By David Ozonoff

Annual Reports from governmental bodies aren’t often significant, much less classic, public health documents. By design they are confined to summaries of an agency’s work over a year’s time and they often don’t even appear until two or more years later. Such was the case for the Annual Report of the Chief Inspector of Factories in Great Britain for the year 1947, which didn’t appear until 1949. Its author was the Chief Inspector himself, a pioneer in occupational health by the name of E. R. A. Merewether.

Originally a general practitioner, Merewether found his way into public health after World War I through tuberculosis work. TB was then the Great Scourge, essentially incurable and disproportionately affecting the poor. Any identifiable and remediable risk factor for TB attracted considerable attention, and exposure to dusty conditions at work was high on the list of suspects. By 1927 Merewether was turning his attention to the workplace environment.

Inhalation of pure silica or silica in talc was a known risk factor for TB, so Merewether began looking at talc workers. Asbestos fiber was another occupational hazard high on the list of possible factors so Merewether had begun to worry about asbestos textile workers. Scarring of the lungs in asbestos workers had been reported since the turn of the century, but all of the few autopsied cases were complicated by pneumonia or other pathological processes, making it difficult to tell if the asbestos associated scarring was a cause or an effect of previous infection, which asbestos had potentially made more likely. While posted to Scotland Merewether met Glasgow’s Medical Officer, H. E. Seiler, who in 1928 reported a “pure” case of pulmonary fibrosis in an asbestos worker: there was no complicating pneumonia or other co-morbidity such as TB. This prompted Merewether, working at the British Factory Inspectorate, in collaboration with an industrial engineer, C.V. Price, to publish the first epidemiological study of the asbestos industry in 1930.

Merewether and Price examined 363 workers involved in opening, carding, stripping, grinding, spinning and weaving in asbestos textiles mills in the UK. The results were dismaying. One in four of the workers had signs of a serious respiratory disease, by then called asbestosis. If they had worked at the trade for more than 20 years the proportion was 80%. In their Report, Price added to the medical findings with a complete description of how the dust hazards could be prevented, including the important element of warning workers of a “sane appreciation of the risk,” and noted that the asbestos textile industry was not the only venue for exposure. Significant hazard could be expected wherever asbestos dust was generated, including shipbuilding, electrical work and insulation work. (Report on effects of asbestos dust on the lungs and dust suppression in the asbestos industry, London:, His Majesty’s Stationery Office, 1930). Asbestos textile work was a public health catastrophe. Within a year Parliament passed legislation to suppress dust and require periodic medical exams.

The 1930 Merewether and Price Report was a British government document, but its medical findings were published simultaneously in a US industrial medical journal (Merewether, “The occurrence of pulmonary fibrosis and other pulmonary affections in asbestos workers,” J. Ind. Hyg. 12:198-222; 239-257, 1930). From that point on, asbestos dust was widely recognized as a primary cause of a particular kind of lung scarring, asbestosis. But there was worse to come.

The first wave of asbestos exposure was so heavy that workers died young, suffocating from lungs so scarred they could no longer move in and out nor pass oxygen to the blood. But as exposures decreased workers began to live longer and in the process unmasked a longer latency disease, lung cancer. Asbestosis could carry its victims off in a decade but lung cancer usually took 15, 20 or more years to develop. In the 1930s it was a relatively rare disease, although extremely deadly, as now. Beginning in the mid 1930s, sporadic medical reports noted the unusual circumstance of a rare disease (lung cancer) coinciding with an even rarer occupational one, asbestosis. By 1942, When Wilhelm Hueper published the first textbook on occupational cancer (WC Hueper, Occupational Cancer and Allied Diseases, Springfield, IL, Chas. C. Thomas, 1942), enough cases had been reported for him to devote over 7 pages to the relationship of lung cancer and asbestosis. Additional cases continued to be reported, including among those who used asbestos products rather than manufactured them continued to appear. It was in this context that Merewether’s Annual Report of the Chief Inspector of Factories for the Year 1947 appeared (published in 1949).

By then the compensation system had produced Registries of deaths from various dust diseases, including silicosis and asbestosis. After noting that asbestosis deaths had leveled off in the 1940s, Merewether reported on a special inquiry into the relationship of asbestosis and lung cancer. In the 22 years preceding the Annual Report there were 235 deaths ascribed to asbestosis at the time of death or for which asbestosis was proven at autopsy. 31, or 13.2%, of these were associated with cancer of the lungs or pleura. By comparison, the proportion of silicosis deaths associated with lung or pleural cancer was only 1.32%, about the same proportion as lung cancer deaths in the general population.

Merewether’s findings were immediately reported in an Editorial in the Journal of the American Medical Association (JAMA), a medical publication received by over half of licensed physicians in the US by virtue of their membership in the AMA. While unsigned, the Editorial is widely believed to have been authored by Hueper, the pioneering occupational cancer epidemiologist and textbook writer. Under the headline, “Asbestosis and Cancer of the Lung (JAMA, 140:1219-1220, 1949)” the Editorial cited Merewether’s results and then reviewed in detail the prior case reports, concluding that lung cancer was a result of pulmonary asbestosis.

As a result of Merewether’s analysis, the asbestos – cancer connection was explicitly stated in the highest profile medical journal in the United States. Because of the Journal’s prominence and wide dissemination, it also marks the point where it can truly be said, beyond doubt, that medical science generally recognized that asbestosis was a cause of lung cancer.

Not bad for a lowly “Annual Report.”

David Ozonoff, MD, MPH is a Professor of Environmental Health at Boston University’s School of Public Health. Under the pen name Revere, he blogged at Effect Measure from 2004 – 2010.