LOS ANGELES (Reuters) - A California mother sued Nalge Nunc International Corp, claiming the company knew, but downplayed risks, that a toxic substance in its popular Nalgene plastic sports bottles could leach into the bottles’ contents and sicken consumers.

The case, filed on Tuesday, is believed to be the first consumer class action over the use of Bisphenol A, or BPA, in plastic sports bottles since Canada moved to ban baby bottles containing the substance and the U.S. government expressed concern over its safety last week.

Nalge Nunc, a unit of Thermo Fisher Scientific Inc, said on Friday it will phase out production of its Outdoor line of polycarbonate containers that include BPA over the next several months.

Wal-Mart Stores Inc also said on Friday it will pull baby bottles and other products made with BPA from its Canada stores immediately and phase the items out of its U.S. stores next year.

The suit, filed in U.S. District Court in Sacramento, accuses Nalge Nunc of continuing to assert that BPA is safe long after dozens of studies linked the substance to hormone disruptions, infertility, early puberty, and cancer.

The lawsuit was brought by Lani Felix-Lozano, who said she bought the company’s reusable beverage containers for herself and her two daughters, now ages 11 and 13, for several years.

“They address the issue of BPA in their bottles (on their Web site); they cite the (Food and Drug Administration) stating that they see no problem with it. The problem is they didn’t cite the many other studies that show there is a risk and there is a great concern about the issue,” attorney Harold Hewell, who represents Felix-Lozano, said.

The lawsuit does not describe any physical ailment suffered by the plaintiffs and seeks unspecified damages.

A spokeswoman for Nalge Nunc could not be reached for comment late on Wednesday.

Industry groups and some scientists defended BPA’s safety, saying there has been no clear corroboration between studies on animals showing BPA to be harmful even at low levels, and risks to human health. (Reporting by Gina Keating; editing by Carol Bishopric)