Is there an association between residential proximity to fracking sites and birth defects?

A recent study to be published in the Environmental Research Journal explores the incidence of birth defects in children born to mothers residing within 10 km of fracking sites.

Study: Residential proximity to unconventional oil and gas development and birth defects in Ohio. Image Credit: RoschetzkyPhotography/Shutterstock.comStudy: Residential proximity to unconventional oil and gas development and birth defects in Ohio. Image Credit: RoschetzkyPhotography/


Oil and gas development produces a slew of toxic chemicals, more so when produced by unconventional methods. Some of these are known to be teratogens or reproductive poisons.

A new study from Ohio, where natural gas production shot up 30-fold in the period between 2010 and 2020, seeks to identify an association between unconventional oil and gas development (UOGD) and birth anomalies.


UOGD refers to the “extraction of oil and gas from previously inaccessible reservoirs through the use of directional drilling and high-volume hydraulic fracturing.”, according to the US Department of Energy, Environmental Protection Agency.

Fracking takes large amounts of fluids that need to be injected into shale and rocks of similar low permeability to produce high-volume hydraulic fracturing (‘fracking’). These techniques multiply the volume of extracted natural gas, making the USA a net exporter of this fossil fuel.

Natural gas is touted as a cleaner fuel than coal. Its extraction will help create new jobs and produce energy independence; accordingly.

However, others point out that these benefits are exaggerated and that building natural gas infrastructure will inevitably lead to a longer period of greenhouse gas emissions from fossil fuels, delaying the transition to renewable energy sources.

Importantly, there is evidence of health risks associated with living near UOGD plants. The incidence of birth defects is relatively high, affecting five million babies worldwide and three in every hundred American babies.

Birth defects are also the number one cause of infant mortality in the United States. Around the world, birth defects cause about 400,000 deaths under the age of five years.

Birth defects may cause a lifelong need for care, both medical and social. While some congenital anomalies are traceable to definite causes, up to 60% are still of unknown causes.

Genetic factors, environmental toxins, alcohol use, and advanced maternal age, as well as certain medications, all increase the risk of such anomalies.

Toxic chemicals in UOGD wastewater and fracking fluids include many associated with reproductive and embryological or developmental abnormalities, including heavy metals, polycyclic aromatic hydrocarbons, and aromatic organic compounds like benzene.

Failure to contain these toxic fluids will inevitably endanger the population residing nearby by contaminating the groundwater or surface water with such chemicals.

Other sources of potential harm to pregnant women and their babies include increased vehicular traffic and diesel combustion near the well sites at such plants, releasing nitrous oxides, fine particulate matter, and the like into the air. Noise pollution, and psychosocial stress are other risk factors.  

Eight older studies have reported evidence of a link between UOGD and an increased risk for birth defects, most commonly heart and neural tube defects (NTDs).

In the current study, the data was taken from birth records with the Ohio Department of Health, including over 4,000 individuals; and from surveillance records, identifying ~2,300 individuals, with one or more of 19 types of congenital anomaly.

There was a total of ~4,600 birth defects from among approximately 960,000 births.

What does the study show?

The most common birth anomaly was hypospadias, followed closely by congenital heart disease and oral clefts. There were over 40,000 births to women living close to UOGD facilities, making up about 4% of the total cohort.

The researchers found that children born to women who lived within a 10 km radius of UOGD were at higher odds for certain birth defects, though not for any birth defect overall. The risk of NTDs was increased by almost 60%, and that of limb reduction defects was doubled.

Spina bifida risk was also doubled, but hypospadias was reduced by almost 40% following UOGD exposure. The latter was an unexpected finding, perhaps reflecting the presence of androgenic as well as anti-androgenic chemicals in the fracking fluid and wastewater. Earlier studies have not specifically mentioned hypospadias results.

Structural defects were not significantly increased overall, but among females, the risk was ~30% higher.

The odds for birth defects were higher among births to women living within 5 km of a UOGD plant and if the exposure was in the first trimester of pregnancy. The highest risk was associated with drinking water exposure.

Lower-class neighborhoods were at greater risk compared to those with better social advantages. However, rural and urban neighborhoods appeared to be at equal risk. The presence of fine particulate matter did not seem to affect the risk.

What are the implications?

Our results suggest a positive association between UOGD and certain birth defects, and findings for neural tube defects corroborate results from prior studies.”

Living near UOGD wells is associated with spina bifida and with limb reduction anomalies. A new parameter, namely, drinking water exposure to UOGD toxicants, was also presented as being associated with birth defects.

This is the only study on the health risks of UOGD in Ohio, despite the boom in its production. Further studies would help frame appropriate guidelines, for instance, on the minimum setback distance from a UOGD well to a receptor, namely, a well that is used for drinking water or a house where people live.

At present, Ohio mandates between 50-200 feet distance between a well drilled in a specific direction and the nearest receptor, such as the latter.

The current study looked at groups of diagnoses that might have been caused by different mechanisms but presented similarly. This could have biased the results to show a false lack of association. To overcome this limitation, larger sample sizes are necessary to ensure adequate statistical power.

Secondly, Ohio has a passive surveillance system, tending to underreport birth defects. This could be corrected by the direct use of hospital records by researchers or by using samples from states with active surveillance systems.

Thirdly, serious anomalies that caused miscarriage or fetal death, or neonatal death would not be captured in the present study, causing falsely low estimates of the risk to the fetus, especially if the baby is already anomalous and more vulnerable to health risks because of UOGD toxicant exposure.

These results, in conjunction with the broader literature, underscore the need to consider impacts to children’s health specifically when developing or improving public health protections around UOGD.”

Journal reference:
Dr. Liji Thomas

Written by

Dr. Liji Thomas

Dr. Liji Thomas is an OB-GYN, who graduated from the Government Medical College, University of Calicut, Kerala, in 2001. Liji practiced as a full-time consultant in obstetrics/gynecology in a private hospital for a few years following her graduation. She has counseled hundreds of patients facing issues from pregnancy-related problems and infertility, and has been in charge of over 2,000 deliveries, striving always to achieve a normal delivery rather than operative.


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