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Jiang H, Justice L, Purtell K, Bates R. Exposure to environmental toxins and early language development for children growing up in low-income households.Clin Pediatr (Phila). 2020;59(6):557-565.
Study objective
To assess the extent to which early childhood exposure to toxicants may be associated with delays in early language development in children born into low-income households.
Draft
A prospective observational study that used data from the Kids in Columbus study – a 5-year birth cohort study of children born into low-income families.
Participant
Participants were mothers who were pregnant or had children under 3 months of age at the time of enrollment; were 18 years or older; and were able to speak English at a conversational level. 80% of participants reported a family income of less than $30,000 per year. Children who were born prematurely or diagnosed with a serious illness were excluded from the study. 322 mother-child dyads participated in the study; However, the study ultimately analyzed data from 190 families after accounting for participant attrition and missing data.
Study parameters assessed
This study examined maternal exposure to environmental toxins during and shortly after pregnancy and 1.5 years after birth. The researchers collected data on child development at ages 1 and 2.
Primary outcome measures
Investigators collected information through home visits to mothers at 5-month intervals, starting from the 2nd month of pregnancy until 4 months after birth and continuing until the child was 2 years old. Investigators asked the mothers questions about exposure to certain environmental toxins. Investigators also administered the Bayley Scales of Infant and Toddler Development 3rd Edition to the children.
At recruitment and 1.5 years after birth, mothers answered a series of questions about their exposure to toxicants. At both time points, investigators asked mothers: (1) whether there was mold in their current home; (2) whether they have used pesticides (at home, on pets, or on lawns/gardens) during pregnancy or within the past year; and (3) whether they regularly (at least weekly) used any of the items from a list of potential household chemicals (glass cleaner, oven cleaner, floor cleaner, drain cleaner, toilet cleaner, shoe polish, solvent, paint stripper, sealant, and bug spray) during pregnancy or within the past year.
In addition, investigators asked mothers at registration whether they had lived within 0.5 miles of any of the following 8 locations in the past 5 years: landfills or landfills, closed and empty factories, heavy traffic, vehicle shutdowns, farms, industrial facilities, polluted lakes or streams, and hydroelectric plants.
Researchers assessed language development in children ages 1 and 2 using the Bayley Scales of Infant and Toddler Development 3rd Edition. They compiled a scaled score that addressed the subdomains of development and cognition. Investigators then examined the relationship to toxicant exposure and language development scores.
Key insights
This study suggests that household toxicant use, particularly household cleaning use during the first and second years of life, has a significant correlation with reduced scores in children's early language and cognitive development. Neighborhood pollution, mold and pesticide exposure were not as severe.
Looking at early language development, exposure to toxicants during pregnancy accounted for 1% to 1.6% of variance in language skills, while exposure to toxicants after birth was correlated with a 6.7% variance in language outcomes at two years. For cognitive outcomes, toxicant exposure during pregnancy corresponded to a variance of 1.8% at 1 year of age and a variance of 3.5% at 2 years of age.
In particular, the use of household cleaners appeared to be most effective. When using household cleaners more than 1 standard deviation above the mean, children scored 0.21 standard deviations lower in language and 0.24 standard deviations lower in cognition.
Practice implications
First, African Americans represent approximately 28.5% of the population of Columbus, Ohio, yet 41% of the participants in this study. One cannot discuss exposure to environmental toxins without also pointing out the structural racism that causes Black and brown populations to be overexposed to environmental toxins. Black and brown people are disproportionately exposed to environmental pollutants resulting from residential segregation, unequal access to economic opportunities, and the concentration of factories, highways, landfills, etc. in nonwhite neighborhoods. These populations bear the brunt of our nation's toxic exposures, and this further contributes to a legacy of health and economic disparities stemming from policies influenced by racial injustice.
Additionally, the chronic stress of living with racism can increase vulnerability to negative health consequences of environmental exposure.1.2
It is imperative that all integrative medicine practitioners view exposure to environmental toxins as more than just a matter of personal choice. Instead, practitioners should understand the widespread impact of systemic racism on health outcomes. We all need to educate ourselves on environmental justice issues and work in our communities to end this particular manifestation of injustice. For more information and resources on how you can advocate for these changes, visit Black Lives Matter and Integrative Medicine for the Underserved.
In particular, the use of household cleaners appeared to be most effective. When using household cleaners more than 1 standard deviation above the mean, children scored 0.21 standard deviations lower in language and 0.24 standard deviations lower in cognition.
Moving on to the results of this particular study, since it is a correlational study, many questions remain regarding the mechanisms by which exposure to toxicants affects language development and cognition. However, while we wait for further research, the take-home message seems clear. Educate pregnant women and parents about the effects of using toxic cleaning products in the home. There are many inexpensive and safe alternatives to toxic cleaning products like vinegar, baking soda and castile soap.
The American Academy of Pediatrics (AAP) has a relevant position on this issue.3In 2012, the AAP released a policy statement on pesticide exposure in children, warning of concerns about acute poisoning and the effects of chronic exposure on long-term development.
While the study reviewed here did not show an impact of pesticide exposure specifically correlated with reduced language development or cognition, it did show that 20% of households used pesticides after 1 year and 30% of households used pesticides after 2 years. This illustrates why pesticide education remains critical. This study is an important addition to the growing literature on the negative impact of toxicant exposure on children. It contains specific action items that are easily applicable in practice: Interview patients about their exposure and provide them with education about alternatives. This is a simple intervention we can offer while working to dismantle the systems that lead to an unequal distribution of environmental risks.