ISSN:1044-3983    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:1044-3983    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:1044-3983    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:1044-3983    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Between 1986 and 1991, 29,584 persons took part in a randomized nutritional intervention trial in Linxian, China, an area whose residents had chronically low intakes of several nutrients and high rates of esophageal and gastric cardia cancer as well as stroke. Using a one-half replicate of a 24factorial design, we randomized individuals to one of eight groups which received combinations of four supplements: retinol and zinc (factor A); riboflavin and niacin (factor B); vitamin C and molybdenum (factor C); and beta-carotene, alpha-tocopherol (vitamin E), and selenium (factor D). Deaths that occurred during 5 years of supplementation were ascertained and classified according to cause. At the end of the supplementation period, we measured blood pressure readings and determined the prevalence of hypertension. Participants who received factor D had reductions in total mortality (9%) and total cancer mortality (13%). These individuals also had the largest reduction in stroke mortality (relative risk = 0.91; 95% confidence interval = 0.76–1.07). End-of-trial hypertension, however, was not less prevalent among those receiving factor D. Our findings contrast with the larger reductions in stroke death and hypertension found in a parallel trial of Linxian subjects with esophageal dysplasia who received a multivitamin/mineral supplement, suggesting an effect largely derived from nutrients other than those received in the present study.

ISSN:1044-3983    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

We propose a residential case-specular method for the study of wire codes and childhood cancer. The method compares the wire codes of case residences with the wire codes of identical residences (specular residences) located in a virtual situation in which the position of the residence or the position of the power line is switched around the center of the street. It is designed to discriminate between the magnetic field hypothesis, which postulates that childhood cancer is affected by magnetic fields and that wire codes are a proxy for magnetic fields,vsthe neighborhood hypothesis, which postulates that childhood cancer is affected by some characteristics of the neighborhood other than magnetic fields and wire codes are a proxy for those characteristics. The method is based on several assumptions that we tested with 400 randomly selected residences. Under certain conditions, the method also may allow effect estimation without requiring the selection of controls and the potential biases that result from control selection. The method is applicable to both past and future studies.

ISSN:1044-3983    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

We conducted a population-based case-control study of bladder cancer in Iowa in 1986–1989 to evaluate the risk posed by tapwater containing chlorination byproducts. We combined information about residential history, drinking water source, beverage intake, and other factors with historical data from water utilities and measured contaminant levels to create indices of past exposure to chlorination byproducts. The study comprised 1,123 cases and 1,983 controls who had data relating to at least 70% of their lifetime drinking water source. After we adjusted for potential confounders, we calculated odds ratios for duration of chlorinated surface water of 1.0 (referent), 1.0, 1.1, 1.2, and 1.5 for 0, 1–19, 20–39, 40–59, and ≥60 years of use. We also found associations with total and average lifetime byproduct intake, as represented by trihalomethane estimates. Positive findings were restricted to men and to ever-smokers. Among men, odds ratios were 1.0 (referent), 1.1, 1.3, 1.5, and 1.9, and among ever-smokers, 1.0, 1.1, 1.3, 1.8, and 2.2, after adjustment for intensity and timing of smoking. Among nonsmoking men and women, regardless of smoking habit, there was no association. Among men, smoking and exposure to chlorinated surface water mutually enhanced the risk of bladder cancer. The overall association of bladder cancer risk with duration of chlorinated surface water use that we found is consistent with the findings of other investigations, but the differences in risk between men and women, and between smokers and nonsmokers, have not been widely observed.

