Relationship of dietary folate and vitamin B6 with coronary heart disease in women.
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Alcohol Drinking↗
Biomedical subjects
D T Wigle
Publications and source records attributed to D T Wigle.
Safe drinking water: a public health challenge.
Disinfection of drinking water through processes including filtration and chlorination was one of the major achievements of public health, beginning in the late 1800s and the early 1900s. Chloroform and other chlorination disinfection by-products (CBPs) in drinking water were first reported in 1974. Chloroform and several other CBPs are known to cause cancer in experimental animals, and there is growing epidemiologic evidence of a causal role for CBPs in human cancer, particularly for bladder cancer. It has been estimated that 14 16% of bladder cancers in Ontario may be attributable to drinking water containing relatively high levels of CBPs; the US Environmental Protection Agency has estimated the attributable risk to be 2 17%. These estimates are based on the assumption that the associations observed between bladder cancer and CBP exposure reflect a cause-effect relation. An expert working group (see Workshop Report in this issue) concluded that it was possible (60% of the group) to probable (40% of the group) that CBPs pose a significant cancer risk, particularly of bladder cancer. The group concluded that the risk of bladder and possibly other types of cancer is a moderately important public health problem. There is an urgent need to resolve this and to consider actions based on the body of evidence which, at a minimum, suggests that lowering of CBP levels would prevent a significant fraction of bladder cancers. In fact, given the widespread and prolonged exposure to CBPs and the epidemiologic evidence of associations with several cancer sites, future research may establish CBPs as the most important environmental carcinogens in terms of the number of attributable cancers per year.
Animals↗
Serum folate and risk of fatal coronary heart disease.
OBJECTIVE: To assess the relationship between serum folate level and the risk of fatal coronary heart disease (CHD) among men and women. DESIGN: Retrospective cohort study with serum folate levels measured from September 1970 to December 1972, with follow-up through 1985. SETTING: Participants in the Nutrition Canada Survey. PARTICIPANTS: A total of 5056 Canadian men and women aged 35 to 79 years with no history of self-reported CHD. MAIN OUTCOME MEASURE: Fifteen-year CHD mortality. RESULTS: A total of 165 CHD deaths were observed. We found a statistically significant association between serum folate level and risk of fatal CHD, with rate ratios for individuals in the lowest serum folate level category (<6.8 nmol/L [3 ng/mL]) compared with the highest category (>13.6 nmol/L [6 ng/mL]) of 1.69 (95% confidence interval, 1.10-2.61). CONCLUSIONS: These data indicate that low serum folate levels are associated with an increased risk of fatal CHD.
Adult↗
Sudden death from asthma in 108 children and young adults.
To identify factors that may contribute to asthma mortality, 108 acute asthma deaths were reviewed. Information was obtained from medical records, next-of-kin, and autopsy records. The fatal asthmatic was characterized by early-onset asthma, severe disease requiring systemic corticosteroids, and prior hospitalization. Risk factors associated with gender, season, employment, and region were also identified. The fatal attack was characterized by an identifiable trigger, delay in seeking medical attention, and rapid deterioration in clinical status. Death due to asthma was confirmed in 95% of autopsied cases. Adrenal cortical abnormalities were recorded for 18.7% of cases. We conclude that, in addition to established risk factors, complications associated with the use of systemic steroids may contribute to the risk for sudden death in this age group.
Adolescent↗
Restructuring of the Chronic Disease Program at the Laboratory Centre for Disease Control.
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Canada↗
Canada's health status: a public health perspective.
Health status assessment and disease surveillance are essential to identify and priorize health issues, to evaluate intervention programs and to plan to meet future needs for health services. Canadians currently benefit by having among the highest life expectancies at birth in the world (81 for females, 74 for males). Disability-free life expectancies for females and males, respectively, were 10.1 and 11.3 years lower for the lowest income quintile compared to the highest. Canada's infant mortality rate in 1990 (7/1000 live births) was one of the lowest in the world but within Canada, the rate in the lowest income quintile (10.5/1000 live births) was almost double that in the highest income quintile (5.8/1000 live births). Fair or poor health was reported by 36% of adult Canadians in the lowest income category in 1990 compared to only 5% in the highest income group. The leading causes of premature death for females in 1991 were breast cancer, coronary heart disease, lung cancer, car crashes, birth defects and suicide; those for males were coronary heart disease, suicide, car crashes, lung cancer, birth defects, and AIDS. Lowest income quintile males had mortality rates at least double those for the highest income quintile for alcohol-related conditions, violence, injuries and emphysema. Cardiovascular diseases, cancer, musculoskeletal diseases, injuries and respiratory diseases imposed the highest direct and indirect economic costs in Canada in 1986. For all of these conditions, improved prevention is possible. For example, the forecasted tobacco-related deaths before age 70 among current male smokers age 15 will far exceed those due to car crashes, suicide, murder, AIDS, and drug abuse combined. Population aging will aggravate trends for many chronic conditions especially those with increasing incidence rates; there will be large increases in the numbers of persons with aging-related cancers, dementias and other conditions. There is an urgent need for Canadian health jurisdictions to ensure that rational priorities, goals/objectives, strategies, and programs are in place to enhance prevention and disease control.
