Asbestos Exposure and Mesothelioma Mortality among Atomic Veterans

An updated evaluation of reported no-observed adverse effect levels for chrysotile, amosite, and crocidolite asbestos for lung cancer and mesothelioma

This analysis updates two previous analyses that evaluated the exposure-response relationships for lung cancer and mesothelioma in chrysotile-exposed cohorts. We reviewed recently published studies, as well as updated information from previous studies. Based on the 16 studies considered for chrysotile (<10% amphibole), we identified the "no-observed adverse effect level" (NOAEL) for lung cancer and/or mesothelioma; it should be noted that smoking or previous or concurrent occupational exposure to amphiboles (if it existed) was not controlled for. NOAEL values ranged from 2.3-<11.5 f/cc-years to 1600-3200 f/cc-years for lung cancer and from 100-<400 f/cc-years to 800-1599 f/cc-years for mesothelioma. The range of best-estimate NOAELs was estimated to be 97-175 f/cc-years for lung cancer and 250-379 f/cc-years for mesothelioma. None of the six cohorts of cement or friction product manufacturing workers exhibited an increased risk at any exposure level, while all but one of the six studies of textile workers reported an increased risk at one or more exposure levels. This is likely because friction and cement workers were exposed to much shorter chrysotile fibers. Only eight cases of peritoneal mesothelioma were reported in all studies on predominantly chrysotile-exposed cohorts combined. This analysis also proposed best-estimate amosite and crocidolite NOAELs for mesothelioma derived by the application of relative potency estimates to the best-estimate chrysotile NOAELs for mesothelioma and validated by epidemiology studies with exposure-response information. The best-estimate amosite and crocidolite NOAELs for mesothelioma were 2-5 f/cc-years and 0.6-1 f/cc-years, respectively. The rate of peritoneal mesothelioma in amosite- and crocidolite-exposed cohorts was between approximately 70- to 100-fold and several-hundred-fold higher than in chrysotile-exposed cohorts, respectively. These findings will help characterize potential worker and consumer health risks associated with historical and current chrysotile, amosite, and crocidolite exposures.

Military exposures and lung cancer in United States veterans

Lung cancer screening begins at age 50, with yearly low dose computed tomography (LDCT) scans until age 80, for patients determined to be high risk due to tobacco smoking. Veterans serving from World War II to the Gulf War are now at the age where LDCT is recommended. This recommendation from the United States Preventative Service Task Force includes patients who have a 20-pack year tobacco history and currently smoke or quit within the last 15 years. This recommendation does not consider additional risk factors such as exposures to lung carcinogens. We discuss unique operational and occupational exposures encountered while serving in the armed forces, which may potentially increase the risk of lung cancers in the Veteran population. The additional risk of lung cancer due to military exposure history is unclear and more work is needed to identify and quantify risk at an individual level. Increasing awareness at the provider level regarding the carcinogenic exposures encountered may allow a larger population of Veterans, not meeting traditional LDCT criteria, to benefit from lung cancer screening.

Mortality from Leukemia, Cancer and Heart Disease among U.S. Nuclear Power Plant Workers, 1957-2011

BACKGROUND

The aim of the Million Person Study (MPS) of Low Dose Health Effects is to examine the level of radiation risk for chronic exposures received gradually over time and not acutely as was the case for the Japanese atomic bomb survivors. Nuclear power plant (NPP) workers comprise nearly 15 percent of the MPS. Leukemia, selected cancers, Parkinson's disease, ischemic heart disease (IHD) and other causes of death are evaluated.

METHODS AND MATERIAL

The U.S. Nuclear Regulatory Commission's Radiation Exposure Information and Reporting System (REIRS) and the Landauer, Inc. dosimetry databases identified 135,193 NPP workers first monitored 1957-1984. Annual personal dose equivalents [Hp(10)] were available for each worker. Radiation records from all places of employment were sought. Vital status was determined through 2011. Mean absorbed doses to red bone marrow (RBM), esophagus, lung, colon, brain and heart were estimated by adjusting the recorded Hp(10) for each worker by scaling factors, accounting for exposure geometry and energy of the incident gamma radiation. Standardized mortality ratios (SMR) were calculated. Radiation risks were estimated using Cox proportional hazards models.

RESULTS

Nearly 50% of workers were employed for more than 20 years. The mean duration of follow-up was 30.2 y. Overall, 29,076 total deaths occurred, 296 from leukemia other than chronic lymphocytic leukemia (CLL), 3,382 from lung cancer, 140 from Parkinson's disease and 5,410 from IHD. The mean dose to RBM was 37.9 mGy (maximum 1.0 Gy; percent >100 mGy was 9.2%), 43.2 mGy to lung, 43.7 mGy to colon, 33.2 mGy to brain, and 43.9 mGy to heart. The SMRs (95% CI) were 1.06 (0.94;1.19) for leukemia other than CLL, 1.10 (1.07;1.14) for lung cancer, 0.90 (0.76;1.06) for Parkinson's disease, and 0.80 (0.78; 0.82) for IHD. The excess relative risk (ERR) per 100 mGy for leukemia other than CLL was 0.15 (90% CI 0.001; 0.31). For all solid cancers the ERR per 100 mGy (95% CI) was 0.01 (-0.03; 0.05), for lung cancer -0.04 (-0.11; 0.02), for Parkinson's disease 0.24 (-0.02; 0.50), and for IHD -0.01 (-0.06; 0.04).

