school districts within Onondaga County. Early literacy is a well-established predictor of later academic success, and disparities in third-grade ELA achievement are strongly linked to long-term educational attainment and upward economic mobility. Given existing evidence tying environmental exposures to cognitive development and learning outcomes, the coexistence of elevated lead poisoning rates and low ELA proficiency in Syracuse raises important questions about their potential relationship. Building on prior research that has established a causal association between lead exposure and academic outcomes, this study aims to determine the relationship between childhood lead poisoning and third-grade ELA proficiency within SCSD, at the neighborhood level. The study is anticipated to conclude that there is a strong correlation between these two variables.

A substantial amount of previous research has documented the adverse health consequences of lead exposure in children, prompting sustained public health messaging for parents aimed at prevention, screening, and remediation. Lead is a noted neurotoxin with no safe level of exposure; its effects are particularly damaging during early childhood, when the brain is rapidly undergoing development. In addition to immediate physical and neurological impacts, researchers have increasingly emphasized the long-term social and economic consequences of lead exposure in one’s early life. Those consequences extend beyond individual outcomes to affect families, neighborhoods, and broader society.

Prior research has determined that lead exposure in childhood is associated with increased rates of antisocial and criminal behavior in adulthood, particularly in highly resource-deprived contexts [1,2]. Muennig [3] similarly found that substantial reductions in childhood blood lead levels were associated with declines in crime rates and increases in on-time high school graduation. These findings suggest that lead exposure may shape the trajectory of a child’s life by impacting cognitive and behavioral regulation in adolescence, thereby increasing the likelihood of adverse outcomes in multiple areas. Other analyses have estimated that the economic costs of childhood lead poisoning reach into the hundreds of billions of dollars, accounting for expenses related to medical treatment, special education services, reduced lifetime earnings, and criminal justice involvement [4]. Collectively, the literature highlights lead exposure as a major contributor to both health inequities and structural socioeconomic disadvantage.

The cognitive impacts of lead exposure are especially pertinent for understanding disparities in educational achievement. Abelsohn and Sanborn [5] concluded that lead exposure impairs both motor function and fundamental cognitive processes, including memory, attention, and executive functioning. These impairments directly affect children’s ability to acquire skills in literacy, classroom learning, and perform on standardized assessments. Historically, many studies have defined elevated blood lead levels using a threshold of 10 μg/dl. However, more recent research has shown that adverse cognitive and academic effects occur well below this level, challenging earlier assumptions about what level of lead exposure is considered “safe”.

Chandramouli et al. [6], for example, found that children with blood lead levels between 5 and 10 μg/dl experienced significant declines in educational achievement, including lower reading and writing scores. While their study did not focus exclusively on third-grade students or standardized ELA testing, it provides critical evidence that relatively low levels of lead exposure can negatively affect academic performance. Consistent with this evolving scientific consensus, the scientific community has begun to apply a lower threshold for identifying elevated blood lead levels. Onondaga County’s Lead Poisoning Prevention Program, which supplies data for the present study, defines elevated blood lead levels as 5 μg/dl, a standard adopted in this analysis.

Needleman’s [7] longitudinal research further reinforces the conclusion that low-level lead exposure has lasting consequences. By following individuals identified as having been exposed to lead in childhood, Needleman demonstrated significant deficits in cognitive functioning—particularly in IQ and attention— persisting into young adulthood. These findings established that even exposure levels once considered low-risk could result in enduring neurological harm. Importantly, the present study extends this work by focusing on blood lead levels measured when children are first tested at ages one and two. This earlier developmental window is critical, as neurological impacts during infancy may have especially profound and lasting effects on later learning and academic achievement. By examining exposure at this stage, the study underscores the importance of early detection and intervention in preventing long-term educational consequences.

This research is also informed by Strayhorn and Strayhorn’s [8] county-level analysis of lead exposure and standardized test performance across New York State. Using data from the New York State Department of Health, the U.S. Census Bureau, and the New York State Department of Education, their study identified a significant association between blood lead levels and academic outcomes while accounting for income a as control variable. Methodologically, the present study adopts a similar approach by averaging lead exposure over multiple years and comparing it to standardized test performance in later years. However, the Strayhorns’ analysis included eighth-grade math scores and relied on cross-county comparisons, which may obscure important variations across both school districts and neighborhoods.

This study builds on and extends the Strayhorns’ work in several important ways. First, it focuses on Syracuse, a high-poverty community with persistent lead exposure risks, allowing for a more detailed examination of neighborhood-level disparities. Second, the analysis is conducted at the census tract level, enabling assessment of neighborhoods in both lead exposure and ELA proficiency within the city. Third, the study incorporates refined confounding factors—specifically household English language proficiency and rent burden—as proxies for socioeconomic status and housing instability. Finally, by holding the school district constant, this research mitigates confounding effects associated with differences in curriculum and instructional priorities. This design isolates neighborhood-level dynamics and reduces the urban–rural and inter-district variation inherent in county-level analyses. As a result, the study offers a more precise assessment of the relationship between early childhood lead exposure and thirdgrade ELA proficiency among children in Syracuse.

