a2 Milk Co. (ASX:A2M, NZE:ATM) started a voluntary recall on May 1 of three batches of its a2 Platinum USA infant milk formula, following the detection of cereulide in product manufactured by Synlait Milk (ASX:SM1, NZE:SML), according to separate Monday filings with the Australian and New Zealand bourses.

The product was sold only in the US via online platforms and select retailers and had already been discontinued before the recall, while all a2 Platinum products sold outside the US remain unaffected, per the filing.

No illnesses have been reported, and any symptoms are typically mild and short-lived, a2 Milk said, adding that it is working with the US Food and Drug Administration and has provided guidance to US consumers who may have purchased the product.

The recall reflects updated guidance from New Zealand authorities on managing cereulide risks, a2 Milk said.

The companies said they do not expect the recall to impact their financial results.