Journal of Toxicology and Environmental Health
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Occupation and bowel cancer John W. Berg & Margaret A. Howell To cite this article: John W. Berg & Margaret A. Howell (1975) Occupation and bowel cancer, Journal of Toxicology and Environmental Health, 1:1, 75-89, DOI: 10.1080/15287397509529309 To link to this article: http://dx.doi.org/10.1080/15287397509529309
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O C C U P A T I O N A N D BOWEL C A N C E R John W. Berg, Margaret A. Howell Epidemiologic Pathology Unit, Carcinogenesis Program, Division of Cancer Cause & Prevention, National Cancer Institute, Bethesda, Maryland
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In the last 25 yr U.S. men but not women over 55 have experienced a 30% rise In bowel cancer risk. One obvious possibility is that occupational risks have increased. As a possible prologue to a major occupational study, we have analyzed what published U.S. and English data exist on occupational mortality. Unfortunately, these data are not recent. The data for broad occupational groups show that mortality rates for colon and rectal cancer are correlated and can reasonably be pooled for studies of specific occupations. In both the United States and Great Britain, professionals appear at high risk for large-bowel cancer. Of U.S. industries with elevated death rates, those composed of white-collar workers are predominant, but the manufacturing Industries as a group also appear to have an elevated risk. Within manufacturing, clusters of occupations concerned with metal work, yarn or textiles, and leather goods show elevated death rates; there are also some parallels in the English data for these occupations. Other less consistent results raised the possibility of hazards in occupations related to dyes, meat handling, smoke inhalation, and chemicals.
INTRODUCTION Bowel cancer is rarely thought of as an occupational disease although it is considered to occur more often than expected in asbestos workers (Hammond et al., 1965). Perhaps the fact that about an equal number of these cancers occur in men and women has obscured the fact that for men over 55 the incidence of bowel cancer is over 30% greater than for women of the same age (Fig. 1). Moreover, this excess risk is about twice what it was 23 yr ago. Such risk differences between the sexes, and particularly the changing ratios, strongly suggest consideration of possible occupational factors. Unfortunately, no recent comprehensive source of data on occupational cancer risks within the United States is available; the U.S. data were collected in 1950 (Guralnick, 1962, 1963a-c). The two English studies (Registrar General's Decennial Supplement, 1957, 1971) are based on data gathered in 1951 and 1961. Even the 1961 English data are not detailed
The authors express their appreciation to Karen L. Beckwith for performing the calculations. Requests for reprints should be sent to Dr. John W. Berg, Iowa State Cancer Registry, Department of Community Medicine, The University of Iowa, College of Medicine, Iowa City, Iowa 52242. 75 Journal of Toxicology and Environmental Health, 1:75-89,1975 Copyright © 1975 by Hemisphere'Publishing Corporation
76
J.W. BERG AND M. A. HOWELL
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AGE FIGURE 1. Male-female ratios for bowel cancer incidence by age groups. U.S. whites, 1947 and 1969-1971 (data from NCI, Biometry Branch, 1974; Dorn and Cutler, 1959).
