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CANCER AND CHLORINATED WATER
1142
CANCER AND CHLORINATED WATER THAT an adequate supply of safe water and basic sanitation are essential elements in primary health care was emphasised at the Alma Ata conference, and the United Nations has declared the years 1981-90 as the International Drinking Water Supply and Sanitation Decade.’ In the 19th century the main stimulus to the development of clean water supplies was a succession of cholera epidemics, and the first and greatest successes of the sanitation services were in the reduction in water-borne bacterial disease. But still all too many communities have nothing better, and sometimes much worse, than the local equivalent of the famous Broad Street pump immobilised in the 1850s by John Snow. Provision of safe water has been both expensive and a challenge to man’s ingenuity, so manifold are the opportunities to be seized on by disease-producing agencies; it requires constant vigilance and swift alertness to newly recognised possibilities of contamination, at source, en route, or in the very processes used to make the water safe to drink. The basic processes everywhere have been filtration and chlorination, and lately the latter 2-4 has been coming under worried attention. The question is-does chlorinated water consumption increase the risk of certain cancers, especially those of bowel and urinary bladder? A possible mechanism is reaction of the chlorine with organic substances in the water to produce carcinogens. Particular suspicion attaches to certain substances in chlorinated water which have proved carcinogenic in laboratory animals.5 Prominent among these substances are the trihalogenated methanes, including chloroform and bromoform, which are sometimes present in considerable amounts, both in natural waters and in chlorinated water.6 In naturally collected water the carcinogens may derive from plants such as bracken. Organic materials may be leached from the soil, possibly humic acids, which will react with chlorine to produce the suspected carcinogens. The difficulty is first to prove a causal connection and then know what to do about it. Some preliminary studies suggested that the continued consumption of chlorinated water might increase the risk of rectal, colonic, and bladder cancer (increased risk ratios of 1’ 13-1933). Five such studies have been conducted in the past few years, covering some 11 398 individuals in several counties in the U.S.A. 2,4 The results are suggestive, but relative risk ratios of less than 2 are always hard to interpret. Doubts are increased by the primitive nature of some of the studies which relied on death certificates and the type of water supply used at the individual’s last address. The last address, of course, may not be the place at which the particular individual had been living at the decisive time, especially in view of the long latent period of many cancers. Moreover the individual may not have used much chlorinated water in his or her drinking or may have done most water drinking away from home. to
1. Water Decade 1981-1990. World Health August-September 1980; 3-35. 2. Maugh TH. New study links chlorination and cancer. Science 1981; 211: 694. 3. National Academy of Sciences. Drinking water and health. Vol. 3. Washington, D.C.: NAS, 1980. 4. Council on Environmental Quality. Drinking water and cancer: Review of recent findings and assessment of risk Washington, D.C.: CEQ, 1980. 5. International Agency for Research on Cancer. Some halogenated hydrocarbons: IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans, vol. 20, Lyons: IARC, 1979: 593. 6. Shackelford WM, Keith LH. Frequency of organic compounds identified in water (EPA600/4-76-062). Athens, Georgia: U.S. Environmental Protection Agency, 1976. 7. Evans IA, Mason J. Carcinogenic activity of bracken. 1965; 208: 913-14.
