Johnson & Johnson said on Friday it is recalling around 33,000 bottles of baby powder in the United States after the U.S. health regulators found trace amounts of asbestos in samples taken from a bottle purchased online.

The voluntary recall is limited to one lot of Johnson’s Baby Powder produced and shipped in the United States in 2018, the company said.

The company’s shares fell 3.6% to $131.40 in early New York Stock Exchange trading.

J&J also said it has started an investigation into the matter and is working with the U.S. Food and Drug Administration to determine the integrity of the tested sample as well as the validity of test results.

A spokesperson for the FDA was not immediately available to comment.

Reuters on Dec. 14 published a special report detailing that the company knew for decades that cancer-causing asbestos could be found in its talc.

J&J has repeatedly said that its talc products are safe, and that decades of studies have shown them to be asbestos-free and that they do not cause cancer.

The FDA test indicated the presence of no greater than 0.00002% of chrysotile asbestos in the tested sample, the company said.

The company’s consumer unit said it was too early to confirm whether cross-contamination of the sample had caused a false positive, whether the sample was taken from a bottle with an intact seal or whether the sample was prepared in a controlled environment.

It also added it could not confirm whether the tested product was authentic or counterfeit.

J&J said its has conducted thousands of tests over the past 40 years that confirm its talc does not contain asbestos.

J&J said in regulatory filings that it faces litigation from 15,500 plaintiffs related to its body powders containing talc.