Materials and Methods

The protocol for this study was reviewed and approved by the LeMoyne College Institutional Review Board (IRB). Provided that this research involved analysis of de-identified administrative records, the study was determined to pose little to no risk to participants.

While the New York State Department of Education (NYSED) reports 3rd grade ELA proficiency rankings, this information is only provided via school report cards on the NYSED website. These data are not available by census tract, which previously limited researchers’ ability to examine neighborhood dynamics.

Through a partnership between SCSD and the Central New York Community Foundation, this study disaggregated the NYSED data at the census tract level. Census tracts were chosen as the unit of analysis rather than zip codes, which are more commonly available, because census tracts provide a more granular understanding of neighborhood variation. A zip code may encompass multiple census tracts with varying levels of lead poisoning. Therefore, disaggregating the data allowed individual neighborhoods to be used as units of analysis. Because there are 52 census tracts in the City of Syracuse, the sample size for this study was n = 52. Because the census tracts are spread across the city’s boundaries, there is no risk of selection bias. Data for both control variables were drawn from the American Community Survey (ACS) (5-Year Estimates).

The Onondaga County Health Department’s Lead Poisoning Prevention Program provides lead poisoning data by neighborhood. Lead poisoning data have been available since 2013. This study uses the average rate of elevated blood lead levels per census tract from 2015-2017 as the independent variable. Onondaga County’s definition of elevated blood lead levels (≥ 5µg/dL) serves as the definition for lead poisoning in this model. Physicians in New York State are required to test children for lead poisoning at ages one and two; therefore, children tested in the years 2015-17 would be in third grade around 2021-23. ELA proficiency scores were averaged across the years 2021 through 2023 by census tract.

NYSED defines substandard ELA proficiency as scoring in the range of Level 1 or Level 2 on standardized ELA assessments. While Level 2 is on track to graduate, it does not meet NYSED’s standards of proficiency, according to a 2021 press release.

Previous studies [5] have demonstrated that the age at which a child is exposed to English is positively associated with language scores later in life, while Yel et al.’s findings [9] suggest that there is a moderate relationship between use of English at home and children’s scores on standardized academic tests (albeit in fifth grade in that study). Given Syracuse’s sizeable population of recent immigrants and New Americans, where many languages are spoken in households, our study accounts for the average level of English proficiency at the household level. Utilizing the ACS 5-Year Estimates across the years 2017-2021, the model controls for the average percentage of households in the census tract where no member 14 years or older speaks only English or speaks a language other than English but still speaks English very well (ACS definition).

Similarly, our study accounts for rent burden, defined as the average percentage of a census tract’s population spending greater than 30% of household income on rent from 2016 to 2020. Previous research [10] identified that lower household income is associated with reduced school readiness among children. Accordingly, we suggest that families who spend more on housing – and consequently have less disposable income – may have children who perform lower on standardized ELA assessments. Data on the percentage of families’ income spent on housing from 2016 to 2020 were obtained from the ACS 5-Year Estimates.

Results

Table 1 presents the variables’ descriptive statistics. The average lead poisoning rate of 10% (SD = 6%) was significantly higher than the national average, known to be around 2.5% [11]. On average, 78% (SD = 12%) of third-graders tested below proficiency in ELA. Both lead poisoning and household English level were significantly skewed to the right, suggesting that some census tracts exhibit higher levels of lead poisoning and lower household English levels. Nearly half of the residents are rent burdened, a trend consistent with national findings [12]. This overview provides context for understanding neighborhood-level conditions in Syracuse.

Table 1: Descriptive Statistics.

Pearson correlations among the variables are shown in Table 2. Lead poisoning was positively associated with substandard ELA proficiency at a modest level (r = 0.381, p < .05). Similarly, household English level had a moderate positive correlation with substandard ELA proficiency (r = 0.351, p < .05). Rent burden was not significantly associated with substandard ELA proficiency (r = 0.195). Household English was not significantly correlated with lead poisoning (r = 0.378), nor was rent burden (r = 0.181). Lastly, rent burden had a small, nonsignificant relationship with household English (r = 0.099).

Table 2: Pearson Correlation Among Variables.

The independent variable was the average lead poisoning rate per census tract from 2015 to 2017, and the dependent variable was the average percentage of third-grade students with substandard ELA proficiency from 2021 to 2023. A bivariate linear regression was conducted to examine the relationship between lead poisoning and substandard ELA proficiency, with the results presented in Figure 1.

Figure 1: Bivariate Regression, Lead Poisoning and Substandard ELA Proficiency (n=52).