Low-dose ionizing radiation and cancer mortality among enlisted men stationed on nuclear-powered submarines in the United States Navy.

BACKGROUND: Men stationed on nuclear-powered submarines are occupationally exposed to external ionizing radiation at very low levels and radiation dose for each individual is closely monitored. Little is known about ionizing radiation (IR) risks of cancer mortality for populations with levels of cumulative ionizing radiation exposure this low. MATERIALS AND METHODS: This historical cohort study followed 85,033 enlisted men who had served on a nuclear-powered submarine in the U.S. Navy between 1969 and 1982 to determine patterns of cancer mortality. Occupational radiation doses were measured by badge dosimeters for each individual for all periods of Navy service potentially involving radiation exposure. Deaths were ascertained through 1995 by searches of multiple national mortality databases. Within-cohort dose-response relationships for cancer mortality were estimated using linear Poisson regression models. Individual-level smoking status was not available so cancer risks were estimated separately for cancers with and without previously published evidence of consistently moderate or strong associations with smoking. RESULTS: A total of 584 cancer deaths occurred during a follow-up period of up to 27 years. The mean and median cumulative occupational radiation doses received while in the Navy were 5.7 and 1.1 milliSieverts (mSv), respectively, range 0-242 mSv. Mortality Excess Relative Risks (ERRs) per 10 mSv and 95% confidence intervals (CI) were 0.053 (CI -0.03, 0.17) for all cancers, 0.052 (CI -0.03, 0.18) for all solid cancers, and 0.003 (CI -0.29, 0.30) for leukemias excluding chronic lymphocytic leukemia. The ERRs per 10 mSv were 0.052 (CI -0.07, 0.17) for cancers previously associated with smoking and 0.012 (CI -0.10, 0.12) for cancers that were not. CONCLUSIONS: The ERR point estimates for solid cancers and leukemia were statistically compatible with those reported in previously published studies of other ionizing radiation-exposed and monitored cohorts, albeit with wide confidence intervals. This study, with high-quality measurements of in-Navy occupational external IR doses, high follow-up proportion, and detailed IR dose-response analyses, is consistent with the premise of small excess cancer risks from low-dose IR.

Mortality of Enlisted Men Who Served on Nuclear-Powered Submarines in the United States Navy.

OBJECTIVE: To describe the long-term mortality experience of a cohort of enlisted men who served on nuclear-powered submarines in the United States Navy and breathed recirculated filtered air for extended periods of time. METHODS: In this historical cohort study we estimated standardized mortality ratios (SMRs) and used within-cohort Poisson regression analyses to address healthy worker biases. RESULTS: Three thousand two hundred sixty three deaths occurred among 85,498 men during 1,926,875 person-years of follow-up from 1969 to 1995. SMRs were reduced for most cause-of-death categories, prostate cancer had a twofold elevation. In within-cohort comparisons, prostate cancer mortality did not increase with duration of submarine service, but ischemic heart disease mortality increased 26% per 5 years of submarine service. CONCLUSIONS: Long periods of submarine service do not increase mortality in most cause-of-death categories. Increased mortality from ischemic heart disease likely reflects the effects of tobacco smoke.

Endothelin-1 in the tumor microenvironment correlates with melanoma invasion.

Endothelin-1 (ET-1) is a vasoactive peptide that also plays a role in the tanning response of the skin. Animal and cell culture studies have also implicated ET-1 in melanoma progression, but no association studies have been performed to link ET-1 expression and melanoma in humans. Here, we present the first in-vivo study of ET-1 expression in pigmented lesions in humans: an ET-1 immunohistochemical screen of melanocytic nevi, melanoma in situ lesions, invasive melanomas, metastatic melanomas, and blue nevi was performed. Twenty-six percent of melanocytic nevi and 44% of melanoma in situ lesions demonstrate ET-1 expression in the perilesional microenvironment, whereas expression in nevus or melanoma cells was rare to absent. In striking contrast, 100% of moderately to highly pigmented invasive melanomas contained numerous ET-1-positive cells in the tumor microenvironment, with 79% containing ET-1-positive melanoma cells, confirmed by co-staining with melanoma tumor marker HMB45. Hypopigmented invasive melanomas had reduced ET-1 expression, suggesting a correlation between ET-1 expression and pigmented melanomas. ET-1-positive perilesional cells were CD68-positive, indicating macrophage origin. Sixty-two percent of highly pigmented metastatic melanomas demonstrated ET-1 expression in melanoma cells, in contrast to 28.2% of hypopigmented specimens. Eighty-nine percent of benign nevi, known as blue nevi, which have a dermal localization, were associated with numerous ET-1-positive macrophages in the perilesional microenvironment, but no ET-1 expression was detected in the melanocytes. We conclude that ET-1 expression in the microenvironment increases with advancing stages of melanocyte transformation, implicating a critical role for ET-1 in melanoma progression, and the importance of the tumor microenvironment in the melanoma phenotype.