For what they are worth, the studies so far seem to show, in those drinking chlorinated water, a slightly increased risk of rectal cancer and a lesser one of colonic and bladder cancer. But, even if taken at face value, the risks seem negligible in the face of the catastrophic problems that would arise were chlorination abandoned: a slightly increased risk of cancer would be a small price to pay for protection against other water-borne diseases. The real interest of such studies at the moment lies in the area of cancer epidemiology. There are many reports of differences in cancer pattern amongst similar communities differentiated by the source of the waters consumed. Some of these might well be re-evaluated and perhaps repeated, such as the classic study in Horrabridge, Devon, by Allen-Price. There is scope for many such studies in medical geography.99
JUXTAORAL ORGAN OF CHIEVITZ IN 1974, Lutman 10 reported finding an indurated area in pterygoid fossa during resection of the cheek and alveolar margin of the mandible for a low-grade squamous-cell carcinoma. The induration contained small nests of epithelial cells adjacent to small nerve fibres, and gave the appearances of a perineural carcinomatous invasion. There was a sharp replyll,12 with the comment that "Americans do not read European journals as much as Europeans read American ones", for it was pointed out that the structure that Lutman had described was well known in the German literature as the organ of Chievitz. In 1885, the Danish histologist Chievitzj had described a rudimentary structure developing and disappearing during the embryonal period, but Zenker’ reported persistence of the neuroepithelial organ throughout life without involution, and termed it the "juxtaoral organ"-perhaps a less satisfactory name than that used by Willis,15 "Chievitz’s paraparotid organ". In 25 consecutive necropsies, 11 juxtaoral organs were found unilaterally and three bilaterally. 16 The organ was situated deep to the medial pterygoid muscle and consisted of two to ten circumscribed epithelial cell nests lying intimately associated with one or more small myelinated nerves. Nearly all the epithelium was squamous-like, but an occasional lumen was present, lined with cuboidal cells. The function of the organ is unknown, but it is a normal anatomical finding, and there is a risk of diagnosing the structure as an invasive squamous-cell carcinoma (especially on frozen section), or mucoepidermoid carcinoma, as shown by Lutman 10 and Miko and Molnar.’’ There could be a chance of unnecessarily extensive surgery, but Chievitz’s organ can be considered, for once, as more a problem for the pathologist than for the surgeon. 8. Allen-Price ED. Uneven distribution of cancer in west Devon, with particular reference to the divers water supplies. Lancet 1960; i: 1235-38. 9. McGlashan ND. Medical geography: Techniques and field studies. London Methuen. 1972. 10. Lutman GB. Epithelial nests in intraoral sensory nerve endings simulating perineural invasion in patients with oral carcinoma. AmJ Clin Pathol 1974; 61: 275-84 11. Lattes, R. Letter to the Editor. Am J Clin Pathol 1974; 62: 570. 12. Krammer, E. B., Zenker, W. Letter to the Editor. Am J Clin Pathol 1974; 62: 571-74 13. Chievitz, J. H. Beiträge zur Entwicklungsgeschichte der Speicheldrüsen Arch Anat Physiol 1885; 9: 401-36. 14. Zenker, W. Organon bucco-temporale Organ), ein nervös epitheliales Organ beim Menschen. Anat Anz 1953-54; 100: 257-65. 15 Willis RA. The borderline of embryology and pathology, 2nd ed London Butterworth, 1962 280. 16. Tschen JA, Fechner RE. The juxtaoral organ of Chievitz. AmJ Surg Pathol 1979, 3: 147-50. 17. Miko T, Molnar P. The juxtaoral organ-a pitfall for pathologists. J Pathol 1981, 133: 17-23.
(Chievitzsches
CANCER AND CHLORINATED WATER THAT an adequate supply of safe water and basic sanitation are essential elements in primary health care was emphasised at the Alma Ata conference, and the United Nations has declared the years 1981-90 as the International Drinking Water Supply and Sanitation Decade.’ In the 19th century the main stimulus to the development of clean water supplies was a succession of cholera epidemics, and the first and greatest successes of the sanitation services were in the reduction in water-borne bacterial disease. But still all too many communities have nothing better, and sometimes much worse, than the local equivalent of the famous Broad Street pump immobilised in the 1850s by John Snow. Provision of safe water has been both expensive and a challenge to man’s ingenuity, so manifold are the opportunities to be seized on by disease-producing agencies; it requires constant vigilance and swift alertness to newly recognised possibilities of contamination, at source, en route, or in the very processes used to make the water safe to drink. The basic processes everywhere have been filtration and chlorination, and lately the latter 2-4 has been coming under worried attention. The question is-does chlorinated water consumption increase the risk of certain cancers, especially those of bowel and urinary bladder? A possible mechanism is reaction of the chlorine with organic substances in the water to produce carcinogens. Particular suspicion attaches to certain substances in chlorinated water which have proved carcinogenic in laboratory animals.5 Prominent among these substances are the trihalogenated methanes, including chloroform and bromoform, which are sometimes present in considerable amounts, both in natural waters and in chlorinated water.6 In naturally collected water the carcinogens may derive from plants such as bracken. Organic materials may be leached from the soil, possibly humic acids, which will react with chlorine to produce the suspected carcinogens. The difficulty is first to prove a causal connection and then know what to do about it. Some preliminary studies suggested that the continued consumption of chlorinated water might increase the risk of rectal, colonic, and bladder cancer (increased risk ratios of 1’ 13-1933). Five such studies have been conducted in the past few years, covering some 11 398 individuals in several counties in the U.S.A. 2,4 The results are suggestive, but relative risk ratios of less than 2 are always hard to interpret. Doubts are increased by the primitive nature of some of the studies which relied on death certificates and the type of water supply used at the individual’s last address. The last address, of course, may not be the place at which the particular individual had been living at the decisive time, especially in view of the long latent period of many cancers. Moreover the individual may not have used much chlorinated water in his or her drinking or may have done most water drinking away from home. to
1. Water Decade 1981-1990. World Health August-September 1980; 3-35. 2. Maugh TH. New study links chlorination and cancer. Science 1981; 211: 694. 3. National Academy of Sciences. Drinking water and health. Vol. 3. Washington, D.C.: NAS, 1980. 4. Council on Environmental Quality. Drinking water and cancer: Review of recent findings and assessment of risk Washington, D.C.: CEQ, 1980. 5. International Agency for Research on Cancer. Some halogenated hydrocarbons: IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans, vol. 20, Lyons: IARC, 1979: 593. 6. Shackelford WM, Keith LH. Frequency of organic compounds identified in water (EPA600/4-76-062). Athens, Georgia: U.S. Environmental Protection Agency, 1976. 7. Evans IA, Mason J. Carcinogenic activity of bracken. 1965; 208: 913-14.
