The agency cites contamination concerns inside Reckitt/Mead Johnson, Perrigo and ByHeart facilities.
The FDA has sent warning letters to three formula companies, red-flagging concerns about serious quality control issues at some manufacturing facilities.
The warning letters were all sent Wednesday to Reckitt/Mead Johnson and Perrigo -- two long-dominating industry forces -- and ByHeart, a relative newcomer to a previously hyperconcentrated market. All three companies had jumped in to ramp up their manufacturing amid an urgent baby formula shortage last year in the wake of major recalls at Abbott, one of the nation's major suppliers.
ABC News was first to report last summer that several major formula makers other than Abbott had also struggled with contamination concerns, particularly with the bacteria Cronobacter sakazakii -- and that those other formula makers had been warned by regulators for subpar conditions and critical equipment deficiencies at the time.
Alongside the publication of new warning letters, the FDA also reassured Americans that it believes prior recalls of baby formula products were "effective in removing the potentially contaminated batches." The agency said parents and caregivers do not need to discard or avoid purchasing formula at this time.
Cronobacter can be widely found in the environment -- but in infants, it can be deadly. Its discovery inside Abbott's Sturgis, Michigan, plant last year prompted a massive voluntary formula recall in February 2022 after four babies who had consumed Abbott's formula contracted a Cronobacter infection.
Two of the infants subsequently died, though Abbott maintains no conclusive evidence has proven its formula caused the babies' illnesses. But Abbott's ultimate shutdown ricocheted from coast to coast, leaving a serious void in the market and forcing families to face empty shelves and scramble for alternatives for months.
Numerous congressional hearings demanded answers from Abbott and the FDA's leadership on why more hadn't been done sooner to identify and fix the issue before it got so bad.
But Abbott has not been alone in facing those operational and contamination concerns.
After previous tests had found Cronobacter, FDA investigators say they have found "significant violations" during inspections ranging from the fall of 2022 through mid-February 2023 inside Reckitt/Mead Johnson, Perrigo and ByHeart facilities, including substandard processes or conditions that could help more pathogens fester.
"For over 130 years, Perrigo has been committed to meeting the needs of consumers, parents and caregivers-and the quality and safety of our products is our highest priority," Perrigo said in a statement obtained by ABC News. "We have rigorous procedures throughout our infant formula manufacturing processes and every batch of infant formula is tested to ensure it meets stringent nutritional, safety, quality, and U.S. Food & Drug Administration regulatory requirements."
"The letter Perrigo received pertained only to its infant formula manufacturing facility located in Wisconsin, which Perrigo acquired from Nestle on November 1, 2022, the statement continued. "This letter relates to a routine inspection by the FDA which began on March 6, 2023 and references FDA's March 8, 2023 communication to the infant formula industry outlining its evolving regulatory expectations. We are in the process of carefully reviewing FDA's letter and plan to work closely with the agency."
The new warning letters detail some of the same concerns that ABC News was first to report last year. And though the companies took corrective actions, the agency said more is needed after these recent inspections.
The letters describe multiple occasions where the FDA says finished formula tested positive for Cronobacter and instances where the companies had failed to sufficiently investigate the contamination's source and prevent it from happening again.
In some instances, the companies failed to consider "other potential sources of contamination," the FDA said.
In Reckitt/Mead Johnson's letter, investigators note the company's "root cause analysis did not consider other potential sources of contamination, such as a history of several internal cracks of varying lengths identified throughout your dryer system, multiple water leaks at your facility, or the standing piles of spilled infant formula product at your facility," emphasizing that the company's investigation "did not consider all potential sources of contamination."
FDA's findings at Reckitt's facility came amid months where the company had also found Cronobacter in "high and critical hygiene zones" of their facility's environment -- from July 2022 to February 2023.
Reckitt also found Cronobacter in their finished formula product at multiple facilities in the fall of 2022.
In February 2023, as ABC reported at the time, Reckitt issued a voluntary recall for two of their batches.
In a statement to ABC News, Reckitt/Mead Johnson Nutrition said "the safety of babies is of the utmost importance to us and we can confirm that all of our infant formula products continue to meet the highest FDA standards for safety and quality. "The FDA's communication is part of its enhanced regulatory oversight and does not relate to any new concerns or issues, as they reflect findings from previous inspections. The company added that it is "confident in the rigor of the programs we have in place to ensure the safety of every infant formula product we ship."
In the new warning letter sent to Perrigo, the FDA details that Cronobacter had been identified in finished formula products on multiple occasions by the company: in two products "during a continuous production campaign that ran from Oct. 23, 2022, to Nov. 2, 2022," another that ran from Jan. 3, 2023, through Jan. 18, 2023, in which another batch formula product tested positive, and another that ran from March 26, 2023 through April 5, 2023, in which another batch of product tested positive.
FDA investigators say they also found Cronobacter from swabbing their facility's environment this March -- noting in their letter that this "was not the first time" they had found it at that facility.
"The detection of C. sakazakii in your facility across multiple independent inspections is significant in that it demonstrates your sanitation procedures have been inadequate to significantly minimize or prevent the presence of C. sakazakii in your facility," the FDA writes to Perrigo. "Once C. sakazakii is established in a production area, personnel or equipment can facilitate the pathogen's movement and contamination of food contact surfaces and finished product."
In March 2023, Perrigo also issued a voluntary recall for some of their formula due to potential Cronobacter contamination, a recall which the FDA says they believe was "effective."
Cronobacter was also found in ByHeart's finished formula which they flagged in October 2022. They issued a voluntary recall in December 2022, blaming the positive sample on their "third-party packaging facility."
In their warning letter to ByHeart, the FDA also notes that various leaks were found in the facility, one in the skylight installed on the roof in June 2022, and another in a worn sealant "around the louver" in a Dryer Tower in December 2022 after "heavy wind and rain."
During environmental swabbing conducted on the same day the leak was identified, four swabs detected Cronobacter in the dryer tower.
"Despite having a leak in December and then detecting Cronobacter spp. via environmental swabbing following the leak, the root cause analysis never considered or evaluated whether the leak may have contributed to the contamination," the FDA's letter said.
"We commend the FDA for its efforts to unify the industry's ongoing work to elevate manufacturing standards and support the Agency's enhanced oversight," a ByHeart spokesperson said in a statement to ABC News. "Providing safe and high-quality infant formula continues to be our top priority and we can assure our customers that no distributed ByHeart product has tested positive for contaminants. There is no disruption to ByHeart's manufacturing and we currently have three production plants across the U.S. that are operating to meet the demand for our formula."
The companies now have 15 days to respond to the warning letters.