Powerful new evidence has emerged of damage from living near fracking sites. Women who live within 3 kilometers (1.9 miles) of a fracking well are more likely to have underweight babies, a common marker of poor health. The effect is strongest for those living within a kilometer (0.6 miles) of a site.
Fracturing of rocks using water, sand, and undisclosed chemicals, known as fracking, to get at oil and gas beneath has exploded in the last decade as new technologies have made it increasingly cost-effective. Wherever fracking has been adopted, debates about its safety have raged in its wake. Pennsylvania was one of the first places where fracking became widespread and is far more populated than some other early locations, so it's a prime site for studying the consequences.
Professor Janet Currie of Princeton University looked at the birth records of 1.1 million babies born in the state between 2004 and 2013 and the distance between their mothers' residences and fracking sites. Most previous studies of the topic relied on county-level data, but Currie had access to the mothers' exact addresses. This data alone would be subject to many potentially confounding variables, notably urban air pollution. However, since new fracking sites opened up mainly after 2008, Currie was also able to compare the weight of siblings whose parents lived in the same location before and after fracking began, greatly increasing the study's reliability.
The mothers closest to fracking sites were 25 percent more likely to have underweight babies after fracking began, Currie and her colleagues report in Science Advances, and the influence is statistically significant between 1-3 kilometers. Currie acknowledges it's unclear whether the specific cause is leaking gas, fumes from diesel generators, water pollution, or some unknown factor.
Underweight babies are more likely die as infants, and do badly at school and suffer asthma if they survive. In addition, low birth weight across a population is usually a sign of broader problems among older children and adults. Currie notes that other health impacts are frequently harder to detect, however, as they take longer to show up.
An estimated 29,000 births occur each year to mothers who live within 1 kilometer of an active fracking site, and the number within 3 kilometers is naturally many times higher.
Even before Currie's work, there was plenty of evidence to support the fears of fracking's opponents. That fracking sometimes triggers small and medium-sized earthquakes is now beyond doubt, and many of the chemicals used are classed as carcinogenic.
Nevertheless, Currie's work is unprecedented for sample size and detailed data. Many parts of the world have banned fracking, and those that have not, unless very sparsely populated, may have a very hard time explaining why they allow it to continue.