Lead in NYC Housing: Who Has Greater Risk for Cognitive Impairment?

Written by: Brandon Sagram

Edited by: Jeffrey Lin, Aaron Springer, Zoee Drimmer, and Amanda Benneh

Illustrated by: Meher Lakdawala

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Introduction

Cognitive impairment is a term that encompasses a range of alterations across different domains of cognition [1]. Specific domains affected by cognitive impairment include difficulties with behavior, memory, learning, concentration, communication, emotional regulation, and more [1]. Conditions often discussed under the umbrella of cognitive impairment include intellectual disabilities, learning disabilities, and neurodevelopmental disorders such as attention deficit/hyperactivity disorder, autism spectrum disorder, and intellectual developmental disabilities. Cognitive impairment is not limited to any particular disease, and is often a manifestation of some other underlying condition, such as vascular conditions like stroke [2], metabolic diseases like diabetes, or deficiencies in minerals like vitamin B12 [3, 4]. Cognitive impairment can be a short-term condition; however, a study that examined the relationship between potentially toxic elements found in urine samples and cognitive performance in residents of Estarreja suggests that extended exposures to toxins can lead to progressive and permanent conditions [1].

In recent years, studies have linked household environmental toxins capable of crossing the blood-brain barrier to cognitive impairment, especially in children. The most prominent toxin is lead, a heavy metal that can accumulate in dust, soil, and water sediment, especially near urban areas where it can persist for years [5]. This article uncovers the mechanistic connections between lead exposure and cognitive impairment in children, which families are most susceptible to these exposures in NYC, and the sociological factors that contribute to the disproportionate impacts. These findings highlight the need for public health solutions necessary to address cognitive impairment disparities in NYC, which can lead to improved health outcomes and academic performance in children.

Lead Toxicology

“So how does lead get into the brain and lead to cognitive impairment in children?” Neurons are the most basic unit of the nervous system, which communicate through secreting chemical messengers, neurotransmitters (NTs), to other neurons. Inside the neuron are vesicles, which are small, membrane-bound sacs that contain NTs. For NTs to be released, calcium ions (Ca²⁺) must bind to receptors on the vesicle surfaces like a lock-and-key mechanism [6]. This causes the vesicle to deliver its NTs from within the cell environment to out of the cell, where the NTs can bind to other neurons [4]. This allows neurons to communicate with each other, allowing for various cognitive functions like learning and memory.

With environmental exposure, lead ions (Pb²⁺) ingested through contaminated drinking water or dust can end up in the bloodstream and interfere with this process. Pb²⁺ can cross the blood-brain barrier through divalent metal transporters, proteins that allow metal ions with a 2+ charge to flow into the neuron. Pb²⁺ can then enter neurons through voltage-gated Ca²⁺ channels, protein structures that allow Ca²⁺ to flow into the neuron. This occurs because Pb²⁺ is structurally similar to Ca²⁺ in size and charge [7]. Once in the neuron, Pb²⁺ can bind to the Ca²⁺ receptors on NT-containing vesicles, blocking that key-hole mechanism for NT release. This prevents chemical messages from being sent, decreasing neuronal communication and ultimately weakening the structural connections between neurons [8].

Clinical Outcomes of Lead Poisoning

Many recent studies have assessed the neurodevelopmental impacts of these changes caused by lead exposure. For example, a 2015 population-based retrospective cohort study, or an observational study on a large group of people over time, researchers in Chicago investigated the impact of blood lead levels (BLLs) on academic performance in 3rd graders. BLLs below 10μg/dL were inversely associated with reading and math scores (as BLL levels increased, reading and math scores decreased), and for a 5μg/dL increase in BLL, the risk of failing increased by 32% for reading [9]. Additionally, a study between 2007-2008 on Egyptian children living in high-risk lead-polluted areas demonstrated that having a BLL greater than 10μg/dL can result in decreased verbal and arithmetic performance IQ by up to 15 points [10]. Outside of academic performance, clinical studies that compared toddlers with varying BLLs have shown that early postnatal lead exposure can lead to abnormal behavior in children, such as social withdrawal, depression, and episodes of aggression [11].

Prevalence of Lead in NYC

For decades, particular areas of NYC’s housing have been plagued by resident exposure to lead, which leads to cognitive impairment outcomes. Lead can be ingested through consuming contaminated drinking water in which the insides of lead service pipes get corroded by acidic water [5]. Studies by the NYC Department of Environmental Protection report the prevalence of lead service pipelines across NYC: 16% of all residential service lines are “Potential Lead” service lines, with a larger proportion of such service lines being in The Bronx (21.2%) and Queens (20.5%) [12].