For what they are worth, the studies so far seem to show, in those drinking chlorinated water, a slightly increased risk of rectal cancer and a lesser one of colonic and bladder cancer. But, even if taken at face value, the risks seem negligible in the face of the catastrophic problems that would arise were chlorination abandoned: a slightly increased risk of cancer would be a small price to pay for protection against other water-borne diseases. The real interest of such studies at the moment lies in the area of cancer epidemiology. There are many reports of differences in cancer pattern amongst similar communities differentiated by the source of the waters consumed. Some of these might well be re-evaluated and perhaps repeated, such as the classic study in Horrabridge, Devon, by Allen-Price. There is scope for many such studies in medical geography.99
JUXTAORAL ORGAN OF CHIEVITZ IN 1974, Lutman 10 reported finding an indurated area in pterygoid fossa during resection of the cheek and alveolar margin of the mandible for a low-grade squamous-cell carcinoma. The induration contained small nests of epithelial cells adjacent to small nerve fibres, and gave the appearances of a perineural carcinomatous invasion. There was a sharp replyll,12 with the comment that "Americans do not read European journals as much as Europeans read American ones", for it was pointed out that the structure that Lutman had described was well known in the German literature as the organ of Chievitz. In 1885, the Danish histologist Chievitzj had described a rudimentary structure developing and disappearing during the embryonal period, but Zenker’ reported persistence of the neuroepithelial organ throughout life without involution, and termed it the "juxtaoral organ"-perhaps a less satisfactory name than that used by Willis,15 "Chievitz’s paraparotid organ". In 25 consecutive necropsies, 11 juxtaoral organs were found unilaterally and three bilaterally. 16 The organ was situated deep to the medial pterygoid muscle and consisted of two to ten circumscribed epithelial cell nests lying intimately associated with one or more small myelinated nerves. Nearly all the epithelium was squamous-like, but an occasional lumen was present, lined with cuboidal cells. The function of the organ is unknown, but it is a normal anatomical finding, and there is a risk of diagnosing the structure as an invasive squamous-cell carcinoma (especially on frozen section), or mucoepidermoid carcinoma, as shown by Lutman 10 and Miko and Molnar.’’ There could be a chance of unnecessarily extensive surgery, but Chievitz’s organ can be considered, for once, as more a problem for the pathologist than for the surgeon. 8. Allen-Price ED. Uneven distribution of cancer in west Devon, with particular reference to the divers water supplies. Lancet 1960; i: 1235-38. 9. McGlashan ND. Medical geography: Techniques and field studies. London Methuen. 1972. 10. Lutman GB. Epithelial nests in intraoral sensory nerve endings simulating perineural invasion in patients with oral carcinoma. AmJ Clin Pathol 1974; 61: 275-84 11. Lattes, R. Letter to the Editor. Am J Clin Pathol 1974; 62: 570. 12. Krammer, E. B., Zenker, W. Letter to the Editor. Am J Clin Pathol 1974; 62: 571-74 13. Chievitz, J. H. Beiträge zur Entwicklungsgeschichte der Speicheldrüsen Arch Anat Physiol 1885; 9: 401-36. 14. Zenker, W. Organon bucco-temporale Organ), ein nervös epitheliales Organ beim Menschen. Anat Anz 1953-54; 100: 257-65. 15 Willis RA. The borderline of embryology and pathology, 2nd ed London Butterworth, 1962 280. 16. Tschen JA, Fechner RE. The juxtaoral organ of Chievitz. AmJ Surg Pathol 1979, 3: 147-50. 17. Miko T, Molnar P. The juxtaoral organ-a pitfall for pathologists. J Pathol 1981, 133: 17-23.
(Chievitzsches