Occupational asthma and work-exacerbated asthma.

Occupational asthma (OA) and work-exacerbated asthma (WEA), collectively known as work-related asthma (WRA), have been recognized as the most prevalent work-related lung diseases in the industrialized world. OA is asthma caused by workplace conditions, and is subdivided into sensitizer-induced (allergic) OA and irritant-induced (nonallergic) OA. WEA is asthma that is made worse, but was not initially caused, by workplace conditions. Although WRA is rarely fatal, patients with WRA frequently experience excessive time lost from work, workplace-specific severe disability, loss of income, job loss, and related psychosocial and financial problems. More than 400 workplace environmental agents have been reported to cause WRA, and are classified by molecular weight and allergenic and irritant properties. Diagnosis of WRA requires confirmation of a diagnosis of asthma plus evidence that the asthma was caused or worsened by workplace conditions. Accuracy of diagnosis is important because either overdiagnosis or missed diagnosis of WRA can be problematic for the patient. Self-reported clinical symptoms alone have only fair sensitivity and specificity for OA. If possible, diagnostic assessment should also include objective evidence with functional and immunologic testing. Treatment and prevention of onset or worsening of WRA can be highly effective and typically include both optimal medical management (generally the same as for non-WRA) and, importantly, avoidance of sensitizer or irritant exposures that caused or exacerbate the asthma. In most cases of OA, prognosis is better with cessation rather than reduction of exposure, and this may require substantial changes in the workplace environment or change of job or even profession.

Posttraumatic stress disorder and the risk of respiratory problems in World Trade Center responders: longitudinal test of a pathway.

OBJECTIVE: Posttraumatic stress disorder (PTSD) is associated with high medical morbidity, but the nature of this association remains unclear. Among responders to the World Trade Center (WTC) disaster, PTSD is highly comorbid with lower respiratory symptoms (LRS), which cannot be explained by exposure alone. We sought to examine this association longitudinally to establish the direction of the effects and evaluate potential pathways to comorbidity. METHODS: 18,896 responders (8466 police and 10,430 nontraditional responders) participating in the WTC-Health Program were first evaluated between 2002 and 2010 and assessed again 2.5 years later. LRS were ascertained by medical staff, abnormal pulmonary function by spirometry, and probable WTC-related PTSD with a symptom inventory. RESULTS: In both groups of responders, initial PTSD (standardized regression coefficient: ß = 0.20 and 0.23) and abnormal pulmonary function (ß = 0.12 and 0.12) predicted LRS 2.5 years later after controlling for initial LRS and covariates. At follow-up, LRS onset was 2.0 times more likely and remission 1.8 times less likely in responders with initial PTSD than in responders without. Moreover, PTSD mediated, in part, the association between WTC exposures and development of LRS (p < .0001). Initial LRS and abnormal pulmonary function did not consistently predict PTSD onset. CONCLUSIONS: These analyses provide further evidence that PTSD is a risk factor for respiratory symptoms and are consistent with evidence implicating physiological dysregulation associated with PTSD in the development of medical conditions. If these effects are verified experimentally, treatment of PTSD may prove helpful in managing physical and mental health of disaster responders.

A review of cancer in U.S. Hispanic populations.

There are compelling reasons to conduct studies of cancer in Hispanics, the fastest growing major demographic group in the United States (from 15% to 30% of the U.S. population by 2050). The genetically admixed Hispanic population coupled with secular trends in environmental exposures and lifestyle/behavioral practices that are associated with immigration and acculturation offer opportunities for elucidating the effects of genetics, environment, and lifestyle on cancer risk and identifying novel risk factors. For example, traditional breast cancer risk factors explain less of the breast cancer risk in Hispanics than in non-Hispanic whites (NHW), and there is a substantially greater proportion of never-smokers with lung cancer in Hispanics than in NHW. Hispanics have higher incidence rates for cancers of the cervix, stomach, liver, and gall bladder than NHW. With respect to these cancers, there are intriguing patterns that warrant study (e.g., depending on country of origin, the five-fold difference in gastric cancer rates for Hispanic men but not Hispanic women). Also, despite a substantially higher incidence rate and increasing secular trend for liver cancer in Hispanics, there have been no studies of Hispanics reported to date. We review the literature and discuss study design options and features that should be considered in future studies.