enough to associate specific exposures with bowel cancer risk. The best we can do with existing information is to study the data in detail to see what occupations may show excess deaths from bowel cancer and what work exposures are important in these occupations. Such data can provide the starting point and impetus for active investigations. METHODS The materials for this study are published compendia of occupational mortality from the United States and Great Britain (Guralnick, 1962, 1963a-c; Registrar General's Decennial Supplement, 1957, 1971). These contain tabulations of occupations as recorded on death certificates, and some contain ratios that provide an indication of the risk for an occupation due to each cause of death. For the U.S. data, certificates of death were obtained on males between the ages of 20 and 64 who died in 1950; death rates based on the certificates for those with work experience (but excluding students, members of the Armed Forces, and inmates of institutions) were applied to occupational groups as counted in the 1950 census population. For the English data, death rates were based on the mortality experience of all males, without the exclusions of the U.S. data. Certificates of death were obtained for two 5-yr periods, 1949-1953 and 1959-1963. Death rates
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77
derived from a 5-yr period were applied to the census population enumerated during the middle year of the 5-yr interval. Two ratios, the Standardized Mortality Ratio (SMR) and the Proportionate Mortality Ratio (PMR), are calculated. The SMR is the ratio of observed to expected deaths multiplied by 100; this ratio compares the tabulated number of deaths in an occupation due to a particular cause of death with the number to be expected had the age-specific death rates for that cause for all occupations prevailed. If the numbers of observed and expected deaths are equal, the SMR is 100, the same as the SMR for all occupations for that cause of death. A low SMR suggests low risk for the cause of death, while a high SMR suggests high risk. There are difficulties in the use of the SMR to indicate occupations at risk. These result from the difference between "current" occupation reported in the census and "usual" occupation reported on the death certificate. Occupations overreported on death certificates, such as Armed Forces in Great Britain, will tend to have high SMRs for all causes, since more individuals die in that occupation than would be predicted from the numbers in the census population. Where there is underreporting on death certificates, such as the English "occupation unspecified," SMRs may be artificially low. The PMR, which does not involve the use of census data, can be used as a check on the effects of over- or underreporting. The PMR is also the ratio of observed deaths to an expected number multiplied by 100. The expected number is obtained by calculating the proportion of all deaths a particular cause, such as bowel cancer, represents in each age group and using the proportions as multipliers of the number of deaths within an occupation. The PMR thus compares the tabulated number of deaths in an occupation due to a particular cause with the number to be expected had the proportion of all deaths due to that cause prevailed. An occupation overreported on death certificates with high SMRs may show PMRs that are not elevated, providing the excess deaths are distributed proportionately as they are for all occupations. Underreported occupations will tend to have higher PMRs than SMRs as will occupations whose SMRs are genuinely low, again depending on the distribution of deaths. It is possible for an elevated PMR to occur in an occupation where the death rate per 100,000 is not excessive; for example, heart disease might account for all deaths in an occupation and yet the occupation could be below expectations for that cause of death in relation to the general population. A high PMR indicates increased mortality risk for the cause of death due to the factors related to the occupational group, providing the SMR is also high. The usual practice of reporting SMRs, which reflects the application of death rates to population figures, is followed in this study. The significance of the PMRs, however, is considered as well as the magnitude of the SMRs. SMRs are shown as given in source documents, but for statistical tests they were recomputed, since some of the tabled values in the U.S. source
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J.W. BERG AND M. A. HOWELL
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documents are spuriously high due to the dropping rather than rounding of digits during computations. The PMRs for the U.S. data are not shown in source documents although the level of significance is given; upon recomputation, a few additional PMRs reached levels of significance. Tests of significance were based on the technique recommended by Bailar and Ederer (1964). To avoid problems in terminology, it should be mentioned that, for some of the sources of information, deaths from colon and rectal cancers were reported separately while in others these deaths were combined. To provide comparable information, ratios for all large-bowel cancer (colon plus rectum) have been calculated where these were not given in the sources. The term colonic cancer will be used in this paper to refer only to large-bowel cancer exclusive of rectal cancer. RESULTS Social Class or Occupational Level Socioeconomic differences often determine what appears to be occupationally linked mortality. Stomach cancer mortality, for example, shows a marked social class gradient with the poorest people having the highest rates (Haenszel, 1967). As a result, occupations at the lower end of the socioeconomic scale usually have high SMRs for stomach cancer. Although colonic cancer is supposed to have a mortality pattern opposite to that of stomach cancer (Wynder et al., 1966), the social class gradient is much smaller and less constant, as can be seen from Table 1, which presents standardized mortality ratios by English social