Experts meet in Bangkok this week to advance what would be the first international treaty to tackle the surging problem of plastic pollution. Final treaty negotiations take place in South Korea in November.

Yet most of the people who have been closely tracking the negotiations — environmentalists, tribal leaders and residents from communities hard-hit by plastic production and waste — are shut out of the talks in Bangkok.

Many plastic industry representatives say they can’t get into the room either.

In a series of letters to the United Nations Environment Programme, the meeting sponsor, hundreds of organizations said the closure runs counter to typical international environmental treaty-making. They said meeting coordinators have a responsibility to be transparent and allow public participation. They worry the approach in Bangkok could set a bad precedent.

In earlier meetings of the UN Intergovernmental Negotiating Committee on Plastic Pollution in 2022 and 2023, countries spent a lot of time debating rules and procedure, including how they would vote on decisions.

At this meeting of subject matter experts, the substance of what could go into the treaty will be discussed in detail. It runs through next week.

Negotiating committee Executive Secretary Jyoti Mathur-Filipp replied in a letter that she wasn’t authorized to let people in and countries had not agreed on having observers participate.

U.N. documents only spell out member states and selected technical experts as participants.

The Bangkok meeting is less formal than a treaty negotiation, she said. It is not unprecedented in U.N. treaty processes for technical experts to meet amongst themselves, Mathur-Filipp said in a written statement to the AP.

That being said, she wrote, observers are important to environmental treaties and “we work very hard” for them to be able to participate.

Anyone who wants to be in the room in Bangkok must either be part of a national delegation or chosen as one of two dozen invited technical experts.

The two expert groups are focused on the chemicals that go into plastic products and how the treaty could be financed. The negotiating countries will then take up those reports at the fifth and final session in South Korea.

In 2022, most of the world’s nations agreed to make the first legally-binding treaty on plastics pollution, including in the oceans. The goal was to complete negotiations by the end of 2024. Thousands of environmentalists, plastic industry representatives, scientists, tribal leaders, waste pickers, and others concerned about plastic pollution have traveled as observers to four continents to share their views at the prior treaty talks.

The International Council of Chemical Associations hoped its scientists and engineers who develop plastic products could provide technical advice at the Bangkok meetings. Chris Jahn, ICCA secretariat, said the association is disappointed but committed to supporting the negotiation process.

Many of the groups voicing concerns about the closure have advocated for a strong treaty, one that limits how much plastic is produced and eliminates toxic chemicals in plastics, rather than one that only deals with plastic waste. At such a critical stage in the process, if there are not enough people in the room in Bangkok who want a meaningful treaty, it could set the stage for a weaker document, leaders at the International Pollutants Elimination Network said.

“When you get close to the end, by starting to close the door when the game is getting tougher, it could be a way to try to avoid that accountability that civil society groups bring to the table,” said Vito Buonsante, policy advisor at IPEN.

In the past, observers were allowed to participate in working groups for the treaty on mercury known as the Minamata Convention, as well as in the treaty that protects human health and the environment from chemicals known as persistent organic pollutants — the Stockholm Convention.

Some countries, including China and Iran, are bringing representatives from industry associations or national oil company officials as part of their delegations to Bangkok.

Environmentalists, scientists, waste pickers and tribal leaders asked to join national delegations too, with some success. Uruguay, the Philippines and the Cook Islands are among the delegations that have nonprofits traveling with them. Scientists will be in Bangkok with several small island and European delegations.

The Indigenous Peoples Caucus is sending one specialist for each expert group. It includes communities whose land, water and air are being contaminated as fossil fuels are extracted and plastic is manufactured using hazardous chemicals, said Frankie Orona, executive director of the Society of Native Nations in Texas, so it could not settle for less. Texas is a global leader in making petrochemicals used in plastics.

“There has been so much discussion about how important it is to have Indigenous knowledge and stakeholder participation. I didn’t think it would go to this extreme, with really limited participation,” Orona said in an interview. “It’s taking away our ability to fully participate and come up with meaningful solutions.”