In​ 2018, the German company Bayer bought the US agrochemical giant Monsanto, inheriting not just its vast portfolio of seeds and pesticides, but also thousands of lawsuits alleging that glyphosate, the active ingredient in Roundup herbicide, causes cancer. Since it was patented in the 1970s, eight billion tonnes of Roundup have been sprayed on fields around the world. It’s the main weedkiller used on 80 per cent of genetically modified crops, as well as many non-GM crops, and it is also a drying agent, which makes it particularly useful in wet countries such as Britain.

Roundup was originally advertised as a less toxic herbicide – even as an environmental choice. It would kill all plants on a site at the roots, meaning a clear field for sowing. In the 1990s, with its patent set to expire, Monsanto succeeded in creating genetically modified soybeans resistant to glyphosate. Now the fields could be sprayed at any time without harming the crops. ‘Roundup Ready’ seeds were released in 1996; in the following two decades, glyphosate use increased fifteen-fold in the US. Concerns about its safety began to surface in the early 2010s. In 2014, a group of British scientists warned that the glyphosate present in food appeared to harm gut bacteria, and that the ‘inert’ ingredients in herbicides such as Roundup, acting in combination with the glyphosate, significantly increased its toxicity. In 2015, the World Health Organisation’s International Agency for Research on Cancer published a report concluding that glyphosate was ‘probably carcinogenic’.

Since then, further studies have pointed to the increased incidence of lymphomas among people, such as farmers and gardeners, who use glyphosate in their work, as well as impaired lung, kidney and liver function. Tests on mammals in captivity have shown an increased risk of cancers from even limited exposure (not to mention the other disastrous effects that glyphosate has on the ecosystems it enters). A recent study in Argentina suggested that glyphosate resistance in bacteria is fuelling antibiotic resistance. Despite these findings, and increased restrictions on glyphosate in many places around the world, the use of glyphosate herbicides on British and American farms has increased in the last decade, encouraged in part by the trend in sustainable farming for ‘regenerative’ agriculture, which advocates limited soil disturbance and therefore frowns on the mechanical destruction of weeds.

In the US, class-action lawsuits have piled up. When Bayer acquired Monsanto, it settled more than 100,000 cases; some sixty thousand others remain unresolved. In 2019 a jury awarded $2.1 billion in compensation and damages (then reduced to $87 million) to an American couple who claimed that Roundup had caused their non-Hodgkin’s lymphoma. Bayer announced it would no longer use glyphosate in its garden products in the US. Diquat, the replacement chemical chosen by Bayer, was the subject of a recent study at Suining Central Hospital in China, which found that it was even more toxic than glyphosate, causing ‘multiple organ dysfunction syndrome’ in rodents. The US Environmental Protection Agency has so far resisted attempts to restrict either diquat or glyphosate. Diquat is banned in the UK, the EU and many other countries besides (including China), but this doesn’t prevent the Swiss company Syngenta from manufacturing diquat-based herbicides in the UK for export to countries, such as Brazil, with weaker protection laws. Brazil, which alongside the US has the highest rates of both glyphosate and diquat use globally, uses the chemicals on major export crops such as soya, coffee and sugarcane. It is the main supplier of soya and coffee to the UK.

In a controversial ruling in 2023, the European Food Safety Authority said that the available data didn’t incontrovertibly prove the carcinogenic effects of glyphosate in humans. The European Commission extended its authorisation of the chemical for ten more years. (The previous extension of the licence was criticised by the European Parliament for relying on an assessment plagiarised from herbicide manufacturers.) The British Health and Safety Executive will soon decide whether to approve glyphosate for a further fifteen years. The problem is that farmers and commercial gardeners depend on the stuff, and Bayer has used that dependency to muscular effect – lobbying, commissioning favourable studies and threatening to halt commercial activity in countries that seek stricter rules.

