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FLUORIDATION AND GASTRIC CANCER
875
FLUORIDATION AND GASTRIC CANCER SiR,-In a letter in your issue of March 26 Dr. Burrowes suggests, by a comparison which he made of deaths in the small towns of Donington and Crowland over a period of ten years, that there may be a relationship between the consumption of naturally fluoridated water and carcinoma of the stomach. During the period 1952-58 inclusive the number of deaths this cause in Donington (population 1917) death 61 years; in Crowland (population was 4, 12 deaths, average age at death 68’5 years; figures for a 2833) 10-year period are not available. It will no doubt be agreed that these towns are too small to provide reliable comparative statistics; any deduction therefrom could only be regarded as trustworthy in proportion as the observations were numerous, and on the assumption that the latter were at the same time accurate and comparable. The public water-supplies in Donington (from West Pinchbeck) and Spalding (from Bourne) are derived from bores in the counties of Holland and Kesteven respectively, the average concentration of fluorine being for the former 0’5 p.p.m. and 0’1 p.p.m. at Spalding. Dr. Burrowes gave the latter value as 0’5 p.p.m. A bore at Deeping St. Nicholas supplies water with a concentration of 2’9 p.p.m. F to Crowland: this supply came into use about a year ago; the earlier supply from Deeping, according to recent information, contained 3 p.p.m. F. As a matter of interest, it is also necessary to take into account the fact that there are indigenous private bores, more common in South Kesteven than in the southern part of the County of Holland, which provide higher concentrations of fluorine. This is due to the occurrence of fluorine contours which run in the direction north to south in the extreme south-east of Kesteven and in the south-west of Holland The concentration of fluorine gradually rises from a mere trace in Kesteven to around 4’5 p.p.m. in Spalding and Crowland in the east. Local statistics do not appear to support any suggestion that there is a causal relationship between the consumption of naturally fluoridated water and the incidence of carcinoma of the stomach in the natural fluoride areas of South Kesteven Rural District (population 14,394) and Spalding Rural District (population 18,890). The average death-rate from carcinoma of the stomach in the former rural district during the years 1944-58 was 0’29 per 1000 of the population, as compared with an average death-rate of 0’29 per 1000 for the same period for the remainder of the County of Kesteven (population 133,500) which has no naturally fluoridated water in the public water-supplies. A similar comparison has been made in the County of Holland; in the Rural District of Spalding, which includes the towns of Donington and Crowland, the average death-rate from carcinoma of the stomach during the years 1952-58 was 0-35 per 1000 of the population, as compared with 0’32 for the remainder of the County of Holland
registered as
due
to
included in Webster’s New cannot therefore be assumed to be of common usage in the United States. The equally objectionable French word, envenimement (which is to be found even in the Petit Larousse), is, to the best of my knowledge, never used by French writers. Let us, by all means, be satisfied with " poisoning " and 6MOMOMM6MMK. R. H. AHRENFELDT. Bransgore, Hampshire. able American work-it is
not
Collegiate Dictionary, and, fortunately,
average age at
(population 102,600). During the years 1947-53, the average death-rate for carcinoma of the stomach in England and Wales was 0’33 per 1000 of the population. During the past six years several papers have been published ucon various asnects of fluoridation in South Lincolnshire, and these 1-5 may be of interest. J. H. CHALMERS CLARKE Sleaford, Lincs. County Medical Officer of Health. n
.
SNAKEBITE
SIR,-Dr. Penman (April 2) is to be congratulated on his attempt to preserve our language from further debasement through pseudoscientific jargon. While the ugly word, " envenomation ", occurs in Webster’s New International Dictionary-a most conservative and valu1. Chalmers
Clarke, J. H. Med. Offr, 1954, 92, 39.
2. Chalmers Clarke, T. H. J. Brit. Waterwks Ass. 1954, 36, 497. 3. Chalmers Clarke, J. H. ibid. 1955, 37, 664. 4. Lament, P. ibid. 1959, 41, 68. 5. Chalmers Clarke, J. H., Mann, J. E. Brit. dent. J. 1960, 108, 181.
