Scientists suspected a link between asbestos and lung cancer as early as 1918.
The news that exposure to asbestos fibres might cause cancer were confirmed in a series of medical studies in the 1920s. But it was a test case in the US Supreme Court in 1969 - half a century later - that impacted on the money men and the politicians. The result was the cause of the near collapse of the Lloyds of London reinsurance market in the early 1990s, and the scandal which I wrote about in my book Broke: Who Killed the Middle Classes?
The case concerned a former asbestos worker called Clarence Borel, and was brought by his widow, Thelma. He had been told so little about the little white asbestos fibres that were to kill him that he used to bring them back to decorate the Christmas tree at home.
The Supreme Court found in favour of Thelma Borel, and as a result, the asbestosis claims began to mount and the ultimate insurers – those with the unlimited liability – turned out to be some of the Lloyds syndicates which specialized in reinsurance. In 1979, the US courts ruled that the insurers were liable for all the years between when the workers were exposed and when they fell ill.
I tell this story because it illustrates how long it takes for the dangers of any profitable process filtering through to the policy-makers and financiers. In the case of asbestos, they were able to finesse it for half a century. Thanks to global communication, it won't take so long this time - but it seems to me highly unlikely that the damage by fracking won't beat the damage from asbestosis by a long way.
The costs in compensation will eventually be huge, but it is the political shift that concerns me here.
That makes yesterday a surprisingly important day. So you might as well remember the date, 19 July 2013 (also, by the way, my father's 80th birthday). It was the day that the coalition announced tax breaks for companies to bring their shale gas mining or fracking techniques to the UK.
As a result, it will turn out to be the day that marks a major radicalisation and popularisation of the green movement. It is the day that will change everything - when every politician will be asked in a decade or so: where were you? What did you say?
Of course I may be wrong, but the series of class actions in the USA against the shale gas industry suggests that I'm not. In any case, for months, or maybe years, nothing much will change. But the first health scares, the first scandal of poisoned children or unborn children, will change everything.
Because the UK is small and densely populated. You can't pump millions of gallons of chemicals for each shale site, especially an inflammable and poisonous chemical like alpha-methylstyrene, under ground in the UK - and certainly not London, Boris - without it turning up in the water supply, then the food we eat, and then our bones. You can't do it without it affecting children's health.
The people who fondly believe you can are likely to be fantasists, dreamers - and politicians.
Not to mention the earthquakes.
Then we will ask who did the long-term studies on the effects on the water table, and find it was barely carried out at all. We will also ask why the polluting companies were given special tax advantages, and will find it was to delay for a few more years the investment that was required in renewable energy.
We will draw parallels with the rise of asbestosis, where the basic effects were known by 1918, and nod our heads wisely and miserably.
The green movement is currently stuck. It lacks the language to break out of its small coterie of middle class supporters. It is politically negligible. But when the health of people's children is at stake, everything changes.
Then people will say that everything in this country comes from the soil, the groundwater and the rocks below, and will ask the politicians responsible why there was so little debate, and why they have such a miserably narrow time horizon that they trash the land for a few more years of gas.
And the politicians will start looking back at their diaries and wonder a little who was right. And finally, exasperated, they will say: but nobody said anything at the time.
It won't actually be true. The truth is that they said nothing themselves. No questions, no debate, no challenge. So remember where you were yesterday - it could turn out to be important.