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EPA Scientist’s “Small Fibers Matter” Asbestos Work To Be Published


Illustration of potential asbestos exposure in a building

Scientist Philip Cook’s thesis that “small fibers matter” as a result of his asbestos research will be published and shared for the first time at this week’s symposium in Duluth, Minnesota, titled “Asbestos-like Mineral Fibers in the Upper Midwest: Implications for Mining and Health Workshop.”

This event on elongated mineral particles is a chance for experts to exchange information about an issue that’s pertinent to the world, and especially in the Midwest.

The hope is for the U.S. government to increase workplace safety standards. Cook’s research would particularly help miners and other industrial workers.

Cook’s work began in Duluth where he set out to find out whether the tiny, thin mineral fragments discovered in Silver Bay were really asbestos and if not, what they actually were and if they’re a health hazard. He invented new methods of isolating and counting the microscopic fibers and ways to test the minerals faster.

He studied the fiber dosage in rats, exposing them to almost a billion fibers in an effort to create long-term exposure. Soon he saw the particles were multiplying.

“We could see some particles were splitting,” said Cook. “They were breaking off, and the dose was increasing. Nobody had observed anything like that before.”

Cook claimed the federal regulation’s way of measuring asbestos fibers in the air is all wrong because it only collects information on the long, thin fibers, rather than the shorter ones as well.

In 1999, he was called upon by Dr. Chris Weis, the Environmental Protection Agency’s (EPA) science advisor for the emergency response operation in Libby, Montana.

“He literally had hundreds of boxes of files and electron micrographs stored in the garage outside of the laboratory,” said Weis about Cook. “And microscope slides. Thousands of microscope slides.”

In Libby, Cook wanted a way to predict which types of mineral fragments would be most harmful. He studied 50 different types, recording their length, width, and other physical metrics.

After testing over 200 different models, he concluded the standard approach using a small pump and collector attached to the worker’s chest to periodically measure fibers did not include most of the fragments in an air sample. He suggested the total surface area was a better predictor of toxicity than size and shape.

Unfortunately, Cook was diagnosed with cancer in 2012 and passed in 2013 before he could publish his results. “Phil was angry at the cancer because it was going to keep him from finishing his work,” said Leo Babeu, one of Cook’s friends.

“He was a unique thinker, and he was a purist,” said Dr. Hilary Carpenter, a toxicologist at the Minnesota Department of Health who also worked on the fibers case. “I think one reason it took him so long to finish his work is that he wanted to be sure he presented it in a way that could not be misinterpreted.”

“He had the model in his head,” said Dr. Dale Hoff, Cook’s boss and the current interim director at the EPA lab, who completed Cook’s research. “What he did was like 98 percent of the technical work. The easy part at the end was taking his equation and showing which minerals are more or less toxic.”