MATERNAL AGE IN MONGOLISM an instance where trisomy 22 has not been found in a patient with mongolism, Dr. Polani and his colleagues (April 2) lay great emphasis on the youth of the patient’s mother at the time of the affected birth. In support of their view that mongolism in births to young mothers may be aetiologically distinct from the condition in offspring of older mothers, they quote assertions by Penrose 12 that maternal age at birth of mongols is bimodally distributed and that mean maternal age is low in cases where a maternal relative is also affected. But there is nothing remarkable in the finding that a mother of a mongol is young. Although the risk of any birth being affected rises sharply with advancing maternal age, the large number of births occurring in the general population at the younger maternal ages results in a proportion of mongols being born to young mothers. In a series3 of 241 mongols born in Birmingham, 20 (8%)
SIR,-In presenting
born to mothers under 25 years of age and 57 (24%) were to mothers under 30 years of age at the time of the birth. Thus, although mongolism is rare among births to young mothers, young women are by no means rare among the mothers of mongols. were
born
The hypothesis of Penrose that the distribution by maternal age at birth of mongols may represent the superimposition of two distributions relating to xtiologically distinct groups of cases, depends largely on a demonstration of bitangentiality in the maternal agedistribution of a series of cases assembled from the literature. It is important to consider alternative explanations of Penrose’s finding.
(1) Since
a series assembled from the literature is heteroin geneous respect of the populations of births from which cases are drawn, its maternal age-distribution may reflect differences between these populations in maternal age-distributions,for all births. Distributions by maternal age for unaffected births exhibit secular and regional variation. (2) The cases in Penrose’s series were largely ascertained at some time after their birth and thus are survivors from an unidentifiable population of affected births. Since early mortality in mongols is high and related to maternal age at birth, the maternal age-distribution for such a series of survivors may most imperfectly resemble that at birth. It is of interest that the series published by Carter and MacCarthy4 and drawn from consecutive maternity-hospital births exhibits no significant bitangentiality of its maternal age-distribution. (3) Even if the preceding explanations are rejected, an observation that maternal age at birth of mongols is bitangentially distributed is hardly surprising since the distribution is the product of the maternal age-distribution for the general population of births and the maternal age-distribution of the risk that a birth is affected. Maternal age at birth for the general population is distributed around a single mode occurring in the 25-29 age quinquennium. The maternal agedistribution of the risk that a birth is affected may be examined by considering maternal age-specific incidence in a series of
1. 2. 3. 4.
Penrose, L. S. J. ment. Sci. 1951, 97, 738. Penrose, L. S. Ann. N. T. Acad. Sci. 1954, 57, 494. Smith, A., Record, R. G. Brit. J. prev. soc. Med. 1955, 9, 51. Carter, C., MacCarthy, D. Brit. J. soc. Med. 1951, 5, 83.
FLUORIDATION AND GASTRIC CANCER SiR,-In a letter in your issue of March 26 Dr. Burrowes suggests, by a comparison which he made of deaths in the small towns of Donington and Crowland over a period of ten years, that there may be a relationship between the consumption of naturally fluoridated water and carcinoma of the stomach. During the period 1952-58 inclusive the number of deaths this cause in Donington (population 1917) death 61 years; in Crowland (population was 4, 12 deaths, average age at death 68’5 years; figures for a 2833) 10-year period are not available. It will no doubt be agreed that these towns are too small to provide reliable comparative statistics; any deduction therefrom could only be regarded as trustworthy in proportion as the observations were numerous, and on the assumption that the latter were at the same time accurate and comparable. The public water-supplies in Donington (from West Pinchbeck) and Spalding (from Bourne) are derived from bores in the counties of Holland and Kesteven respectively, the average concentration of fluorine being for the former 0’5 p.p.m. and 0’1 p.p.m. at Spalding. Dr. Burrowes gave the latter value as 0’5 p.p.m. A bore at Deeping St. Nicholas supplies water with a concentration of 2’9 p.p.m. F to Crowland: this supply came into use about a year ago; the earlier supply from Deeping, according to recent information, contained 3 p.p.m. F. As a matter of interest, it is also necessary to take into account the fact that there are indigenous private bores, more common in South Kesteven than in the southern part of the County of Holland, which provide higher concentrations of fluorine. This is due to the occurrence of fluorine contours which run in the direction north to south in the extreme south-east of Kesteven and in the south-west of Holland The concentration of fluorine gradually rises from a mere trace in Kesteven to around 4’5 p.p.m. in Spalding and Crowland in the east. Local statistics do not appear to support any suggestion that there is a causal relationship between the consumption of naturally fluoridated water and the incidence of carcinoma of the stomach in the natural fluoride areas of South Kesteven Rural District (population 14,394) and Spalding Rural District (population 18,890). The average death-rate from carcinoma of the stomach in the former rural district during the years 1944-58 was 0’29 per 1000 of the population, as compared with an average death-rate of 0’29 per 1000 for the same period for the remainder of the County of Kesteven (population 133,500) which has no naturally fluoridated water in the public water-supplies. A similar comparison has been made in the County of Holland; in the Rural District of Spalding, which includes the towns of Donington and Crowland, the average death-rate from carcinoma of the stomach during the years 1952-58 was 0-35 per 1000 of the population, as compared with 0’32 for the remainder of the County of Holland
registered as
due
to
included in Webster’s New cannot therefore be assumed to be of common usage in the United States. The equally objectionable French word, envenimement (which is to be found even in the Petit Larousse), is, to the best of my knowledge, never used by French writers. Let us, by all means, be satisfied with " poisoning " and 6MOMOMM6MMK. R. H. AHRENFELDT. Bransgore, Hampshire. able American work-it is
not
Collegiate Dictionary, and, fortunately,
average age at
(population 102,600). During the years 1947-53, the average death-rate for carcinoma of the stomach in England and Wales was 0’33 per 1000 of the population. During the past six years several papers have been published ucon various asnects of fluoridation in South Lincolnshire, and these 1-5 may be of interest. J. H. CHALMERS CLARKE Sleaford, Lincs. County Medical Officer of Health. n
.
