Summary of retrospective asbestos and welding fume exposure estimates for a nuclear naval shipyard and their correlation with radiation exposure estimates

Mesothelioma mortality within two radiation monitored occupational cohorts

Purpose: The risk of mesothelioma, including cancers of the pleura and peritoneum, was examined within two large cohorts of workers monitored for exposure to ionizing radiation. Methods and materials: Mortality was assessed among 253,632 workers routinely monitored for external radiation, including 30,724 industrial radiographers (IR) at shipyards, 142,583 workers at nuclear power plants (NPP), and 83,441 IR who had not worked at an NPP or shipyard. Follow-up was from 1969 through 2011. Standardized mortality ratios (SMRs) and 95% confidence intervals (CIs) were computed; observed numbers of deaths from mesothelioma (including cancers of the pleura and peritoneum) and asbestosis were compared with numbers expected based on age-, sex-, and calendar year-specific national mortality rates. Job history and quantitative asbestos exposure data were unavailable, but work at a shipyard was taken as a surrogate for the likelihood of exposure. Cox proportional hazards models were used to estimate hazard ratios (HRs) for mesothelioma in relation to estimated cumulative radiation exposure to the lung. Results: The mean duration of follow-up was 25.3 years (max 42 years). The mean cumulative lung dose was 28.6 mGy (7.3% > 250 mGy). Nearly 20% of the workers had died by 2011. A total of 421 mesothelioma deaths were found (75% occurring after 1999) with increased SMRs among workers monitored in shipyards (SMR 9.97; 95% CI 8.50-11.63) and for NPP workers (SMR 5.55; 95% CI 4.88-6.29), but not for IR who had not worked in shipyards (SMR 1.15; 95% CI 0.53-2.19). Likewise, deaths from asbestosis (n = 189) were also increased for shipyard and NPP workers (SMR = 18.1 and 9.2, respectively), but not among workers who never worked at a shipyard or NPP (SMR = 0.70; n = 1). Radiation dose to the lung was not associated with a statistically meaningful dose-response trend for mesothelioma in the combined cohorts (HR at 100 mGy = 1.10; 95% CI 0.96-1.27; p = .18), nor was mesothelioma risk associated with radiation exposure among IR who had not worked in a shipyard and assumed minimally exposed to asbestos. Conclusions: An elevated rate of death from mesothelioma was observed in two radiation-exposed occupational groups with potential for asbestos exposure. The increased risk of death from asbestosis, combined with little evidence of a rising trend in mesothelioma mortality with increasing radiation exposure, suggests that the mesothelioma (and asbestosis) excess in these workers was due to asbestos exposure in shipyards and power plants and not to occupational low-dose radiation.

Pulmonary exposure to metal fume particulate matter cause sleep disturbances in shipyard welders

Sleep disorders may pose a risk to workers in the workplace. We aimed to investigate the associations between metal fume fine particulate matter (PM_2.5) and sleep quality in workers. We assessed the effects of personal exposure to metal fume PM_2.5 on lung functions, urinary biomarkers, and sleep quality in shipyard welding workers. In total, 96 welding workers and 54 office workers were recruited in the present study; office workers were exposed to 82.1 ± 94.1 μg/m³ PM_2.5 and welding workers were exposed to 2166.5 ± 3149.1 μg/m³. Welding workers had significantly lower levels of FEV25-75 than office workers (p < 0.05). An increase in 1 μg/m³ PM_2.5 was associated with a decrease of 0.003 ng/mL in urinary serotonin (95% CI = -0.007-0.000, p < 0.05) in all workers and with a decrease of 0.001 ng/mL in serotonin (95% CI = -0.004-0.002, p < 0.05) in welding workers, but these were not observed in office workers. There was no significant association of PM_2.5 with urinary cortisol observed in any workers. Urinary serotonin was associated with urinary Cu, Mn, Co, Ni, Cd, and Pb. Urinary cortisol was associated with Cu, Mn, Co, Ni, Cd, and Pb. Sixteen subjects were randomly selected from each of the office and welding workers for personal monitoring of sleep quality using a wearable device. We observed that welding workers had greater awake times than did office workers (p < 0.05). Our study observed that exposure to heavy metals in metal fume PM_2.5 may disrupt sleep quality in welding workers.

