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Biomedical subjects

D L Preston

Publications and source records attributed to D L Preston.

At least 37 records · Page 2Linked to original sources
PubMed2000

Bone cancers in Mayak workers.

Bone cancer mortality risks were evaluated in 11,000 workers who started working at the "Mayak" Production Association in 1948-1958 and who were exposed to both internally deposited plutonium and external gamma radiation. Comparisons with Russian and U.S. general population rates indicate excess mortality, especially among females, plutonium plant workers, and workers with external doses exceeding 1 Sv. Comparisons within the Mayak worker cohort, which evaluate the role of plutonium body burden with adjustment for cumulative external dose, indicate excess mortality among workers with burdens estimated to exceed 7.4 kBq (relative risk = 7.9; 95% CI = 1.6-32) and among workers in the plutonium plant who did not have routine plutonium monitoring data based on urine measurements (relative risk = 4.1; 95% CI = 1.2-14). In addition, analyses treating the estimated plutonium body burden as a continuous variable indicate increasing risk with increasing burden (P < 0.001). Because of limitations in current plutonium dosimetry, no attempt was made to quantify bone cancer risks from plutonium in terms of organ dose, and risk from external dose could not be reliably evaluated.

Adult↗
PubMed2000

Liver cancers in Mayak workers.

Liver cancer mortality risks were evaluated in 11,000 workers who started working at the "Mayak" Production Association in 1948-1958 and who were exposed to both internally deposited plutonium and external gamma radiation. Comparisons with Russian liver cancer incidence rates indicate excess risk, especially among those with detectable plutonium body burdens and among female workers in the plutonium plant. Comparisons within the Mayak worker cohort which evaluate the role of plutonium body burden with adjustment for cumulative external dose indicate excess risk among workers with burdens estimated to exceed 7.4 kBq (relative risk = 17; 95% CI = 8. 0-36) and among workers in the plutonium plant who did not have routine plutonium monitoring data based on urine measurements (relative risk = 2.8; 95% CI = 1.3-6.2). In addition, analyses treating the estimated plutonium body burden as a continuous variable indicate increasing risk with increasing burden (P < 0.001). Relative risks tended to be higher for females than for males, probably because of the lower baseline risk and the higher levels of plutonium measured in females. Because of limitations in current plutonium dosimetry, no attempt was made to quantify liver cancer risks from plutonium in terms of organ dose, and risk from external dose could not be reliably evaluated.

Body Burden↗
PubMed1999

Studies of the mortality of atomic bomb survivors. Report 12, part II. Noncancer mortality: 1950-1990.

This report updates the data on noncancer mortality for 86,572 atomic bomb survivors with dose estimates in the Radiation Effects Research Foundation's Life Span Study cohort. The primary analyses are based on more than 27,000 noncancer disease deaths that occurred in the cohort between October 1, 1950, and December 31, 1990, 30% more than in the previous report. The present analyses strengthen earlier findings of a statistically significant increase in noncancer disease death rates with radiation dose. Increasing trends are observed for diseases of the circulatory, digestive and respiratory systems. Rates for those exposed to 1 Sv are elevated about 10%, a relative increase that is considerably smaller than that for cancer. However, estimates of the number of radiation-related noncancer deaths in the cohort to date (140 to 280) are 50 to 100% of the number for solid cancer. The data do not yet clarify the shape of the dose response. There is no significant evidence against linearity, but the data are statistically consistent with curvilinear dose-response functions that posit essentially zero risk for doses below 0.5 Sv. Similarly, while the data are consistent with substantial variation in the excess relative risk with age at exposure or attained age, there is no statistically significant dependence on these factors. In view of the small relative risks and the lack of understanding of biological mechanisms, we emphasize consideration of whether the findings could be explained by misclassification, confounding or selection effects. Based on available data, we conclude that such factors are unlikely to fully explain the observed dose response. A significant dose response is also seen for deaths from blood diseases with an excess relative risk that is several times greater than that seen for solid cancer. Particular attention is paid to the possibility that this apparent effect is a consequence of the attribution of leukemia or other cancer deaths to noncancer blood diseases. We find that misclassification does not explain this excess risk. As in earlier reports, suicide rates tend to decrease with increasing dose.

