A group of U.S. lawmakers is urging Secretary of State Marco Rubio not to support Colombia’s plans to restart aerial spraying of coca crops in the Amazon, warning of risks to human health and the environment.

STEVEN GRATTAN MEXICO CITY — A group of U.S. lawmakers on Thursday urged Secretary of State Marco Rubio not to support Colombia’s plans to restart aerial spraying of coca, the plant used to make cocaine, warning that the practice could threaten human health and fragile ecosystems in the Amazon rainforest.

In a letter led by U.S. Rep. Mark Pocan, D-Wis., and signed by 18 other lawmakers, including Reps. Alexandria Ocasio-Cortez, D-N.Y., Rashida Tlaib, D-Mich., and Jim McGovern, D-Mass., the group expressed concern over reports that President Donald Trump’s administration had encouraged Colombia to revive the program, which involves spraying herbicides from aircraft to kill coca plants.

The proposal would revive a decades-old U.S.-backed strategy that was suspended in 2015 over health concerns. The Colombian government argues that aerial spraying offers a faster, safer way to eradicate coca crops in areas controlled by armed groups, while critics say it has failed to curb cultivation in the long term and risks harming rural communities and the environment.

President Abelardo de la Espriella’s government has proposed a pilot project to spray up to 1,000 hectares (2,471 acres) of coca crops in Putumayo, an Amazonian department bordering Ecuador and Peru. The project would replace glyphosate, a widely used weedkiller at the center of earlier spraying campaigns suspended over health concerns, with glufosinate ammonium, another herbicide that has faced scrutiny over its potential health risks and is no longer approved for use in the European Union.

In a Sept. 10 statement, Colombia’s National Police said the pilot would undergo scientific evaluation and exclude protected areas, water sources and territories belonging to communities with special legal protections.

The Associated Press requested comment from the Colombian presidency on the lawmakers’ letter but had not received a response by the time of publication.

“We have serious concerns about both health concerns for people in that region and environmental concerns in such an environmentally sensitive area,” Pocan told the AP.

Pocan said the lawmakers wanted Washington to explain whether it was supporting the program and what safeguards were being considered.

A decades-old drug strategy makes a comeback Colombia suspended aerial spraying with glyphosate in 2015 after the World Health Organization’s cancer research agency classified the herbicide as “probably carcinogenic to humans.”Despite decades of U.S.-backed counternarcotics efforts, Colombia remains the world’s largest cocaine producer, with coca cultivation reaching a record 261,000 hectares in 2024, according to the latest available United Nations figures.

Supporters argue that aerial eradication offers a faster and safer alternative to sending security forces into dangerous coca-growing areas. Critics say spraying can damage legal crops and push farmers to clear new areas of forest to replace destroyed plantations.

The government’s proposed replacement herbicide, glufosinate ammonium, lost its approval for use in the European Union in 2018. Lawmakers warned that it also poses potential health and environmental risks.

Colombia’s Constitutional Court has established strict conditions for restarting spraying, including safeguards for human health and the environment and consultation with affected communities.

In September, a court in Putumayo temporarily halted the pilot, finding that the government had not demonstrated compliance with those requirements. A subsequent ruling maintained the suspension. Pocan said he had met elected officials from the affected region who expressed concerns.

“The Amazon is one of the world’s most important resources and anything that’s going to potentially hurt that region is problematic, period,” he said.

Critics warn spraying could push coca deeper into the Amazon Environmental organizations warn that renewed eradication could accelerate deforestation by pushing coca growers into more remote areas.

Andrew Miller of Amazon Watch, a nonprofit that advocates for rainforest protection and Indigenous rights, warned that destroying coca crops in Putumayo could push cultivation into more remote parts of the Amazon, driving further deforestation and violence against local communities.

“Renewed aerial fumigation would be a militarized strategy in repetition of the futile war on drugs, destined to fail in the long term,” he said.

The lawmakers’ letter also criticized the Trump administration’s dismantling of the U.S. Agency for International Development, or USAID, which previously funded sustainable agriculture, ecotourism and other alternatives to coca cultivation in Colombia’s Amazon region.

The lawmakers gave Rubio until Nov. 13 to explain whether Washington had pressured Colombia to restart spraying or offered financial or logistical support. They also asked about the proposed use of glufosinate ammonium and how the administration plans to replace programs that helped farmers find alternatives to growing coca.

Colombian Sen. Sandra Chindoy said decades of spraying had failed to address coca cultivation while putting communities and their environment at risk.

“The Amazon is not a spraying laboratory,” she said in comments provided to the AP. “Putumayo needs investment, life and dignified opportunities, not more poison for our people or our land.”