CONCLUSION

Prolonged exposure to radiation increased the risk of leukemia other than CLL among NPP workers. There was little evidence for a radiation-association for all solid cancers, lung cancer or ischemic heart disease. Increased precision will be forthcoming as the different cohorts within the MPS are combined, such as industrial radiographers and medical radiation workers who were assembled and evaluated in like manner.

Living with mesothelioma: A qualitative study of the experiences of male military veterans in the UK

PURPOSE

The UK has the highest incidence of mesothelioma in the world. Evidence in the United States suggests that mesothelioma may disproportionately affect military veterans. However, there has been no investigation of the experience of UK veterans living with mesothelioma. The Military Mesothelioma Experience Study (MiMES) aimed to understand the experience and health/support needs of British Armed Forces personnel/veterans with mesothelioma.

METHODS

Semi-structured interviews were conducted with 13 veterans living with mesothelioma, and nine family members of veterans living with mesothelioma. Participants were recruited via charities and asbestos support groups. Data were analysed using thematic analysis.

RESULTS

Participants' experiences are presented using three themes, i) exposure to asbestos and awareness of asbestos related diseases, ii) using military strategies to cope with mesothelioma and iii) preferences for information and support. MiMES indicates that the nature and range of UK military veterans' asbestos exposure is varied and not limited to high risk occupations. Participants' knowledge of asbestos and experience of mesothelioma influenced their experiences of diagnosis. Participants had coping strategies influenced by their military experiences. Assistance in navigating health and military systems was considered beneficial, especially if support was provided by professionals with knowledge or experience of the military. Attributes which may inhibit veterans from seeking professional support are discussed.

CONCLUSION

MiMES provides insight into how UK military veterans experience and cope with mesothelioma. Key implications focus on the role that Mesothelioma Nurse Specialists, Asbestos Support Groups and veterans groups play in providing acceptable support for UK veterans.

Is there an association between a history of military service and cancer diagnosis? Results from a US national-level study of self-reported outcomes

PURPOSE

To examine cancer prevalence in men with and without military service history, using national-level self-reported outcomes.

METHODS

A cross-sectional survey-based US study, including men aged 18 and above from the Health Information National Trends Survey database between 2011 and 2014. The primary endpoint was self-reported cancer prevalence. Multivariable logistic regression analyses assessed the association of various covariates with the prevalence of cancer.

RESULTS

A total of 4,527 men were analyzed, with 1,352 (29.9%) reporting a history of military service. Compared to men with no military service history, men with a military service history were older (median of 65 [IQR 56, 74] vs. 53 [IQR 41, 62] years, p < 0.0001), more commonly Caucasian (71.4% vs. 61.4%, p < 0.0001), born in the US (95.6% vs. 79.5%, p < 0.0001), attained higher education level and annual household income (p < 0.0001), and consisted of more smokers(58.3% vs. 44.5%, p < 0.0001). The age-adjusted comparison demonstrated a higher cancer prevalence in men with military service history (20.5% vs. 7.6%, p < 0.0001). Specifically, genitourinary, dermatological, gastrointestinal, and hematological cancers were generally more prevalent. Adjusting for all available confounders, multivariable models showed that military service history was associated with 1.56 (95% CI 1.20-2.03), and 1.57 (95% CI 1.07-2.31) increased odds of having any cancer, and specifically genitourinary cancer, respectively.

CONCLUSIONS

Further research is needed to ascertain whether the association between military service and increased cancer diagnosis results from better screening programs or increased exposure to risk factors during military service.

Mortality among U.S. military participants at eight aboveground nuclear weapons test series

BACKGROUND

Approximately 235,000 military personnel participated at one of 230 U.S. atmospheric nuclear weapons tests from 1945 through 1962. At the Nevada Test Site (NTS), the atomic veterans participated in military maneuvers, observed nuclear weapons tests, or provided technical support. At the Pacific Proving Ground (PPG), they served aboard ships or were stationed on islands during or after nuclear weapons tests.

MATERIAL AND METHODS

Participants at seven test series, previously studied with high-quality dosimetry and personnel records, and the first test at TRINITY formed the cohort of 114,270 male military participants traced for vital status from 1945 through 2010. Dose reconstructions were based on Nuclear Test Personnel Review records, Department of Defense. Standardized mortality ratios (SMR) and Cox and Poisson regression models were used in the analysis.

