Risk of Lung Cancer Mortality in Nuclear Workers from Internal Exposure to Alpha Particle-emitting Radionuclides

BACKGROUND

Carcinogenic risks of internal exposures to alpha-emitters (except radon) are poorly understood. Since exposure to alpha particles-particularly through inhalation-occurs in a range of settings, understanding consequent risks is a public health priority. We aimed to quantify dose-response relationships between lung dose from alpha-emitters and lung cancer in nuclear workers.

METHODS

We conducted a case-control study, nested within Belgian, French, and UK cohorts of uranium and plutonium workers. Cases were workers who died from lung cancer; one to three controls were matched to each. Lung doses from alpha-emitters were assessed using bioassay data. We estimated excess odds ratio (OR) of lung cancer per gray (Gy) of lung dose.

RESULTS

The study comprised 553 cases and 1,333 controls. Median positive total alpha lung dose was 2.42 mGy (mean: 8.13 mGy; maximum: 316 mGy); for plutonium the median was 1.27 mGy and for uranium 2.17 mGy. Excess OR/Gy (90% confidence interval)-adjusted for external radiation, socioeconomic status, and smoking-was 11 (2.6, 24) for total alpha dose, 50 (17, 106) for plutonium, and 5.3 (-1.9, 18) for uranium.

CONCLUSIONS

We found strong evidence for associations between low doses from alpha-emitters and lung cancer risk. The excess OR/Gy was greater for plutonium than uranium, though confidence intervals overlap. Risk estimates were similar to those estimated previously in plutonium workers, and in uranium miners exposed to radon and its progeny. Expressed as risk/equivalent dose in sieverts (Sv), our estimates are somewhat larger than but consistent with those for atomic bomb survivors.See video abstract at, http://links.lww.com/EDE/B232.

Short-term air pollution exposure decreases lung function: a repeated measures study in healthy adults

BACKGROUND

Daily changes in ambient concentrations of particulate matter, nitrogen oxides and ozone are associated with increased cardiopulmonary morbidity and mortality, with the lungs and their function being a vulnerable target.

METHODS

To evaluate the association between daily changes in air pollution and lung function in healthy adults we obtained annual lung function measurements from a routine worker health surveillance program not designed for research purposes. Forced Vital Capacity (FVC), Forced Expiratory Volume in the first second (FEV1), FEV1/FVC and Peak Expiratory flow (PEF) from a cohort of 2449 employees were associated with daily measurements of PM₁₀, NO₂ and ozone at a nearby monitoring station in the North of Belgium. Repeated measures were available for the period 2011-2015.

RESULTS

The mean (SD) PM₁₀ concentration on the day of the lung function test was 24.9 (15.5) μg/m³. A 10 μg PM₁₀/m³ increase on the day of the clinical examination was associated with a 18.9 ml lower FVC (95% CI: -27.5 to -10.3, p < 0.0001), 12.8 ml lower FEV1 (-19.1 to -6.5; p < 0.0001), and a 51.4 ml/s lower PEF (-75.0 to -27.0; p < 0.0001). The FEV1/FVC-ratio showed no associations. An increase of 10 μgNO₂/m³ was associated with a reduction in PEF (-66.1 ml/s (-106.6 to -25.6; p < 0.001)) on the day of the examination.

CONCLUSIONS

We found negative associations between daily variations in ambient air pollution and FVC, FEV1 and PEF in healthy adults.

[Medical interventions: external and internal decontamination of people]

In most cases, external contamination of persons can be monitored easily. Nevertheless, proper measurement techniques must be used. For that reason, contamination measurements must be carried out by health physics professionals. In all efforts to decontaminate intact skin, care must be taken to prevent skin damage. Internal contamination can pose much more problems. Here, decontamination is based on dilution and/or complexation therapy, thus reducing the uptake in critical organs and tissues. Also by stimulating the excretion of radionuclides, internal doses can be reduced significantly. Treatment of contaminated wounds always is a priority because of the internal contamination risk. Radioactive waste has to be collected on an individual basis (for dosimetry purposes). Distance must be kept between radioactive waste and monitoring instruments. Every effort should be made to prevent the spread of contamination; only urgent life saving actions may be an exception. There certainly will be a need for counseling those suffering from the psychological impact of (even minor) contamination accidents. From a public health perspective, the long term psychosocial effects of nuclear catastrophes may eventually be more prevalent than their physical health consequences. Each (general) practitioner should be vigilant to suspicious clinical signs that may be radiation related. However, high threshold doses to critical organs (bone marrow, skin, small intestine) must be crossed before clinical signs arise. In Belgium, several most interesting texts regarding radiation problems have already been distributed to medical and paramedical professionals, partly by the authorities.

Radiation exposure and cause specific mortality among nuclear workers in Belgium (1969-1994)

Cause specific mortality was studied in nuclear workers from five nuclear facilities in Belgium and compared to the general population. For the 1969-1994 period, mortality in male nuclear workers is significantly lower for all causes of death and for all cancer deaths. The same conclusions are reached if one assumes a latency period of 20 y between the first irradiation and cancer induction. In female workers, mortality due to all causes and all cancer deaths is not different from that of the general population. Analysis of cause specific mortality was performed for male and female workers for three endpoints: specific cancer sites, cardiovascular and respiratory diseases. No significant increase in mortality was observed. In male workers, the influence of cumulative dose was also investigated using four dose levels: no significant correlation was found. Smoking habits may be a confounding factor in smoking related health conditions.