Would that we had the energy.

It was back in the early 1980s. My thoracic surgical colleague asked if I could help him with one of his patients who had developed breathing problems after a lobectomy. The man was on a respirator, the consequence (it turned out) of a post-operative attack of asthma. By the time he had recovered, the pathologist reported the resected lobe to have contained not cancer but pneumoconiotic massive fibrosis. By chance, I happened to be researching miners' diseases, so I asked him which coalmine he had worked in. He replied that he had been a shale miner, an occupation in which pneumoconio-sis was thought not to have occurred. Well, now it seemed it had, and a trawl through the pathology records of the local hospital led to the discovery of a number of other examples, some of which had been associated with lung cancer. This coincided with the early-1980s oil crisis. The US government was looking towards exploiting the vast oil reserves locked in shale in the Rocky Mountains in Colorado and was anxious to make an assessment of any risks to workers. Exploitation of oil shale had started after the discovery of deposits in Scotland in the mid-19th century by James Young, a Glasgow chemist. This had led to the 1876 description by Joseph Bell, an Edinburgh surgeon and Conan Doyle's model for Sherlock Holmes, of shale oil as a cause of skin cancer among the workers producing the paraffin and, later, among spinners exposed to it in the Lancashire cotton industry. Could inhalation of shale dust be a cause of lung cancer? A carefully worded case report was drawn to the attention of the US National Institute of Occupational Safety and Health. A search through the archives of the oil industry revealed the presence , in large boxes, of manuscript records of the original oil shale industry's Provident Fund set up in 1960 before the industry finally closed; these included names, addresses and dates of birth of all employees together with records of their jobs within the industry—the answer to an epidemiologist's prayer. A programme grant from the US Department of Energy followed, and the health consequences of working in the industry were described, 20 years after it had ceased to exist. It did not cause lung cancer. I was reminded of this story, which illustrates an advantage in epidemiology to having one foot in clinical medicine, by recent …