Bottles made by SIGG before August 2008 had trace amounts of BPA in the epoxy liners. (Donald King/Associated Press)Aluminum bottle manufacturer Sigg has issued a public apology following an earlier admission some of its bottle liners contain trace amounts of bisphenol A (BPA).

The Swiss manufacturing company revealed last month that bottles sold before August 2008 have water-based epoxy liners containing trace amounts of BPA. Sigg has denied the liners leach the chemical and says that testing in the U.S. and Switzerland has confirmed this.

High-end Sigg bottles became popular when Health Canada announced in April 2008 that it would ban the import and sale of polycarbonate baby bottles containing BPA. The chemical, found in hard plastics such as baby bottles, water bottles as well as can liners, has been linked in some U.S. studies to early-onset puberty, prostate and breast cancers, as well as infertility in animals.

According to marketing monitor Advertising Age, Sigg's sales rose 250 per cent between 2006 and 2007 as concerns about BPA escalated. The bottles are sold in upmarket health food, outdoor adventure and baby stores in Canada as well as retailers such as Whole Foods.

In March 2008, CBC News reporter Curt Petrovich had asked Sigg's Swiss product manager Christian Roth if there was any BPA in the plastic liner of its bottles. At the end of a series of email exchanges, Roth told Petrovich there was "no trace of any BPA."

Steve Wasik, CEO of Sigg Switzerland, claimed its bottles were never marketed as BPA-free.

"I am sorry that we did not make our communications on the original Sigg liner more clear from the very beginning," Wasik wrote on the company's website Wednesday.

Wasik said Roth was not lying, rather, he was answering a different question about whether BPA had leached out of the lining, a question Petrovich had never asked. Roth was fired two months ago for what Wasik called "inaccuracies in his messages."

Wasik also knew BPA was in the liner of Sigg's bottles, but said an agreement with the supplier not to disclose its ingredients made it impossible to admit.

"We were operating again under what we thought was an obligation to our supplier, right or wrong. We had no other supplier in place who could provide us a formula so we could continue to do business. Now we know it was the wrong decision. Now we know we should have, you know, put the consumer first," Wasik said Thursday.

"It's hard to believe this company has been so dumb," said Rick Smith of Toronto-based Environmental Defence, an advocacy group that has lobbied hard to have BPA banned felt betrayed.

"They're playing Russian roulette with their own brands. I mean, I'm somebody who's used Sigg bottles in the past. There's no way I'm going to buy one ever again because I'm not sure this company can be believed at all," Smith said Friday.

In August 2008, the company introduced its EcoCare liner, which it claimed contains no BPA. Sigg has posted images on its website showing the appearance of both the old and new liners so consumers can identify which one they have.

It has also introduced a voluntary exchange program, allowing consumers with older model liners to send them in to be exchanged for a new, BPA-free liner.