Wellcome Trust Centre for the History of Medicine at UCL, Euston House, 24 Eversholt Street, London NW1 1AD, UK.
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Rickets |
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Rickets was not a new disease in the 19th century. Descriptions of its physical signs can be found in early Chinese, Greek, and Roman texts. It seems, however, first to have become common in England around 1600, at a time when atmospheric pollution by coal smoke first became severe. Already in the 1650s it was noted that keeping clothes clean was problematic in smoky London.4 At this time, the appearance of rickets as a new disease within recent decades was noted by Daniel Whistler and Francis Glisson, who also described its uneven geographical distribution: commoner in the south and west of the country than in Scotland and the north.5
By the mid 19th century, rickets was widespread throughout urban Britain, as in several north European countries. Contemporaries linked the rise of the disease to the great growth of cities that followed the industrial revolution. They were overcrowded, unplanned, sunless cities, whose peoples lived in dark and overcrowded conditions, meagrely fed, in conditions of poverty. In the space of a century, Britain became an urban country: in 1801, one-fifth of her population lived in towns; by 1901, four-fifths did so. Britains skies became overcast from smoke, both from the great new industries, and from the millions of domestic coal fires kept burning for heating and cooking purposes. Coal consumption soared. The countrys coal output rose from 17.4 million tonnes in 18111815, to 287.4 in 1913. Consumption doubled between 1830 and 1850, and again to 1875.6 Little sunlight penetrated the urban smoke canopy, and it also encouraged women and children to spend their time indoors, out of the constant fall of oily, smoky smuts. For many babies and small children, the physical consequences of sunlight deprivation were compounded by poor diets and misguided childcare practices. The diets of working class women and children too often consisted largely of bread and tea, with sugar and the occasional smear of jam or margarine. Babies of all social classes were generally weaned on papbread and water or bread and milk, depending on local custom; and they were often also kept indoors throughout the winter months. The impact of urban life on the incidence and distribution of rickets was very plain. A survey undertaken by the British Medical Association in the 1880s revealed a sharp distinction between the high incidence of rickets in the great urban conglomerations, and its virtual absence from small towns with populations of less than 5000, villages, and the countryside.7
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John Snow and medical science |
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Snows epidemiology of rickets |
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Justus von Liebig (18031873) was a name to conjure with in the 1850s. An innovative, entrepreneurial German chemist, Liebigs object was to extend the boundaries of chemistry into agriculture, medicine, pharmacy, industryto establish it as the most significant fundamental science for the modern age.12 He was especially influential in Britain, where ambitious groups of young chemists, doctors, and engineers adopted him as an icon for their own professionalizing campaigns. Snows invocation of Liebigs observations on alum and its action on the chemical properties of wheat was, by way of an imprimatur for his own earlier surmise, that the sulphuric acid of alum would destroy the phosphate of lime in wheat, and thus its value in bone formation. Indeed, it was by this time widely accepted that a shortage of phosphate of lime in the diet caused rickets.1,13
Arthur Hill Hassall (18171894) was Londons best known contemporary microscopist and food analyst. He had recently (18511854) published a series of devastating analytical reports on London foodstuffs in The Lancet.14 Science here was again to the fore. Not only was Hassall using the newly rigorous technology of the microscope,15 and the skills of the chemist in making his analyses, but the popular impact of his work had been greatly heightened by sets of diagrams illustrating pure and adulterated foodstuffs under both medium and high-powered magnifications.16 Snows linking of his own analytical technique to Hassalls was intended to demonstrate both the sophistication and scientific credentials of his research methods.
The scrupulousness with which Snow detailed the highest scientific authorities for his chemical and analytical evidence sits oddly with the reticence he displayed in producing statistical or witness testimony for his arguments in respect of eating habits, type of bread consumed, and the distribution of rickets. As regards the latter, he excused himself: as my inquiries have only been of a colloquial nature, I hesitate to mention places and persons. He had not even attempted a correspondence survey, although this was a method employed by other contemporary investigators. He did suggest a design for a comparative statistical inquiry, but had made no attempt to implement it himself. The article thus establishes that alum destroys the bone-hardening factor in bread, and that London bread is highly adulterated with alum. The inference is that a diet composed largely of such bread causes rickets, but the link is not scientifically proven.
