Exposing pregnant women to a common air pollutant may impact their children's intelligence.
Polluting young minds. I'm Bob Hirshon and this is Science Update.
Air pollution may adversely affect a child's intelligence—starting in the womb. This according to a new study in Krakow, Poland, led by Columbia University environmental health scientist Frederica Perera. Her team monitored healthy, non-smoking pregnant women for exposure to common air pollutants called polycyclic aromatic hydrocarbons, or PAH's. The children of women with higher PAH exposure scored lower on cognitive tests at age five.
And that's of concern because of the link between such tests and future academic performance.
The study controlled for such factors as the mother's education, and exposure to secondhand smoke and lead. Perera says the only real way to reduce the risk of PAH's is to produce less of them, by burning less fossil fuel. I'm Bob Hirshon for AAAS, the Science Society.
Making Sense of the Research
It's obvious that air pollution can negatively impact people's health—by aggravating asthma, for example, or in more extreme cases, contributing to lung cancer. However, this study shows that the effects of air pollution aren't limited to those who actually breathe it in directly. Rather, it shows these pollutants can find their way into a developing fetus, with measurable consequences later in life.
Polycyclic aromatic hydrocarbons, or PAH's, are a by-product of burning fossil fuels like coal and oil. It's hard to escape them entirely, but some areas have higher concentrations of PAH pollution than others. This study tracked pregnant women's exposure to PAH in two ways: First, the researchers gave the women a small, backpack-mounted air sampling device, which they wore at all times during their pregnancy. Second, the women came in for regular checkups, and blood and urine samples were taken to look for chemical signatures of PAH exposure.
The researchers continued to follow the women's children after they were born. At the age of five, each child took a test of intellectual ability, similar to an IQ test. They then divided the group of children in half, with those of higher prenatal PAH exposure in one group, and lower PAH exposure in the other group. High-exposure children scored worse on the cognitive test than closely matched low-exposure children, even after accounting for many potential confounding factors, including PAH exposure after birth.
The difference was small but statistically significant: the equivalent of about 2.8 IQ points. That may not seem like much, but consider that a small difference in a score on a standardized test could make the difference between qualifying for a scholarship or not, getting into a particular college, and so forth. And the findings raise larger concerns about chronic PAH exposure, which continues throughout one's life from both air pollutants (especially in urban areas) and dietary sources (like smoked or barbecued foods). On the flip side, if PAH pollutants can impact a developing fetus, it stands to reason that other environmental pollutants also may have a significant impact in the womb.
Now try and answer these questions:
- What are PAH's? What are their sources?
- How did the researchers test the effects of prenatal exposure to PAH's?
- Why were the backpack air monitors necessary? Why not simply take air samples from where the women lived and worked?
- Why was it important to separate out the effects of PAH exposure after birth?
In the Science NetLinks Science Update lesson Asian Brown Cloud, you'll hear about an effort to measure the pollution over Asia and assess its impact on humans and the environment.
In the Science NetLinks Science Update lesson Crystal Meth, students learn how even a single hit of crystal meth by a pregnant mother can cause birth defects.