US biotech firm Monsanto has been ordered to pay US$289M in damages after a jury found the company liable for a terminally ill man’s cancer, allegedly stemming from Monsanto’s glyphosate-based Roundup herbicide.

The jury determined that Dewayne Johnson, 46, had contracted cancer from Roundup during his years of work as a groundskeeper and that Monsanto – acting with “malice and oppression” – had failed to warn him of the chemical’s possible health hazards, wrote The Guardian on 11 August.

Mr Johnson’s lawyers argued that Monsanto had opposed science and targeted researchers and academics who had spoken publically about glyphosate’s possible health risks.

During the month-long trial, Johnson’s attorneys presented internal Monsanto email which they said demonstrated how the firm had ignored expert warnings, sought favourable scientific analyses and helped “ghostwrite” research encouraging continued Roundup use, according to The Guardian.

Glyphosate is the world’s most commonly used herbicide and Roundup was registered in 130 countries and approved for use on more than 100 crops – such as soyabeans and canola.

However, in 2015, the World Health Organization’s International Agency for Research on Cancer (IARC) found that glyphosate was “probably carcinogenic to humans”.

Monsanto vice president Scott Partridge dismissed any link between glyphosate and cancer and said the company would appeal the verdict which “doesn’t change more than four decades of safe use and science”.

Partridge claimed that the IARC, whose research was quoted to persuade the jury of the link between glyphosate and cancer, was corrupt and that the organisation performed no testing or analysis and “simply rendered an opinion”.

A report by Reuters in October 2017 revealed that the IARC had dismissed and edited findings from a draft of its glyphosate review that did not support its final conclusion.

Partridge further argued that the internal company emails presented by Johnson’s lawyers had been taken “completely out of context”.

Monsanto, which was acquired by Bayer in June, was facing more than 4,000 cancer lawsuits in the USA, with the next scheduled to begin in St Louis, Missouri, later in the autumn, wrote The Guardian.

Reuters reported on 13 August that Bayer’s shares had plunged by more than 10% following the Monsanto fines.