Recent advances in research on radiation adaptive responses

The radiation adaptive responses have been typically demonstrated as an acquired resistance induced by a low dose of radiation to a large (challenge) dose administered after some interval. The responses have been demonstrated in various types of cultured cells; the endpoints include micronucleus formation, sister chromatid exchange, mutation induction, in vitro transformation, and cell death. The adaptive response has been also demonstrated in the whole body system; mice irradiated with a small dose developed a resistance against a lethal irradiation. The response was also demonstrated in terms of radiation and carcinogen induced tumors. The adoptive responses seem to work in a protective way against radiation damage and contradicts what is assumed in the current radiation protection system: radiation is harmful, no matter how low the dose is. (author)