All dose limits are presently determined by using the Linear No-Threshold dose hypothesis (LNT).

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The straight-line portion of these types of curves above Earth background has been the basis for the Linear No-Threshold Dose hypothesis, or LNT.

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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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That "something" could be hormone levels in utero, epigenetic factors that turn autism susceptibility genes "on" and "off" during development, or the fact that young girls have in general better social skills than boys and so need a bigger "dose" of what causes ASD to cross that threshold to being impaired.

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