The International Agency for Research on Cancer has reclassified the herbicide glyphosate, the world's most popular weed killer, as a carcinogen that poses a greater potential danger to industrial users than to homeowners.

On Thursday the French-based research arm of the World Health Organization cited what it described as convincing evidence that the herbicide produces cancer in lab animals and more limited findings that it can cause non-Hodgkin's lymphoma in humans as well.

This new labeling is troubling as the glyphosate-based herbicide Roundup is used in industrial agriculture worldwide and is in fact the preferred weapon for killing Colombian cocaine harvests.

Over the past two decades more than 4 million acres of land have been sprayed to kill the coca plants that produce cocaine.

The ongoing fumigation program has provoked hostility from Colombia's left-wing for years.

Opponents of the fumigation compare the spraying to the U.S. military's use of the Agent Orange herbicide during the Vietnam War.

As part of a deal to put an end to the a 50-year long conflict, leftist rebels in Colombia are currently demanding an end to the spraying of the herbicide as part of any coming peace deal.

The chairman of an expert panel advising the Colombian government on its drug strategy, Daniel Mejia, has explained that the report is by far the most authoritative one on the subject to date and could end up putting an end to the fumigation program.

According to The Associated Press, Mejia, who is also a botanist, said, "Nobody can accuse the WHO of being ideologically biased."

Mejia's own research, based on a study of medical records from 2003 to 2007 and published last year, found higher rates of skin problems and miscarriages in districts targeted by the herbicides.