One of the UK’s largest DIY retailers is reviewing the sale of Roundup weedkiller products amid mounting concerns about their use, after a US jury found that the herbicide had caused a terminally ill man’s cancer.

The manufacturer of the weedkiller, Monsanto, has insisted that British consumers are safe to continue using Roundup products, which are widely sold at DIY stores and used by British farmers. But a spokesperson for Homebase said it would be reviewing its product range after the ruling in California.

A spokesperson for B&Q said it had already been undertaking a broader review of all garden products in an attempt to manage the range responsibly.

On Friday, Dewayne Johnson, a 46-year-old former groundskeeper, was awarded $289m (£226m) in damages from Monsanto after a jury ruled that Roundup had caused his terminal blood cell cancer and the company had failed to warn him of the health risk from exposure.

The jury also found that Monsanto had “acted with malice or oppression” and ruled that it knew or should have known the weedkiller was dangerous. During the trial, the court heard that Johnson may have just months to live and his wife had been forced to work two jobs to help pay for his treatment for non-Hodgkin’s lymphoma.

Facebook Twitter Pinterest Dewayne Johnson was awarded £226m in damages from Monsanto. Photograph: Josh Edelson/AFP/Getty Images

Monsanto’s vice-president, Scott Partridge, said on Friday that hundreds of studies had shown that glyphosate, one of the world’s most widely used herbicides and a key ingredient of Roundup, does not cause cancer. Monsanto would be appealing against the jury’s verdict, he added.

“It is completely and totally safe, and the public should not be concerned about this verdict. It is one that we will work through the legal process to see if we can get the right result. The science is crystal-clear,” he said.

“The jury made a decision, but the decision that a jury or a judge makes has to be based on the weight of the evidence, and the overwhelming weight of the evidence that went in the trial was that science demonstrates glyphosate is safe; there’s no credible evidence to the contrary.”

The German pharmaceutical group Bayer, which owns Monsanto, said: “Bayer is confident, based on the strength of the science, the conclusions of regulators around the world and decades of experience, that glyphosate is safe for use and does not cause cancer when used according to the label.”

The scientific world, however, has raised doubts about glyphosate. A ruling in 2015 by the World Health Organization’s international agency for research on cancer (IARC) classified glyphosate as “probably carcinogenic to humans”.

Campaigners are now calling for a review of pesticide regulations in the UK after the case, saying that glyphosate poses a risk to public health, soils and the environment.

More than 2m hectares (5m acres) of farmland across Britain are treated with glyphosate annually, according to a study of government data by Oxford Economics.

Emma Hockridge, head of policy at the Soil Association, described the ruling as a “dramatic blow” to the pesticide industry. “This is a landmark case, which highlights not only the problems caused by glyphosate, but also the whole system of pesticide use. We need to urgently change our systems of weed control to stop relying on herbicides,” she said.

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But the National Farmers’ Union (NFU) said use of the pesticide should not be reviewed after the court ruling. Glyphosate’s licence was extended for five years in Europe by the EU last November, despite a petition by 1.3 million EU citizens calling for a ban.

The NFU’s deputy president, Guy Smith, who is also an active livestock and arable farmer, said: “We’re in the same place as when they ruled it was safe to use. We don’t think the opinion of a Californian jury should change that.

“Its most common use in UK farming is to kill weeds in the autumn before seeds are planted. On my land right now, I’m spraying it today. Without glyphosate, I would have to plough and cultivate the land. That would use extra diesel, which is bad for the soil and the environment.”

A spokesperson for B&Q said: “We continually aim to manage our garden products responsibly and have a record of acting ahead of legislation where appropriate; we led the way in removing three pesticides in 2013 and neonicotinoids from our flowering plants in 2018. We offer alternatives to glyphosates, and we are currently undertaking a broader review of all our garden products.”

A spokesperson for Wilko said it was not reviewing Roundup products, but added that it was “watching the situation carefully and will respond appropriately.”

The Department for Environment, Food and Rural Affairs, which is responsible for pesticide regulation, said: “Decisions on the use of pesticides should be based on a careful scientific assessment of the risks.”