The European Union on Monday moved closer to barring children from social media, in what would be the largest effort to date in the growing global movement to create age limits for apps like TikTok and Instagram.

Experts delivered a report to the European Commission president, Ursula von der Leyen, recommending that the European Union restrict access to social media for children under the age of 13 unless they are supervised by a parent or teacher.

The report, by a child psychiatrist, Professor Jörg Fegert, and an epidemiologist, Dr. Maria Melchior, also recommended that teens from age 13 to 18 should only have access to social media platforms that have introduced safety features such as limits on infinite scrolling. It said that toddlers under the age of 3 should have no screen time at all.

The recommendations are the first step toward a law that would bar children and teens from using certain social media sites. Ms. von der Leyen, who appointed the panel’s members, is expected to announce the proposed law in September during the annual State of the European Union address.

“It is very clear that we need age-appropriate restrictions to platforms,” Ms. von der Leyen said on Monday.

“This is not about whether children can access social media. It is about whether and when social media can access our children.”

Across Europe, children now spend four to six hours a day on social media, and almost 60 percent of children had experienced emotional and psychosocial problems online, Ms. von der Leyen said.

The report adds to a worldwide movement to limit children’s screen time and exposure to social media. Companies have faced a backlash amid concerns by parents about addiction and the technology’s potential to harm young people’s mental health.

Australia last year became the first country in the world to bar children under 16 from using social media. Since then, countries including Denmark, France, Germany, Spain, India, Indonesia and Malaysia have implemented or are considering similar rules.

In the United States, Florida passed a ban in 2024 on social media use for those under 14 without parent permission.

If the European Union introduces a new law, it would represent by far the biggest effort worldwide to bar children from social media. Roughly 450 million people live in the European Union, and about 18 percent of the population is under the age of 18.

But passing a new law would require a lengthy policymaking process that involves negotiations among the national governments that comprise the 27-nation European Union — a group that does not always agree on the need for new laws and regulation.

How such rules would be implemented also remains an open question. In Australia, critics have said teens are easily sidestepping the blocks and that the law has not fulfilled its promise.

Even without a ban, regulators in Brussels are trying to force social media companies to change their policies. Last week, authorities told Meta it must change the “addictive design” of Instagram and Facebook, or risk a hefty fine. TikTok is facing similar demands as part of another investigation.

The prospective buyers eyeballed, sniffed and ran their fingers through the merchandise. There were lectures, a happy hour and a speed-dating session between customers and sellers, complete with demonstrations and take-home samples.

The product? Manure from Dutch cows and pigs, muck that farmers in the Netherlands are newly desperate to sell.

The offbeat market, in Minikowo, Poland, attracted Dutch salesman and more than a dozen Polish agricultural suppliers and farm representatives on a recent sunny afternoon. The day stood as an example of how businesses in Europe and around the world are contending this year with overlapping challenges of climate change, increased environmental regulation, a green transition and global conflict.

Earlier this year, stricter European Union regulations fully kicked in to limit the amount of manure Dutch farmers can spread on their fields, because the nitrogen-laden runoff it produces might leach into waterways and pollute them. Given the limitations, Dutch farms now produce more animal waste than their farmers can use.

That has prodded the Dutch to try to market their manure in countries like Germany, France and Poland, which are further away from hitting their nitrogen allowance.

The Dutch push to make manure a hotter product got an unexpected boost from the conflict in the Middle East. After Israel and the United States attacked Iran in February and shipping traffic effectively stopped through the Strait of Hormuz, global prices for both artificial mineral fertilizer and the fuel necessary to produce it soared.

The jumps left many farmers across Europe looking for alternatives.

Though prices for nitrogen fertilizers eased in the wake of a preliminary peace deal, the situation in the strait remains volatile. And repeated global shocks might leave farmers in places like Minikowo convinced that they should use made-in-Europe, natural backups in addition to imported fertilizers.

The Dutch are hoping they’ll look toward the nation’s manure.

“Manure smells, everybody knows,” Tomasz Piechota, a professor in the Department of Agronomy at the Poznan University of Life Sciences, told the assembled crowd at the manure “matchmaking” event in Poland. “My grandmother taught me, all the time, that it was the smell of money.”

The conflict in the Middle East “certainly doesn’t hinder the cause” of selling manure, said Jouke Knol, the organizer of the event and a counselor for agriculture at the Dutch Embassy in Warsaw.

Even before this year, Dutch officials have been attacking their figurative mountain of unwanted manure from multiple angles.

They are first trying to make manure more usable at home. Renure, a cutting-edge product that comes from processed manure and is less damaging for the environment, was recently approved for use.

The European Union has also been considering paving the way for the use of other processed manure products — digestates, semiliquid byproducts that are not as harmful for the environment. Allowing them could relieve pressure on farmers who are looking for artificial fertilizer alternatives because of the higher prices.

Manure isn’t a perfect substitute for man-made mineral fertilizer, but using it can allow farmers to spread less of the manufactured kind.

“If the prices for mineral fertilizers go up, farmers are likely to look for substitute products,” said Harm Smit, a project leader for emission reduction and manure valuation at Wageningen Livestock Research, part of a university in the Netherlands.

The Dutch are also trying to produce less manure. The government has been buying out farmers in environmentally sensitive areas. Fewer cows equals less cow refuse.

The quickest solution is to increase manure exports. Last year, the Dutch government appointed a “manure ambassador,” Raymond Knops, who traveled Europe peddling the product.

Exports to Belgium and Germany are up notably, but prices are so low that farmers aren’t yet making money and are still paying to offload their manure. With so much of it unusable in the Netherlands, the cost of doing so has jumped.

Still, many manure sellers do not think that the Polish market is ready to start taking Dutch manure en masse — yet. The event in Minikowo drew fewer interested buyers than organizers had originally hoped, and some attendees sounded skeptical. It costs a lot to transport manure, which is wet and heavy compared with mineral fertilizers, for a long distance.

Others were more hopeful. In Minikowo, Tim Alders was representing his Dutch manure processing company, Vlako.

He had with him a large empty jar packed with his product. He had also brought plastic cups with twist-on lids (the kind one might use for a urine sample) filled with take-home samples.

Standing by his display table, Mr. Alders explained that he already exports to France and Germany. He often also sends a few trucks of the natural fertilizer to Poland, which is farther away and thus has tougher economics as an export market.

“With Poland, it’s always geopolitical, or emotional,” he said of his demand. “Most of the time, it’s that the price of chemical fertilizers is going up.”

Mr. Knol, the organizer, was also hopeful. The geopolitics, he said, will make “processed manure from the Netherlands more attractive.”