To the Editor: In his exploration of the health advocacy potential of modern clinicians, Gruen1 observes that the public first needs to be convinced that “the profession has its own house in order”. Unfortunately, one room in that house accommodates one of the serious health threats identified by the author: terrorism. Currently, over 95% of the world’s radiopharmaceuticals are generated from highly enriched (bomb-grade) uranium (HEU), an unnecessary nuclear weapons proliferation hazard.2 Prompt conversion of the global medical isotope supply chain to low enriched uranium (LEU, containing less than 20% uranium 235, so not viable for weapons production) is technically feasible.3 Clinicians are thus uniquely placed to advocate conversion to the use of LEU, while pressuring their imaging and isotope providers to end reliance on HEU, thereby blocking one of the most vulnerable pathways to producing a “terrorist bomb”.

But, as Gruen suggests, we can do even more through “collective advocacy” to address the much larger nuclear threat: that is, the 26 000-plus nuclear weapons remaining in the arsenals of Russia, the United States, the United Kingdom, France, India, Pakistan, Israel, China and North Korea. While a sophisticated terrorist group armed with home-manufactured nuclear weapons could devastate a few cities, the existing nuclear-armed states have the capacity to destroy between tens and thousands of urban centres and their populations within a few short hours.

Worse still, recent research indicates that 100 Hiroshima-sized (ie, “small”) nuclear weapons exploded on major cities would be capable of precipitating a “nuclear winter” that could persist for 10 years.4 The dispersal of carbonaceous material into the stratosphere from major urban firestorms could dramatically reduce terrestrial sunlight, lower surface temperatures by several degrees, shorten the growing season, reduce rainfall and trigger global famine. One billion deaths from starvation is a realistic assessment of the consequences.5 Such a catastrophic scenario is within the firepower capacity of all currently nuclear-armed nations except North Korea.

A new generation of medical students and young physicians has launched several initiatives over the past few years to challenge this threat, including the Nuclear Weapons Inheritance Project and Target X (http://www.ippnw-students.org). Most recently, International Physicians for the Prevention of Nuclear War launched the International Campaign to Abolish Nuclear Weapons (http://www.icanw.org), whose goal is to establish a nuclear weapons convention to eliminate all nuclear weapons once and for all.

By ending our reliance on bomb-grade HEU in medical imaging, we can certainly begin to put our own house in order. But let’s also follow Virchow’s lead: let’s “engage with the broader social concerns that cause illness and harm”,1 get active for our patients’ — and our own — wellbeing, and help prevent a global nuclear pandemic.