Fifty years after the Seveso disaster, its legacy must be protected

Fifty years ago, on 10 July 1976, a devastating environmental disaster occurred at the Icmesa chemicals factory in northern Italy. A reactor containing trichlorophenol overheated, and the resulting runaway reaction led to the release of a huge vapour cloud that drifted south over the nearby town of Seveso. Around 35,000 residents suffered the largest exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) ever recorded in what became a turning point for chemicals safety regulations. As local health official Giuseppe Ghetti said at the time: ‘What has happened here will remain in world history.’

The unfortunate truth is that progress in chemicals regulation and process safety has often come at the cost of such accidents and catastrophes. In the aftermath of industrial disasters like Seveso, or Flixborough in the UK or Bhopal in India, scientists have collaborated across disciplines and borders to learn from these mistakes. The Seveso disaster led to the creation of the Seveso directive – Europe’s key legislation to protect against industrial accidents – and its lessons have been exported around the world. Yet today, that legacy is at risk of being forgotten as environmental controls are rolled back in the US and the country severs its international partnerships.

Seveso became a milestone in chemicals regulation, but it also gave rise to the largest study into the effects of dioxin exposure on women. In the immediate aftermath of the disaster, amid confusion and deliberate obfuscation by Icmesa’s management, many residents were not evacuated and hid in their homes for weeks. A team from Desio Hospital set about collecting thousands of blood samples from that population. At the time, there was no method to detect dioxin in blood, and the initial small-scale studies relied on proxies to estimate exposure.

It was another 20 years until those samples could be studied properly. In 1996, a collaboration between those far-sighted physicians and Brenda Eskenazi’s group at the University of California, Berkeley in the US was at last able to do so using methods developed by the US Centres for Disease Control (CDC). With the world-leading CDC facilities, and funding from US and Italian agencies (running the roughly 1000 samples cost $1million (£750,000) alone) the Seveso Women’s Health Study (SWHS) tracked the impact of dioxin exposure over the following two decades.

When events like Seveso happen, society owes a debt to those affected

Projects like the SWHS demonstrate how scientists working together in open, collaborative efforts benefit humanity. They also exemplify the strategic policy approach adopted by the US that sought to position the country as the global leader in science and health. Yet speaking with researchers today, there is a sense of disbelief that the US now seems to be retreating from these roles. In the wake of budget and staff cuts at research agencies, restrictions on foreign collaborations and withdrawal from global organisations, some express doubts that a project like SWHS would get off the ground today.

As the president of the US National Academies of Science Marcia McNutt said recently, the last year in US science policy has been ‘filled with turmoil’. Just last month, a new proposal was published by the US Office of Management and Budgets that would prohibit collaborations with countries deemed adversaries or that are under sanctions – a list that makes many multilateral projects impossible. Partnerships with China are a key part of US chemistry research – but the new proposal would make these much more difficult. More concerning for researchers is the intention to align federally funded research with ‘American values’ by giving political appointees the final say on grants, and the power to terminate them.

These changes are creating deep uncertainty. Researchers report having to pause or postpone projects, and of being reluctant to embark on new collaborations. This disruption may be short-lived, but even a few months’ delay is amplified when projects take years to complete and must coordinate with labs around the world. More worryingly, the changes suggest the doctrine of ‘America first’ means the US is turning inward, withdrawing from the international community and ceding its position of leadership. If that’s true, the community must adapt and respond by strengthening its networks and collaborations – science must transcend borders because diseases and disasters treat all nations the same.

When a tragedy like Seveso happens, society owes a debt to those affected. It falls to scientists to help repay that debt – to learn from our mistakes and apply the lessons so that generations to come inherit a better world. That way, a tragedy like Seveso not only remains in history – it can help change our future.