No serious adverse effects of treatment were reported, but the researchers note that these cannot be ruled out.

虽然未见严重的治疗副作用报道，但是研究人员指出这些影响不能不予考虑。

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The researchers ruled out radiation as a possible cause of the apparent sex reversal but suggested environmental contaminants that mimic hormones or water temperature changes could be the culprits.

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And every option has to be ruled out before the researchers will acknowledge that these vital chemical building-blocks might be "indigenous" or home grown and therefore open a door to the possibility of life on Mars.

BBC: New age of exploration in the hunt for extreme life

Although ice can become contaminated, researchers ruled it out as the source of contamination after testing revealed that it did not contain coliform bacteria.

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