PFAs

For Decades, Polluters Knew PFAS Chemicals Were Dangerous But Hid Risks From Public

As far back as 1950, studies conducted by 3M showed that the family of toxic fluorinated chemicals now known as PFAS could build up in our blood. By the 1960s, animal studies conducted by 3M and DuPont revealed that PFAS chemicals could pose health risks. But the companies kept the studies secret from their employees and the public for decades. Here is a timeline of internal memos, studies and other company documents detailing the two companies’ history of deception.

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1950


3M mice study reveals that PFAS builds up in blood.

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1956


Stanford University study finds that PFAS binds to proteins in human blood.

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1961


DuPont toxicologist warns that PFAS chemicals enlarge rat and rabbit livers.

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1962


Volunteers who smoke PFAS-laced cigarettes get “polymer fume fever.”

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1963


3M technical manual deems PFAS toxic.

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1965


DuPont rat study shows increased liver and kidney weight and increased spleen size.

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1966


The Food and Drug Administration rejects a DuPont petition to use PFAS chemicals as a food additive, citing liver studies.

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1966


3M study finds that PFAS causes “acute oral toxicity” in rats.

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1970


3M warns Fire Journal, the magazine of the National Fire Protection Association, that PFAS is toxic to fish.

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1970


DuPont scientists say PFAS is “highly toxic when inhaled.”

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1973


DuPont study shows liver damage from exposure to PFAS in food packaging.

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1975


3M is informed that PFAS builds up in human blood samples.

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1975


DuPont warns 3M about “toxic effects” of PFAS in food packaging.

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1977


3M tests workers and animals to measure PFAS in blood.

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1977


3M finds PFOS, the PFAS chemical in the company’s Scotchgard fabric treatment, “more toxic than anticipated.”

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1978


3M animal tests find lesions on spleen, lymph nodes and bone marrow.

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1978


3M concludes that PFOS and PFOA, a PFAS chemical used to make DuPont’s Teflon, “should be regarded as toxic.”

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1979


DuPont survey of employees in its Parkersburg, W.Va., Teflon plant finds possible evidence of liver damage.

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1981


3M and DuPont reassign female workers after animal studies reveal PFAS damages the eyes of the developing fetus.

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1983


3M identifies PFAS’ potential harm to the immune system as a cause for concern.

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1984


3M documents rising fluorine levels in workers’ blood.

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1984


DuPont detects PFAS in the tap water in Little Hocking, Ohio, but does not alert the local water utility.

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1987


3M PFOA animal study finds tumors.

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1989


3M study finds elevated cancer rates among PFAS workers.

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1990


3M study finds risk of testicular cancer from exposure to PFOA, also known as C8.

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1992


DuPont study finds elevated cancer rates among workers.

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1992


Former 3M scientist finds male PFOA workers more likely to die from prostate cancer.

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1995


DuPont scientist expresses concern over long-term PFAS health effects.

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1997


DuPont study finds heightened cancer rates among workers at the Parkersburg plant.

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1998


3M scientists report that PFAS moves through the food chain.

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1998


3M provides EPA evidence that PFAS accumulates in blood.

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1998


3M animal study finds liver damage from PFAS exposure.

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1999


3M scientist describes PFOS as “the most insidious pollutant since PCB.”

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2000


3M animal study finds increased liver size from PFOS exposure.

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2003


Chemical industry consulting firm urges DuPont to prepare defense strategy for the unfolding PFOA scandal in Parkersburg, W. Va., including EWG’s investigations.

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