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Biomedical subjects

R K Severson

Publications and source records attributed to R K Severson.

At least 73 records · Page 4Linked to original sources
PubMed1988

Acute nonlymphocytic leukemia and residential exposure to power frequency magnetic fields.

Recent research has suggested that nonionizing radiation in the form of power-frequency magnetic fields may play some role in carcinogenesis in general and in acute nonlymphocytic leukemia in particular. Much of the epidemiologic evidence is preliminary in nature and the methods of previous studies have been criticized. In order to further evaluate this hypothesis, a population-based case-control study of adult acute nonlymphocytic leukemia and residential exposure to power-frequency magnetic fields was carried out in western Washington state. Analyses were based on 114 cases who were newly diagnosed from 1981 to 1984 and identified from a population-based cancer registry, and 133 controls who were chosen from the study area by random digit dialing. Magnetic field exposure was estimated from external electrical wiring configurations within 140 ft (42.7 m) of each subject's residence. In addition, magnetic fields were measured inside the subject's residence at the time of interview. Neither the directly measured magnetic fields nor the surrogate values based on the wiring configurations were associated with acute nonlymphocytic leukemia.

Acute Disease↗
PubMed1988

Next-of-kin attitudes regarding participation in an epidemiologic case-control study.

We assessed next-of-kin's attitudes about participating in an epidemiologic case-control study of adult acute nonlymphocytic leukemia. Responses from a mailed questionnaire indicated that 95 per cent were glad they participated. While 74 per cent benefited, 18.5 per cent were bothered in some way. Results concerning the need to obtain physician permission before contacting next-of-kin were inconclusive; however, 8 of 10 females contacted by the case's physician considered consent necessary.

Adult↗
PubMed1987

Cigarette smoking and leukemia.

Cigarette smoking has not been consistently associated with the subsequent development of leukemia. However, many of the earlier epidemiologic studies of leukemia have not considered specific histologic subtypes separately. The association between cigarette smoking and adult acute nonlymphocytic leukemia was examined in a case-control study of 114 patients and 133 controls. Cigarette smoking was associated with a significantly increased risk of acute myelocytic leukemia (relative risk estimate = 1.78, 95% confidence interval = 1.01 to 3.15) along with a significant (P less than 0.001) dose-response based on the total number of years of cigarette smoking. Since this is a preliminary study, more analyses of other epidemiologic studies are needed before it can be concluded that there is a causal association.

Adult↗
PubMed1987

Residential magnetic and electric fields.

A magnetic flux density (MFD) and electric-field (E-field) data-acquisition system was built for characterizing extremely low-frequency fields in residences. Every 2 min during 24-h periods, MFD and E-field measurements were made in 43 homes in King, Pierce, and Snohomish counties of Washington State. The total electrical energy used in each residence during the 24-h measurement period was also recorded, and maps were drawn to scale of the distribution wiring within 43 m (140 ft) of these homes. Finally, on a separate date, field measurements were made in each home during an epidemiological interview. The results of this study can be summarized as follows: 1) 24-h-average MFD measured at two separate points in the family room were correlated, as were a 24-h-average bedroom measurement and the mean of the two family-room measurements. 2) The 24-h-average family-room MFD and E-field measurements were uncorrelated. 3) The 24-h-average total harmonic distortions of family-room MFD and E-fields were less than about 24% and 7%, respectively. 4) Residential MFD exhibited a definite 24-h (diurnal) cycle. 5) The 24-h-average and interviewer-measured MFD were correlated. 6) Residential 24-h-average MFD were correlated with the wiring code developed by Wertheimer and Leeper. 7) An improved prediction of 24-h-average residential MFD was obtained using the total number of service drops, the distance to neighboring transmission lines, and the number of primary phase conductors.

Electricity↗
PubMed1987

Factors affecting place of death in Washington State, 1968-1981.

