Low doses of radiation can cause cardiovascular disease, according to work carried out by mathematicians¹ at Imperial College.

帝国理工学院的数学家通过研究发现，低剂量的辐射即可导致心血管疾病。

Survivors² of the atomic bomb attack in Japan have shown higher levels of heart disease and strokes" width="226" border="0" src="/upimg/091023/4_070229_1.jpg" />
Survivors of the atomic bomb attack in Japan have shown higher levels of heart disease and strokes

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 mechanism³ that suggests radiation kills monocytes（单核细胞）, which travel across the arterial（动脉的） wall to mop up a protein called MCP-1.

High levels of MCP-1 are thought to cause the inflammation（发炎，红肿） which leads to cardiovascular disease（心血管病）.

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 cholesterol⁴（胆固醇） 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 valid⁵ 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, said the results of the mathematical model were interesting: "As it is based very largely on mathematical modelling, its findings cannot be taken as definitive⁶.

"However it does propose a plausible⁷ biological mechanism and, most importantly, a mechanism that is testable by experiment."

Professor Richard Wakeford, of the University of Manchester, said: "More research like this is needed if the results of epidemiological studies（传染病研究） 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 drawn⁸ without laboratory validation⁹ of the key assumptions."