NICK SCHIFRIN: Last year, the U.S. exported more than 950 million tons of plastic waste meant for recycling, and a significant portion of that ended up in Southeast Asia.

The region has been inundated after China blocked all but the cleanest plastic waste imports in 2018.

Special correspondent Fred de Sam Lazaro looks at how one country, Thailand, is dealing with the problem.

FRED DE SAM LAZARO: Plastic is everywhere in Thailand, used by street vendors for curries, soups and sauces, in fruit and vegetable markets, grocery stores and everywhere in between.

About two million tons of plastic waste were generated every year in Thailand over the past decade.

Sittipong Lerdveelawut, and his wife, Supreta Lukshampad (ph), built their family business around recycling plastic.

SITTIPONG LERDVEELAWUT, Sunee Recycle 59 Group (through translator): We buy recycled plastic, then grind it down into little particles, and then they wash it, they heat it.

Then they wash it again.

The end product turns out into some fine particle, kind of like sugar.

And, basically, that is used for other factories to make recycled plastic products in Thailand.

FRED DE SAM LAZARO: It's tedious and far from straightforward.

There are thousands of different types of plastic with different additives, and they cannot be melted down together.

The highest premium is on cleaner stuff.

At this East Bangkok plant, a worker spends his day peeling labels off piles of water bottles.

And, overall, only a small fraction of plastic is repurposed, according to Wijarn Simachaya, president of the Thailand Environment Institute.

WIJARN SIMACHAYA, President, Thailand Environment Institute: Only 25 percent, and the rest go to landfill, go to open dumping.

FRED DE SAM LAZARO: Seventy to 80 percent of the land-based plastic waste... WIJARN SIMACHAYA: Yes, go to the canal, and then to the river, and then to the ocean.

FRED DE SAM LAZARO: OK, so that's a significant amount of plastic pollution.

WIJARN SIMACHAYA: Yes.

FRED DE SAM LAZARO: And the volume of plastics has spiked since 2018, after China, a major importer of used plastic, banned the practice, sending the business of plastic waste into Southeast Asian countries like Thailand.

Estimates range from 150,000 to more than 550,000 tons, but actual figures could be even higher.

PUNYATHORN JEUNGSMARN, Ecological Alert and Recovery Thailand: And that's when the plastic waste import problems really boomed in Thailand.

FRED DE SAM LAZARO: Environmentalist Punyathorn Jeungsmarn says new recycling facilities have sprung up to take on the new glut, with little regulation.

He works with EARTH, a Thai group that documents the impacts of industrial pollution.

PUNYATHORN JEUNGSMARN: And we were also seeing a lot more communities that are affected by dirty recycling factories and plastic waste factories.

WATCHAREE SAMANGIN, Community Health Volunteer (through translator): They hire some people to separate the different plastics, and the scraps that had no value would be gathered into a pile and burned in an open area.

FRED DE SAM LAZARO: Watcharee Samangin is a community health volunteer in a rural area of Chon Buri province about 65 miles east of Bangkok.

She says people she served began to notice health impacts they blamed on a nearby plastic recycling plant.

WATCHAREE SAMANGIN (through translator): People living near where they burned the plastic waste experienced irritation in the nose with an extremely foul smell.

Sometimes, it's worse at night, so it causes a lot of disturbance and other health issues.

FRED DE SAM LAZARO: Following complaints and protests, the plant was shot down.

PUNYATHORN JEUNGSMARN: We have found that in Chon Buri province, in particular, there are smaller facilities dealing with plastic waste, a lot of which are also imported.

FRED DE SAM LAZARO: We visited That Thong, where a large plant owned by a company called Ken United continues to operate.

It's guarded by high walls and cameras, closed off to outsiders.

Local residents worry not only about the health impacts, but the environment in an area dependent on agriculture.

Some 20 to 30 families who live in the area surrounding the Ken United factory have complained to environmental groups and to local authorities about health consequences they have suffered since the factory came online.

But when we visited, no one was willing to share their stories on camera in this community.

It could be a consequence of a defamation lawsuit that's been filed by the company against one family who spoke out.

Our attempts to reach the company, which is owned by international investors, were not successful.

Meantime, the flood of imported plastic waste has depressed prices, severely affecting the lives of informal waste pickers, who are key to collecting plastics for recycling.

They are some of this country's poorest people.

PUNYATHORN JEUNGSMARN: So, when the plastic -- the price of plastic waste goes down,there's less incentive for people to collect waste.

FRED DE SAM LAZARO: Informal workers like 66-year-old Thongsri Kaewkalong, whose only wages are what she receives for the scrap she collects.

THONGSRI KAEWKALONG, Waste Collector (through translator): Before, my daily earnings were about $27.

Now they shrunk to $8.40 per day.

Many of my colleagues in the business have stopped doing it.

FRED DE SAM LAZARO: Her meager earnings are based on how much they can carry.

It's often a job of last resort for those with little education.

Bunthom Fangrith is 72.

BUNTHOM FANGRITH, Waste Collector (through translator): I was laid off from my job as a construction worker because I am too old.

It's difficult to support myself and my daughters.

My daily profit now is just 100 baht.

FRED DE SAM LAZARO: That's less than $3.

VARAWUT SILPA-ARCHA, Former Thai Former Minister of Natural Resources: Thailand is not an international dumping ground.

FRED DE SAM LAZARO: Varawut Silpa-archa is a former minister of natural resources and environment.

VARAWUT SILPA-ARCHA: We have had quite a few cases where I have kindly requested the concerned authorities to shut a container and return it to its rightful owner.

FRED DE SAM LAZARO: Thailand announced it will restrict plastic waste imports starting next year and completely ban the shipments starting in 2025.

But enforcement is a challenge.

Shipments can be mislabeled or simply smuggled past a customs system that isn't fully transparent and not equipped to inspect all containers.

PUNYATHORN JEUNGSMARN: It's possible to import certain waste as paper.

We have seen plastic waste falsely declared as paper before.

FRED DE SAM LAZARO: And it's harder to enforce at the local level, according to Wijarn Simachaya.

WIJARN SIMACHAYA: Some decision-makers don't care about environmental issues like garbage, wastewater.

FRED DE SAM LAZARO: The decision-makers, the local politicians... WIJARN SIMACHAYA: The local politicians.

FRED DE SAM LAZARO: ... they don't care?

WIJARN SIMACHAYA: They don't - - yes, yes, they don't care.

FRED DE SAM LAZARO: It's estimated that the Chao Phraya River carries about 4,000 tons of plastic waste into the Gulf of Thailand each year.

Former Minister Varawut has a message to rich nations, from where much of it comes: You own it.

VARAWUT SILPA-ARCHA: For those who produces all these rubbish and try to dump it somewhere, I must say, please, deal with your own mess.

Don't dump it on someone else's, because, eventually,it's not just us that's going to be affected.

It's you as well.

When Mother Nature kind of takes back her balance, mankind will be affected.

So, please, stop doing what you are doing.

FRED DE SAM LAZARO: Plastic waste exports have steadily declined over the past decade, in part because of China's ban.

Still, in 2021, the U.S. exported some 1.2 billion pounds of scrap plastic.

For the "PBS NewsHour," I'm Fred de Sam Lazaro in Bangkok, Thailand.

NICK SCHIFRIN: Fred's reporting is a partnership with the Under-Told Stories Project at the University of St. Thomas in Minnesota.