Why did Snow publish this incomplete piece of research? Why did he not complete the statistical analysisa task comparable, surely, to his work on cholera and the London water company fields in 18491854?17 The article explicitly states that he thought it better to publish an imperfect inquiry, so that the medical profession might be alerted and the question resolved more quickly. Was he overburdened by his anaesthetic caseload, with the business of earning a living? Or had the chronic ill health and renal disease which he suffered sapped his energy and capacity for a rigorous research inquiry?18 Had he completed it, what would such an inquiry have demonstrated? Could hewould hehave proved his case?
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The geography of rickets |
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Palms analysis began with the recognition that rickets is essentially a form of malnutrition, and he admitted that, it is most natural to think first of food in studying its aetiology. By a process of elimination, he reached the fact that countries immune to rickets enjoyed abundant sunshine and clear skies. Britain, by contrast, suffered grey skies and want of sunshine, compounded in towns by a perennial pall of smoke, and ... high houses cut off from narrow streets a large proportion of the rays which struggle through the gloom. It was in the narrow alleys where the children of the poor played, he noted, that this exclusion was worst, and it was here that most victims of rickets were found. Palm urged investigation of the physiological and therapeutic actions of sunlight: although the action of light on plants had received much attention, he observed, physiological chemistry has yet not much to tell us as to the action of light in animal nutrition. In the early decades of the 20th century, scientific research began to unravel the complex relationship between sunlight and dietary vitamin D in the aetiology of rickets.22,23
Where does Snows observation that children fed home-baked bread were free of rickets fit with the established model of rickets causation? Was it purely fortuitous? It may have been. Merei recorded rickets in Newcastle-on-Tyne in the early 1850s. And it is possible, as Snow himself almost admitted, that those northern diets contained other elements that kept rickets at bay if not milk, then eggs or fish or bacon. Or maybe the medical practices in which he worked lay in areas where, as yet, the pall of smoke was not too dense, and children playing outside did so in sunlight.
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References |
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2 West C. Lectures on the Diseases of Infancy and Childhood. London: Longman, Green, 1854, p. 802.
3 West C. Lectures on the Diseases of Infancy and Childhood. 7th Edn. London: John Churchill, 1884, p. 793.
4 Brimblecombe J. The Big Smoke. A History of Air Pollution in London since Medieval Times. London: Routledge, 1987, pp. 30, 63.
5 Kiple K (ed.). Cambridge World History of Human Disease. Cambridge: Cambridge University Press, 1993, p. 978.
6 Mosley S. The Chimney of the World. A History of Smoke Pollution in Victorian and Edwardian Manchester. Cambridge, The White Horse Press, 2001, p. 16.
7 British Medical Journal 1889;i:114.
8 Ellis R. The Case Books of Dr John Snow. Medical History 1994, Suppl.14, pp. xviiixix.
9 Bynum WF. Science and the Practice of Medicine in the Nineteenth Century. Cambridge: Cambridge University Press, 1994.
10 Petersen J. The Medical Profession in mid-Victorian London. Berkeley and London: University of California Press, 1978.
11 Snow J. On the adulteration of bread as a cause of rickets. Lancet 1857;ii:45. (Reprinted Int J Epidemiol 2003;32:33637.)
12 Brock WH. Justus von Liebig. The Chemical Gatekeeper. Cambridge: Cambridge University Press, 1997, p. x.
13 Bence Jones H. A course of lectures on animal chemistry. Lancet 1850;i:38.
14 Hassall AH. Food and its Adulterations. Reports of the Analytical Sanitary Commission for the Lancet. London: Longman, Brown, Green and Longman, revised edition, 1855.
15 Bracegirdle B. JJ Lister and the establishment of histology. Medical History 1977;21:18791.[Medline]
16 Filby FA. A History of Food Adulteration and Analysis. London: George Allen and Unwin Ltd, 1934, pp. 19495.
17 See Snow SJ. Commentary: Sutherland, Snow and water: the transmission of cholera in the nineteenth century. Int J Epidemiol 2002; 31:90811.
18 Ellis R. The Case Books of Dr John Snow. Medical History 1994, Suppl.14, p. xx.
19 British Medical Journal 1889;i:114.
20 Hirsch A. Handbook of Geographical and Historical Pathology. London: New Sydenham Society, 1886, vol 3, pp. 73242.
21 Palm TA. The geographical distribution and aetiology of rickets. Practitioner 1890;45:27079, 32142, pp. 274, 33342.
22 Chick H. Study of rickets in Vienna 19191922. Medical History 1976; 20:4649.
23 Mellanby E. Experimental rickets. The effect of cereals and their interaction with other factors of diet and environment in producing rickets. London: Medical Research Council Special Report Series, no. 93, 1925.