Tom's of Maine responded to CNN's inquiries about the letter in a statement, telling the news agency that it is "working with the FDA and are remedying the issues raised in their May inspection of the Tom's manufacturing plant in Sanford, Maine."

Further, the company said it doesn't believe any contaminated products were shipped out of the facility. "We have always tested finished goods before they leave our control, and we remain fully confident in the safety and quality of the toothpaste we make," the statement continued.

"In addition, we have engaged water specialists to evaluate our systems at Sanford, have implemented additional safeguards to ensure compliance with FDA standards, and our water testing shows no issues."