After investigating reports that more than 400 babies were sickened and 10 died in connection with homeopathic teething products, the Food and Drug Administration confirmed Friday that it had indeed found elevated levels of the toxic substance, belladonna, in the products.

Belladonna, also known as deadly nightshade, was the prime suspect of the investigation from the beginning, which Ars reported about last fall. Nevertheless, the products’ maker, Hyland’s, would not agree to recall the products when it was notified of the FDA’s conclusion, the agency reported.

In a response to Ars, Hyland's has acknowledged that there are some inconsistencies in the amount of belladonna in its products, but the company said that it has not seen any evidence from the FDA indicating that the elevated levels were toxic or excessive. “The current data [seen by the company] indicate that the measured samples all fall well within an accepted margin of safety,” Hyland’s spokesperson, Mary Borneman, told Ars. As such, the company said it does “not see any action necessary.”

In the FDA’s announcement, Dr. Janet Woodcock, director of the FDA’s Center for Drug Evaluation and Research explained that: “the body’s response to belladonna in children under two years of age is unpredictable and puts them at unnecessary risk."

Hyland’s has been on the defense since the FDA warned about the products last September. In an October press release, the company referred to the agency’s warnings as a source of “confusion” and assured consumers that the products are safe and effective. Still, the company discontinued distribution in the US.

The National Center for Homeopathy, which has ties with Hyland’s, slammed the FDA, calling the agency’s warnings “arbitrary and capricious.” In an “action alert,” the organization went on to suggest that warning was prompted by “groups interested in seeing homeopathy destroyed” and led to “fear mongering” by the media.

As before, the FDA is urging parents to avoid the homeopathic teething products and toss any already purchased. The FDA does not evaluate or approve the homeopathic products, which have no proven health benefit.

Belladonna is an active ingredient in those products, but is supposed to be heavily diluted. Homeopaths believe that ailments and diseases can be cured by trace amounts or “memories” of toxic substances that mimic or cause similar symptoms. Homeopathy is a pseudoscience that has been squarely debunked , offering no more than a placebo effect.

The FDA said it had found inconsistent amounts of belladonna in Hyland’s products. Some of the amounts were “far exceeding” what was intended.

Belladonna poisoning can cause seizures, vomiting, difficulty breathing, lethargy, excessive sleepiness, muscle weakness, skin flushing, constipation, difficulty urinating, blurred vision, and confusion.

Last November, another maker of homeopathic products, Raritan Pharmaceuticals, recalled belladonna-containing teething products. Around the same time, the Federal Trade Commission announced that it will begin requiring makers of homeopathic products to add warnings in advertisements and on packaging that state that: 1) there is no scientific evidence that they are effective, and 2) any claims of effectiveness are only based on homeopathic theories, which are not accepted by science.

In response, the National Center for Homeopathy said they were "deeply concerned" and had formed a task force to "identify the most strategic and appropriate collective course of action."

This post was updated at 6:15 ET when we received comments from Hyland's.