Page last updated at 23:03 GMT, Thursday, 22 October 2009 00:03 UK

Low dose radiation 'harms heart'

Geiger counter
Nuclear workers have been shown to have higher rates of heart disease in some studies

Low doses of radiation can cause cardiovascular disease, according to work carried out by mathematicians at Imperial College.

They have constructed a model which suggests that the risk would increase as the dose increases.

Studies have shown that nuclear workers exposed to long-term doses of radiation have higher levels of heart disease.

But experts said it was too early to draw such conclusions without the biological research to back it up.

Controversial theory

The team at Imperial College, writing in the journal PLOS Computational Biology, say they explored a novel mechanism that suggests radiation kills monocytes, which travel across the arterial wall to mop up a protein called MCP-1.

More research like this is needed if the results of epidemiological studies are to be properly understood, but there is still some way to go before it may be reliably concluded that low-level radiation can increase the risk of circulatory disease
Professor Richard Wakeford, University of Manchester

High levels of MCP-1 are thought to cause the inflammation which leads to cardiovascular disease.

Their model was consistent with the rates of heart disease seen in nuclear workers and also predicted the changes in MCP-1 caused by high levels of cholesterol in the diet.

Dr Mark Little, who led the research, said: "For the first time we have shown a mechanism that could explain the kind of cardiovascular disease risks that have been seen in the occupational studies.

"If the mechanism is valid it implies that risks from low-dose radiation exposures like medical and dental X-rays, which until now have been assumed to result only from cancer, may have been substantially underestimated."

Mechanism testable

Professor Steve Jones, of Westlakes Research Institute who formerly worked for British Nuclear Fuels (BNF) and who has published his own research on the links between radiation and circulatory disease in nuclear workers, said the results of the mathematical model were interesting: "As it is based very largely on mathematical modelling, its findings cannot be taken as definitive.

"However it does propose a plausible biological mechanism and, most importantly, a mechanism that is testable by experiment."

Professor Richard Wakeford, of the University of Manchester who also formerly worked for BNF, said: "More research like this is needed if the results of epidemiological studies are to be properly understood, but there is still some way to go before it may be reliably concluded that low-level radiation can increase the risk of circulatory disease."

Professor Dudley Goodhead, former director of the MRC Radiation and Genome Stability Unit, said: "This paper puts forward a highly complicated mathematical model, which makes many assumptions, to explore one possible causal mechanism.

"Such conclusions should not be drawn without laboratory validation of the key assumptions."



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