Impact of chemical exposure on cancer mortality in a French cohort of uranium processing workers

BACKGROUND

Nuclear workers may be exposed to a variety of chemical hazards, in addition to radiation. We examined the effect of chemical exposures on cancer mortality among French uranium processing workers at the AREVA NC Pierrelatte facility.

METHODS

A cohort of 2,897 uranium processing workers employed for at least 6 months was followed from 1968 through 2006. Exposure to uranium and potentially carcinogenic chemicals was assessed with a plant-specific job-exposure matrix. Mortality hazard ratios (HRs) for cancers of the lung, lymphohematopoietic system, kidney and bladder, brain and central nervous system (BCNS), and prostate were estimated for each specific chemical exposure, with Cox regression models stratified for sex and calendar period and adjusted for socioeconomic status. Additional adjustments enabled us to examine the effect of co-exposure to uranium and other chemicals.

RESULTS

Exposure to aromatic solvents was associated with increased risk of BCNS malignancies after adjustment for other chemicals (HR=6.53, 95% CI=1.14-37.41; n=6) and for other chemicals and uranium (HR=7.26, 95% CI=0.90-58.19) in the annual exposure status model. Selected groups of lymphohematopoietic cancers were found associated with solvent exposure. Inconclusive results were found regarding chromium (VI) exposure, since only 2 workers died from lung cancer among 109 exposed.

CONCLUSION

Based on our pilot study, it seemed important to take into account chemical exposures in the analyses of cancer mortality among French uranium processing workers.

Malignant pleural mesothelioma risk among nuclear workers: a review

Exposure to ionising radiation has been suggested as a causal risk factor for malignant pleural mesothelioma (MPM). Studies of patients treated by radiotherapy for primary cancers have suggested that radiation contributes to the development of secondary MPM. Here we examined the risk to nuclear workers of MPM related to exposure to low doses of occupational radiation at low dose rates. All results concerning MPM risk in published studies of nuclear workers were examined for their association with radiation exposure and potential confounders. We found 19 relevant studies. Elevated risks of pleural cancer were reported in most (15/17) of these studies. Eight reported risks higher for radiation monitored workers than for other workers. However, of 12 studies that looked at associations with ionising radiation, only one reported a significant dose-risk association. Asbestos was an important confounder in most studies. We conclude that studies of nuclear workers have not detected an association between ionising radiation exposure and MPM. Further investigations should improve the consideration of asbestos exposure at the same time as they address the risk of MPM related to occupational exposure of nuclear workers to low doses of ionising radiation at low dose rates.

Lung cancer incidence and survival in chromium exposed individuals with respect to expression of anti-apoptotic protein survivin and tumor suppressor P53 protein

OBJECTIVE

Workers chronically exposed to hexavalent chromium have elevated risk of lung cancer. Our study investigates the incidence of lung cancer types, age at onset of the disease, and survival time among chromium exposed workers with respect to the expression of anti-apoptotic p53 and pro-apoptotic survivin proteins.

MATERIAL AND METHODS

67 chromium exposed workers and 104 male controls diagnosed with lung cancer were analyzed. The mean exposure time among workers was 16.7 ±10.0(SD) years (range 1- 41 years). To investigate the possible regulation of survivin by p53 we examined the expression of both proteins using immohistochemical visualization.

RESULTS

Chromium exposure significantly decreases the age of onset of the disease by 3.5 years (62.2 ±9.1 in the exposed group vs. 65.7 ±10.5 years in controls; P=0.018). Small cell lung carcinoma (SCLC) amounted for 25.4% of all cases in chromium exposed workers and for 16.3% in non-exposed individuals. The mean survival time in the exposed group was 9.0 ±12.7 vs. 12.1 ±21.9 months in controls, but this difference was not significant. Survivin was predominantly expressed in both cell nucleus and cytoplasm, whereas p53 was expressed in the nucleus. There was a negative correlation between survivin and p53 expression. A decreased intensity of expression and fewer cells positive for survivin was detected in SCLC compared with other types of lung cancer. p53 was expressed in 94.1% and survivin in 79.6% of the samples analyzed.

CONCLUSION

The study calls attention to decreased expression of survivin, as opposed to p53, in small cell lung carcinoma.