Indications of repair of radon-induced chromosome damage in human lymphocytes: An adaptive response induced by low doses of X-rays
- Univ. of California, San Francisco, CA (United States)
- Pacific Northwest Research Labs., Richland, WA (United States); and others
Naturally occurring radon is a relatively ubiquitous environmental carcinogen to which large numbers of people can be exposed over their lifetimes. The accumulation of radon in homes, therefore, has led to a large program to determine the effects of the densely ionizing a particles that are produced when radon decays. In human lymphocytes, low doses of X-rays can decrease the number of chromatid deletions induced by subsequent high doses of clastogens. This has been attributed to the induction of a repair mechanism by the low-dose exposures. Historically, chromosome aberrations induced by radon have been considered to be relatively irreparable. The present experiments, however, show that if human peripheral blood lymphocytes are irradiated with low doses of X-rays (2 cGy) at 48 hr of culture, before being exposed to radon at 72 hr of culture, the yield of chromatid deletions induced by radon is decreased by a factor of two. Furthermore, the numbers of aberrations per cell do not follow a Poisson distribution but are overdispersed, as might be expected because high-linear energy transfer (high LET) a particles have a high relative biological effectiveness compared to low-LET radiations such as X-rays or {gamma} rays. Pretreatment with a low dose of X-rays decreases the overdispersion and leads to a greater proportion of the cells having no aberrations, or lower numbers of aberrations, than is the case in cells exposed to radon alone. It therefore appears that the putative chromosomal repair mechanism induced by low doses of sparsely ionizing radiation is also effective in reducing cytogenetic damage induced by a particles, which hitherto had been thought to be relatively immune to repair processes. 24 refs., 3 figs., 3 tabs.
- Research Organization:
- OAK (Oakland Operations Office, Oakland, CA)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC03-76SF01012
- OSTI ID:
- 513350
- Report Number(s):
- CONF-9201184-; ISSN 0091-6765; TRN: 97:000798-0002
- Journal Information:
- Environmental Health Perspectives, Vol. 101, Issue Suppl.3; Conference: 1. international conference on environmental mutagenesis in human populations at risk, Cairo (Egypt), 19-24 Jan 1992; Other Information: PBD: Oct 1993
- Country of Publication:
- United States
- Language:
- English
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