SNAKEBITE
SIR,-Dr. Penman (April 2) is to be congratulated on his attempt to preserve our language from further debasement through pseudoscientific jargon. While the ugly word, " envenomation ", occurs in Webster’s New International Dictionary-a most conservative and valu1. Chalmers
Clarke, J. H. Med. Offr, 1954, 92, 39.
2. Chalmers Clarke, T. H. J. Brit. Waterwks Ass. 1954, 36, 497. 3. Chalmers Clarke, J. H. ibid. 1955, 37, 664. 4. Lament, P. ibid. 1959, 41, 68. 5. Chalmers Clarke, J. H., Mann, J. E. Brit. dent. J. 1960, 108, 181.
MATERNAL AGE IN MONGOLISM an instance where trisomy 22 has not been found in a patient with mongolism, Dr. Polani and his colleagues (April 2) lay great emphasis on the youth of the patient’s mother at the time of the affected birth. In support of their view that mongolism in births to young mothers may be aetiologically distinct from the condition in offspring of older mothers, they quote assertions by Penrose 12 that maternal age at birth of mongols is bimodally distributed and that mean maternal age is low in cases where a maternal relative is also affected. But there is nothing remarkable in the finding that a mother of a mongol is young. Although the risk of any birth being affected rises sharply with advancing maternal age, the large number of births occurring in the general population at the younger maternal ages results in a proportion of mongols being born to young mothers. In a series3 of 241 mongols born in Birmingham, 20 (8%)
SIR,-In presenting
born to mothers under 25 years of age and 57 (24%) were to mothers under 30 years of age at the time of the birth. Thus, although mongolism is rare among births to young mothers, young women are by no means rare among the mothers of mongols. were
born
The hypothesis of Penrose that the distribution by maternal age at birth of mongols may represent the superimposition of two distributions relating to xtiologically distinct groups of cases, depends largely on a demonstration of bitangentiality in the maternal agedistribution of a series of cases assembled from the literature. It is important to consider alternative explanations of Penrose’s finding.
(1) Since
a series assembled from the literature is heteroin geneous respect of the populations of births from which cases are drawn, its maternal age-distribution may reflect differences between these populations in maternal age-distributions,for all births. Distributions by maternal age for unaffected births exhibit secular and regional variation. (2) The cases in Penrose’s series were largely ascertained at some time after their birth and thus are survivors from an unidentifiable population of affected births. Since early mortality in mongols is high and related to maternal age at birth, the maternal age-distribution for such a series of survivors may most imperfectly resemble that at birth. It is of interest that the series published by Carter and MacCarthy4 and drawn from consecutive maternity-hospital births exhibits no significant bitangentiality of its maternal age-distribution. (3) Even if the preceding explanations are rejected, an observation that maternal age at birth of mongols is bitangentially distributed is hardly surprising since the distribution is the product of the maternal age-distribution for the general population of births and the maternal age-distribution of the risk that a birth is affected. Maternal age at birth for the general population is distributed around a single mode occurring in the 25-29 age quinquennium. The maternal agedistribution of the risk that a birth is affected may be examined by considering maternal age-specific incidence in a series of
1. 2. 3. 4.
Penrose, L. S. J. ment. Sci. 1951, 97, 738. Penrose, L. S. Ann. N. T. Acad. Sci. 1954, 57, 494. Smith, A., Record, R. G. Brit. J. prev. soc. Med. 1955, 9, 51. Carter, C., MacCarthy, D. Brit. J. soc. Med. 1951, 5, 83.