class and U.S. occupational level. It should be noted that the social classes from the two time periods of the English data are not equivalent and are not the same as U.S. occupational levels. However, there are enough similarities for an examination of trends. A review by Wynder and Shigematsu (1967) suggested that colon cancer in men has some relationship to higher socioeconomic level. The present data for colonic cancer also indicate that the highest level of class, I (which is the professional level), has the highest rate, but only for English men over 65 is there a regular progression from high rates to low with decreasing social class. For rectal cancer, except for U.S. farm workers (who have the lowest rates for both sites), the rates are lowest in the highest class and tend to be fairly high in social class V (U.S. laborers except farm and English unskilled occupations), although there are exceptions. When colon and rectal cancer deaths are combined, the rather weak opposite social class gradients tend to cancel out and essentially disappear. Occupational Groups Occupational groups are broad categories, and it is unlikely that their mortality rates will reveal specific occupational risks. The main value of
OCCUPATION AND BOWEL CANCER
79
TABLE 1. Standardized Mortality Ratios (SMR) for Colonic and Rectal Cancers in Males, Separate and Combined by English Social Class and U.S. Occupational Level" High Area
Years
Age
Measure
Low
1
II
III
IV
V
Farm
124 121 108 120 148
107 101 107 99 116
111 102 102 105 100
97 92 97 92 95
107 99 91 109 84
75
98 86 93 89 101
113 108 102 106 104
105 94 103 98 97
122 103 106 120 96
61
112 105 102 105 102
100 93 100 95 96
113 101 98 114 90
70
Colon United States Great Britain
1950 1949-1953
20-64 20-64
1959-1963
15-64 65-74
65+
SMR SMR PMR6 SMR PMR
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Rectum United States Great Britain
1950 1949-1953
20-64 20-64
1959-1963
15-64 65-74
65+
SMR SMR PMR SMR PMR
93 86 79 79 77
Colon plus Rectum United States Great Britain
1950 1949-1953
20-64 20-64
1959-1963
15-64 65-74
65+
SMR SMR PMR SMR PMR
112 105 95 102 115
104 94 101 95 109
Sources: Guralnick, 1962; Registrar General's Decennial Supplement, 1957,1971. "Levels and classes are not equivalent except for the relative positions of the subgroups in the high to low sequence. "Sources give PMRs (proportionate mortality ratios) only for age 65 and over.
occupational groupings is that there are enough men in each category to provide reasonably reliable separate rates for rectal cancer and colonic cancer, since for specific occupations only data on total large-bowel cancer are available. By occupational groups, mortality rates from colonic cancer and from rectal cancer in the 1950 U.S. and the 1961 English data were found to be almost as highly correlated (r's in the .70s) as they are in geographic data (Berg and Howell, 1974). In most instances, any group with a high incidence of colonic cancer had a fairly high mortality from rectal cancer and vice versa, as can be seen in the English data in Table 6 (appended at the end of this paper). It appears that while an environmental factor may preferentially affect one segment of the large bowel, it acts to some extent on both rectum and colon. Occupational hazards, then, would not be expected to differ markedly for the two sites. There appears to be little cost in considering
80
J.W. BERG AND M. A. HOWELL
rectal and colonic cancer together when searching for occupational risks, and the gain in information due to increased numbers of cases is appreciable.
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Specific Occupations For specific U.S. occupations, SMRs are only available for all large-bowel cancer (Guralnick, 1963a). One hundred and forty-seven occupations are listed. Of these, enough bowel cancer deaths were reported for 87 that SMRs could be calculated. For 45 of the 87, the SMR was over 115, suggesting the possibility of excess risk. The occupations with SMRs of 115 or higher for bowel cancer can be divided into three groups. Table 2 lists these occupations for which the SMR for bowel cancer was high, but the PMR was not significantly elevated. Since the PMRs are low, there is no evidence that men in these occupations develop bowel cancer relatively more often than they do other cancers or other diseases; such occupations are, therefore, unlikely ones in which to search for occupational risks. Eighteen of the 45 occupations with elevated SMRs fell into this category and so were not considered further.
TABLE 2. Occupations with Standardized Mortality Ratios (SMR) of 115 or Higher and Nonsignificant Proportionate Mortality Ratios (PMR) for Colonic and Rectal Cancers Combined, United States, 1950, Males Aged 20-64
No. 144 119 127 143 146 90 102 137 41 123 132 130 46 124 68 82 48 63
Occupation Laborers, transportation, except railroad Cooks, except private household Longshoremen and stevedores Laborers, railroads and railway express Laborers, wholesale and retail trade Taxicab drivers and chauffeurs Operatives and kindred workers, transportation equipment, except motor vehicle Laborers, food and kindred products Bakers Policemen, sheriffs, and marshalls Laborers, primary metal industries Laborers, furniture, saw, and planing mills, miscellaneous wood products Compositors Waiters, bartenders, and counter workers Stationary engineers Mine operatives and laborers Electricians Painters (construction), paperhangers, and glaziers
No. of deaths
SMR
PMR0
28 51 20 75 55 41
200 179 167 153 153 146
70 102 97 87 91 99
46 27 25 46 46
144 6 142 139 139 131
103 77 104 94 83
30 33 67 59 106 54 103
130 127 126 126 123 117 117
70 108 108 106 65 98 90
Source: Guralnick, 1963a. Calculated for this report; only the significance level was available from source document. Calculated for this report
OCCUPATION AND BOWEL CANCER
81
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TABLE 3. Professional and Related Occupations with Standardized Mortality Ratios (SMR) of 115 or Higher and Proportionate Mortality Ratios (PMR) for Colonic and Rectal Cancers, United States, 1950, Males Aged 20-64
No.
