Researchers from the University of Pittsburgh Graduate School of Public Health released a study last week which showed that babies born to women living near high-density shale gas drilling and fracking sites in three southwestern Pennsylvania counties were more likely to have lower birth weights than babies born to women living further away.
The researchers stopped short of claiming there was a causal link between low baby birth weights and drilling sites, but argued that the study showed a “concerning association” between the two factors, which indicates that further studies on the subject are needed.
“Our work is a first for our region and supports previous research linking unconventional gas development and adverse health outcomes,” said Dr. Bruce Pitt, study co-author and chair of the Department of Environmental and Occupational Health in the Graduate School of Public Health. “These findings cannot be ignored. There is a clear need for studies in larger populations with better estimates of exposure and more in-depth medical records.”
The study, published on the website PLOS ONE and funded by the Heinz Endowments, built on findings of earlier studies in Colorado and in Pennsylvania by investigators at Cornell University.
The Pitt study reviewed 15,451 births in Washington, Westmoreland and Butler counties between 2007 and 2010, and cross-referenced the mother’s residences to Marcellus Shale gas wells that had been hydraulically fractured or ”fracked,“
Emissions from drilling and fracking operations emit a variety of air pollutants, according to prior studies cited by Mr. Pitt, including benzene, a carcinogen, volatile organic compounds or VOCs, metals, and polycyclic aromatic hydrocarbons known as PAHs.
”We know that developing fetuses are sensitive to those emissions components,“ Mr. Pitt said. “So the agents are there and pathways are plausible, but we cannot connect these things yet. We need more and larger, more sensitive studies.”
The study found that mothers who lived closest to the densest shale gas development, including some as close as a quarter mile to multiple wells, were 34 percent more likely to have babies who were ”small for gestational age“ than women who lived further away.
According to the researchers, this finding still held after adjusting the results for other factors that could influence birth weight, including prenatal care, race and whether the mother smoked or not.
The study was heavily criticised by the Marcellus Shale Coalition, drilling industry advocacy organization, for being scientifically-flawed and funded by a “group with a long and clear record of financially supporting anti-shale activism.”
In an article on their website, the Marcellus Shale Coalition argued that the study was not peer-reviewed and built upon earlier findings (from Cornell University) that have already been debunked.
What is more, they argued that the definition of “lower birth rate” accepted by the researchers for the purpose of the study as “babies that are in the smallest 10 percent of babies born of that gestational age” differs from the widely accepted definition by the National Institutes of Health (NIH).
According to the National Institutes of Health (NIH), the standard criterion and definition of low birth weight (LBW) is less than 2,500 grams. Likewise, according to the Pa. Dept. of Health, a baby is born with LBW when its weight is less than 5.5 lbs (2,500 grams) at birth. According to the study’s own data, the average birth weight in the four quartiles varies from 3,323.1 grams to 3,370.4 grams – well above the 2,500 gram LBW definition, consistent with NIH and the Pa. Dept. of Health.
Additional criticism against the study included:
- no baseline was established for low birth rates that would include non-shale-developing states,
- no baseline established for the birth weight statistics and other similar data of women in the region prior to shale development occurring,
- assumption was made that the birth certificate records’ addresses were in fact where the mothers actually lived during their pregnancy.
The full article from the Marcellus Shale Coalition can be found here.
The Pitt study was funded with part of a $70,000 grant from the Heinz Endowments to the University of Pittsburgh for multiple research projects. Heinz did not direct and had no input into the Pitt research study or the journal article, Mr. Pitt said.
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