ISSN:1044-3983    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

We evaluated the association between chlorination byproducts and colon and rectal cancer risk in a population-based case-control study conducted in Iowa in 1986–1989. Data were gathered from 685 colon cancer cases, 655 rectal cancer cases, and 2,434 controls. We calculated odds ratios for the 560 colon cancer cases, 537 rectal cancer cases, and 1,983 controls for whom water exposure information was available for at least 70% of their lifetime. We estimated exposure to chlorination byproducts with two types of measures: duration of lifetime at residences served by chlorinated water and estimated lifetime trihalomethane exposure. For rectal cancer, we observed an association with duration of chlorinated surface water use, with adjusted odds ratios of 1.1, 1.6, 1.6, and 2.6 for 1–19, 20–39, 40–59, and ≥60 years of exposure, compared with no exposure. Rectal cancer risk was also associated with several different measures of estimated lifetime trihalomethane exposure. For colon cancer and subsites, we detected no important increase in risk associated with duration of chlorinated surface water, nor with trihalomethane estimates. When we evaluated chlorination byproducts jointly with other factors, we found larger relative risk estimates for rectal cancer among subjects with low dietary fiber intake. The risk related to ≥40 years of exposure to a chlorinated surface water source was 2.4 (95% confidence interval = 1.5–4.0) for persons with low fiber intake and 0.9 (95% confidence interval = 0.4–1.8) for persons with high fiber intake, relative to the risk of persons with high-fiber diets and no exposure to chlorinated surface water. We observed a similar risk differential for low and high levels of physical activity.

ISSN:1044-3983    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

We conducted a prospective study (N = 2,967) to evaluate the relation of spontaneous abortion with use of electrically heated beds (electric blankets and heated water beds) during pregnancy. At interview, 61.5% of women were at less than 12 weeks gestation, and 38.5% were between 13 and 16 weeks; thus, very early pregnancy losses would have been excluded. Information regarding exposure to electric beds was obtained for the month of conception and the 7 days before interview. Electric blanket use at conception was associated with an increased risk of spontaneous abortion in the unadjusted analysis [relative risk (RR) = 1.84; 95% confidence interval (CI) = 1.08–3.13], but adjustment for other factors reduced the risk slightly [odds ratio (OR) = 1.74; 95% CI = 0.96–3.15]. Heated water bed use was not associated with an increased risk of spontaneous abortion at conception (OR = 0.59; 95% CI = 0.33–1.07) or at interview (OR = 0.63; 95% CI = 0.36–1.12). Measures of dose response (daily use, hours of use, or temperature setting) were not associated with increased risk. Wire code data were obtained for the first, or only, house lived in during pregnancy. Women living in homes classified as “very high” or “ordinary high” current configuration were not at greater risk than women living in homes with buried wires. Nor was there any trend for increased risk of spontaneous abortion by wire code category. This study does not support the hypothesis that use of electric beds or residence in a high current configuration home increases the risk of spontaneous abortion; however, it indicates that electric blanket use at the time of conception and in early pregnancy may be associated with a slight increase in risk of pregnancy loss.

ISSN:1044-3983    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

We examined the effect of decision latitude and work demand on risk of myocardial infarction in a former Soviet Bloc country and analyzed whether these factors contributed to the educational gradient in myocardial infarction in this population. We conducted a case-control study among full-time working men in the general population of five districts of the Czech Republic. Cases were 179 men 25–64 years of age with a first nonfatal myocardial infarction diagnosed in selected districts over a 1-year period, and controls were 784 men in the same age group randomly selected from the population register. We used logistic regression to estimate the odds of developing myocardial infarction in relation to self-reported work demand and decision latitude at work and the contribution of these factors as well as standard risk factors to socioeconomic differences in the risk of myocardial infarction. Cases reported lower decision latitude and lower work demand than controls. Age-adjusted odds ratios for the highestvslowest quartiles of decision latitude and work demand were 0.43 (95% confidence interval = 0.25–0.75) and 0.54 (95% confidence interval = 0.31–0.93), respectively. Further adjustment for coronary risk factors and education did not change these estimates. Decision latitude accounted for part of the association between education and myocardial infarction, and decision latitude and risk factors jointly explained virtually all of it. The association between decision latitude at work and myocardial infarction found in our study is consistent with research in western populations and may partly explain the socioeconomic gradient in myocardial infarction.

ISSN:1044-3983    

出版商:OVID    

年代:1998

数据来源: OVID