Is fracking polluting the air?
Corrections & Clarification: This story has been updated to include a paragraph that notes a challenge to the findings of the birth-defect study from Environmental Health Perspectives.
Toxic air pollution from fracking causes a wide spectrum of health problems for Americans across the country, an environmental group charged in a report released Tuesday.
"The health risks from fracking are not limited to what's in our drinking water -— oil and gas operations are also poisoning the air we breathe," said senior scientist Miriam Rotkin-Ellman of the Natural Resources Defense Council (NRDC), which produced the report.
The report said Americans who live near oil and gas drilling wells are exposed to fracking-related air pollution in the form of chemicals such as benzene and formaldehyde.
Fracking is a drilling process that blasts huge amounts of water mixed with sand and chemicals deep underground to break apart shale deposits and extract gas and oil from the rock's pores. It has spread across the country, leading to a production boom.
The NRDC said the pollution causes at least five serious types of health problems, including respiratory problems, birth defects, blood disorders, cancer and nervous system impacts. About one in four Americans live within a mile of an oil or gas well.
In Colorado, for example, an evaluation of birth defects in areas with high concentrations of oil and gas activity found that mothers who lived near many oil and gas wells were 30% more likely to have babies with heart defects.
The birth-defect study appeared in the peer-reviewed journal Environmental Health Perspectives in April 2014 and has not been formally rejected or debunked by the journal.
However, Dr. Larry Wolk, executive director of the Colorado Department of Public Health and Environment and the chief medical officer for the state rejected the findings of the paper soon after its publication, saying that "it is difficult to draw conclusions from this study, due to its design and limitations" and that "many factors known to contribute to birth defects were ignored in this study."
The NRDC report was a compilation of recent research on the subject, not a new peer-reviewed study.
In 2012, the Environmental Protection Agency issued rules addressing the problems of air pollutants released by the drilling process, according to EPA press secretary Liz Purchia.
Another study this year in Environmental Health Perspectives found that people living near natural-gas wells were more than twice as likely to report upper-respiratory and skin problems than those farther away. That study did not find a significant increase in neurological, cardiovascular or gastrointestinal symptoms among those living closer to natural gas wells.
The oil and gas industry said fracking is a safe way to boost the U.S. economy and decrease dependence on foreign sources of energy. "Natural gas delivers local air and health benefits," according to Energy in Depth, a group of the Independent Petroleum Association of America
The group quotes the Pennsylvania Department of Environmental Protection, which stated that "cumulative air contaminant emissions across the state have continued to decline," even as fracking increased in the state from 2008-12.