Natural gas that has been derived from hydraulic fracking is now the most commonly used fuel in gas fireplaces and kitchen ranges. It rose to that level over the past 15 years, with little examination of the health risks of the chemicals that are used in fracking and released when the gas is burned.

“Few if any people have actually tested for what else is in this gas,” says Nathan Phillips, a College of Arts & Sciences earth and environment professor, one of the country’s foremost experts on natural gas leaks and explosions in the United States. “It’s 90 to 95 percent methane, but what else?”

Phillips and a team of researchers from several universities and nonprofits are finding out, and they are concerned. Of the 108 volatile organic compounds, or substances that easily become vapors or gases, found in gas from four Massachusetts municipalities tested, 27 are chemicals that are considered hazardous by federal Clean Air Act standards, and 12 are suspected carcinogens.

Phillips’ early findings were presented at the symposium Natural Gas Infrastructure and Public Health, from Local to Global, held January 30, 2018, at the Photonics Center. Although the full study has not yet been finalized or submitted for publication, Phillips talked to Bostonia about questions raised by his study and the problems with fossil fuel dependence.

Nathan Phillips, CAS earth and environment professor. Photo by Jackie Ricciardi

Bostonia: How do hazardous substances get into natural gas during fracking?
Phillips: It’s a combination of stuff that was already in the ground and stuff that is part of that cocktail or mixture, the proprietary compound. Different companies have their own recipes of substances that they don’t in many cases have to reveal. We’re having to sleuth and reverse-engineer this weird mix of stuff. Stuff that’s nasty going into the ground and nasty coming out of the ground. It’s complicated to pull it apart.

What happens when a hazardous substance or carcinogen gets burned on a person’s kitchen range?
It’s not entirely clear, but generally speaking, organic compounds will tend to be combusted when burned. Benzene, for example, doesn’t combust fully. Incomplete combustion is a problem in homes when 100 percent of the gas isn’t burned.

Study coresearcher Curt Nordgaard, a Boston-based pediatrician who presented at the symposium, has not gotten to what human exposure means. Right now, we’re talking about the potential for health consequences, but in terms of how much and in what situations people are getting exposed, that’s a follow-up study.

Did the results surprise you? Alarm you?
Yes, because I had been assuming that there was a robust filtration process of some sort.

Also, the stove study tested gas in Massachusetts, and in fact, all gas is not the same gas. It comes from different areas. I’d be careful to not assume that what we found in Boston corresponds to California or other areas. It’s like sourcing food: all spinach is not the same and you have to think about where it came from. Gas has a provenance—it comes from a certain place, and that makes studying it challenging.

Where does Boston’s natural gas supply come from generally?
Increasingly, much of it is coming from the Marcellus Shale, which stretches from upstate New York south through Pennsylvania to West Virginia and west to parts of Ohio. A lot of this is coming from there and blended with conventional gas from a variety of places, including Canada and Texas.

How much of the natural gas piped into greater Boston is fracked?
More than half. Probably up to about 80 percent. It started to rise in the mid 2000s when the rise of fracking started to take off.

You typically study gas leaks, including the “mother of all gas leaks” last year in Porter Ranch, Calif., where residents there suffered nosebleeds and headaches.
That definitely inspired this work. What really struck me was when I saw California health officials inform the residents that the health impacts that they were experiencing on the streets were due to the gas, and I realized that the levels of concentration on the streets and sidewalks in Boston can be as high. Even outside, there are issues that we need to be concerned about involving the health impacts of gas leaks.

What could a concerned cook do to mitigate problems in the kitchen?
Ventilation is important. Sometimes fans don’t exhaust the air to the outside; they trap it or sometimes it doesn’t go anywhere.

What do you use to cook in your home?
In my home, we’re on an electric range. We do have gas in my home that heats our water, but we cook on an electric range.

I understand that we can’t change everything overnight—that it’s got to be a process. We have to move expeditiously to the cleaner energy systems. At some level, we’re all complicit as consumers.

One of my areas of research is moving forward on alternatives. There are excellent alternatives that are becoming more and more viable. They’re cleaner and they outperform gas. Cooking with induction is an electrical form of cooking and superior to cooking with gas, and it’s cleaner and much more efficient. It takes a third the amount of energy to heat up water as gas does.

Megan Woolhouse can be reached at mgwj@bu.edu.