Colombia wants to resume spraying a toxic chemical to fight cocaine. Critics say it's too risky

Two AT- 802 planes fumigate coca fields in San Miguel, 400 miles south of Bogota, Colombia, on Dec. 11, 2006.

Bogota (CNN)Colombia wants to resume aerial spraying of a toxic chemical in remote rural areas to stop the growth of coca, the chief ingredient of cocaine -- despite stark health concerns.

The spraying typically uses glyphosate, a chemical that the World Health Organization has linked to cancer and classified as "probably carcinogenic to humans." Colombia's government claims it can be done safely -- but critics argue it's dangerous and ineffective.
In 2015, then-president Juan Manuel Santos halted the practice but his successor President Ivan Duque -- with prodding from US President Donald Trump -- is now pushing for a hearing before Colombia's environmental licenses authority, in order to obtain permission to restart the controversial practice.
Duque's government says eradicating coca crops will limit trafficking and violence by drug gangs, which it has blamed for seven massacres in August that killed 36 people, including several children.
    Cocaine production is currently around an all-time high in Colombia. According to the latest UN drug report, based on 2017 figures, Colombia produces around 70% of the world's cocaine, and while the crop size has declined slightly, the output is actually growing because of better productivity.
    Cocaine "is the principal stream of revenues for the criminal groups that are behind these recent massacres," Colombia's Defense Minister Carlos Holmes Trujillo said on August 24.
    Suspending aerial fumigation had been a "serious mistake," he said.

    'A toxic fog'

    Aerial fumigation allowed authorities to target illegal coca crops in hard-to-reach and often dangerous corners of Colombia.
    The government has pledged that future aerial fumigations will not take place in protected areas and national parks, Rafael Guarin, President Duque's national security advisor, told CNN, and only function within the parameters set by the environmental license authority.
    A plane sprays coca fields in San Miguel, on Colombia's southern border with Ecuador on Dec. 15, 2006.
    Jose David Hernandez, a farmer in rural Antioquia, who grew coca until 2018, remembers the aerial fumigations in 2003 and 2004.
    The herbicide would fall on the field like a toxic fog and cause irritation so painful that workers' skins would start bleeding, he said.
    Tens of miles away from the closest hospital, farmers would try to heal the wounds with an artisanal ointment that would bleach the skin. To this day, Hernandez told CNN his arms and legs have whiter spots where he applied the ointment trying to heal his wounds.
    The scientific debate on the dangers of glyphosate is ongoing. While the WHO has linked glyphosate to cancer, the US Environmental Protection Agency "find that there are no risks of concern to human health when glyphosate is used in accordance with its current label."
    Monsanto, the US company that manufactures glyphosate, recommends that users wear personal protection equipment. But in Colombia, the herbicide is often sprayed over a vast amount of land often without warnings to the workers in the fields, including farmers tending to the coca plants or others cultivating legal crops nearby.
    Critics of aerial fumigations also say there are risks beyond the potential for cancer, including concerns over damage to delicate plant life in a country regarded as one of the most biologically diverse nations on the planet.
    In 2008, Ecuador brought a case to the International Court of Justice alleging Colombia's aerial spraying near their joint border was harming its own natural environment. The court sided with Ecuador.

    A complicated political history

    Public health concerns are only part of the calculation.
    Duque's opponents see the reintroduction of spraying as a bad policy at the worst possible time, and fear the resumption could alter the delicate balance that followed the end of the civil war in 2016.
    Santos's ban on aerial fumigations had a strong political component. At the time, his government was negotiating with the far-left guerrilla group Revolutionary Armed Forces of Colombia, or FARC, to bring an end to a conflict that had ravaged Colombia for more than five decades.
    FARC used to control large swathes of rural territory and profit from the cocaine trade. The aerial fumigations specifically targeted FARC's core strength.
    A police officer stand in front of herbicide containers at an anti-narcotic police base in Villa Garzon, near the southern Colombia's border with Ecuador, on Dec. 15, 2006.
    Ending the fumigations was therefore a core part of the peace deal that Santos signed with the FARC in 2016 -- although the agreement left some wiggle room for the government -- while the Supreme Court a year later ruled in favor of an indigenous community that argued glyphosate was a health risk.
    The Colombia Constitutional Court -- a separate body that determines if laws are in accordance with the constitution -- last year ruled the government would need to show that spraying glyphosate was safe before aerial spraying could resume and left it to environmental licenses authority to determine when those conditions were met.

    Does it even work?

    Critics of aerial fumigation dispute its effectiveness as well, saying the practice does little to reduce cocaine production.
    Aerial fumigations destroy all crops in a targeted area, not just coca plants but also agricultural products such as plantains, maize, yucca that farmers often grow in the same parcels, as the Colombian constitutional court recognized in a 2015 case.
    "I can tell you from direct experience, if a farmer doesn't want to grow coca, and the Army come and spray over his field with produce, I guarantee the first thing the farmer will do is start growing coca, because what else can he do once all his produce is destroyed?" Hernandez told CNN.
    Toby Muse, a cocaine expert and the author of Kilo: Inside the Deadliest Cocaine Cartels, told CNN that destroying coca crops through aerial fumigations was an ineffective response: "The solution is always going to be working with coca farmers to produce an alternative to growing coca."
    Such programs of crop substitution saw thousands of Colombian farmers swapping coca for coffee, cocoa and other crops following the 2016 peace agreement.
    Hernandez, the farmer, took advantage of such a program to stop growing coca and now oversees the implementation of other crop substitutions on behalf of the National Confederation of Coca, Marijuana and Poppy Growers COCCAM, which supports farmers who switch to legal crops.
    "Eradication by substitution is much more effective; when you spray pesticides, 70 to 80% of the same area goes back to re-growing coca within the same year," Hernandez said.
    But the momentum behind crop substitution has been lost in recent years.
    In the months following the peace agreements, there were great hopes of roads, bridges and infrastructure connecting the remote rural regions of Colombia to the main urban areas, and by doing so providing mar