As Jennifer Clapp shows in Titans of Industrial Agriculture (MIT, £38), over the last two centuries farmers in the West have become wedded to a handful of big companies producing machinery, seeds, fertiliser and pesticides. The machinery came first, with a few enterprising companies monopolising the market in the mid-19th century. There were attempts to resist. Clapp discusses the Grange, an American farming coalition, founded in 1867, which copied the structure of the Freemasons to build a national organisation based on local chapters. The aim was to better educate farmers and to improve their bargaining power. They secured the passage of several laws to regulate railroad transportation and grain storage rates, lobbied to be able to buy farming machinery at wholesale prices, and set up rival cooperatives to manufacture their own ploughs. But they lacked the funding or political power to compete with the big commercial companies, which, once they reached market saturation in the 1880s, turned on each other in the so-called Harvester Wars. As each sought to outdo the others in advertising, bribery and sabotage, the cost of sales became unsustainable and J.P. Morgan intervened, in a manoeuvre typical of the Gilded Age, to broker a merger of the five largest firms: the International Harvester Company began trading in 1902. Despite attempts to place limits on monopoly power through the Sherman Antitrust Act of 1890, the new business now controlled 85 per cent of the US market for harvesters.

A similar pattern can be seen in the history of the fertiliser industry. The rush for nitrogen fertilisers that began in the 1840s culminated in the War of the Pacific (1879-84), during which Chile fought Bolivia and Peru for control of guano-rich coastal territory. Hundreds of thousands of labourers, many of whom had been transported from China, mined sodium nitrate or dug guano in South America for export to North America and Europe. As the environmental historian Edward D. Melillo has shown, the scale of the 19th-century nitrogen trade was such that, in a matter of decades, the Earth’s nitrogen cycle had been transformed. Before the fertiliser boom, nitrogen cycles were localised, self-sustaining systems. Guano mania changed that. Depriving millions of seabirds of their nesting habitats and local communities of an agricultural resource, nitrogen raided from millennia-old deposits in the Americas was now sent across the world to improve the fertility of Europe’s soils, which had been degraded by intensive farming. From there nitrogen made its way into the food, sewers and rivers of European countries, and was dispersed into the sea. After it began to be produced synthetically in the early 20th century, the excess nitrogen released into waterways began to cause toxic algal blooms and marine dead zones.

The Green Revolution of the 1950s and 1960s, when American institutions promoted the industrialisation of agriculture around the world, is often taken as the starting point of the modern food system. In most countries this meant the adoption of new farming technologies and seed varieties, leading to a rise in the yield for staples such as wheat, rice and maize. It also meant, increasingly, a farming monoculture, as self-reliant, small-scale farms planting a vast array of cultivars were replaced by larger systems planting seeds provided by the same manufacturers. Clapp goes against the consensus in arguing that the starting point was in fact much earlier, though she does note the role of multinationals and philanthropic organisations such as the Rockefeller Foundation in supporting America’s Big Agriculture drive. Monsanto and other companies anticipated the sales that would follow if they could enter markets such as Mexico and the Philippines, and offered financial backing to associated research centres.

What Clapp overlooks, however, are the countervailing currents. In the immediate postwar years, there were significant US-led efforts to redress land inequality, such as the Land to the Tiller projects carried out in Japan, Taiwan, South Korea and Italy, and later in the Philippines and Vietnam. Daniel Immerwahr’s Thinking Small: The United States and the Lure of Community Development (2014) describes the mixed outcomes of such projects around the world. When the allied powers arrived in Japan at the end of the war, for example, the country was on the brink of a food crisis, with rice in dangerously short supply and many reliant on the black market to survive. In a bid to avert mass starvation, civil unrest and a rise in support for the Japanese Communist Party, the government oversaw the transfer of two million hectares of farmland from landlords to cultivators through compulsory purchases and discounted resale.

While bans on glyphosate and diquat may eventually be introduced, companies will be hard at work developing their replacements. Icafolin, a novel herbicide developed by Bayer, is slated to go on sale in Brazil and Australia in 2028; applications for approval in the US, Canada and the EU are underway. Studies on its health and ecological impact have yet to be completed. Meanwhile, farmers are finding ways to reduce their reliance on industrial inputs. Through seed-saving and community seed banks, there has been a revival of diverse cultivars and varieties of heritage crops. As alternatives to patented seeds that prioritise yields, these have other useful properties such as resistance to drought, frost, disease or pests. The cost of commercial fertilisers, a third of which are shipped through the Strait of Hormuz, has soared since the start of the Iran conflict. Natural methods of making soil more fertile – from fermentation to growing crops which can be used as ‘green manure’ – are an alternative to expensive imports. Holistic approaches to weed management will be crucial if a more resilient food system is to flourish in the gaps of Big Ag’s dominance.