Cause of Death↗
PubMed1998

Skin tumor risk among atomic-bomb survivors in Japan.

OBJECTIVES: Elevated risks of skin cancer following high doses of ionizing radiation have long been known. Recent reports on atomic-bomb survivors indicate that nonmelanoma skin cancer can be induced at low to medium doses. We studied atomic-bomb survivors to determine the effects of radiation on specific histologic types of skin cancer and to describe the dose-response relationship. METHODS: Cases of melanoma, nonmelanoma skin cancers, and Bowen's disease were ascertained between 1958 and 1987 for the 80,000 cohort members through the population-based Hiroshima and Nagasaki (Japan) tumor registries augmented by searches of other records. RESULTS: An excess of basal cell carcinoma (n = 80), with some suggestion of a non-linear dose-response, was observed. The excess risk decreased markedly as age at exposure increased, and there was no evidence for an interaction between ionizing and ultraviolet radiation. No dose-response was found for squamous cell carcinoma (n = 69). The excess relative risk point-estimates were large, but statistically nonsignificant for both melanoma (n = 10) and Bowen's disease (n = 26). CONCLUSIONS: The basal layer of the epidermis appears to be quite sensitive to radiation carcinogenesis, particularly at a young age. The suprabasal layer seems to be more resistant, as shown by the lack of an association for squamous cell carcinomas.

Adolescent↗
PubMed1998

Statistical issues in biological radiation dosimetry for risk assessment using stable chromosome aberrations.

Biological dosimeters are useful for epidemiologic risk assessment in populations exposed to catastrophic nuclear events and as a means of validating physical dosimetry in radiation workers. Application requires knowledge of the magnitude of uncertainty in the biological dose estimates and an understanding of potential statistical pitfalls arising from their use. This paper describes the statistical aspects of biological dosimetry in general and presents a detailed analysis in the specific case of dosimetry for risk assessment using stable chromosome aberration frequency. Biological dose estimates may be obtained from a dose-response curve, but negative estimates can result and adjustment must be made for regression bias due to imprecise estimation when the estimates are used in regression analyses. Posterior-mean estimates, derived as the mean of the distribution of true doses compatible with a given value of the biological endpoint, have several desirable properties: they are nonnegative, less sensitive to extreme skewness in the true dose distribution, and implicitly adjusted to avoid regression bias. The methods necessitate approximating the true-dose distribution in the population in which biological dosimetry is being applied, which calls for careful consideration of this distribution through other information. An important question addressed here is to what extent the methods are robust to misspecification of this distribution, because in many applications of biological dosimetry it cannot be characterized well. The findings suggest that dosimetry based solely on stable chromosome aberration frequency may be useful for population-based risk assessment.

Calibration↗
PubMed1997

Cancer mortality among atomic bomb survivors exposed in utero or as young children, October 1950-May 1992.

Cancer mortality for the period from October 1950 through May 1992 was analyzed in atomic bomb survivors exposed in utero. Risk estimates for this group were also compared to those for survivors who were less than 6 years old at the time of exposure. The cohorts studied include 807 in utero survivors and 5,545 persons exposed during childhood with all members of both groups having estimated doses of at least 0.01 Sv. The comparison group includes 10,453 persons with little (<0.01 Sv) or no exposure. Analyses were limited mainly to cancer deaths occurring between the ages of 17 and 46. Only 10 cancer deaths were observed among persons exposed in utero. However, there is a significant dose response with an estimate of excess relative risk per sievert (ERR/Sv) of 2.1 (90% confidence interval of 0.2 to 6.0). This estimate does not differ significantly from that for survivors exposed during the first 5 years of life. The cancer deaths among those exposed in utero involved leukemia (2), female-specific organs (3) and digestive organs (5). Nine deaths occurred in females, where the excess risk for all solid cancers has a 90% confidence interval on the ERR/Sv of 1.6 to 17. Significant risks were found for cancers of the digestive system [90% confidence interval (CI) on the ERR/Sv of 0.7 to 20] and for female-specific cancers (90% CI on the ERR/Sv of 0.7 to 42). These risks do not differ significantly from those seen in females exposed as children. There were no deaths from solid cancer in men exposed in utero. The ERR/Sv has an upper 95% confidence bound of 2.5 which does not differ from that for exposed children, where the upper 95% confidence bound is 1.5. The sexes differ even when female-specific cancers are excluded from the comparison. Although there were only two leukemia deaths among those exposed in utero, the leukemia death rate for this group is higher than that in the comparison group (P = 0.054) with an exposure effect that is about half the magnitude and not significantly different from that seen after childhood exposure (P = 0.103). However, there is no evidence of a dose response among those exposed in utero because no high-dose leukemia deaths were observed, a result that differs considerably from that for those exposed as children. There is a need for caution in the interpretation of these data. First, the number of cancer deaths is small; second, there is unexplained significant difference in the mortality from solid cancer between the sexes; and third, the excess of leukemia in those exposed in utero is not reflected in an increasing dose response.

