3 M's Big Cleanup

Why it decided to pull the plug on its best-selling stain repellant

At first, Dr. Larry R. Zobel and other researchers at 3M Co. figured the findings had to be a mistake. Investigators from Cornell University, using a powerful new technique to scan the blood of 3M's factory workers, were testing some serum they bought from commercial blood banks to establish base lines for the machines. The highly sensitive devices kept turning up the same odd result: Tiny amounts of a chemical 3M had made for nearly 40 years were showing up in blood drawn from people living all across the country, even in places far from 3M factories. "It took months before all the chemists were convinced that it was there," recalls Zobel, 3M's medical director. "There was disbelief."

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