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Public Radio's Environmental News Magazine (follow us on Google News)

A Gravel Danger

Air Date: Week of

The landscape of Cappadocia, Turkey, mirrors stone formations found in Dunn County, such as the tall, thin spires capped with harder stone, called fairies chimneys. Both areas experienced volcanic activity that produced erionite, millennia ago. (Photo: wikimedia)

Asbestos exposure can cause the deadly cancer mesothelioma but a lesser-known mineral called erionite is even more potent than asbestos, and it’s completely unregulated. Erionite is found in rock formations in at least a dozen U.S. western states. Aubrey Miller, Senior Medical Advisor for the National Institute of Environmental Health Sciences, led a study on the health effects of erionite exposure. He tells host Bruce Gellerman about the dangers of the naturally occurring mineral and its public health implications.


GELLERMAN: It’s Living on Earth, I'm Bruce Gellerman. Chances are, if you watch late-night TV, you’ve seen an ad like this:

[AD: Attention if you've been diagnosed with mesothelioma, a rare form of lung cancer, normally caused by exposure to asbestos you may qualify for a cash settlement. I'm attorney Bob Goldwater. If you’ve been diagnosed with mesothelioma, call me right now.]

GELLERMAN: Mesothelioma is rare in most places, but not in the small town of Libby, Montana. About 400 residents there have died and 17 hundred are sick from their exposure to asbestos released from a mine owned by W.R Grace & Company.

The EPA declared Libby its first public health emergency, and has spent nearly 400 million dollars cleaning the mess up. Residents charge state officials knew all along the mineral dust was killing them, yet failed to intervene. So they filed a lawsuit, and this week, a Montana judge approved a 43 million dollar settlement.

Now, federal health officials say mesothelioma can also be caused by an even deadlier, but less known mineral - erionite. The National Institute of Environmental Health is investigating this unregulated substance. Epidemiologist Dr. Aubrey Miller, Captain in the U.S. Public Health Service, is the lead researcher.

Dunn County, North Dakota tests high for the dangerous mineral, erionite. (photo: Wikimedia).

MILLER: Well, erionite is a mineral fiber and it’s very similar in its look to asbestos. These fibers are naturally occurring in rocks, primarily ones that are formed from volcanic activity millions of years ago. And as you disturb the rocks, or you break them open, they release the mineral fibers. It’s actually found in about 12 states. You know, mostly out west. As we begin to develop more and more, we’re beginning to get into it more and more.

GELLERMAN: Well, I guess people in Dunn County, North Dakota, drive over it quite a bit!

MILLER: Yeah, so there’s a situation - they have these small mountains or hills that they use for rock. And they were mining those hills for rock to use on their roads, and had been doing so for several decades, and unbeknownst to them, that rock contained amounts of erionite, and they would grind it up, and use the rock on roads. Several hundred miles worth of roads within North Dakota, and I think it extends Montana and South Dakota, we’ve been told.

GELLERMAN: So you did some sampling and what did you find?

Dwellings carved into cliffs in Cappadocia increased exposure to erionite and raised overall rates of the cancer, mesothelioma. (Photo: Wikimedia)

MILLER: So we did sampling in a number of ways. We actually drove cars up and down on the roads. We checked the school busses, because there is about 30 miles of school bus routes, and we did sampling along side the busses where the kids would stand and inside the busses. We did some sampling in an auto shop that they use for maintenance of the vehicles that spread the gravel, and we measured these erionite fibers in their breathing zone.

GELLERMAN: What kind of levels did you find?

MILLER: The levels are ... if it was asbestos, you would say, well, those levels are of concern, but there are no guideposts for erionite. So we went then to Turkey to try to see, well, how does the level in North Dakota compare to the level in Turkey that have remarkably high disease.

GELLERMAN: In Turkey, I guess the people were living in houses made out of the stuff!

MILLER: Yeah, so it has been used for centuries because the rock was kind of soft, and people could kind of dig them out - those rocks - and make caves. And they actually, for centuries, people kind of grew up in those areas and they lived in caves and then they moved into more modern houses. But they’re still there, and they continue to have very high rates of disease. And, just to give you a feel for it, in a couple of these towns - up to almost 50 percent of the people that die from a non … not an injury from an accident, are dying from mesothelioma.

GELLERMAN: And that’s from the erionite.

MILLER: From the erionite, exactly, from their exposures to erionite. The levels that we found in North Dakota would be more comparable to the levels that we saw in towns that had between one and ten percent rate of mesothelioma, vs. the towns that had very high rates of disease.

GELLERMAN: Well, if somebody told me that I had a one in ten chance of coming down with this dreaded disease just simply because of the gravel in front my house, I’d head for the hills.

Erionite has been found in over a dozen US states. (Map by Emily Chow for FairWarning)

MILLER: This is one of those substances that raises our levels of concern. It certainly seems to be a stronger or more potent carcinogen than a lot of the asbestos that’s been looked at. You know, we didn’t really think we had much of a problem of it here in the United States - that it was all over there in Turkey - but unfortunately that’s not the case here.

GELLERMAN: What do you think people should do who might be exposed, say in Dunn County, North Dakota?

MILLER: So one thing about these diseases, and partly to make it clear, there hasn’t been any disease identified right now in North Dakota, that's one thing that we're starting to look at, but it takes a long time for these diseases to develop.

So, mesothelioma in particular, you may have up to 40 years from the time you’re exposed to the time you’ll get the disease. A lot of the people there say: "Well, we don’t see any disease here yet, so should we be worried?" Well, the exposures are there, and there is a long latency between getting the disease. So we want to do what we can now to start making people aware, and start being more proactive - for a public health stance - to help ensure that we don’t end up with an epidemic of disease.

GELLERMAN: Well, Dr. Miller, thanks so much. Really appreciate it.

MILLER: Thank you very much for having me.

GELLERMAN: Epidemiologist Aubrey Miller is with the US Public Health Service, researching the mineral erionite.



Read more about erionite on Fair Warning

The NIEHS recently hosted an inter-disciplinary workshop on erionite:


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