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Minerals in the Air

NRRI looks at dust samples from Iron Range

For 30-plus years the questions have hung in air like so much dust: What exactly are people on the Mesabi Iron Range breathing in and is it dangerous?

Tamara Diedrich, lead investigator for NRRI’s portion of the research.
NRRI geologists, experts in characterizing the minerals underground, are now applying their skills to the mineral particles that are produced during taconite mining and the pellet making process. The goal is to understand the composition of the dust from the east end of the Iron Range to the west, including Silver Bay, so this information can be used by the University of Minnesota School of Public Health to assess possible health impacts. The two university organizations are lead participants in the Minnesota Taconite Workers Lung Health Partnership.

It is hoped that the three-year study will finally answer questions about whether the dust caused by mining operations causes health problems—especially mesothelioma, and other lung diseases—in miners and community residents. Mesothelioma is a rare but deadly form of cancer that is almost always related to asbestos exposure.

NRRI’s task will be to collect and analyze airborne dust samples from areas around the taconite plants with instruments that separate the particles by size. Samples will also be collected in communities along the Iron Range to understand what residents are exposed to. Nearby lake sediments will also be collected by paleolimnology scientist Euan Reavie at NRRI’s Ely Field Lab to reconstruct the historical composition of airborne dust generated by mining activity.

“When it comes to human health, what we’re interested in are the particles that can be transported into the lung,” explained Tamara Diedrich, lead investigator for NRRI’s portion of the research. “Your nose and throat are pretty good at filtering out the larger particles. It’s the smaller ones, less than five microns, that can be retained by the body.”
Diedrich holds a doctorate in geology from Arizona State University.

UMD’s new electron microscope will be used to study the tiny particles (one micron equals 1,000,000th of a meter) that are specifically three times as long as they are wide. Why so specific?

The Mining Safety and Health Administration uses the 3:1 length-to-width ratio to describe “asbestos.” The crushing of taconite ore by mining operations across the Mesabi Iron Range produces similar elongated mineral particles. Only on the easternmost portion of the range, near Northshore Mining, are some of the particles chemically identical to amosite asbestos, causing longstanding concern about their exposure to workers and the public. Geologists know that the elongated particles on the western portion of the Iron Range have a different, non-asbestos composition, but they will also be studied by NRRI researchers. Silica dust is also generated by taconite industries and will be studied.
“We’re characterizing all of the dust, all of the particles that meet the right size criteria,” added NRRI geologist Larry Zanko. “We’ll have quantitative data of what they’re made out of, how much there is in the air and in what size fractions.”

The sample gathering will be in full swing this spring. NRRI is a major sponsor of the research, providing up to $500,000 from the NRRI portion of the Permanent University Trust Fund. Legislative funding will be needed to move the scientific data collected into answers to the questions about Iron Range air quality..

by June Kallestad

UMD home page editor, Cheryl Reitan,
NEW RELEASES, UMD media contact, Susan Latto,, 218-726-8830

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