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For decades, Colombia used aerial spraying of the herbicide glyphosate to kill coca crops used to make cocaine. But it stopped the practice in 2015 because of concerns about human health risks posed by the chemical.


Pandemic upends Colombia’s controversial drug war plan to resume aerial spraying

Science’s COVID-19 reporting is supported by the Pulitzer Center.

The COVID-19 pandemic has at least temporarily derailed a controversial plan by Colombia’s government to resume aerial spraying of a potent chemical used to kill coca crops that feed the global trade in cocaine.

Late last month, a Colombian court ruled that the spraying of the herbicide glyphosate, which some studies have linked to human health and environmental problems, cannot resume until the government informs and consults with affected communities—a process that has been severely disrupted by the ongoing pandemic. The government had planned to hold virtual meetings with the communities, but environmental and human rights groups went to court to challenge that plan, arguing that Colombia’s rural communities often lack reliable internet, cellphone, or radio service. In a 27 May ruling, the court sided with the groups, ordering the government to rethink its consultation plan.

Colombia is the world’s largest producer of cocaine, and for decades the government used glyphosate to kill coca crops in an effort to reduce the supply of the drug. But in 2015, after the World Health Organization’s cancer research agency concluded that glyphosate “probably” caused cancer in humans, Colombia canceled its aerial spraying program, which had been heavily supported by the U.S. government’s counternarcotics program. Since then, Colombia’s Constitutional Court has said the government can resume spraying only if it meets certain conditions, such as protecting nature reserves, consulting with residents in areas to be sprayed, and completing studies of human health and environmental risks.

Colombian President Iván Duque Márquez has been facing pressure to resume glyphosate spraying from U.S. President Donald Trump, and both leaders have argued that Colombia’s production of coca has grown to worrying levels in recent years. Earlier this year, the Colombian government announced it hoped to use a variety of methods to eradicate 130,000 hectares of coca this year and stepped up its efforts to restart aerial spraying.

Critics of aerial spraying raised alarm. The human health risks posed by exposure to glyphosate have been fiercely debated, but studies have linked the herbicide to birth defects and other problems. A 2017 study conducted in Colombia found increased risk of skin disorders, respiratory ailments, and miscarriages among people living in areas sprayed with glyphosate. “Our results are based on aerial fumigations where they used small planes and had very little control over where the droplets fell” says economist Adriana Camacho of the University of Los Andes, one of the authors. More controlled spraying, she adds, could reduce risks to people.

Other studies have found that glyphosate, which kills a broad array of plants, can have harmful effects on wildlife, including mammals and insects. A 2019 study conducted by researchers at the National University of Colombia showed the chemical can damage the nervous and respiratory systems of some native fish, sometimes resulting in death. An additional worry, critics say, is that coca eradication—including spraying—can promote deforestation by prompting farmers to relocate their plantations into woodlands.

A 2016 study also found that aerial spraying was costly and inefficient compared with other methods. Planes had to spray 32 hectares in order to achieve a 1-hectare decrease, and the authors estimated spraying cost $2400 per hectare, meaning it cost about $57,000 to eliminate a single hectare of coca.

The government has not said how it will respond to the recent court ruling. In the meantime, it is facing other lawsuits aimed at blocking aerial spraying, brought by local coca growers who argue the government has not lived up to promises made after the settlement of Colombia’s long civil war to help them transition to other livelihoods. But Gabriel John Tobón Quintero, a specialist on environmental and rural studies at the Pontifical Xavierian University, believes the government will eventually figure out a way to follow through on its plan to resume aerial spraying. “The political decision,” he says, “has already been made and announced months ago.”