A study was carried out to determine factors affecting place of death (home, hospital, nursing home or "other places") among all 426,115 resident deaths in Washington State during 1968-1981, using death certificate information. Sixteen percent of deaths occurred at home, 74% in institutions (51% in hospitals, 23% in nursing homes) and 9% at "other places." Age, marital status and cause of death all strongly affect place of death. Further, the effect of each factor was strongly dependent on the others. Sex had no effect on place of death after controlling for other factors. Elderly people died relatively more frequently in nursing homes, infants and middle aged people in hospitals and young adults in "other places." The frequency of deaths at home was quite constant by age. Hospitals were the most common place of death following both vascular disease (including heart attack) and neoplasms, and nursing homes were the most common place of death following cerebrovascular disease (including "stroke"). Race, socioeconomic status and urban or rural residents affected the place of death only slightly or not at all. The place of death pattern changed little during the time period 1968-1981, except for a slight increase in frequency of home deaths and a corresponding decrease in the frequency of deaths in other places. Among cancer patients, the likelihood of death at home was positively associated with longer periods of survival after diagnosis. Cancer patients of hospitals serving targeted populations, such as veterans, were relatively more likely to die in a hospital and less likely to die in a nursing home compared to other cancer patients, suggesting that the "targeted" hospitals are sometimes serving a nursing home function. There was a marked difference in the terminal cancer caseload by hospital. The number of cancer deaths per cancer diagnosis varied widely across hospitals (0.1 to 1.6) and was unrelated to size of the hospital or level of services offered. Intervention aimed at affecting place of death, such as increasing the number of deaths at home, will need to take account of the joint effect of age, marital status and disease.

Adolescent↗
PubMed1987

Breast cancer incidence and month of birth: evidence against an etiologic association.

To investigate the potential relationship between month of birth and breast cancer risk, the authors examined the month of birth of 14,289 women with breast cancer and 38,151 women with cancer of sites other than the breast. All cases were newly diagnosed between 1974 and 1984, and were identified through the Cancer Surveillance System, one of 10 population-based cancer registries comprising the Surveillance, Epidemiology and End Results Program of the National Cancer Institute in the United States. Although breast cancer cases exhibited spring and fall peaks in their month of birth (confirming a previous report), the month of birth of non-breast cancer cases followed a similar distribution. Such patterns have also been reported from populations in other parts of the United States, western Europe, Japan and Australia. These findings suggest that the seasonal variation observed in month of birth of women who develop breast cancer is a reflection of the pattern of births in the underlying population, rather than a new variant in breast cancer epidemiology.

Adult↗
PubMed1987

Soft tissue sarcoma and non-Hodgkin's lymphoma in relation to phenoxyherbicide and chlorinated phenol exposure in western Washington.

A population-based case-control study was conducted in western Washington State to evaluate the relationship between occupational exposure of men aged 20-79 to phenoxyacetic acid herbicides and chlorinated phenols and the risks of developing soft tissue sarcoma (STS) and non-Hodgkin's lymphoma (NHL). Occupational histories and other data were obtained by personal interviews for 128 STS cases and 576 NHL cases, diagnosed between 1981 and 1984, and for 694 randomly selected controls without cancer. Among the study subjects with any past occupational exposure to phenoxyherbicides, the estimated relative risk and 95% confidence interval of developing STS was 0.80 (0.5-1.2), and of developing NHL, 1.07 (0.8-1.4). Risk estimates of developing STS and NHL associated with past chlorophenol exposure were 0.99 (0.7-1.5) and 0.99 (0.8-1.2), respectively. No increasing risk of either cancer was associated with overall duration or intensity of chemical exposure or with exposure to any specific phenoxyherbicide per se. However, estimated risks of NHL were elevated among men who had been farmers, 1.33 (1.03-1.7), forestry herbicide applicators, 4.80 (1.2-19.4), and for those potentially exposed to phenoxyherbicides in any occupation for 15 years or more during the period prior to 15 years before cancer diagnosis, 1.71 (1.04-2.8). Increased risks of NHL were also observed among those with occupational exposure to organochlorine insecticides, such as DDT [1.82 (1.04-3.2)] and organic solvents [1.35 (1.06-1.7)], and to other chemicals typically encountered in the agricultural, forestry, or wood products industries. These results demonstrate small but significantly increased risks of developing NHL in association with some occupational activities where phenoxyherbicides have been used in combination with other types of chemicals, particularly for prolonged periods. They do not demonstrate a positive association between increased cancer risks and exposure to any specific phenoxyherbicide product alone. Moreover, these findings provide no evidence of increased risks of developing NHL associated with chlorinated phenol exposure or of developing STS associated with exposure to either class of chemical.

Adult↗
PubMed1984

A case-control study of asbestos in drinking water and cancer risk.