Adult↗
PubMed1997

Issues in the comparison of risk estimates for the population in the Techa River region and atomic bomb survivors.

Plutonium production in the former Soviet Union began in 1949 at the Mayak Production Association located between the cities of Chelyabinsk and Ekaterinbourg in the southern Ural mountains about 1200 km east to Moscow. During the first few years of Mayak's operation, almost 30,000 people living on the banks of the Techa River received significant internal and external exposures as a consequence of the release of large quantities of radioactive materials from Mayak. Studies of levels of radioactive contamination and health effects in this population began in the early 1950s. A systematic follow-up of a fixed cohort that includes all people who were living in Techa River villages in 1949 was begun about 30 years ago. In this paper we describe the Techa River cohort, outline the nature of the exposures and discuss the status of follow-up for the period from 1950 through 1989. While noting the limitations of the current epidemiological follow-up data, we also compare the demographic and mortality structure of the Techa River cohort with the Life Span Study cohort of Japanese atomic bomb survivors. It is seen that, despite a number of limitations, the current data suggest that the risks of mortality from leukemia and other cancers increase with increasing radiation dose in the Techa River cohort. This finding suggests that, with continued improvements in the quality of the follow-up and dosimetry, the Techa River cohort has the potential to provide quantitative estimates of the risks of chronic low-dose-rate radiation exposures for an unselected general population that will be an important complement to the estimates based on the Life Span Study that are used as the primary basis for numerical assessments of radiation risk.

Environmental Exposure↗
PubMed1996

Studies of the mortality of atomic bomb survivors. Report 12, Part I. Cancer: 1950-1990.

This continues the series of periodic general reports on cancer mortality in the cohort of A-bomb survivors followed by the Radiation Effects Research Foundation. The follow-up is extended by the 5 years 1986-1990, and analysis includes an additional 10,500 survivors with recently estimated radiation doses. Together these extensions add about 550,000 person-years of follow-up. The cohort analyzed consists of 86,572 subjects, of which about 60% have dose estimates of at least 0.005 Sv. During 1950-1990 there have been 3086 and 4741 cancer deaths for the less than and greater than 0.005 Sv groups, respectively. It is estimated that among these there have been approximately 420 excess cancer deaths during 1950-1990, of which about 85 were due to leukemia. For cancers other than leukemia (solid cancers), about 25% of the excess deaths in 1950-1990 occurred during the last 5 years; for those exposed as children this figure is nearly 50%. For leukemia only about 3% of the excess deaths in 1950-1990 occurred in the last 5 years. Whereas most of the excess for leukemia occurred in the first 15 years after exposure, for solid cancers the pattern of excess risk is apparently more like a life-long elevation of the natural age-specific cancer risk. Taking advantage of the lengthening follow-up, increased attention is given to clarifying temporal patterns of the excess cancer risk. Emphasis is placed on describing these patterns in terms of absolute excess risk, as well as relative risk. For example: (a) although it is becoming clearer that the excess relative risk for those exposed as children has declined over the follow-up, the excess absolute risk has increased rapidly with time; and (b) although the excess relative risk at a given age depends substantially on sex and age at exposure, the age-specific excess absolute risk depends little on these factors. The primary estimates of excess risk are now given as specific to sex and age at exposure, and these include projections of dose-specific lifetime risks for this cohort. The excess lifetime risk per sievert for solid cancers for those exposed at age 30 is estimated at 0.10 and 0.14 for males and females, respectively. Those exposed at age 50 have about one-third these risks. Projection of lifetime risks for those exposed at age 10 is more uncertain. Under a reasonable set of assumptions, estimates for this group range from about 1.0-1.8 times the estimates for those exposed at age 30. The excess life-time risk for leukemia at 1 Sv for those exposed at either 10 or 30 years is estimated as about 0.015 and 0.008 for males and females, respectively. Those exposed at age 50 have about two-thirds that risk. Excess risks for solid cancer appear quite linear up to about 3 Sv, but for leukemia apparent nonlinearity in dose results in risks at 0.1 Sv estimated at about 1/20 of those for 1.0 Sv. Site-specific risk estimates are given, but it is urged that great care be taken in interpreting these, because most of their variation can be explained simply by imprecision in the estimates.

