Previous investigations have shown that trivalent arsenic is inducing chromosomal aberrations and sister chromatid exchanges (SCEs). In a search for the genotoxic mechanism we have studied the effects of the oxygen-radical-scavenging enzymes superoxide dismutase (SOD) and catalase (CAT) on arsenic-induced SCEs in cultured human lymphocytes. The results indicate that SOD and possibly also CAT have a protective effect against arsenic-induced DNA damage. Arsenic, which is emitted in environmental pollutions e.g. from smelters and coal-fired power plants, appears to be underestimated as environmental mutagen and potential synergist to ionizing radiation.
Our recent studies have shown a significant increase in the frequency of chromosomal aberrations in human amniotic cells after exposure to a sinusoidal 50 Hz, 30 microT (rms) magnetic field. To evaluate further interactions between chromosomes and electromagnetic fields, we have analyzed the effects of intermittent exposure. Amniotic cells were exposed for 72 h to a 50 Hz, 30 microT (rms) magnetic field in a 15 s on and 15 s off fashion. Eight experiments with cells from different fetuses were performed. The results show a 4% mean frequency of aberrations among exposed cells compared to 2% in sham-exposed cells. The difference is statistically significant, with P < 0.05 both excluding and including gaps. In another series of eight experiments, the cells were exposed in the same way but with the field on for 2 s and off for 20 s. Also in these experiments a similar increase in the frequency of chromosomal aberrations was seen, but only when the analysis included gaps. Continuous exposure for 72 h to 300 microT, 50 Hz, did not increase the frequency of chromosomal aberrations. The background electromagnetic fields at different locations within the two incubators used was carefully checked and was nowhere found to exceed 120 nT. Likewise, the background level of chromosomal aberrations in cells cultured at different locations in the incubators showed no significant interculture differences.
Frequencies of spontaneous abortion were studied in populations located at different distances from the Rönnskår smelter in northern Sweden. The smelter emits a number of potentially genotoxic substances like lead, arsenic and sulphur dioxide to the environment. In the population located close to the smelter a significant increase of the abortion frequency was found, compared to more distantly located populations.
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