In the 1950s, to be simplistic and conservative, the world governing bodies decided to just draw in that line anyway, all the way down to zero, dictating that there was no threshold.

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The bill would reduce the threshold in both England and Wales to zero and extend the opportunity to switch to cover sewerage as well as water.

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The committee has concluded that there is no compelling evidence to indicate a dose threshold below which the risk of tumor induction is zero.

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