Adolescent↗
Serum iron and risk of fatal acute myocardial infarction.
We assessed the relation of serum iron, dietary iron, and the use of iron supplements to the risk of fatal acute myocardial infarction in the Nutrition Canada Survey cohort. We found an association between serum iron and risk of fatal acute myocardial infarction, with rate ratios for males and females in the highest category of serum iron (> or = 175 micrograms per dl) of 2.18 [95% confidence intervals (CI) = 1.01-4.74] and 5.53 (95% CI = 1.69-18.12), respectively. We found no important association between risk of fatal acute myocardial infarction and either dietary iron or iron supplement use among the 9,920 participants included in this study.
Acute Disease↗
Non-Hodgkin's lymphoma and agricultural practices in the prairie provinces of Canada.
OBJECTIVES: The aim of this study was to provide an update of a cohort study (1971-1985) that previously reported a significant trend in the risk of non-Hodgkin's lymphoma among male Saskatchewan farm operators according to fuel-oil expenditures and herbicide spraying for farms less than 1000 acres (2570 hectares) by including two additional Canadian prairie provinces, two additional years of follow-up, and data from the 1981 Census of Agriculture. METHODS: Information on farmers from 1971 records of the Census of Agriculture was linked to 1971 records of the Census of Population, to 1981 records of the Census of Agriculture, and to death records. Poisson regression was used to estimate risks according to herbicide spraying and fuel and oil expenditures. RESULTS: The addition of a further two years of follow-up resulted in lower risk estimates associated with herbicide spraying for Saskatchewan. No excess risk was observed between herbicide spraying and non-Hodgkin's lymphoma for Alberta or Manitoba in the 1971 data. However, a significantly increased risk of non-Hodgkin's lymphoma according to acres sprayed with herbicides was observed for the three provinces combined when the herbicide spraying data from the 1981 Census of Agriculture was used [> or = 380 acres (> or = 939 hectares) sprayed, rate ratio 2.11, 95% confidence interval 1.1-3.9]. CONCLUSIONS: Although the current results are not entirely consistent with the original Saskatchewan analysis, they support the overall finding of an association between herbicides and risk of fatal non-Hodgkins lymphoma. Prospective cohort studies are needed to overcome the limitations of existing epidemiologic studies.
Adult↗
Risk assessment of physical activity and physical fitness in the Canada Health Survey mortality follow-up study.
The effect of physical fitness and physical activity on all-cause mortality and mortality due to cardiovascular disease (CVD), cancer and other causes was examined using a population-based representative sample of the Canadian population. A total of 691 deaths occurred among persons age 30-69 during the 7-year follow-up period. Of these, 37, 33 and 30% died of CVD, cancer and other causes, respectively. The effect of each risk factor on mortality was assessed using logistic regression analysis. Adjustment was made for age, sex, smoking and body mass index in the case of mortality due to CVD, all causes and causes other than CVD and cancer. Models for mortality due to cancer included adjustment for age, sex, smoking and alcohol consumption. For all cause mortality, those individuals who did not pass the physical fitness tests had significantly higher risks of death than those that passed. For CVD mortality, subjects whose physical activity was moderate were protected, and those who did not pass the physical fitness tests had substantially higher risks of death due to CVD. The risk of death due to cancer was not significantly related to physical activity or physical fitness. Persons who failed the physical fitness tests had significantly elevated risks of death due to causes other than CVD or cancer. Our findings support the conclusion that persons who are physically fit have an overall reduced risk of death independent of other major risk factors. Moderate levels of physical activity appear to be protective against cardiovascular disease.
Adult↗
Increasing brain cancer rates in Canada.