Epidemiology of respiratory health outcomes among World Trade Center disaster workers: review of the literature 10 years after the September 11, 2001 terrorist attacks.

Tens of thousands of workers participated in rescue, recovery, and cleanup activities at the World Trade Center (WTC) site in lower Manhattan after the terrorist attacks on September 11, 2001 (9/11). The collapse of the WTC resulted in the release of a variety of airborne toxicants. To date, respiratory symptoms and diseases have been among the most examined health outcomes in studies of WTC disaster workers. A systematic review of the literature on respiratory health outcomes was undertaken to describe the available information on new onset of respiratory symptoms and diseases among WTC disaster workers after September 11, 2001. Independent risk factors for respiratory health outcomes included being caught in the dust and debris cloud, early arrival at the WTC site, longer duration of work, and delaying mask and respirator use. Methodological challenges in epidemiologic studies of WTC disaster workers involved study design, exposure misclassification, and limited information on potential confounders and effect modifiers. In the 10 years after 9/11, epidemiologic studies of WTC disaster workers have been essential in investigating the respiratory health consequences of WTC exposure. Longitudinal studies along with continued medical surveillance will be vital in understanding the long-term respiratory burden associated with occupational WTC exposure.

Prevalence of workplace exacerbation of asthma symptoms in an urban working population of asthmatics.

OBJECTIVES: We used an interviewer-administered questionnaire to investigate workplace exacerbation of asthma symptoms (WEAS) among low-income, minority, working asthmatics admitted Bellevue Hospital Center in New York City from 2001 to 2002. We hypothesized that a high prevalence of WEAS would be found in this population among all jobs held and a subset of individual occupational classifications. MEASUREMENTS AND MAIN RESULTS: Of 301 subjects, 51% reported WEAS in their current or most recent job; 71% reported WEAS in any job. Prevalences (95% confidence intervals) of WEAS in common job classifications were 61% (49-73%) in janitorial jobs, 50% (33-67%) in garment and textile manufacturing jobs, and 38% (23-55%) in construction jobs. CONCLUSION: WEAS is prevalent in this urban minority population.

Endothelin-1 induces CXCL1 and CXCL8 secretion in human melanoma cells.

The endothelin pathway plays a critical role in melanoma tumor progression by a variety of mechanisms that enhance tumor cell growth, invasion, and metastasis. Here, we investigate the effect of this pathway on CXC chemokine expression in human melanoma cells and melanocytes. As determined by ELISA, endothelin-1 (ET-1) induces CXCL1 and CXCL8 secretion in three human melanoma cell lines in a concentration-dependent fashion. These responses are mediated by the endothelin-B receptor and are sustained over a 40 h time course. ET-1 does not induce CXCL1 secretion in primary human melanocytes but ET-3, an endothelin isoform, induces a low level of CXCL1 secretion in certain cultures. Neither ET-1 nor ET-3 induces secretion of CXCL8 in primary human melanocytes; thus, this response may be specific for melanocytic cells that have undergone malignant transformation. We have previously demonstrated that ET-1 induces changes in the expression of adhesion molecules in melanoma cells such that invasion and metastasis are favored. This study demonstrates that ET-1 additionally induces secretion of CXC chemokines critical for melanoma metastasis and tumor progression.

Occupational health among Latino workers: a needs assessment and recommended interventions.

Evidence suggests that Latino workers, along with other minority and low-income workers, face a higher risk for occupational disease than do other workers. Targeted surveillance and primary prevention interventions have been lacking or inadequate. The authors estimate the number of occupational disease deaths and new cases in Latino workers in the United States. Then, using data from New York City, they find that Latino workers are disproportionately employed in more hazardous occupations and underrepresented in less hazardous jobs. They suggest a comprehensive approach to address workplace disease in Latino workers, which involves primary prevention interventions, clinical services, educational approaches, research and surveillance, unionization and organization of workers, and legislation and regulation.