Children born in bad financial situations already have it extremely tough, as they have to invariably worry about adult concerns, such as whether their families have basic necessities. A study performed at the Columbia Center for Children’s Environmental Health (CCCEH) found that children born to mothers experiencing economic hardship and exposure to higher levels of pollutants scored significantly lower in intelligence tests than children born to mothers in stable economic conditions and less exposure to the pollutants.
The researchers studied 276 mother-child pairs, a subset of CCCEH’s ongoing urban birth cohort study in New York City, from pregnancy through early childhood. Mothers self-reported material hardship during pregnancy and at multiple times throughout their child’s early childhood. Material hardship is a measure used to assess an individual’s unmet basic needs with regard to food, clothing, and housing. The Columbia researchers, led by Frederica Perera, PhD, and director of CCCEH, previously reported that that prenatal exposure to airborne PAH (polycyclic aromatic hydrocarbons) as a result of pollution during gestation (the time period during which we are in our mother’s womb) was associated with development delay at age three, reduced verbal and full scale IQ at age five, and symptoms of anxiety and depression at age seven.
Image Source: Thanasis Zovoilis
You might look at this study, however, and say to yourself, “How are these researchers positive that both pollution and economic hardship impact IQ? Couldn’t it just be one of the two?” The answer to this inquiry is addressed in the next stage of the experiment.
Researchers utilized the Wechsler Intelligence Scale to assess IQ in children at the age of seven. In order to determine the measure of prenatal exposure to the pollutants, PAH-DNA adducts in cord blood (blood from the umbilical cord) were used. Simply explained, a DNA adduct is a piece of DNA covalently attached to a chemical, typically a cancer-causing one. In this situation, PAH is the cancer-causing chemical that leads to problems in DNA’s natural ability to heal itself.
The issue of “causation vs. correlation”, is imperative in science; scientists strive to determine whether two items actually have a plausible link. Therefore, statistical tests have been established in order to determine whether an association is legitimate or not, and the phrase “statistically significant” implies that the association has passed the tests and is deemed plausible.
The researchers observed that, among children whose mothers reported greater material hardship, the group with high levels of PAH-DNA cord adducts significantly scored lower on tests of full scale IQ, perceptual reasoning, and working memory compared to those children with lower levels of adducts. They observed statistically significant interactions between both prenatal and recurrent material hardship and high levels of cord adducts on children’s working memory scores. The same significant relationships between adducts and IQ were not observed in the low material hardship group.
These findings further solidify the growing argument that socioeconomic factors play a role in fetal development, as they can worsen the negative effects of toxic physical “stressors” like air pollutants. These studies prove that helping disadvantaged people is as much grounded in science as it is in politics.
Feature Image Source:WFP nutrition program by UNAMID