Occupation0
No. of deaths
SMR
PMR6
16 70 9 6
Musicians and music teachers Tailors and furriers Designers and draftsmen Clergy
20 46 24 46
222C 209 c 171 r f 153C
130 138* 203 c 131
15 1 34
Lawyers and judges Accountants and auditors Insurance agents and brokers
46 67 57
148 d 140 rf 139rf
160c \39d 131
35
Real estate agents and brokers
39
139
106
31 39
Bookkeepers Salesmen and sales clerks, retail trade Engineers, civil Other professional, technical, and kindred workers Managers, officials, and proprietors, manufacturing
26 191
137 130 c
144 122C
27
129
129
77
126
124
Diabetes
149
120^
140c
Brain tumors
11 25 28
Other causes of death with higher SMRs Nephritis, cirrhosis Diabetes, heart disease Hypertension/stroke, nephritis, diabetes Brain tumors, leukemia Lymphomas, heart disease, diabetes Prostate cancer, lymphomas, heart disease, diabetes Rheumatic heart disease Lymphomas, heart disease, diabetes
Source: Guralnick, 1963a. "Listed from high to low on the basis of the SMR. Calculated for this report; only the significance level was available from source document. c Ratio is significantly above 100 at the 1% level; tests of significance were made for this report. Ratio is significantly above 100 at the 5% level; tests of significance were made for this report.
Table 3 lists a second group of occupations in which SMRs for bowel cancer were higher than 115. Unlike the group tabulated in Table 2, the PMRs for this group were also elevated. These occupations have been grouped together because they are in the higher, professional or near professional occupational levels for which it is difficult to conceive of occupational exposures to specific carcinogens. For this group, we would suggest searching for nonoccupational, "cultural" causal factors. For instance, dietary factors may be responsible for some of these elevated risks in view of recent evidence implicating high meat, and particularly high beef, consumption in the development of cancer of the large bowel (Berg et al., 1973). An interesting triad of other diseases also appears in these occupations—diabetes, lymphosarcoma, and coronary heart disease. All of these causes of death are particularly prominent among insurance agents, real estate agents, and salesmen and salesclerks in retail trade, while one or two are also present in most of the other occupations. This grouping of diseases
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J.W. BERGANDM.A.HOWELL
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seems generally to be characteristic of managers and sales people and may suggest a cultural aspect for lymphoma distribution. Table 4 presents the occupations that remain at possible risk for bowel cancer after exclusion of those whose apparent risk may be accounted for by statistical artifacts and by social or cultural factors. They have excess bowel cancer mortality, whether measured by the SMR or PMR, and are not in the professional or managerial categories. These are the occupations in which an industrial exposure might be found. Within this list, some of the occupations seem to form clusters with similar exposures (Gafafer, 1966). One such cluster is a group of metal workers: millwrights, machinists and jobsetters, tool makers, and die makers and setters. They would have exposure to chlorinated cutting oils, lubricating oils, and metal cleansing TABLE 4. Industrial Occupations with Standardized Mortality Ratios (SMR) of 115 or Higher and Proportionate Mortality Ratios (PMR) for Colonic and Rectal Cancers, United States, 1950, Males Aged 20-64
No.
