Source: Reuters [OL]

Radiation, even in very small doses, is far more damaging to health than previously thought, a leading science magazine said Thursday. Most scientists now believe radiation below the internationally-accepted level of one millisievert per year can damage DNA in a new way that could harm the gene pool, wreck future generations and kill, the New Scientist said. ``It's a horrifying concept. But we now have early indications that it may be happening,'' Eric Wright of Britain's Medical Research Council (MRC) told the magazine.

The deadly effects of the atomic bombs dropped on the Japanese cities of Hiroshima and Nagasaki, or of the world's worst nuclear accident at Chernobyl in Ukraine in 1996, are well documented. But Wright says radiation can also damage cells in a way that cannot be detected until they have divided several times, in what he calls radiation-induced genomic instability. ``I regard the phenomenon as established,'' he said. ``There is no doubt that genomic instability is a real consequence of radiation exposure.''

The magazine said Wright's studies on mice and in humans, and at least six other projects around the world, showed the progeny of cells exposed to low-dose radiation had more chromosome aberrations than normal cells. The research also revealed that some people are more vulnerable to genetic instability than others. Although not yet proven, Wright believes induced genomic instability causes cancers like leukemia and may result in small increases in many other diseases. It could also aid the development of brain disorders such as Alzheimer's and Parkinson's diseases and increase developmental defects in fetuses.

Dudley Goodhead, also of the MRC, supports the theory and says just a tiny particle can damage a cell and boost the risk of disease. But David Cox of Britain's National Radiological Protection Board, citing the medical surveillance of the Hiroshima and Nagasaki victims, told the New Scientist there was no evidence to support the theory that genomic instability can increase the risk of diseases or kill. But although irrefutable proof is still lacking, the magazine said the genomic instability theory was already causing other scientists working in radiation protection to question the existing safeguards.

Note: The application of cytotoxicology utilizes the fact that quickly dividing cells are affected first by damage from radiation and chemotherapeutic agents, thus accumulating lethal changes more rapidly than surrounding tissue. As anyone who has been forced to go through these treatments will tell you they either suffered or were advised the potential existed that they could suffer damage to epithelial tissues..- in addition to the fast growing cancer cells (lining tissues of the bladder and digestive tract. A tissue which replaces itself essentially within 7 days in most individuals..) Many of the radiation studies also yield results based upon study of these same tissue groups. The long term effects on more slowly dividing tissue (such as male gamete cells - sperm) may yield much the same, but far more subtle results, as the time required for damage to manifest through replication is longer, carrying this damage into the next generation.