An astrophysicist with the Dublin Institute for Advanced Studies plays an international role in assessing radiation risks to aircraft crew and astronauts. Dick Ahlstrom reports
Ireland has no formal space programme but an Irish physicist has developed a key role in assessing the safety of space travel. His experimental data has also helped set EU standards for radiation exposure limits to aircraft flight crews.
Prof Denis O'Sullivan has been putting experiments on board NASA spacecraft for 35 years and for more than a decade has measured the radiation risks faced by pilots and cabin crew on board conventional aircraft. An astrophysicist at the Dublin Institute for Advanced Studies, he currently leads an EU research programme in air crew safety involving seven European laboratories and last week saw his ninth experiment being carried aloft into space.
All of us receive a radiation dose from the sun and also cosmic rays coming from deep space. This radiation dose increases the more time we spend on aircraft and the furtherer from the equator we fly.
The urgent need to have a clear understanding of the radiation levels involved were seen in research published yesterday in the British Medical Journal title, Occupational and Environmental Medicine. It carried a number of Scandinavian studies indicating flight crews carried an increased risk of contracting breast and skin cancer.
One Icelandic study showed a fivefold increased risk of breast cancer. And while a separate Swedish study didn't establish an increased breast cancer risk, it found an increased risk of malignant melanoma among both male and female cabin crew and an increased risk of other skin cancers among the men.
O'Sullivan, with colleague, Dr Dazhuang Zhou, is co-ordinating an international team looking at cabin crew radiation exposures. "We have been flying detectors on everything from the Concord down to the Irish Government jet," he said. Airlines around the world have co-operated in this activity. "It is telling us the radiation exposure increases with altitude as we might have guessed." It also confirmed that the further from the equator we fly the greater the exposure.
In 1990 the International Commission on Radiological Protection recommended that exposure of aircrew to cosmic radiation should be considered occupational exposure. The legal consequences of this were that the EU brought in legislation recently to protect aircrew, a decision reached after an assessment of O'Sullivan's data.
He has spent years studying astronaut exposure in spacecraft and in the International Space Station (ISS). His ninth experiment, a collaboration with a Belgian group, reached the ISS after a Soyuz lift-off just last Saturday.
The institute team is providing cosmic ray exposure measurements on a colony of bacteria supplied by the Belgians. The areas of particular interest are bacterial genetic stability and DNA rearrangement after exposure.
There is growing interest in what happens during prolonged space flights to bacteria that travel with the crew. "We were invited to take part in the American/Russian mission to the ISS," he said. "Our job is to measure the actual amount of radiation that hits the bacteria and the microbiologists in Belgium will assess the impact on the bacteria." Radiation can cause mutations in DNA, changes that might alter the characteristics of a given organism.
Changed organisms could present an unexpected danger to crew or cause damage to materials, explains O'Sullivan. He has collaborated with NASA for 35 years. "I actually worked with the lunar samples that Neil Armstrong brought back with him on the Apollo 11 flight to the moon," he says.
