The research, used to help avoid a ban, claimed ‘severe impacts’ on farming if glyphosate was outlawed

Monsanto secretly funded academic studies indicating “very severe impacts” on farming and the environment if its controversial glyphosate weedkiller were banned, an investigation has found.

The research was used by the National Farmers’ Union and others to successfully lobby against a European ban in 2017. As a result of the revelations, the NFU has now amended its glyphosate information to declare the source of the research.

Monsanto was bought by the agri-chemical multinational Bayer in 2018 and Bayer said the studies’ failure to disclose their funding broke its principles. However, the authors of the studies said the funding did not influence their work and the editor of the journal in which they were published said the papers would not be retracted or amended.

Glyphosate is sold by Bayer as Roundup and is the world’s most widely used weedkiller. The World Health Organization’s cancer agency, the IARC, declared that glyphosate was “probably carcinogenic to humans” in 2015 but several international agencies, including the European Food Safety Authority (EFSA), subsequently came to opposite conclusions.

Last year courts in the US ordered Monsanto to pay damages of up to $2bn (£1.5bn) to individuals with cancer and faces many more lawsuits. Bayer said it “stands fully behind its glyphosate-based products”.

The new revelations centre on studies published in 2010 and 2014 by researchers at ADAS, an agricultural and environmental consultancy in the UK. The analyses concluded “the loss of glyphosate would cause very severe impacts on UK agriculture and the environment”. They suggested a 20% fall in wheat and rapeseed production. However, other researchers at another consultancy, the Andersons Centre, said: “[We] believe that this may be rather high.”

Glyphosate weedkiller allows planting without ploughing, which helps stop carbon being released to the atmosphere. The ADAS research indicated a 25% increase in greenhouse gas emissions – a rise of 12m tonnes a year – if glyphosate was banned.

The ADAS research was used by the NFU in lobbying against an EU ban in 2017 when the renewal of the licence for glyphosate was being considered. The industry lobby group, the Glyphosate Task Force (now renamed the Glyphosate Renewal Group), also used the research, as did the Crop Protection Association.

Despite a petition from 1.2 million citizens calling for a ban, the pesticide licence was renewed for five years. However, this was far shorter than the 15 years that had been sought.

The secret funding of the ADAS studies was uncovered by a German transparency campaign group, LobbyControl. In December, LobbyControl revealed two pro-glyphosate German studies that were partly funded by Monsanto and published in 2011 and 2015 without the funding being declared.

“This is an unacceptable form of opaque lobbying,” said Ulrich Müller at LobbyControl. “Citizens, media and decision-makers should know who pays for studies on subjects of public interest. The studies also used very high figures for the benefits of glyphosate and for possible losses in case of a ban. These extreme figures were then used to spin the debate.”

The tendency of the results of scientific studies to favour their funders – called funding bias – is widely recognised in research on chemical toxicity, tobacco and pharmaceutical drugs.

A spokesman for Bayer said the company always disclosed its funding of third-party scientific publications. “The lack of reference to the funding of these studies does not meet Bayer’s principles,” he said.

He added: “Glyphosate-based herbicides have been used safely and successfully for more than 40 years. They are one of the most thoroughly studied products of their kind. We have no reason to doubt the methods, content or results of the studies conducted by ADAS.”

Sarah Wynn, at ADAS and one of the authors of the studies, said: “As with other companies in our field, it is entirely normal for external organisations to fund research studies. However, it has always been our core principle that our research is never influenced in any way by those that fund us.” ADAS is now leading another project on glyphosate that was partly funded by Monsanto.

Leonard Copping, editor of the journal Outlooks on Pest Management, in which the studies were published, said: “The authors did not advise me of the source of the funding. For this reason it was not disclosed. Conflict of interests is important but not relevant in this case. The papers will not be amended or retracted.”

However, following an enquiry from the Guardian, the NFU has amended its glyphosate material. “We are happy to add a line to the online article stating that the research on this occasion was funded by Monsanto,” said an NFU spokesman.

Bayer said farmers around the globe rely on glyphosate to provide enough food for the world’s growing population. But campaigners claim Monsanto has defended the product by ghostwriting research papers for regulators and using front groups to discredit critical scientists and journalists. In 2017, the Guardian revealed that EFSA based its recommendation that glyphosate was safe on an EU report that copied and pasted analyses from a Monsanto study.