Occupation0
No. of deaths
SMR
PMR*
135
Laborers, transportation equipment
34
340 c
117
121
39 20 21
279C 182 rf . 175*
172C 183 d 124
55
Firemen, fire protection Millwrights Shoemakers and repairers, except factory Machinists and job setters
160
167C
127C
88 80
Spinners and weavers, textile Laundry and dry cleaning operatives
21 29
162* 16lrf
164 d 128
Operatives and kindred workers, leather and leather products Meat cutters, except slaughter and packing house
40 37
160 c
174C
142
111
Cirrhosis, arteriosclerotic heart disease, lymphosarcomas
25 39
139 130
131 112
31
124
111
Work accidents Nephritis, stomach cancer, stroke Work accidents
21
117
175 rf
31
115
135
61
67
110
81
52 105
76 108 72
Linemen and servicemen, telegraph, telephone, and power Operatives and kindred workers, yarn, thread, and fabric mill Brakemen and switchmen, railroad Operatives and kindred workers, paper and allied products Toolmakers and die makers and setters
Other causes of death with higher SMRs Homicide, syphilis, TB, pneumonia, stomach cancer Work accidents Cirrhosis, lung cancer, hypertensive heart disease Rheumatic fever, kidney cancer TB, cirrhosis, pneumonia, nephrosis, homicide
Rheumatic heart disease
Source: Guralnick, 1963a. "Listed from high to low on the basis of the SMR. Calculated for this report; only the significance level was available from source document. c Ratio is significantly above 100 at the 1% level; tests of significance were made for this report. Ratio is significantly above 100 at the 5% level; tests of significance were made for this report.
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OCCUPATION AND BOWEL CANCER
83
solvents. In this group, the excess cancer risk exists only for the craftsmen. No related high-risk group of laborers was found. Such is not the case for workers manufacturing transportation equipment. In these occupations, the laborers have the highest SMR, 340, recorded for the group of occupations shown in Table 4. The manufacturing of transportation equipment involves many kinds of exposures, but the overlap with the exposures of machinists seems substantial. Spinners and weavers, operatives and kindred workers in yarn, thread, and fabric mills, shoemakers and repairers, and operatives in leather and leather products form a second cluster. All of these occupations are likely to have similar exposures to multiple dyes, metallic compounds, and solvents related to the many chemical treatments applied to natural and synthetic products. Gafafer (1966), for example, links textile workers to more than 30 enumerated chemical hazards. Operatives in the paper manufacturing industry also have multiple possible chemical exposures while the range of solvents in the dry cleaning industry is equally impressive. In these high-risk groups, there are ample possible contacts with potential carcinogens and promoters. Firemen obviously are exposed to smoke inhalation and to chemicals such as carbon tetrachloride used in fire extinguishers. They show high SMRs for most vascular diseases and lung cancer as well as bowel cancer, although the SMR of 279 for bowel cancer far exceeds that for any other cause of death. It would seem worthwhile to determine if this high rate still exists and also whether there is evidence of polycyclic hydrocarbons in their intestine after smoke inhalation. Linemen, at least the subset who are cable workers and splicers, are exposed to chlorodiphenyls, chloronaphthalamines, dyes, resins, and solvents (Gafafer, 1966). Railroad brakemen presumably would be exposed to more lubricating oils than other railroad workers though none of the other occupations with a similar type of relatively simple exposure appears on the high-risk list. A high risk for meat cutters might be expected on the basis of other epidemiologic data previously mentioned that suggest meat consumption is related to bowel cancer risk (Berg et al., 1973). The 1950 U.S. data were also tabulated by industry (Table 7, appended at the end of this paper). Table 5 abstracts the list and presents those industries and occupations identified in source documents as having significantly high PMRs. In addition, the occupations in Tables 3 and 4 whose PMRs, on recomputation, reached significance are included. The occupations shown in Table 5 are those that presumably best account for the high industry rates. The previously noted higher risk at the higher occupational levels (Level III and above, composed of white-collar workers) is again predominant. The manufacturing industry as a whole, however, also has an elevated PMR. Two industries within manufacturing have quite high SMRs: "footwear, except rubber" (SMR of 174) and "other textile mill products" (SMR of 155). The
84
J.W. BERG AND M. A. HOWELL
TABLE 5. Summary Table Showing Standardized Mortality Ratios (SMR) for Occupations and Industries at High Risk0 for Colonic and Rectal Cancers Combined, United States, 1950, Males Aged 20-64 Industrial group
SMR Level
Manufacturing
