by Martin Mittelstaedt

Health Canada is calling bisphenol A a dangerous substance, making it the first regulatory body in the world to reach such a determination and taking the initial step toward measures to control exposures to it.

Although the government won't announce specific bans or restrictions, the designation as dangerous could pave the way for the hormonally active chemical to be listed as toxic under the Canadian Environmental Protection Act, which would allow Health Minister Tony Clement to issue specific measures to curb its use.

Bisphenol A, or BPA, is one of the most widely used synthetic chemicals in modern industry. It is the basic building block for polycarbonate, the see-through, shatter-proof plastic that resembles glass, and is also used to make the epoxy resins lining the insides of most tin cans, along with some dental sealants, sports helmets, and compact discs.

Experts are worried about BPA in food and beverage containers. Products such as CDs aren't considered a problem.

getSLinks("topStoriesInSection","LAC.20080415.TOXIC15",5); "Bisphenol A is in every Canadian home. It threatens the health of every Canadian. Moving against it would be a hugely significant victory for public health and the environment," said Rick Smith, executive director of Environmental Defence, a group that has been campaigning for a ban on the chemical from food containers.The conclusion by Health Canada that BPA is a possible threat, expected to be announced as early as tomorrow, will amount to one of the most important regulatory decisions regarding a single chemical in decades, and will put pressure on its counterparts at both the European Union and the U.S. Food and Drug Administration to reconsider their approval.

"If this chemical is listed as toxic [by Health Canada], it will be an internationally significant decision," Mr. Smith said.

Under Health Canada's regulatory approach, the government department, along with Environment Canada, is expected later this week to release a draft assessment indicating that bisphenol A endangers people and the environment. The document outlining this finding will be open for a 60-day public comment period. If no new information is made available through the consultation to overturn the finding, the government will issue a final report outlining control measures within a year.

The government had a deadline of mid-May to issue its BPA assessment but is moving earlier because of intense public interest.

The expected announcement will also win the Harper government praise among environmentalists, who have been harsh critics of the Conservatives' approach to climate change but will find it hard to criticize groundbreaking action on a chemical pollutant.

U.S. tests have found that more than 90 per cent of the population carries in their bodies trace residues of the chemical, whose molecular shape allows it to mimic the female hormone estrogen. Small amounts of BPA can leach from food and beverage containers during use, such as when they are heated, exposed to harsh dishwashing chemicals, or contain acidic substances. Health Canada is testing Canadians' BPA levels, but the results will not be available for several years.

In response to concerns over the safety of BPA, many specialty retailers, including Mountain Equipment Co-op, have pulled polycarbonate plastic containers from their stores, and BPA-free bottles are been flying off shelves, creating shortages. Hudson's Bay Co. announced last month that it had "secured large quantities" BPA-free baby products, a sign of how quickly even the mass market has moved against the chemical.

Independent researchers in dozens of studies have linked trace BPA exposures in animal and test-tube experiments to conditions involving hormone imbalances, including breast and prostate cancer, early puberty and changes in brain structure, particularly for exposures during key points of fetal or early neonatal development.

However, industry-funded testing has been unable to confirm these findings. The trade association representing major manufacturers, the American Chemistry Council. based in Arlington, Va., submitted two studies to Health Canada during its assessment indicating BPA has no harmful effects at low doses.

Until now, regulators in other countries have accepted the industry's assertion that BPA is harmless at the tiny, parts-per-billion type exposures from canned food and plastic beverage containers. A part per billion is roughly equal to one blade of grass on a football field, although natural hormones such as estrogen are active at far lower concentrations, around a part per trillion.

Polycarbonate is sometimes identified by the recycling industry's symbol of the number seven inside a triangle, with the letters PC nearby.

Canada takes stance on BPA

A U.S. study found that more than 90 per cent of people carry trace amounts of the chemical in their bodies. The Canadian government is expected to announce as early as tomorrow that it is a dangerous substance.

WHAT IS IT?

Used to make polycarbonate plastics and epoxy resins. Common items:

{bull} Baby bottles

{bull} Flatware

{bull} Watercooler bottles

{bull} Liners for food and beverage cans

{bull} Seals for cavity-prone teeth

Polycarbonate plastic tends to leach bisphenol A with age and after heating.

WHAT DOES IT DO?

Bisphenol A (BPA) is a compound that mimics estrogen, which can disrupt the endocrine system and could induce adverse hormonal responses. Studied effects on animals give rise to fear that low-level exposure might cause similar effects in human beings.

POSSIBLE EFFECTS

{bull} Permanent changes to genital tract

{bull} Increase prostate weight

{bull} Decline in testosterone

{bull} Breast cells predisposed to cancer

{bull} Prostate cells more sensitive to hormones and cancer

{bull} Hyperactivity

THE PROCESS

NORMALLY

1. Estrogen binds with its receptor

2. Estrogen and receptor cause a biological response

WHEN BPA IS PRESENT

1. BPA binds to and reacts with the estrogen receptor

2. BPA and receptor cause a biological response

BPA IN CANNED FOOD

Source: Environmental Working Group (EWG)
© 2008 The Globe and Mail