OBJECTIVE: To analyse brain cancer patterns in Canada, particularly according to age and sex distributions, temporal patterns and regional variations. Changes in diagnostic techniques, survival rates and trends by tumour type were also examined. DESIGN: Descriptive epidemiologic study based on Canada-wide population data for 1959-88. OUTCOME MEASURES: Rates of death, incidence and admission to hospital because of brain cancer, as well as survival time and methods of diagnosis. SUBJECTS: Incidence and death rates and time trends were examined for Canada as a whole, by province and by census division. RESULTS: The rates of death from brain cancer increased rapidly among Canadians aged 55 years or more from 1959 to 1988. In particular, age-adjusted death rates increased by 117%, 797% and 118% among men 65 to 74 years, 75 to 84 and 85 or more respectively. The corresponding increases among women were 138%, 535% and 400%. The incidence rates also increased substantially. The trends in incidence rates by tumour type indicated that the increase was more pronounced for glioblastomas. The incidence rates of cases detected histologically, radiologically and clinically all increased. CONCLUSIONS: Because glioblastomas are generally easier to diagnose than astrocytomas and because the incidence rates of glioblastomas were found to increase substantially, the increased brain cancer rates among elderly people may not be entirely attributable to improved diagnostic techniques. However, analytic investigations of the impact of changes in diagnostic procedures on brain cancer trends are needed to clarify this issue.
Adolescent↗
The relationship of suicide rates to sociodemographic factors in Canadian census divisions.
The correlates of suicide rates were determined by conducting a multivariate study of sociodemographic indicators and suicide rates of 261 Canadian census divisions. Twenty-one sociodemographic variables were entered into a stepwise multiple linear regression to develop a model for suicide rates. The important variables were mortality rate for all causes of death, the age of the population, average family income, population density, proportion with no religious affiliation, proportion of Francophones, unemployment, immigration, proportion of Native people, a regional effect for British Columbia and the north, and growth by mobility, explaining 62% of the observed variation. This spatial ecologic analysis highlights the importance of cultural differences in explaining the variation of suicide rates. The analysis supports the previously found negative relationship between income and suicide while contrasting from previous studies in determining a inverse relationship with unemployment and an inverse relationship with the age distribution.
Canada↗
Mortality study of Canadian male farm operators: non-Hodgkin's lymphoma mortality and agricultural practices in Saskatchewan.
A cohort study of the mortality experience (1971-1985) of male Saskatchewan farmers has been conducted. This study involved linkage of records of the almost 70,000 male farmers identified on the 1971 Census of Agriculture and the corresponding Census of Population to mortality records. Pesticide exposure indices for individual farm operators for the year 1970 were derived from the 1971 Census of Agriculture records. Although the cohort as a whole had no excess mortality for any specific causes of death, including non-Hodgkin's lymphoma, significant dose-response relationships were noted between risk of non-Hodgkin's lymphoma and acres sprayed in 1970 with herbicides, as well as with dollars spent on fuel and oil for farm purposes in 1970. Using Poisson regression modeling, we found that relative risks for the highest level of herbicide use (greater than or equal to 250 acres sprayed) and fuel purchased in 1970 (greater than or equal to $900) on farms less than 1,000 acres total area were 2.2 (95% confidence interval = 1.0-4.6) and 2.3 (95% confidence interval = 1.1-4.7), respectively.
Adult↗
Major risk factors for cardiovascular disease mortality in adults: results from the Nutrition Canada Survey cohort.
The cardiovascular mortality experience of over 7000 Canadians ages 35-79 years free of self-reported heart disease or stroke who participated in the Nutrition Canada survey is presented. The effects of various risk factors on cardiovascular disease mortality were assessed using multivariate Poisson regression analyses. Factors associated with a significantly increased risk of dying included cigarette smoking, hypertension, diabetes and, for women, serum cholesterol. Relative risks were similar for those ages 35-64 years compared to those 65-79 years for diabetes but were higher among those 35-64 years for cigarette smoking, diastolic hypertension, obesity and serum cholesterol (females only). Individuals drinking three or more drinks daily had a relative risk of 3.18 for stroke. Population attributable risks for smoking, hypertension, elevated serum cholesterol and diabetes, respectively, were 47%, 21%, 7% and 8% for men and 10%, 21% 18% and 16% for women.
Adult↗
Cancer mortality among a group of fluorspar miners exposed to radon progeny.
