The effects of acute high level radiation exposure are well documented as are the longer term effects of radiation on the incidence of lung, breast, salivary gland, thyroid and haematological malignancy.2
Keloid scar formation (secondary to the flashburn effects of nuclear bombs), cataract, infertility and cardiovascular disease are also highly prevalent in Hiroshima (Ur-235) and Nagasaki (Pl-239) survivors.3 4
Ascertaining the long term effects of whole body radiation on the lung is more difficult. Radiation-induced mutations in the conserved region of the p53 tumour suppressor gene are well recognised and likely to be implicated in the greater incidence of cancer.5
Likewise, use of multicolour fluorescent in situ hybridisation (mFISH) to investigate chromosome abnormalities in New Zealand nuclear test veterans (compared to carefully matched non-exposed individuals) has shown significantly higher (p<0.0001) frequencies of chromosomal abnormalities (275 translocations and 12 dicentrics in 9360 cells versus 96 translocations and 1 dicentric in 9548 cells in the controls), as well as a significant excess of complex chromosomal rearrangements in the veterans.6
Others however have argued that a single non-fatal total body irradiation dose does not produce permanent or chronic somatic damage.7
The incidence of UIP is less certain, although poorly validated reports of ‘lung fibrosis’ in the Hiroshima bomb survivors have suggested an incidence of 0.8%, equating to an OR of 2.01 over the non-exposed population.8
Plutonium (Pu-239) inhalation at an annual lung dose of >10 mSv is more firmly associated with lung fibrosis (‘plutonium pneumosclerosis’) and there are similar reports for workers in the USA involved in underground uranium mining during 1942–1971. Interestingly, intrapleural administration of radioisotopes (eg, Au-198) produces a pleural reaction with reportedly little collateral lung damage.9
Despite the above data, the Radiation Exposure Compensation Act passed by the US Congress in 1990 does not list lung fibrosis as a compensable injury in ‘onsite’ observers of the Nevada, Pacific, Trinity or South Atlantic atmospheric nuclear test sites.
It is also recognised that the damage produced in the lung is less of a function of the total dose of radiation, more the rate at which the dose is delivered. Hence fractionation of a dose appears to reduce the severity of lung injury. The extent of lung damage at least in the acute setting can also vary widely between individuals. In patients receiving radiotherapy for breast or lung cancer or lymphoma, where normal tissue in unavoidably captured, three phases of lung injury are recognised, including an acute phase, radiation pneumonitis and late radiation fibrosis.10
In such cases pulmonary fibrosis is usually well established by 12 months. Radiation therapy to the lung has also been reported to cause reactivation of pulmonary tuberculosis, pleural effusion, secondary pneumothorax, rib fractures and tracheoesophageal fistula.10
Estimating the precise radiation exposure in our patient is difficult. Data derived from the British Nuclear Test Veterans Association (http://www.bntva.com/history/history.htm) indicate that our patient was 20 miles away from three airburst (2200–2400 m) detonations ranging in size from 200 to 720 kiloton. Support for this claim and the lack of personal shielding comes from contemporary photographs (). A moratorium on such atmospheric nuclear tests was announced in 1958. We speculate that the close proximity of our patient to three large nuclear detonations and the fact that he has two other conditions well recognised to be associated with radiation injury (bladder carcinoma and atherosclerosis of a major artery), together with the chronicity of his pulmonary fibrosis all support a causal link. The Ministry of Defence have reported that on-board dosimetry showed background levels of radiation only and, in contrast to the USA (1990 Radiation Exposure Compensation Act), have denied compensation for British Servicemen (see 1998 McGinley and Egan v The United Kingdom, European Court of Human Rights, http://www.hrcr.org/safrica/access_information/ECHR/mcginley_egan.html
). Such dosimetry however may have grossly underestimated the exposure to α-particles and the later exposure to contaminated dust, rain and sea water.
- Pulmonary fibrosis may result from acute radiation injury and should be suspected in individuals exposed to high level whole body radiation.
- Pulmonary fibrosis, especially if occurring secondary to a defined insult, can be associated with stable symptoms and preserved lung function.
- Careful history taking in patients with idiopathic pulmonary fibrosis/usual interstitial pneumonia is important to identify patients with secondary causes.