846 



(3) Revised national primary drinking water reg- 

 ulations promulgated under paragraph (2) of this 

 subsection shall be primary drinking water regula- 

 tions which specify a maximum contaminant level 

 or require the use of treatment techniques for each 

 contaminant for which a recommended maximum 

 contaminant level is established or which is listed 

 in a rule under paragraph (1)(B). The maximum 

 contaminant level specified in a revised national 

 primary drinking water regulation for a contami- 

 hant shall be as close to the recommended 

 maximum contaminant level established under 

 paragraph (1)(B) for such contaminant as is 

 feasible. A required treatment technique for a con- 

 taminant for which a recommended maximum: 

 contaminant level has been established under para- 

 graph (1)(B) shall reduce such contaminant to a 

 level which is as close to the recommended maxi- 

 mum contaminant level for such contaminant as is 

 feasible. A required treatment technique for a con- 

 taminant which Is listed under paragraph (1)(B) 

 shall require treatment necessary in the Adminis- 

 trator's judgment to prevent known or anticipated 

 adverse effects on the health of persons to the 

 extent feasible. For purposes of this paragraph, the 

 term "feasible" means feasible with the use of the 

 best technology, treatment techniques, and other 

 means, which the Administrator finds are generally 

 available (taking cost into consideration). 



(4) Revised national primary drinking water 

 regulations shall be amended whenever changes In 

 technology, treatment techniques, and other means 

 permit greater protection of the health of persons, 

 but in any event such regulations shall be reviewed 

 at least once every 3 years. 



(5) Revised national primary drinking water 

 regulations promulgated under this subsection (and 

 amendments thereto) shall take effect eighteen 

 months after the date of their promulgation. Regu- 

 lations under subsection (a) of this section shall be 

 superseded by regulations under this subsection to 

 the extent provided by the regulations under this 

 subsection. 



(6) No national primary drinking water regula- 

 tion may require the addition of any substance for 

 preventive health care purposes unrelated to con- 

 tamination of drinking water. 



(c) Secondary regulations; publication of proposed 

 regulations; promulgation; amendments. 



The Administrator shall publish proposed na- 

 tional secondary drinking water regulations within 

 270 days after December 16, 1974. Within 90 days 

 after publication of any such regulation, he shall 

 promulgate such regulation with such modifications 

 as he deems appropriate. Regulations under this 

 subsection may be amended from time to time. 



(d) Regulations; public hearings; administrative con- 

 sultations. 



Regulations under this section shall be prescribed 

 in accordance with section 553 of Title 5 (relating 

 to rulemaking) , except that the Administrator shall 

 provide opportunity for public hearing prlor.to pro- 

 mulgation of such regulations. In proposing and 

 promulgating regulations under thU section the 



Administrator shall consult with the Secretary and 

 the National Drinking Water Advisory founcU. 

 (e) Study; maximum contaminant level determina- 

 tion; adverse effect of contaminants of undeter- 

 mined levels; report to Congress; funds. 



(1) The Administrator shall enter into appropri- 

 ate arrangements with the National Academy of 

 Sciences (or with another independent scientific 

 organization if appropriate arrangements cannot be 

 made with such Academy) to conduct a study to. de- 

 termine <A) ■ the maximum . Qpjitaminant levels 

 which should be recommended under subsection 

 (b) (2) of this section in order to protect the health 

 of persons from any known or anticipated adverse 

 effects, and (B) the existence of any contaminants 

 the levels of which in drinking water cannot be de- 

 termined but which may have an adverse effect on 

 the health of persons. 



(2) The result of the study shall be reported to 

 Congress no later than 2 years after December 16, 

 1974. The report shall contain (A) a summary and 

 evaluation of relevant publications and unpublished 

 studies; (B) a statement of methodologies and 

 assumptions for estimating the levels at which ad- 

 verse health effects may occur; (C) a statement of 

 methodologies and assumptions for estimating the 

 margin of safety which should be incorporated in 

 the national primary drinking water regulations; 

 (D) TDroposals for recommended maximum con- 

 taminant levels for national primary drinking water 

 regulations, based on the methodologies, assump- 

 tions, and studies referred to in clauses (A) , (B) , 

 and (C) and in paragraph (4) ; (E) a list of con- 

 taminants the level of which in drinking water 

 cannot be determined but which may have an ad- 

 verse effect on the health of persons; and (P) 

 recommended studies and test protocols for future 

 research on the health effects of drinking water con- 

 taminants, including a list of the major research 

 priorities and estimated costs necessary to conduct 

 such priority research. 



(3) In developing its proposals for recommended 

 maximum contaminant levels under paragraph (2) 

 (D) the National Academy of Sciences (or other 

 organization preparing the report) shall evaluate 

 and explain (separately and in composite) the im- 

 pact of the following considerations: 



(A) The existence of groups or individuals in 

 the population which are more susceptible to ad- 

 verse effects than the normal healthy adult. 



(B) The exposure to contaminants in other 

 media than drinking water (including exposures 

 in food, in the ambient air, and in occupational 

 settings) and the resulting body burden of con- 

 taminants. 



(C) Synergistic effects resulting from exposure 

 to or interaction by two or more contaminants. 



(D) The contaminant exposure and body 

 burden levels which alter physiological function 

 or structure in a manner reasonably suspected of 

 increasing the risk of illness. 



(4) In making the study under this subsection, the 

 National Academy of Sciences (or other organiza- 

 tion) shall collect and correlate (A) morbidity and 



