(Beyond Pesticides, October 26, 2023) The increasing prevalence of neurodevelopmental disorders (NDDs) in the United States has raised concerns about the impact of toxic exposures on child development. A comprehensive review by Devon Payne-Sturges, PhD, and colleagues in Environmental Health Perspectives analyzes the literature about disparities in NDDs in vulnerable and marginalized populations. The review investigates over 200 studies and reveals that fewer than half of these studies actually examine disparities, and most fail to provide a rationale for their assessments. The authors also offer practical suggestions for improving future research, including better methods for characterizing race and socioeconomic status and interpreting effect modification in environmental epidemiologic studies of health disparities.
Associate Professor Devon Payne-Sturges, PhD, at the University of Marylandâ€™s School of Public Health, one of the lead authors of the study and a former policy specialist at the U.S. Environmental Protection Agency (EPA) said, â€śFDA and EPA can act nowâ€”not laterâ€”to protect families from neurotoxic chemicals in consumer products and in the environment.â€ť
Tanya Khemet Taiwo, PhD, the other lead author and assistant professor at Bastyr University in Seattle said, â€śWe need more stringent environmental standards to address pollution that is disproportionately impacting low-income communities and communities of color, but itâ€™s just as important that we find a way to improve the unjust systems and social policies that create harmful conditions in the first place.â€ť
Given the disproportionate toxic burden in the U.S., children from marginalized groups and low-income families are more likely to face a variety of harmful exposures that can negatively affect childhood development. These disparities are linked to neurodevelopmental disorders. NDDs are defined as conditions related to the functioning of the nervous system and the brain, including: attention-deficit/hyperactivity disorder (ADHD), autism, learning difficulties, intellectual disability (cognitive impairment), conduct disorders, cerebral palsy, and challenges related to vision and hearing.
Among the 218 studies written between 1974 and 2022 that were investigated by Dr. Payne-Stuges et al., the following patterns emerged:
- Black and Hispanic children have higher exposure to organophosphate pesticides, commonly used in agriculture.
- Black and Hispanic mothers have elevated levels of phthalates, chemicals found in food packaging, personal care products, and other environmental sources.
- Low-income and Black children have more significant lead exposures compared to their higher-income and white counterparts.
- Communities of color and low-income neighborhoods experience a disproportionate exposure to air pollution.
- Babies residing in economically disadvantaged neighborhoods exposed to air pollution during their first year of life are at a higher risk of being diagnosed with autism compared to those in more affluent areas.
Environmental justice scholars have connected the unequal and disproportionate toxic exposures to discriminatory policies and practices, including racial residential segregation. Despite decades of executive orders addressing environmental justice, the recognition of unequal pollution distribution in historically marginalized communities has recently gained federal research funding through the Justice40 Initiative and other policies. However, there has been a history of commitments that have not played out, as envisioned by its supporters. A U.S. General Accountability Office (GAO) report, Environmental Justice: Federal Efforts Need Better Planning, Coordination, and Methods to Assess Progress (2019), found, â€śMost of the 16 agencies that are members of the interagency working group on environmental justiceâ€”created by Executive Order 12898 in 1994â€”reported taking some actions to identify and address environmental justice issues, such as creating data tools, developing policies or guidance, and building community capacity through small grants and training.â€ť However, GAO concluded that â€ś…few agencies have measures or methods for assessing progress, and the working group has not provided guidance to help agencies with such assessments.â€ťÂ
Beyond Pesticides issued an action in 2021 that points to a generation of EPA neglect of farmworker childrenâ€™s exposure to the neurotoxic insecticide chlorpyrifos. The pesticide and the family of organophosphates, of which it is a part, targets the nervous system in humans. EPA had negotiated a withdrawal from the market of all residential uses of chlorpyrifos in 2000 because of the neurotoxic effect on children, but left the agricultural uses on the market, with a few exceptions. This left farmworker children exposed to chemical drift in their communities and schools, while EPA took no action for nearly two decades. Children are particularly at risk because they take in greater amounts of pesticides relative to their body weight than adults, and their developing organ systems are typically more sensitive to toxic exposures. The agency finally negotiated a withdrawal of agricultural uses in 2022.
The Payne-Sturges et al. review emphasizes the potential shortcomings of relying solely on models of â€śeffect modificationâ€ť to assess health disparities because it often addresses only one aspect of the problem. Many studies in the review focus on lead and air pollution exposures, which often affect under-resourced communities housing marginalized populations. These communities may face multiple hazardous exposures from sources like high-traffic roads, industrial facilities, deteriorating municipal infrastructure, and substandard housing. Such conditions can have cumulative effects, and historical and continued segregation contributes to repeated toxic exposures. Despite this, most studies in the review assessed these exposures independently.
The review highlights that children continually exposed to known neurotoxic substances often experience delayed diagnoses and barriers to necessary services. Moreover, cognitive impairments and poor academic achievement can exacerbate economic hardship. Consequently, measures of neurodevelopmental delay and impairment might be more effective in assessing the impact on underserved groups.
While many environmental studies consider socio-demographic factors tied to health disparities like race, income, education, and other sociodemographic factors, there is a recent shift toward evaluating NDD factors in collecting data. Yet, solely looking at individual race and ethnicity might not capture the full extent of structural racism. According to the authors, looking at area-based indicators of structural racism, such as unemployment rates, rental percentages, segregation metrics, and police activity frequency, could improve our understanding of racial disparities.
The authors of the study consider the complex paradigms and racist structures underlying the toxic disparities. They note that greater diversity in research teams and collaboration with community members with firsthand experience is vital. The authors stress the importance of stakeholder engagement in interventions and addressing the structural barriers contributing to environmental health disparities. The Equal Protection Clause of the 14th Amendment is cited as a potential tool to protect children from hazardous exposures and reduce community exposure through regulation and public health practices.
The review aligns with a history of awareness of the disproportionate exposure to neurotoxic chemicals experienced by children of color and those from low-income families. Ultimately, this research aims to reduce the burden of hazardous exposures on children’s health and promote more equitable protection against neurotoxic chemicals.
You can make a change by eliminating neurotoxic pesticides on your property and working toward the passage of organic land care policies in your community. To get started, see Beyond Pesticides’ Tools for Change webpage. Beyond Pesticides will continue to monitor progress on inequities related to pesticides, agriculture, farmworker well-being, and the health of BIPOC communities in the U.S. For current reporting on matters related to environmental justice, see Beyond Pesticidesâ€™ Daily News Blog EJ archives.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: Disparities in Toxic Chemical Exposures and Associated Neurodevelopmental Outcomes: A Scoping Review and Systematic Evidence Map of the Epidemiological Literature, Sweeping UMD Review Finds Deep Disparities in Childhood Exposure to Neurotoxins