The authors conducted a case-control, interview-based study of the risk of developing cancer from asbestos in drinking water. The Everett, Washington area was selected for the study because of the unusually high concentration of chrysotile asbestos in the drinking water it draws from the Sultan River (200 X 10(6) fibers/liter). Through a population-based tumor registry, the authors identified 382 individuals with cancer of the buccal cavity, pharynx, respiratory system, digestive system, bladder, or kidney, diagnosed between 1977 and 1980, and then interviewed them or their next-of-kin. The authors conducted similar interviews of a control group of 462 individuals. Finally, interviews were validated in several ways, including comparing the collected data with that from secondary sources. Estimates of exposure to asbestos in drinking water were based on residence and workplace history, and on individual water consumption. Four different measures of exposure were used. Cancer risk was estimated by logistic regression and other methods. The authors found no convincing evidence for cancer risk from imbibed asbestos. Exposure was similar between cases and controls. Confidence intervals for relative odds for almost all sites included unity. Out of 84 dependent estimates of risk by sex, site, and exposure measure, 63 indicated a protective effect and 21 indicated an increased risk. In instances where relative odds differed appreciably from unity for both males and females, the effect was protective. The relative odds of cancer for 20 years of exposure to Sultan River drinking water varied from 0.92 to 0.99 for females and 0.82 to 1.01 for males for all study sites grouped. For cancer of the digestive system, the corresponding range was 1.03 and 1.08 for females and 0.85 to 1.00 for males. There were six statistically significant associations (p less than 0.05). All involved male stomach (eight cases) and male pharynx (four cases), and indicate elevated risk. This number of significant associations is close to that expected (for the number of comparisons made). The female risks for these two sites indicate a protective effect, and it is concluded that the male results are probably due to chance.

Adult↗
PubMed1983

Cancer risk from asbestos in drinking water: summary of a case-control study in western Washington.

We conducted a case-control, interview-based study of the risk of developing cancer from asbestos in drinking water. An area that included Everett, Washington, was selected for the study because of the unusually high concentration of chrysotile asbestos in drinking water from the Sultan River. Through a population-based tumor registry, 382 individuals with cancer of the buccal cavity, pharynx, respiratory system, digestive system, bladder, or kidneys, diagnosed between 1977 and 1980, were identified, and they or their next of kin were interviewed. We conducted validation checks of our interviews, including a comparison with secondary sources. Data on asbestos exposure were collected based on residence and workplace history, and on individual water consumption. Logistic regression was used to estimate cancer risk. We found no convincing evidence for increased cancer risk from imbibed asbestos. Confidence intervals for relative risks for almost all sites included unity. There were significantly elevated risks only for male stomach and male pharyngeal cancer, but these sex-inconsistent results, based on small numbers of cases, are probably due to other factors.

Adult↗
PubMed1982

Cancer incidence in relation to asbestos in drinking water in the Puget Sound region.

Population-based and proportional odds ratios for various cancers, based on incidence data from 1974-1977 and mortality data from 1965-1975 for western Washington State, were calculated in relation to three measures of exposure to asbestos in community water supplies. Six odds ratios were calculated for each neoplasm that occurred in sufficient numbers in each sex. About half of the 332 odds ratios calculated were above unity and half were below unity, and no more of them differed significantly from unity at the 5% level than would be expected by chance. Odds ratios for tumors of the small intestine were consistently elevated in both sexes, as were those for neoplasms of the thyroid, eye, testis, and prostate in males; however, odds ratios for brain tumors and leukemia were consistently less than one in both sexes. Chance is the most likely explanation for these findings. Results of this study and prior studies of cancer in relation to waterborne asbestos are inconsistent, and provide little evidence that asbestos in community water supplies has altered the risk of any cancer. However, all investigations conducted to date are correlational studies which have an inherently higher probability of failing to detect actual increased risks associated with imbibed asbestos, and additional studies of individual exposures are warranted. Neoplasms of the pancreas and small intestine should be included in such studies.

Adult↗
PubMedDate not supplied

Human T-cell lymphotropic virus type I (HTLV-I) antibodies in pre-diagnostic serum of patients with familial adult T-cell leukemia/lymphoma (ATL).

In a study of 7498 American men of Japanese ancestry in Hawaii, 26 incident cases of leukemia or non-Hodgkin's lymphoma were identified after a follow-up period of 19 years. Two of the cases, who were brothers, were diagnosed with adult T-cell leukemia/lymphoma (ATL). Both of these brothers had human T-cell lymphotropic virus type I (HTLV-I) antibodies in their stored serum which were obtained 4 and 18 years before diagnosis. None of the 24 patients with other hematologic malignancies or the 26 matched controls were HTLV-I antibody positive. This finding lends further support for a role of HTLV-I in the etiology of adult T-cell leukemia/lymphoma.

Aged↗