I have read that it is possible to treat drinking water with uranium contamination to levels at or below 20 µg/L. I have also read that EPA proposed an MCL of 20 µg/L in 1991. Why is uranium regulated at 30 µg/L and not 20 µg/L?
EPA invoked discretionary authority under section 1412(b)(6) of the Safe Drinking Water Act to set an MCL for uranium at a level higher than the feasible level. Based on the relatively modest annual cancer risk reductions between 30 µg/L and 20 µg/L, the expected modest kidney toxicity risk reductions between 30 µg/L and 20 µg/L, and the high annual compliance costs for an MCL of 20 µg/L, EPA determined that the benefits did not justify the costs at the feasible level. EPA determined that an MCL of 30 µg/L maximizes the health risk reduction benefits at a cost justified by the benefits (65 FR 76708, 76715; December 7, 2000).
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