If humanity has an epitaph, it might read something like this: “Knackered by the things we missed.” It is true that several existential threats are widely known and widely discussed. But some of the greatest dangers we face appear on almost no one’s radar.

How often have you thought about this one: spreading sewage sludge on farmland? I would guess very few would include it in their top civilisational hazards. Despite the best efforts of a handful of us, it trundles on, unknown to most. Surprising as it may seem, new research suggests that it could help call time on us.

In principle, we should return human waste to farmland, as it is rich in nutrients. But thanks to years of regulatory failure, this waste in many countries is now contaminated with a vast range of toxins. Some come from runoff into the sewers: from roads, building sites, homes and commercial premises. But what we are now discovering is that a great volume of contaminants is introduced deliberately.