108 c
11
II
III
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III
III IV IV IV
Wholesale and retail trade
112
C
III
III
Finance, insurance, and real estate Professional and related services Public administration
114"
99
118 C
Occupation
SMR
Industry
SMR
Managers, officials, and proprietors, manufacturing Designers and draftsmen
120
Machinery, except electrical
702
777
Electrical machinery, equipment and supplies
724
Foremen, manufacturing, durable goods Machinists and job setters
110 Motor vehicles and motor vehicle equipment
114
Millwrights6 Spinners and weavers, textile 6 Operatives, leather and leather products Operatives and kindred workers, paper and allied productse
182d 162d
Other textile mill products Footwear, except rubber
155d
Managers, officials, and proprietors, wholesale and retail trade Salesmen and sales clerks, retail trade
167d
160d
J
174C
117 114C
130d
General merchandise and five and ten cent stores Apparel and accessories stores All other retail trade
117
202c
129° 136d
Other clerical and kindred workers (other than bookkeepers)
108
Banking and other finance
1
Lawyers and judges
148d
1
Accountants and auditors^ U0d
Legal, engineering, 177C and miscellaneous professional services
III
111
III
Other clerical and kindred workers' (other than bookkeepers) Firemen, fire protection
108
Postal service
130d
279*
Note: An italic SMR indicates that the PMR is significantly higher than the PMR for combined groups. "Occupations and industries reported as having significantly high PMRs. Listed only by industrial group and not by industry. Ratio is significantly above 100 at the 1% level; tests of significance were made for this report. Ratio is significantly above 100 at the 5% level; tests of significance were made for this report. PMR was not shown as significant in source document; found to be so upon recalculation. Repeated elsewhere for completeness. ff May be misplaced by industrial group since the occupation is usually classified under "Business services."
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high SMR for footwear manufacturing corresponds to the high SMRs found for the occupations of shoemakers and repairers (Table 4) and operatives in leather and leather products. Components of the "other textile mill products" industry include the industries of dyeing and finishing textiles except knit goods and of carpets, rugs, and other floor coverings. These occupational and industrial risks (Tables 4 and 5) have some parallels in the more recent English data (Table 6). The first obvious point of agreement is the high risks for professionals in both countries. Another possible parallel may be the high risk for U.S. metal workers and the high rates for the English Order V (furnace, forge, foundry, and rolling mill) workers. Leather workers (Order IX) and textile workers (Order X) in the English data correspond quite well to the U.S. occupations and industries concerned with leather and yarn, but the PMRsfor these two English orders are only slightly above expected values. For the remaining U.S. occupations in Table 4 that may be at risk for bowel cancer, comparisons with counterpart English occupations cannot be made, since the latter are components of larger occupational groups. Despite this, there is some reason for taking seriously the remaining high U.S. rates even though a number of them do not reach levels of significance. DISCUSSION AND CONCLUSIONS Bowel cancer attacks more people in the U.S. than any other cancer except skin cancer, and only lung cancer kills more people (NCI, 1973). It is an environmental cancer, since the rates rise toward U.S. levels in groups who come to this country from low-incidence areas. Because it is a widespread cancer, at least some of the causal factors also must be widespread. This does not mean that there may not also be additional occupational factors, only that such factors and the resulting occupational cancers may not be conspicuous against a background of general high incidence. Because the factors have not been conspicuous does not mean they could not be real and important. Not only could they be producing high rates of bowel cancer in some occupational subgroups, but the same factors at lower dosage could play a role in the risks of the general population. Despite the paucity and low specificity of the existing data on industrial risks for bowel cancer, we believe that, because of the importance of the disease, further investigations should be made of the leads pointed out here. While it is true that some chemical exposures can be identified for just about any manufacturing or laboring occupation, the groupings described here do not appear to be random ones. The need for additional studies become greater in view of the growing difference in bowel cancer rates for men and women. The same observation suggests that ongoing and future studies of cancer risks of particular occupations should include a careful look at bowel cancer incidence.