A cohort study of the mortality experience (1950-1984) of 1,772 Newfoundland underground fluorspar miners occupationally exposed to high levels of radon daughters (mean dose = 382.8 working levels months) has been conducted. Observed numbers of cancers of the lung, salivary gland, and buccal cavity and pharynx were significantly elevated among these miners. A highly significant relation was noted between radon daughter exposure and risk of dying of lung cancer; the small numbers of salivary gland (n = 2) and buccal cavity and pharynx (n = 6) cancers precluded meaningful analysis of dose response. Attributable and relative risk coefficients for lung cancer were estimated as 6.3 deaths per working level month per million person-years and 0.9% per working level month, respectively. Relative risk coefficients were highest for those first exposed before age 20 years. Cigarette smokers had relative and attributable risk coefficients comparable to those of nonsmokers. Relative risks fell sharply with age, whereas attributable risks were lowest in the youngest and oldest age groups. The results suggest that efforts to raise existing occupational exposure standards may be inappropriate.
Epidemiologic Methods↗
Deaths in Canada from lung cancer due to involuntary smoking.
Recently published evidence indicates that involuntary smoking causes an increased risk of lung cancer among nonsmokers. Information was compiled on the proportion of people who had never smoked among victims of lung cancer, the risk of lung cancer for nonsmokers married to smokers and the prevalence of such exposure. On the basis of these data we estimate that 50 to 60 of the deaths from lung cancer in Canada in 1985 among people who had never smoked were caused by spousal smoking; about 90% occurred in women. The total number of deaths from lung cancer attributable to exposure to tobacco smoke from spouses and other sources (mainly the workplace) was derived by applying estimated age- and sex-specific rates of death from lung cancer attributable to such exposure to the population of Canadians who have never smoked; about 330 deaths from lung cancer annually are attributable to such exposure.
Adult↗
Important risk factors for death in adults: a 10-year follow-up of the Nutrition Canada survey cohort.
Data on mortality among over 8000 Canadians aged 35 to 79 years who participated in the Nutrition Canada survey are presented. The effects of various risk factors on mortality were assessed with a multivariate Poisson regression analysis. Factors associated with a significantly increased risk of death over a 10-year follow-up period ending in 1981 included cigarette smoking, hypertension and diabetes mellitus. A shallow U-shaped mortality pattern was observed for body mass index and for serum cholesterol level. No statistically significant increases in risk were associated with alcohol consumption. The population attributable risks for smoking, hypertension and diabetes were 39%, 8% and 6% respectively for men and 21%, 12% and 7% respectively for women.
Adult↗
Cancer patterns in Canada.
Cancer is diagnosed in about 70 000 Canadians each year and is the leading cause of the loss of potential years of life before age 75 among women. Life-threatening forms of cancer will develop in at least one of every three Canadian newborns during their lifetimes if current cancer risks are not reduced. Lung and breast cancers are, respectively, the leading causes of premature death due to cancer among men and women. Compared with other countries Canada has low death rates for stomach cancer but high rates for certain smoking-related cancers (those of the lung and of the mouth and throat), leukemia and cancers of the colon, breast and lymphatic tissues. Newfoundland has the highest rates of death from stomach cancer and the lowest rates of death from prostatic cancer, whereas the western provinces have the opposite pattern. The rates of death from lung cancer among men are highest in Quebec, the province with the highest prevalence of smoking. In Canada the overall rates of death from cancer increased by 32% among men from 1951 to 1983. However, among women they declined by 12% from 1951 to 1976 and increased from 1976 to 1983, particularly among those aged 55 to 74. The rising rates of death due to lung cancer were primarily responsible for these increases. Lung cancer will likely displace breast cancer as the leading cancer killer of Canadian women by 1990. Given the relatively low survival rates for cancers caused by smoking and the lack of substantial improvement in rates for the most frequent types of cancer, preventive strategies that include effective measures to reduce tobacco consumption are urgently required.
Adult↗
Socioeconomic disparities in risk factors for cardiovascular disease.
Despite a general decline in mortality rates in recent decades, these rates are substantially higher among lower socioeconomic groups. To determine target groups for preventive health promotion programs, the prevalence of risk factors for cardiovascular disease by socioeconomic group in Canadian adults aged 20 to 69 years was examined through comparison of estimates from the 1978-79 Canada Health Survey, the 1981 Canada Fitness Survey and the labour force smoking surveys of 1975 and 1983. Level of education was used as a measure of socioeconomic status. The risk factors considered were cigarette smoking, overweight, obesity, elevated diastolic blood pressure, physical inactivity, excessive alcohol consumption, elevated serum cholesterol level, diabetes mellitus and the conjoint use of oral contraceptives and cigarettes. The prevalence of the risk factors tended to be higher among men and women with a low level of education. The results were consistent with those of recent Canadian studies showing that both men and women in lower socioeconomic groups are more likely to die from cardiovascular disease.
Adult↗