RESULTS

Most atomic veterans were enlisted men, served in the Navy at the PPG, and were born before 1930. Vital status was determined for 96.8% of the veterans; 60% had died. Enlisted men had significantly high all-causes mortality SMR (1.06); officers had significantly low all-causes mortality SMR (0.71). The pattern of risk over time showed a diminution of the 'healthy soldier effect': the all-causes mortality SMR after 50 years of follow-up was 1.00. The healthy soldier effect for all cancers also diminished over time. The all-cancer SMR was significantly high after 50 years (SMR 1.10) primarily from smoking-related cancers, attributed in part to the availability of cigarettes in military rations. The highest SMR was for mesothelioma (SMR 1.56) which was correlated with asbestos exposure in naval ships. Prostate cancer was significantly high (SMR 1.13). Ischemic heart disease was significantly low (SMR 0.84). Estimated mean doses varied by organ were low; e.g., the mean red bone marrow dose was 6 mGy (maximum 108 mGy). Internal cohort dose-response analyses provided no evidence for increasing trends with radiation dose for leukemia (excluding chronic lymphocytic leukemia (CLL)) [ERR (95% CI) per 100 mGy -0.37 (-1.08, 0.33); n = 710], CLL, myelodysplastic syndrome, multiple myeloma, ischemic heart disease, or cancers of the lung, prostate, breast, and brain.

CONCLUSION

No statistically significant radiation associations were observed among 114,270 nuclear weapons test participants followed for up to 65 years. The 95% confidence limits were narrow and excluded mortality risks per unit dose that are two to four times higher than those reported in other investigations. Significantly elevated SMRs were seen for mesothelioma and asbestosis, attributed to asbestos exposure aboard ships.

Non-Melanoma Skin Cancer in Outdoor Workers: A Study on Actinic Keratosis in Italian Navy Personnel

Occupational exposure to ultraviolet radiation is one of the main risk factors for non-melanoma skin cancer (NMSC) development. The most common variants of NMSC are basal cell carcinomas, squamous cell carcinomas, and actinic keratosis (AK). The latter is nowadays considered by most authors as an early squamous cell carcinoma rather than a precancerous lesion. Outdoor workers have a higher risk of developing NMSC because they spend most of the working day outside. The aim of this descriptive study was to assess the prevalence of skin lesions, especially AK, in a professional category of individuals exposed to ultraviolet (UV) radiation: the Italian Navy. From January to June 2016, a questionnaire and a total skin examination of 921 military personnel were administered by medical specialists (dermatologists) in seven different Italian Navy centres. AK was detected in 217 of 921 (23.5%) workers. Older age, outdoor occupation, longer working life, and fair skin seem to promote the development of AK. Of the 217 workers with AK, 187 (86.2%) had lesions in chronically sun-exposed skin areas. Italian Navy personnel have a high AK prevalence. Further studies are needed to investigate occupational hazards and their health effects among outdoor workers to promote protective behaviour and raise awareness of skin cancer.

The Million Person Study, whence it came and why

PURPOSE

The study of low dose and low-dose rate exposure is of immeasurable value in understanding the possible range of health effects from prolonged exposures to radiation. The Million Person Study (MPS) of low-dose health effects was designed to evaluate radiation risks among healthy American workers and veterans who are more representative of today's populations than are the Japanese atomic bomb survivors exposed briefly to high-dose radiation in 1945. A million persons were needed for statistical reasons to evaluate low-dose and dose-rate effects, rare cancers, intakes of radioactive elements, and differences in risks between women and men.

METHODS AND MATERIALS

The MPS consists of five categories of workers and veterans exposed to radiation from 1939 to the present. The U.S. Department of Energy (DOE) Health and Mortality study began over 40 years ago and is the source of ∼360,000 workers. Over 25 years ago, the National Cancer Institute (NCI) collaborated with the U.S. Nuclear Regulatory Commission (NRC) to effectively create a cohort of nuclear power plant workers (∼150,000) and industrial radiographers (∼130,000). For over 30 years, the Department of Defense (DoD) collected data on aboveground nuclear weapons test participants (∼115,000). At the request of NCI in 1978, Landauer, Inc., (Glenwood, IL) saved their dosimetry databases which became the source of a cohort of ∼250,000 medical and other workers.

RESULTS

Overall, 29 individual cohorts comprise the MPS of which 21 have been or are under active study (∼810,000 persons). The remaining eight cohorts (∼190,000 persons) will be studied as resources become available. The MPS is a national effort with critical support from the NRC, DOE, National Aeronautics and Space Administration (NASA), DoD, NCI, the Centers for Disease Control and Prevention (CDC), the Environmental Protection Agency (EPA), Landauer, Inc., and national laboratories.

CONCLUSIONS

The MPS is designed to address the major unanswered question in radiation risk understanding: What is the level of health effects when exposure is gradual over time and not delivered briefly. The MPS will provide scientific understandings of prolonged exposure which will improve guidelines to protect workers and the public; improve compensation schemes for workers, veterans and the public; provide guidance for policy and decision makers; and provide evidence for or against the continued use of the linear nonthreshold dose-response model in radiation protection.