While all of us are susceptible to the effects of pollution, children, infants, and fetuses in utero are uniquely sensitive to pollutants as their young brains grow and develop. Special protection from pollutants is needed because of the speed and timing of brain development early in life, before and after birth. In her book, A Terrible Thing to Waste: Environmental Racism and Its Assault on the American Mind, science writer Harriet Washington makes the case that environmental assaults on the developing brain—that are disproportionately inflicted on communities of color—can have lifelong implications.
The Centers for Disease Control and Prevention lists three key factors that affect early brain development: nutrition; positive or negative experiences with people and the world; and exposure to toxins and infections. I recently had the honor to contribute to a study examining the science around the interactions of these focus points, with specific attention on racial, ethnic, and socioeconomic disparities in brain development.
This review examined the effects of neurotoxic exposures and disparities on children’s brain development, cognition, and behavior by race, ethnicity, and economic status. The results tell a complex story about how racial and ethnic minoritized groups and children from low-income families may be harmed by exposures to neurotoxicants.
Let’s break our results down.
What we studied
Our team pulled together the existing scientific literature published up to November 2022 that examined:
- Children ages 0-18, exposed prenatally or postnatally (while living their regular lives) to seven neurotoxic chemicals including: lead, air pollution, organophosphate pesticides, phthalates, PBDE flame retardants, PCBs, and chemical mixtures.
- A wide array of neurodevelopmental outcomes, including cognition, behavior, psychological impacts, motor and sensory effects, and birth anomalies.
Early in the study, we met with 16 community and environmental justice leaders for two listening sessions. Some of the groups represented were Alaska Community Action on Toxins, Alianza Nacional de Campesinas, Farmworker Association of Florida, Inc and the National Black Child Development Institute, who have been collaborating with communities for years to address the impacts of exposure to toxins. We incorporated what we heard into how we extracted information as well as how we discussed the results. There was great interest in not only looking at the neurodevelopmental toxicants in our list, but also chemical mixtures. Looking at the effects of multiple exposures to chemicals cumulatively better reflects the real life experiences of impacted communities.
In our analysis, we extracted the methods, the quantitative results, and reviewed the findings and dug into which populations had higher exposures and which populations had worse outcomes. We also looked for studies that investigated interactions between exposures AND measures of adversity AND outcomes. Additionally, we examined the use of, and explanation for, how race and ethnicity were determined, and if authors defined what these attributes were intended to represent.
What we found
We found that children from families with low incomes and families of color are exposed to more neurotoxic chemicals and experience greater health harms than white children and children from wealthier families.
We found that most researchers don’t pose questions around how race, ethnicity, and economic hardship interact with neurotoxicant exposures to produce differing outcomes. In the few studies that did consider these factors, researchers found that chemical exposures are more strongly associated with learning, attention, and behavior problems for children in families that are also exposed to social adversities created by biased structures and systems. Although this finding was generally the case, it was not fully consistent across all studies.
We also found that authors were able to estimate benefits to the neurological health of minoritized children from polices and environmental programs aimed at reducing exposures, including cleaning up Superfund sites and reducing TRI reporting facilities’ emissions.
Here are the facts.
Exposure comparisons
- Low-income and Black children had higher exposures to lead.
- Children in communities of color and low-income communities were more highly exposed to air pollution.
- Black and Hispanic children were exposed to higher levels of organophosphate pesticides.
- Black and Hispanic mothers had higher levels of phthalates in their urine, which is used to predict how much got into their bodies in the first place. (Phthalates are neurotoxic chemicals in plastics).
Outcome comparisons
- Approximately 80% of papers that evaluated socioeconomic status (SES) found stronger relationships between exposures and harms in lower SES groups.
- Of the studies that evaluated differences by race or ethnicity, 63% found stronger relationships between exposures and harms by race and 60% by ethnicity.
Interactions
- Babies living in economically disinvested neighborhoods in their first year of life and exposed to air pollution were more likely to be diagnosed with autism.
- Low socioeconomic status magnified the adverse impact of lead exposure on children’s cognitive function.
- Air pollution exposures were associated with lower Performance IQ scores (a test intended to measure fluid reasoning, spatial processing, attentiveness to details, and visual-motor integration) among children from low socioeconomic status families.
- Air pollution exposures were associated with worse memory functioning scores among Hispanic and Black boys who were also exposed to high prenatal stress.
What must be done
We recommend that all levels of government work to limit, lower, or eliminate existing pollution levels and toxic chemical use (including pesticides); halt locating and permitting new chemical and plastics manufacturing plants in or near communities of color and low-income communities; and enact stronger workplace protections against exposure to pollutants. Policymakers should not wait for further evidence to act. This perpetuates harm.
Environmental health researchers must better document how and why children living in poverty and children of color are suffering the greatest harms. Furthermore, collaboration with communities where their lived experience, knowledge, and expertise is acknowledged and honored with decision-making power is crucial to successfully alleviate harm. We have certainly benefited from the listening sessions and our continued learning and collaboration with these groups.
We need to address unequal systems and social policies that create harmful conditions in the first place in addition to addressing pollution in or near low-income communities and communities of color. Setting environmental standards to protect historically under-resourced populations is urgently needed.
However, it’s important for scientists to remember that Black, Brown, and other racially and economically marginalized people are not inherently or uniformly more vulnerable, simply by virtue of their race, ethnicity, or socioeconomic status. For this reason, it is important for scientists to intentionally measure what they’re really interested in rather than using “race” as a catch-all term. For example, if the assumption is that race or ethnicity stands as a proxy for exposure to discrimination, then also measure discrimination. If the assumption is that race or ethnicity is a proxy for stress, then also measure stress. In the end, this leads to more actionable results. As Robin Collins, the EPA Senior Advisor to the Administrator for Environmental Justice, says “We don’t lack capacity, we lack access”.
Dr. Aisha S. Dickerson, in commentary on our article, provided important insight as well:
“…[M]easures of individual race and ethnicity may not reliably account for structural racism, which is more commonly observed via differences in housing along with service provision for children with impairments and their families. Therefore, studies of racial disparities may be improved by examining area-based measures of structural racism such as percentage of unemployment residents, percentage of rental units, segregation indices, and frequency of police activity.”
There is work here for everyone. We recommend that scientists use existing evidence to advocate for change and prevention, and avoid continued studies looking for thresholds of acceptable exposure when immediate action like bans can be more protective of public health. Finally, we found very few studies with American Indian and Alaska Native populations. This is because of a long underlying history of harm and scientific extraction. Collaborating with American Indian and Alaska Native populations to support existing community-based participatory research, co-creating research programs, would be a start to address issues raised by these communities and Nations.
Protecting children’s brains, early in life and in utero, must be one of our highest priorities as a society—and it is essential that we protect ALL children’s brains.