Studies have also been conducted by the NYC Healthy Homes Program, which reveal a geospatial assessment of the rates of elevated BLLs in children under six years old across NYC [13]. When comparing the results on the prevalence of lead service lines across NYC and the rates of elevated BLLs in children under six years old, there is noticeable overlap in many regions. Areas in Southeast Queens, Jamaica, Southwest Queens, and West Queens have high percentages of “Potential Lead” service lines ranging from 40-80% [12], which reflect their higher childhood elevated BLL rates of 12.9 to 15.6 per 1,000 children [13]. Additionally, multiple areas in The Bronx with higher percentages of “Potential Lead” service lines [12] share childhood elevated BLL rates ranging from 10.2 to 14.7 per 1,000, such as Throggs Neck, Pelham, and Fordham [13]. The overlap between the two studies demonstrates the positive correlation between the prevalence of lead service pipes and rates of elevated BLLs in children in NYC. 

Associations between Socioeconomic Status and Lead Exposure

The residential populations of NYC areas with high lead exposure are associated with certain social determinants of health (non-medical factors that can influence well-being). Socioeconomic status (SES) is a significant predictor of environmental health disparities. In NYC, SES is particularly important due to how economically and racially stratified the city is. A study conducted by the NYC Health Department reveals the prevalence of rent-burdened households across various NYC neighborhoods [14]. The term “rent-burdened” refers to households where more than 30% of resident income goes to rent [14].

Results show that many neighborhoods plagued by lead exposure are also characterized by high percentages of rent-burdened households. Many regions in the South and West regions of Queens, which had higher rates of childhood elevated BLLs as discussed earlier, also share higher percentages of rent-burdened households. For instance, most neighborhoods in Southwest Queens, Jamaica, and Southeast Queens share a prevalence of rent-burdened households of at least 50%, with the highest percentage in the central area of Jamaica, with 61.43% [14]. Moreover, many neighborhoods in West Queens, such as Elmhurst, Corona, and Jackson Heights, have percentages ranging between 58.4% and 65.49% [14]. Ultimately, high rent costs can leave residents with too little money for food and other essentials [14]. This financial burden can make it harder for residents of lower SES to avoid exposure to household toxins; for example, such residents are likely to resort to drinking lead-contaminated tap water over bottled water, an expense that can accumulate over time.

Associations between Redlining and Lead Exposure

The impacts of low socioeconomic status hardships in NYC are exacerbated systemically via policy-related discriminatory practices such as redlining. Redlining is a practice of systemic racism that’s characterized by a maldistribution of resources to minority groups [15]. In the 1930s, the Home Owners Loan Corporation graded neighborhoods within large US cities based on their perceived lending risk. Neighborhoods that were full of Black or non-White Hispanic residents were given a ‘D’ grade, which told lenders not to provide loans to residents of these areas [12]. This economic disinvestment of residents identifying as racial minorities led to many Black and Hispanic households being denied access to financial resources for housing [15], forcing minority residents to live in substandard housing conditions.

Studies have demonstrated how redlining practices have impacted the exposure of household toxins to minority groups. The Second National Health and Nutrition Examination Survey collected data on BLLs in children between 1976 and 1980 in lead belt neighborhoods in Brooklyn that were targets of redlining practices, such as Bedford-Stuyvesant, Crown Heights, and Fort Greene [16]. Results from the survey highlighted that Black-identifying children between six months and two years old had significantly higher mean BLLs than White-identifying children of the same age [16]. These results emphasized that redlining restricted families of color to neighborhoods full of dilapidated apartments where children would be exposed to flaking and peeling lead-based paints.

Despite this data being taken between 1976 and 1980, the domino effects of redlining persist to this day. Data from the NYC Healthy Homes Program study in 2023 indicates that Bedford-Stuyvesant and Crown Heights, neighborhoods that were observed in The Second National Health and Nutrition Examination Survey, have childhood elevated BLL rates of 15.0 per 1,000 children [13]. These rates remain among some of the highest in NYC, illustrating that residents living in one redlined neighborhood still live in housing conditions that promote high lead exposure. Moreover, data from the 2020 U.S. Census demonstrates that the resident populations of Bedford-Stuyvesant and Crown Heights are predominantly Black and Hispanic [17]. Even after decades, children of color in once redlined NYC neighborhoods are still disproportionately exposed to lead compared to their White counterparts. The lack of change in childhood lead exposure in these neighborhoods targeted by redlining demonstrates the lack of political capital that residents of redlined areas have. Even if families are aware of the issue, it’s unlikely that they will be heard and have their immediate needs addressed due to the stigma that redlining created among households of color [18].

Conclusion

The connection between housing, health, and education is undeniable: poor housing conditions lead to poor health, which contributes to poor academic outcomes. This ultimately reflects a public health crisis that demands urgent intervention. Moving forward, to support children who are impacted by lead exposure, education and advocacy need to increase. Clinics located within NYC areas with a high prevalence of lead-service pipelines should educate families about the severity of household toxin exposure to children through newsletters, allowing parents and guardians to take proactive measures. Additionally, it’s important to advocate for the housing rights of residents with historically lower political capital. Today, there are local grassroots organizations such as the NYCHA Tenants Alliance and the WE ACT for Environmental Justice that are able to put pressure on policymakers to respond to the complaints of politically and economically disadvantaged families. Addressing these issues at the intersection of housing, health, and education is a critical step to break the cycle of disadvantage and help promote healthy cognitive development for all children in NYC.

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