Chromosomal and other blood tests for exposure to chemicals and radiation

Many agents that cause cancer do so by damaging DNA. This DNA damage can often be detected by analysing chromosomes. In humans, environmental and occupational exposures to chemicals and ionising radiation may be detected by analysis of chromosome damage in white blood cells obtained from a modest (approximately 10 millilitres) blood sample. A variety of tests are available to investigate damage to chromosomes such as dicentric tests, translocation tests, micronucleus tests and sister chromatid exchange tests. It is well established that exposure to certain chemical agents (for example,Testa et al, 2002), ionising radiations (for example, Voisin et al, 2004; Edwards et al, 2005) and ultraviolet light (for example, Emri et al, 2005) can cause damage detectable in chromsome tests. Chromosome aberration tests cannot however reliably detect exposure to electro-magnetic fields and radiations such as those emitted by power lines (Hone et al, 2003) or mobile phones or base stations (Vijayalaxmi and Obe, 2004).

DNA damage arises from several causes. People are being constantly exposed to radical damage at the molecular level as a result of dietary and metabolic processes as well as from external sources such as ionizing radiation from natural background. There are protective enzymes such as superoxide dismutase and catalase occurring naturally in cells and tissues that can mitigate the effects of such oxidative damage. These are normal cellular constituents and they occur at varying levels between and within individuals. There is a school of thought that such processes evolved in parallel with the ever present damaging effects of free radicals in order to protect the individual and the species.

To what extent the blood levels of the factors and enzymes involved in these protective metabolic mechanisms can provide a measure of long term exposure to low-level man-made radiations, either ionising or non-ionising, is far from clear.

References

Edwards AA, Lindholm C, Darroudi F, Stephan G, Roman H, Barquinero J, Barrios L, Caballin MR, Roy L, Whitehouse CA, Tawn EJ, Moquet J, Lloyd DC and Voisin P (2005). Review of translocations detected by FISH for retrospective biological dosimetry applications. Radiat. Prot. Dosim, 113, 396-402.

Emri G, Wenczl E, van Erp P, Jans J, Roza L, Horkay I and Schothorst AA (2000). Low doses of UVB and UVA induce chromosomal aberrations in cultured human skin cells. J. Invest. Dermatol, 115, 435-40.

Hone P, Edwards A, Halls J, Cox R and Lloyd D (2003). Possible associations between ELF electromagnetic fields, DNA damage response processes and childhood leukaemia. Br. J. Cancer, 88,1939-41.

Testa A, Ranaldi R, Carpineto L, Pacchierotti F, Trindelli D, Fabiani L, Giuliani AR, Ursu M, Rossini A, Materozzo F, Petyx M and Leoni V (2002). Cytogenetic biomonitoring of workers from laboratories of clinical analyses occupationally exposed to chemicals. Mutat. Res, 26, 73-82.

Vijayalaxmi and Obe G (2004). Controversial cytogenetic observations in mammalian somatic cells exposed to radiofrequency radiation. Radiat. Res, 162, 481-96.

Voisin P, Roy L and Benderitter M (2004). Why can't we find a better biological indicator of dose? Radiat. Prot. Dosim, 112, 465-69.

HPA offers tests for exposure to ionising radiation.

Last reviewed: 4 September 2008