Adolescent↗
PubMed1996

Mortality study of atomic-bomb survivors: implications for assessment of radiation accidents.

To determine the possible late effects of atomic-bomb radiation, the Life Span Study (LSS) cohort of about 120,000 individuals, including 93,000 atomic bomb survivors and 27,000 non-exposed controls, was established by the Radiation Effects Research Foundation (RERF). Mortality in this cohort has been under study since 1950. Deaths are routinely identified through the family registry system and ascertainment is virtually complete. Cancer incidence data for the LSS cohort are also available from the Hiroshima and Nagasaki population-based tumour registry established in 1958. The central finding of the LSS is an increase in cancer risk. Besides the well-known increase in leukaemia, increases in solid cancer such as cancers of the lung, breast, stomach and thyroid have also been demonstrated. Radiation-induced leukaemia occurred 2 to 3 years after exposure, reached its peak within 6 to 8 years after the bombing, and has since declined steadily. However, this has not been true of solid cancer. Radiation-induced solid cancer begins to appear at later ages than such cancer is normally prone to develop, and continues to increase proportionally with the increase in mortality or incidence in the control group as it ages. Survivors who were exposed in the first or second decade of life have just entered the cancer-prone age and have so far exhibited a high relative risk in association with radiation dose. Whether the elevated risk will continue or will fail with time is not yet clear. It is important to continue long-term follow-up of this cohort to document the changes with time since exposure. Beyond cancer risk, increased risk of non-cancer mortality is also suggested, although it is not conclusive.

Adult↗
PubMed1995

Radiation studies.

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Government Agencies↗
PubMed1994

Cancer incidence in atomic bomb survivors. Part I: Use of the tumor registries in Hiroshima and Nagasaki for incidence studies.

More than 30 years ago, population-based tumor registries were established in Hiroshima and Nagasaki. This report, the first of a series of papers on cancer incidence, describes methodological aspects of the tumor registries and discusses issues of data quality in the context of the Life Span Study (LSS) cohort, the major atomic bomb survivor population. The tumor registries in Hiroshima and Nagasaki are characterized by active case ascertainment based on abstraction of medical records at area hospitals, augmented by tissue registries operational in the area and a number of clinical and pathological programs undertaken over the years among the atomic bomb survivors. Using conventional measures of quality, the Hiroshima and Nagasaki tumor registries have a death certificate-only (DCO) rate of less than 9%, a mortality/incidence (M/I) ratio of about 50%, and a histological verification (HV) rate in excess of 70%, which place these registries among the best in Japan and comparable to many established registries worldwide. All tumor registry data pertaining to the LSS population were assembled, reviewed and handled with special attention given to the quality and uniformity of data based on standardized procedures. Special studies and monitoring programs were also introduced to evaluate the quality of the tumor incidence data in the LSS. Analyses were performed to examine the quality of incidence data overall and across various substrata used for risk assessment such as age, time and radiation dose groups. No significant associations were found between radiation dose and data quality as measured by various indices. These findings warrant the use of the present tumor registry-based data for studies of cancer incidence in the atomic bomb survivors.

Adolescent↗