The mortality of workers at the Hanford Plant in southeastern Washington who have been exposed to penetrating external ionizing radiation is studied. Deaths are analyzed statistically and compared to standardized mortality ratios. Cancer deaths in particular are examined. (ACR)
The authors examined the prevalence of congenital malformations among births in Benton and Franklin counties, in southeastern Washington State, from 1968 through 1980. The Hanford Site is in this area and serves as a major employer. In addition, various agriculturally and chemically related activities are in the area. Hospital and vital records were used to identify 454 malformation cases among 23,319 births; this yielded a malformation rate of 19.6 per 1,000 births, a rate similar to those reported in other studies. The rates of specific malformations ascertained during the first year of life were compared with combined rates from the states of Washington, Oregon, and Idaho from the Birth Defects Monitoring Program. Among defects that would be expected to be comparably ascertained, a statistically significant elevated rate of neural tube defects was observed (1.72 per 1,000 births vs. 0.99 per 1,000). Rates of deft lip were significantly lower in Benton and Franklin counties than in the Birth Defects Monitoring Program (0.59 per 1,000 vs. 1.17 per 1,000). For congenital heart defects, pyloric stenosis, and Down syndrome, which are often not diagnosed in the newborn period, Birth Defects Monitoring Program data did not offer appropriate comparisons. The rates of these defects did not appear to be elevated in relation to rates found in other relevant populations. When rates of neural tube defects were compared with those in populations other than the Birth Defects Monitoring Program, the Benton and Franklin county rates were still considered to be elevated. The increased bicounty rate cannot be explained by employment of the parents at Hanford or by the impact of plant emissions on the local population.
Updated analyses of mortality data on workers at the Hanford Site, Oak Ridge National Laboratory (ORNL), and Rocky Flats Weapons Plant are presented with the objective of providing a direct assessment of health risks resulting from protracted low-dose exposure to ionizing radiation. For leukemia, the combined excess relative risk estimate was negative (-1.0 per Sv), and confidence limits excluded risks that were more than slightly larger than those forming the basis of ICRP recommendations. For all cancer except leukemia, the excess relative risk estimate was 0.0 per Sv, but confidence limits indicated consistency with estimates several times those forming the basis of ICRP recommendations. Of 24 cancer types tested, 12 showed positive correlations with radiation dose and 12 showed negative correlations, as would be expected by chance fluctuation. Cancer of the esophagus, cancer of the larynx, and Hodgkin's disease showed statistically significant correlations with radiation dose (P < 0.05), but these correlations were interpreted as likely to have resulted from bias or chance fluctuation. Evidence of an increase in the excess relative risk with increasing age at risk was found for all cancer in both Hanford and ORNL, and both populations showed significant correlations of all cancer with radiation dose among those 75 years and older. Although this age effect may have resulted from bias in the data, its presence suggests that risk estimates based on nuclear worker data be interpreted cautiously.
In a case-control study, the authors investigated the association of parental occupational exposure to low-level external whole-body penetrating ionizing radiation and risk of congenital malformations in their offspring. Cases and controls were ascertained from births in two counties in southeastern Washington State, where the Hanford Site has been a major employer. A unique feature of this study was the linking of quantitative individual measurement of external whole-body penetrating ionizing radiation exposure of employees at the Hanford Site, using personal dosimeters, and the disease outcome, congenital malformations. The study population included 672 malformation cases and 977 matched controls from births occurring from 1957 through 1980. Twelve specific malformation types were analyzed for evidence of association with employment of the parents at Hanford and with occupational exposure to ionizing radiation. Two defects, congenital dislocation of the hip and tracheoesophageal fistula, showed statistically significant associations with employment of the parents at Hanford, but not with parental radiation exposure. Neural tube defects showed a significant association with parental preconception exposure, on the basis of a small number of cases. Eleven other defects, Including Down syndrome, for which an association with radiation was considered most likely, showed no evidence of such an association. When all malformations were analyzed as a group, there was no evidence of an association with employment of the parents at Hanford, but the relation of parental exposure to radiation before conception was in the positive direction (one-tailed p value between 0.05 and 0.10). Given the number of statistical tests conducted, some or all of the observed positive correlations are likely to represent false positive findings. In view of strong contradictory evidence, based on no demonstrated effects in genetic studies of atomic bomb survivors in Hiroshima and Nagasaki, it is unlikely that these correlations result from a cause and effect association with parental radiation exposure.