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J.W. BERG AND M. A. HOWELL
TABLE 6. Standardized Mortality Ratios (SMR) for Colonic and Rectal Cancers, Separate and Combined, and Proportionate Mortality Ratios (PMR) by Combined Sites by Occupation Order, England and Wales, 1959-1963, Males Aged 15-64 SMR
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Occupation order0 Armed Forces (British and foreign) Glass and ceramics makers Textile workers Furnace, forge, foundry, rolling mill workers Food, drink, and tobacco workers Leather workers Professional, technical workers, artists Service, sport, and recreation workers Gas, coke, and chemical makers Transport and communications workers Laborers Clothing workers Electrical and electronic workers Clerical workers Painters and decorators Engineering and allied trades workers Sales workers Construction workers Woodworkers Miners and quarrymen Administrators and managers Farmers, foresters, fishermen Warehousemen, storekeepers, packers, bottlers Makers of other products Drivers of stationary engines, cranes, etc. Paper and printing workers
PMR*
Order no.
Colon
Rectum
XXVI IV X
156 133 122
168 121 133
128 127
109
V
116
133
124
116C
XII IX
115 115
119 112
117 114
113 104
XXV
113
82
99
132*
XXIII
110
119
114
96
III
110
88
100
108
XIX XVIII XI
108 108 108
106 122 100
107 114 104
100 80 96
VI
107 104
101
114 98 103
110 101 102
106 103 99
VII XXII XV VIII II XXIV 1
101 99 97 96 96 95 90
102 91 103 95 111 79 92
101 95 100 96 103 88 91
101 106 108 105
XX XIV
85 82
100 88
92 85
90 102
XVII XIII
78 78
92 53
84 67
85 78
XXI XVI
Colon plus Rectum*
Colon plus Rectum 95
161
.
128
U5d 112C
Source: Registrar General's Decennial Supplement, 1971. "Listed from high to low on the basis of the SMR for colon cancer. Calculated for this report; not available from source document. c Ratio is significantly above 100 at the 5% level; tests of significance were made for this report. Ratio is significantly above 100 at the 1% level; tests of significance were made for this report.
OCCUPATION AND BOWEL CANCER
TABLE 7. Standardized Mortality Ratios (SMR) for Colonic and Rectal Cancers Combined, by Industrial Group and Industry, United States, 1950, Males Aged 20-64
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SMR All industries Industrial group Agriculture, forestry, and fisheries Mining Construction Manufacturing Transportation, communication, and other public utilities Wholesale and retail trade Finance, insurance, and real estate Business and repair services Personal services Entertainment and recreation services Professional and related services Public administration Industry Agriculture Forestry and fisheries Coal mining Crude petroleum and natural gas extraction Mining and quarrying, except fuel Construction Logging Sawmills, planing mills, and mill work Miscellaneous wood products Furniture and fixtures Glass and glass products Stone and clay products Primary iron and steel industries Primary nonferrous industries Fabricated metal industries Machinery, except electrical Electrical machinery, equipment, and supplies Motor vehicles and motor vehicle equipment Aircraft and parts Ship and boat building and repairing Railroad and miscellaneous transportation equipment All other durable goods Meat products Bakery products Other food industries Tobacco manufacturers Knitting mills Yarn, thread, and fabric mills Other textile mill products Apparel and other fabricated textile products Paper and allied products
100 70 90 101 108 114 /12 114 110 107 145 99 118 70 — 96 81 89 101 104 73 — 108 93 101 100 106 702 124 114 104 129 — 95 100 — 105 — — 127 155 100 90
87
88
J.W. BERG ANDM. A. HOWELL
TABLE 7. Standardized Mortality Ratios (SMR) for Colonic and Rectal Cancers Combined, by Industrial Group and Industry, United States, 1950, Males Aged 20-64 (continued)
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SMR Industry (continued) Printing, publishing, and allied industries Chemical and allied products Petroleum and coal products Rubber products Footwear, except rubber Leather and leather products, except footwear Not specified manufacturing industries Railroads and railway express service Street railways and bus lines Trucking service and warehousing Water transportation Air transportation All other transportation Telecommunications Electric and gas utilities Water supply, sanitary services, and other utilities Wholesale trade Food and dairy products stores and milk retailing General merchandise and five and ten cent stores Apparel and accessories stores Furniture, home furnishings, and equipment stores Motor vehicles and accessories retailing Gasoline service stations Drugstores Eating and drinking places Hardware, farm implement, and building material retailing All other retail trade Banking and other finance Insurance and real estate Business services Automobile repair services and garages Miscellaneous repair services Private households Hotels and lodging places Laundering, cleaning, and dyeing services All other personal services Entertainment and recreation services Medical and other health services Educational services Welfare, religious, and membership organizations Legal, engineering, and miscellaneous professional services Postal service Federal public administration State and local public administration
108 89 92 130 774 — — 113 127 129 — — 114 116 85 79 75 111 777 202 78 114 93 129 143 108 129 136 106 112 108 110 59 116 116 125 145 97 60 121 777 130 89 133
Source: Guralnick, 1963a. Note: An italic SMR indicates that the PMR is significantly higher than the PMR for combined occupations; the dash indicates that the SMR was not computed.
