Sunday, April 27, 2008; A10

1891

Bisphenol A is synthesized by chemists.

1930s

Scientists discover that BPA is an artificial estrogen, but it is eclipsed by a stronger synthetic estrogen, DES. (DES is used until the 1970s, when it is removed from the market after it was found to cause reproductive cancers in girls.)

1953

BPA is used to make a hard, strong plastic called polycarbonate, a material that becomes common in a wide variety of everyday items, including water coolers, eyeglasses and baby bottles.

1976

Congress passes the Toxic Substances Control Act, the first law in the United States to regulate industrial chemical compounds. BPA is one of 62,000 compounds grandfathered in, presumed safe by the Environmental Protection Agency

1993

The EPA sets a safety standard for BPA based on high-dose studies. This remains the standard, despite studies during the next 15 years linking very low doses to cancer, diabetes, fertility problems and behavioral disorders

1997

Frederick vom Saal at the University of Missouri at Columbia publishes the first study that links low-level BPA exposure to prostate cancer. The "low dose" is 25 times lower than EPA's "safe" dose. Meanwhile, the FDA finds BPA leaching from the epoxy linings of metal cans of baby formula.

1999

Consumer Reports finds that BPA leaches from baby bottles when heated.

2003

The Center for the Evaluation of Risk to Human Reproduction at the National Toxicology Program evaluates BPA as a reproductive and developmental toxin. The center, part of the National Institutes of Health, hires a contractor, Sciences International, to lead the assessment.

2003-2006

Sciences International performs the literature review for BPA toxicity, choosing and summarizing studies for an expert advisory panel. The panel finds BPA is safe.

2007

February: Congress launches an investigation after learning that Sciences International also performed work for two BPA manufacturers, Dow Chemical and BASF. Two months later, NIH fires Sciences International, but the BPA advisory panel still draws upon its work.

July 24: The National Toxicology Program finds no impropriety in Sciences International's work on BPA, but critics say the firm excluded low-dose studies from the literature it reviewed.

Aug. 2: An NIH-funded panel of 38 international experts in BPA finish a comprehensive review of current knowledge of BPA health risks and human exposures. Known as the Chapel Hill panel, the group concludes that BPA exposure at current levels presents a clear risk to human health.

Nov. 26: BPA advisory panel issues its final report, minimizing BPA risks. It expresses "some concern" about the neural and behavioral impacts but no significant concern about links to breast and prostate cancer, obesity and reproductive problems.

2008

Jan. 17 - Feb. 5: The House Committee on Energy and Commerce begins investigating the use of BPA in the lining of metal cans that contain infant formula. It also demands that the FDA clarify its position on the safety of BPA.

Feb. 7: A coalition of environmental and public health groups in the United States and Canada releases a study showing that BPA leaches out of baby bottles into heated liquids.

April 16: The National Toxicology Program raises "some concern" about possible links between BPA and cancer, diabetes, fertility problems and behavioral disorders, based on its review of the advisory panel report, the Chapel Hill panel findings and other recent studies. Rep. John D. Dingell (D-Mich.), chairman of the House Committee on Energy and Commerce, calls on the FDA to reconsider the safety of BPA in products for infants and children.

April 18: Health Canada announces that BPA will be deemed a "dangerous substance," making Canada the first country to ban the chemical from baby products.

April 18-21: Playtex says it will stop using BPA in baby bottles and cups, Nalgene announces it will drop BPA from its bottles, and Wal-Mart and Toys R Us say they will phase out baby bottles containing BPA.

SOURCES: Environmental Working Group; Washington Post staff research