TELOK GONG, Malaysia — Black sedans with government plates raced through a town near Malaysia’s main seaport, flashing blue sirens as they approached rogue trash dumps.
The raid, in the town of Telok Gong this week, was among the latest efforts by officials to shut down unlicensed dumps holding plastic scrap imported from the United States and other rich countries.
“Everybody knows those dumps are illegal,” said Modh Faiz Tamsir, a butcher hawking fly-covered beef in a parking lot on Telok Gong’s main drag. “We don’t like them.”
After China, once the world’s primary dumping ground, abruptly imposed restrictions on “foreign garbage” in late 2017, countries across Southeast Asia began taking in the West’s plastic waste.
Within months, Malaysia, which has a sizable ethnic Chinese population, had replaced China as the world’s largest importer of plastic scrap. But this country, and others across the region, soon saw the waste as an environmental nightmare, and a heavy backlash has begun. With public support, some advocacy groups have urged officials to permanently ban the import of plastic waste.
But at a time when the world is awash in such plastic, some experts worry that this backlash could block the flow of raw material to Southeast Asia’s aboveboard recyclers and manufacturers — and raise the chances that plastic scrap will end up in rivers, oceans, dumps and illegal burn sites.
By imposing blanket bans on imported waste, “you’re potentially risking damaging the good recyclers’ business,” said Kakuko Nagatani-Yoshida, the United Nations Environment Program’s coordinator on chemicals and waste in the Asia-Pacific region.
“When those people lose a business opportunity, then in the future you have fewer options for waste management,” she added. “And I don’t think any government should have fewer options; you always need more.”
China’s abrupt waste restrictions of 2017 were a response to years of pollution there by low-end recycling. They caused anxiety across a vast supply chain that includes waste companies and municipal recyclers in the United States and other developed economies.
“The exporter countries’ pants were on fire,” said Yuyun Ismawati, a co-founder of the Indonesian environmental group BaliFokus. “They realized they had underestimated China’s seriousness.”
Around the same time, unlicensed trash dumps, many of them owned by mainland Chinese investors, began appearing in the back alleys of Telok Gong and other towns near Southeast Asian ports.
“They just popped out of nowhere two years ago,” said Soh Ah Boon, the Malaysian owner of a junkyard about 15 miles by car from Telok Gong that collects material from local sources.
By March 2018, the peak of the surge, Malaysia was importing about 139,000 tons of plastic waste per month, up from about 22,000 tons per month a year earlier, according to official trade data analyzed by Khor Yu Leng, an economist in Singapore who studies Southeast Asian commodities. The United States was the largest source, followed by Japan, Britain and Germany, she said.
As plastic imports rose across Southeast Asia, pollution became more noticeable — typically in the form of trash-clogged rivers or smoke from ragtag incineration sites, according to environmental groups.
Local opposition grew, too.
“Who would like it when someone comes to your neighborhood and tears the place up?” Mr. Soh said at his junkyard between drags of a cigarette.
In response, Southeast Asian governments issued waste-import restrictions of various shapes, sizes and durations. Thailand imposed an indefinite ban on electronic waste last summer, for example, while Vietnam stopped issuing waste-import licenses and vowed to stop importing scrap plastic by 2025.
In the Philippines last week, officials returned a shipment of wastethat had been mistakenly sent there from Canada several years ago, and vowed to send another back to Hong Kong.
“Load that up on a ship and I will advise Canada that your garbage is on the way,” President Rodrigo Duterte of the Philippines said of the Canadian shipment in early May. “Prepare a grand reception. Eat it if you want to.”
In Malaysia, the campaign against imported waste has been led by Yeo Bee Yin, the 36-year-old environment minister. On a trip last week to Port Klang, down the road from Telok Gong, she said the government would soon return 10 of about 60 containers with waste from the United States and elsewhere that had been smuggled into illegal processing facilities.
Ms. Yeo’s campaign may be a way to score public relations points against countries, including the United States, that have criticized Malaysia for its high rates of deforestation and other severe environmental problems, said Helena Varkkey, an expert on pollution in Southeast Asia at the University of Malaya in Kuala Lumpur.
“This is a ‘Here’s a taste of your own medicine,’” she said. Ms. Yeo’s office could not be reached for comment.
But whatever the motivation, one danger may be that legal recyclers across Southeast Asia will now miss a chance to both scale up their business and help mitigate environmental problems, including the scourge of plastics in the oceans.
Some plastic waste, if properly sorted and classified, is already being used in the region as a raw material for high-end manufacturing and as a replacement for fossil fuels in cement kilns, among other uses. And because municipal waste sorting here is virtually nonexistent, importing plastic scrap is often the only way for recycling companies to achieve economies of scale.
But the current waste crackdowns have not clearly distinguished between truly hazardous garbage and other types of plastic that can be safely recycled again and again, said Douglas Woodring, the founder of the Ocean Recovery Alliance, a nonprofit based in California and Hong Kong that works on plastic pollution.
“You’re categorizing these as a dangerous substance, which they are not if you process them the right way,” he said. “They’re just like any other commodity — like copper, steel, metal, wood and paper.”
Some recyclers are already feeling the effects. Officials in the Philippines, for example, declined to issue import permits last month for a shipment of plastic-waste-based fuel that is produced in Australia and used in the production of cement, customs paperwork shows.
In a report explaining the decision, a Philippine customs official noted that the import request had been rejected partly because of “past and present controversies on the importation of waste.” He also said the shipment had emitted a “pungent smell inherent to municipal waste” upon inspection at a Philippine port.