OCCUPATION AND BOWEL CANCER
89
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REFERENCES Bailar, J.C., III and Ederer, F. 1964. Significance factors for the ratio of a Poisson variable to its expectation. Biometrics 20:639-643. Berg, J. W. and Howell, M. A. 1974. The geographic pathology of bowel cancer. Cancer 34:807-814. Berg, J. W., Haenszel, W. arid Devesa, S. S. 1973. Epidemiology of gastrointestinal cancer. In Seventh national cancer congress proceedings, pp. 459-464. Philadelphia: Lippincott. Dorn, H. F. and Cutler, S. 1959. Morbidity from cancer In the United States, Public Health Monograph no. 56. Washington, D.C.: Gov. Printing Office. Gafafer, W. M. 1966. Occupational diseases. A guide to their recognition. Public Health Service Publication no. 1097. Washington, D.C.: Gov. Printing Office. Guralnick, L. 1962. Mortality by occupation and industry among men 20 to 64 years of age: United States, 1950. U.S. Dept. of Health, Education, and Welfare, Vital Statistics-Special Reports, vol. 53, no. 2. Washington, D.C.: Gov. Printing Office. Guralnick, L. 1963a. Mortality by occupation and cause of death among men 20 to 64 years of age: United States, 1950. U.S. Dept. of Health, Education, and Welfare, Vital Statistics-Special Reports, vol. 53, no. 3. Washington, D.C.: Gov. Printing Office. Guralnick, L. 1963b. Mortality by industry and cause of death among men 20 to 64 years of age: United States, 1950. U.S. Dept. of Health, Education, and Welfare, Vital Statistics-Special Reports, vol. 53, no. 4. Washington, D.C.: Gov. Printing Office. Guralnick, L. 1963c. Mortality by occupation level and cause of death among men 20 to 64 years of age: United States, 1950. U.S. Dept. of Health, Education, and Welfare, Vital Statistics-Special Reports, vol. 53, no. 5. Washington, D.C.: Gov. Printing Office. Haenszel, W. 1967. Epidemiology of gastric cancer. In Neoplasms of the stomach, ed. G. McNeer and G. T. Pack, pp. 3-28. Philadelphia: Lippincott. Hammond, E. C , Selikoff, I. J. and Churg, J. 1965. The United States with special reference to intra-abdominal neoplasia. Ann. N.Y. Acad. Sci. 132:519-525. NCI. 1973. National cancer institute 1973 fact book. U.S. Dept. of Health, Education, and Welfare Publication no. (NIH) 73-512. Bethesda, Md.: National Institutes of Health. NCI, Biometry Branch. 1974. The third national cancer survey advanced three year report. Bethesda, Md.: National Institutes of Health. Registrar General's Decennial Supplement, England and Wales 1951. 1957. Occupational mortality tables Part II Volume 2. London: Her Majesty's Stationery Office. Registrar General's Decennial Supplement, England and Wales 1961. 1971. Occupational mortality tables. London: Her Majesty's Stationery Office. Wynder, E. L. and Shigematsu, T. 1967. Environmental factors of cancer of the colon and rectum. Cancer 20:1520-1561. Wynder, E., Graham, S. and Eisenberg, H. 1966. Conference on the etiology of cancer of the gastrointestinal tract. Report of Research Committee, World Health Organization on Gastroenterology, New York, June 10-11, 1965. Cancer 19:1561-1566.
Received January 28, 1975 Accepted May 26, 1975