It's about as inconspicuous as a ubiquitous chemical can be: It coats the insides of soft drink cans, a barrier against spoilage and contamination.
But to some critics, Bisphenol-A is itself the health risk. Now, a group of Coca-Cola shareholders want to strike a blow against the substance.
Packaged goods companies use Bisphenol-A to guard against contaminants and extend shelf life, but critics fear it may be dangerous for pregnant women, very young children and unborn babies. Regulators in China, Europe and elsewhere have cracked down: The European Commission voted to ban the chemical from plastic baby bottles by the middle of this year.
Investors will vote Wednesday on a resolution that would require Coca-Cola to issue a report disclosing how it is responding to concerns about the safety of BPA, and outlining a plan to develop alternatives to BPA.
Coke's board of directors want investors to reject the resolution, arguing that its cans are safe. "We believe that we are already more than adequately transparent" on the BPA issue, Coke said in a response. "Beyond what we currently disclose, the company has a legitimate need to protect proprietary information — both ours and our suppliers."
The company pointed out that regulatory agencies in Australia, Germany, Japan, New Zealand and the U.S. have said BPA is safe as currently used in Coca-Cola packaging.
This is the second year that Coca-Cola has fielded a BPA-related shareholder proposal. In 2010, a proposal calling for a detailed report on the risks BPA may pose to Coca-Cola's reputation or market share received 22 percent of the vote.
Coca-Cola says it is working with several suppliers to find alternatives to can liners containing BPA, which is a key component in the making of epoxy resins and polycarbonate plastic. For decades, it has been widely manufactured and used in the U.S.
Standardized toxicity tests generally indicate low levels of human exposure to BPA are safe, the Food and Drug Administration said 15 months ago.
But the FDA said it had "some concern" about the potential effects of BPA on the brains and prostate glands of fetuses, infants and young children. A variety of agencies are conducting in-depth studies to clarify uncertainties about the chemical's risks.
Then, six months ago, Canada's environmental minister added BPA to the country's lists of toxic substances.
As BPA has grown more controversial, some companies have adjusted. ConAgra Foods has begun packaging tomatoes in non-BPA lined cans. Heinz, the big ketchup company, has also explored non-BPA alternatives.
Critics are trying to move that process along. To date, more than 25 lawsuits have been filed against companies that use BPA in their products, according to San Francisco-based shareholder advocacy group As You Sow. The group has tallied 66 state laws passed in the last eight years banning BPA in products geared toward babies and toddlers. Nearly two dozen additional bills are pending.
"Coca-Cola has failed year after year to provide investors or consumers with sufficient evidence that it is taking steps to address these very serious public health concerns," said Michael Passoff, the group's senior strategist.