Letters to the Editor |
Re: Mortality experience of male workers at a UK tin smelter
Dear Sir,It was interesting to read the observation that a UK tin smelter's workers may have had an increased risk of lung cancer [1]. I had also investigated this issue in a rather smaller cohort of 640 workers employed between 1921 and 1955 in a Bootle (Liverpool) smelter, presented as the Milroy Lectures for 1964. This was published perhaps too long ago for the authors to have been aware of the results [2,3], when we too did not find a total cancer excess, with too few lung cancers to draw any conclusions.
This was in spite of extremely high exposures to tin oxide fume (see Figure 1), as well as tin oxide dust from bag emptying, sufficient to cause a large number of patients to be the first cases of stannosis found in this country [4]. It was unlikely that these fumes were contaminated with carcinogens, arsenic, PAHs, etc.
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The authors mention exposure to carcinogens in their cohort. It would be helpful to know more about tin smelting at Capper Pass, and whether they have any information on the concentration of known carcinogens there. How was tin ore handled from the time it arrived from abroad [3]? How did the ore arrive at their works—in bags? Where did the ore come from: alluvial ore is quite different from mined ore. Was anything known of the occupations of the employees that would have allowed estimates of exposure to be made? Did any have stannosis [4]? Were any necropsies made that would have allowed elemental analysis of lung tissue [5]?
As a separate issue, it is particularly interesting that their non-ferrous metal workers had such a low mortality from ischaemic heart disease in view of their high exposure to what would now be regarded as nanoparticles and the postulated association of such particles in air pollution with cardiac disease [6]. This tends to support the concept that surface contamination of particles with iron is a necessary factor in initiating harmful inflammatory reactions.
8 Long Hey Road, Caldy, Wirral CH48 1LZ, UK
e-mail: drajrcaldy{at}onetel.com
References
- Binks K, Doll R, Gillies M, et al. Mortality experience of male workers at a UK tin smelter. Occup Med (Lond) 2005;55:215–226.
- Robertson AJ. The romance of tin. Lancet 1964;1:1289–1293.
- King EJ, Fletcher CM. Pneumoconiosis due to tin oxide. In: Symposium on Industrial Pulmonary Disease. Chapter 14. J & A Churchill, 1960.
- Robertson AJ, Whitaker PH. Radiological changes in pneumoconiosis due to tin oxide. J Fac Radiol 1955;6:224–233.[CrossRef]
- Robertson AJ, Rivers E, Nagelschmidt G, Duncomb P. Stannosis. Lancet 1961;1:1089–1093.[CrossRef][ISI][Medline]
- Seaton A, Donaldson K. Nanoscience, nanotoxicology and the need to think small. Lancet 2005;364:923–924.
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