No evidence linking methane inhibitors for cows to human health problems

"They are killing us off with our food supply," reads a December 13, 2024 X post claiming to share details about the cow feed additive Bovaer 10.

Other posts spread across X, Instagram and Facebook implying approval of the product in Canada would be harmful to humans, sometimes citing text that discussed the supposed risks to human fertility, eyes and skin from the active ingredient, 3-nitrooxypropanol (3NOP).

The posts often encouraged others not to drink store-bought milk and instead opt for the potentially risky unpasteurized version of the beverage. Publications in other languages, including Dutch, German, Slovak and Finnish, claimed Bovaer 10's integration was compromising different countries' food supply.

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Screenshot of an X post taken December 19, 2024

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Screenshot of an Instagram post taken December 19, 2024

Similar claims spread in the United Kingdom, prompting a campaign to throw milk away.

Bovaer 10 is a product from the Dutch company DSM-Firmenich and is advertised as a feed additive which can be given to cows to reduce their methane emissions and limit greenhouse gases produced by the beef and dairy industry (archived here). Canada is seeking to cut methane emissions across its economy as part of a broad strategy to fight climate change.

Some users linked the product to the World Economic Forum, a nonprofit think tank that is often a target for unfounded conspiracy theories. The company's CEO, like many other executives, has participated in WEF events.

Reverse image search reveals many of the posts shared screenshots of  a US Food and Drug Administration (FDA) document explaining the risks of human contact with 3NOP (archived here).

However, this does not mean that beef and dairy products from cows consuming Bovaer 10 are dangerous for humans, food safety experts said.

The Canadian Food Inspection Agency (CFIA) approved Bovaer 10 for use in Canada in January (archived here) and said in a December 18 email that when the additive is fed to cattle, 3NOP is rapidly metabolized by the animals' stomachs so it does not appear in dairy or beef products from the cow.

"When used according to the label, 3NOP does not impact fertility or reproduction in cattle," the agency said. "Owing to its extensive metabolism, 3NOP is not present in milk or meat and therefore does not reach consumers."

DSM-Firmenich also confirmed that its product "never enters into milk or meat," saying in a December 2 statement that it has been "safely in commercial use for over two years" (archived here). 

No traces in milk

The CFIA said it evaluated the safety and efficacy of 3NOP and determined it could perform its intended purpose of reducing methane emissions from cattle. Similarly, the European Food and Safety Authority told AFP it had evaluated Bovaer in 2021 and concluded it was safe for its proposed use (archived here).

Nico Peiren, a senior researcher at the Flanders Research Institute for Agriculture, Food and Fisheries in Belgium (archived here), said that 3NOP is broken down by the rumen, the first stomach of the cow.

"After administration, the additive is active for about 3 hours and then degrades back into nitrate and alcohol," he said in a December 4, 2024 email. "This is also why it is not found in milk." 

Jan Dijkstra, an associate professor of animal nutrition at Wageningen University in the Netherlands (archived here), said that before being broken down, 3NOP blocks the enzyme responsible for methane production in the cow's stomach, reducing emissions by about 25 percent. He said the inhibitor is also safe for the cow.

"As soon as you stop giving Bovaer to a cow, rumen methane production increases again; within 24 hours the cow is back to its 'old' level," he said in an interview on December 5.

Dijkstra said that studies of 3NOP did show negative effects in lab animals, but only at a high concentration which is not fed to cows.

Occupational warning

The FDA safety label included in many of the posts explains recommended handling of the product in its concentrated form. It says 3NOP should not be fed undiluted and warns that it "may damage male fertility and reproductive organs, is potentially harmful when inhaled, and is a skin and eye irritant."

Dijkstra pointed out these warning statements are related to the safe handling of 3NOP, rather than the risks of consuming products from animals treated with Bovaer 10.

He said warning labels for pure products in a manufacturing setting will often have cautionary instructions that do not apply once the ingredient has been diluted.

"You can't translate that [the warning label for handling the pure product] to the farmer or consumer," he said.

Read more of AFP's reporting on misinformation about the environment here.