Radiotherapy for breast cancer reduces disease recurrence and breast cancer mortality. However, it has also been associated with increased second cancer risks in exposed sites.We evaluated long-term second cancer risks among 182 057 5-year survivors of locoregional invasive breast cancer diagnosed between 1973 and 2000 and reported to US NCI-SEER Program cancer registries. Multivariate Poisson regression was used to estimate the relative risk (RR) and excess cases of second cancer in women who had surgery and radiotherapy, compared with those who had surgery alone. Second cancer sites were grouped according to doses received from typical tangential breast fields.By the end of 2005 (median follow-up=13.0 years), 15 498 second solid cancers had occurred, including 6491 contralateral breast cancers. The RRs for radiotherapy were 1.45 (95% confidence interval (CI)=1.33-1.58) for high-dose second cancer sites (1+ Gy: lung, oesophagus, pleura, bone and soft tissue) and 1.09 (1.04-1.15) for contralateral breast cancer ( approximately 1 Gy). These risks decreased with increasing age and year of treatment. There was no evidence of elevated risks for sites receiving medium (0.5-0.99 Gy, RR=0.89 (0.74-1.06)) or low doses (<0.5 Gy, RR=1.01 (0.95-1.07)). The estimated excess cases of cancer in women treated with radiotherapy were as follows: 176 (95% CI=69-284) contralateral breast cancers or 5% (2-8%) of the total in all 1+year survivors, and 292 (222-362) other solid cancers or 6% (4-7%) of the total.Most second solid cancers in breast cancer survivors are not related to radiotherapy.
PURPOSE Survivors of hereditary retinoblastoma have excellent survival but substantially increased risks of subsequent bone and soft-tissue sarcomas, particularly after radiotherapy. Comprehensive investigation of sarcoma risk patterns would inform clinical surveillance for survivors. PATIENTS AND METHODS In a cohort of 952 irradiated survivors of hereditary retinoblastoma who were originally diagnosed during 1914 to 2006, we quantified sarcoma risk with standardized incidence ratios (SIRs) and cumulative incidence analyses. We conducted analyses separately for bone and soft-tissue sarcomas occurring in the head and neck (in/near the radiotherapy field) versus body and extremities (out of field). RESULTS Of 105 bone and 124 soft-tissue sarcomas, more than one half occurred in the head and neck (bone, 53.3%; soft tissue, 51.6%), one quarter in the body and extremities (bone, 29.5%; soft tissue, 25.0%), and approximately one fifth in unknown/unspecified locations (bone, 17.1%; soft tissue, 23.4%). We noted substantially higher risks compared with the general population for head and neck versus body and extremity tumors for both bone (SIR, 2,213; 95% CI, 1,671 to 2,873 v SIR, 169; 95% CI, 115 to 239) and soft-tissue sarcomas (SIR, 542; 95% CI, 418 to 692 v SIR, 45.7; 95% CI, 31.1 to 64.9). Head and neck bone and soft-tissue sarcomas were diagnosed beginning in early childhood and continued well into adulthood, reaching a 60-year cumulative incidence of 6.8% (95% CI, 5.0% to 8.7%) and 9.3% (95% CI, 7.0% to 11.7%), respectively. In contrast, body and extremity bone sarcoma incidence flattened after adolescence (3.5%; 95% CI, 2.3% to 4.8%), whereas body and extremity soft-tissue sarcoma incidence was rare until age 30, when incidence rose steeply (60-year cumulative incidence, 6.6%; 95% CI, 4.1% to 9.2%), particularly for females (9.4%; 95% CI, 5.1% to 13.8%). CONCLUSION Strikingly elevated bone and soft-tissue sarcoma risks differ by age, location, and sex, highlighting important contributions of both radiotherapy and genetic susceptibility. These data provide guidance for the development of a risk-based screening protocol that focuses on the highest sarcoma risks by age, location, and sex.
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