Someone made off with more than 16,000 boxes of defective tampons and sold them to an unknown number of stores in unknown locations. The manufacturer has no idea where they are and issued a warning to consumers that they may pose a health risk if used.

Dallas-based Kimberly-Clark, the maker of Kotex Natural Balance, said the tainted tampons are "not fit for use" because they may have increased levels of bacteria, metallic particles or "imperfect raw materials." The boxes were slated for destruction, but a company investigation found they were stolen and sold fraudulently between October 2011 and June 2012.

As of Friday, about 7,500 of the boxes have been recovered, company spokesman Bob Brand told QMI Agency. That leaves thousands more still out there.

"At this time, we have no indication that any of this product is in Canada," Brand said. But, he added, "We have no idea where the products, which were stolen and distributed outside KC's distribution channels, may have ended up."

Kimberly-Clark said they have not received any complaints about the product in question but urged consumers to check if they have any of the black-market tampons and stop using them. Lot numbers of the affected boxes can be found on the company's website (kimberly-clark.com).