CHESTERTOWN, Maryland (Reuters) - Duffy Mitchell has cut fiberglass, slathered epoxy resin and twisted rubber hoses at his boat repair shop here on the Chesapeake Bay for more than a dozen years.
He faces a heightened risk of cancer because of his exposure to styrene, a chemical found in each of those products and in dozens of other consumer items, according to a U.S. government report.
Last month's health warning from the Department of Health and Human Services' National Toxicology Program has set off a bruising battle with the makers of styrene, a chemical compound derived from crude oil.
"All the chemicals we use concern me," Mitchell said. "Is it dangerous? Sure, yeah. But aren't all chemicals?"
Mitchell, 56, and his four employees wear ventilation masks and protective suits when working with styrene-based products.
Still, the risks for Mitchell are even higher because he smokes, and styrene is in cigarette filters.
For those who don't smoke or work on boats like Mitchell, the warning raises more questions than it answers about the safety of common consumer goods such as plastic utensils, toys and packaging.
National Toxicology Program scientists said last month that they believe styrene metabolizes when it comes in contact with the human body, bonding with oxygen to form styrene oxide, a chemical that has the ability to alter DNA and cause cancer.
But the findings are littered with caveats that are now fodder for industry lawyers hoping to get the NTP to recant the report.
Phrases like "limited evidence" and "reasonably anticipated" are strewn throughout the NTP's nine-page report.
Styrene plastic forks are safe to use, the report says, without specifying, for instance, the risk of them shattering into small pieces that children could ingest.
Government scientists effectively have seen just enough evidence to posit a link between styrene and cancer, but not enough for ironclad proof.
"We've tried to make it clear that a listing in the report doesn't necessarily mean that encountering that substance in any minute quantity means you'll get cancer," said NTP Associate Director John Bucher. "But in the instance of styrene, you have what we believe is limited epidemiological evidence of association with human cancers."
Last year nearly 9 billion pounds (4.1 billion kilograms) of styrene were made in the United States alone, according to the American Chemistry Council.
Styrene producers including LyondellBasell, one of the largest in North America, are now blasting the government's science as premature and inaccurate.
They point to a decision last month by European Union health regulators, who said they did not believe styrene poses a cancer risk in humans.
"The NTP doesn't provide any health benefit by raising concerns where other people have not found any," said Jack Snyder, executive director of the industry-funded trade group Styrene Information Research Center.
LyondellBasell Chief Executive Jim Gallogly went a step further.
"Frankly, we do not agree with the science," he said. "We would like sound science to prevail, and that's why we're requesting the government to immediately review that finding."
The fight shows no signs of slowing down. Last week the NTP won the first round when a federal judge said he would not grant the trade group's request for an injunction that would have revoked the styrene report.
Both sides are due back with the judge later this month.
In the interim, Mitchell and thousands of others who work with styrene are left wondering whether the substance is safe. But they carry on with their lives anyway.
"My wife worries more about me climbing under a 50-ton boat we have up on slings," Mitchell said. "She doesn't want me crushed."
Reporting by Ernest Scheyder; Editing by Lisa Von Ahn