(a) The state board shall adopt primary drinking water standards for contaminants in drinking water that are based upon the criteria set forth in subdivision (b) and shall not be less stringent than the national primary drinking water standards adopted by the United States Environmental Protection Agency. A primary drinking water standard adopted by the state board shall be set at a level that is as close as feasible to the corresponding public health goal placing primary emphasis on the protection of public health, and that, to the extent technologically and economically feasible, meets all of the following:

1. (1) With respect to acutely toxic substances, avoids any known or anticipated adverse effects on public health with an adequate margin of safety.
2. (2) With respect to carcinogens, or any substances that may cause chronic disease, avoids any significant risk to public health.

(b) The state board shall consider all of the following criteria when it adopts a primary drinking water standard:

1. (1) The public health goal for the contaminant published by the Office of Environmental Health Hazard Assessment pursuant to subdivision (c).
2. (2) The national primary drinking water standard for the contaminant, if any, adopted by the United States Environmental Protection Agency.
3. (3) The technological and economic feasibility of compliance with the proposed primary drinking water standard. For the purposes of determining economic feasibility pursuant to this paragraph, the state board shall consider the costs of compliance to public water systems, customers, and other affected parties with the proposed primary drinking water standard, including the cost per customer and aggregate cost of compliance, using best available technology.

(c)

1. (1) The Office of Environmental Health Hazard Assessment shall prepare and publish an assessment of the risks to public health posed by each contaminant for which the state board proposes a primary drinking water standard. The risk assessment shall be prepared using the most current principles, practices, and methods used by public health professionals who are experienced practitioners in the fields of epidemiology, risk assessment, and toxicology. The risk assessment shall contain an estimate of the level of the contaminant in drinking water that is not anticipated to cause or contribute to adverse health effects, or that does not pose any significant risk to health. This level shall be known as the public health goal for the contaminant. The public health goal shall be based exclusively on public health considerations and shall be set in accordance with all of the following:

   1. (A) If the contaminant is an acutely toxic substance, the public health goal shall be set at the level at which no known or anticipated adverse effects on health occur, with an adequate margin of safety.
   2. (B) If the contaminant is a carcinogen or other substance that may cause chronic disease, the public health goal shall be set at the level that, based upon currently available data, does not pose any significant risk to health.

   3. (C) To the extent information is available, the public health goal shall take into account each of the following factors:

      1. (i) Synergistic effects resulting from exposure to, or interaction between, the contaminant and one or more other substances or contaminants.
      2. (ii) Adverse health effects the contaminant has on members of subgroups that comprise a meaningful portion of the general population, including, but not limited to, infants, children, pregnant women, the elderly, individuals with a history of serious illness, or other subgroups that are identifiable as being at greater risk of adverse health effects than the general population when exposed to the contaminant in drinking water.
      3. (iii) The relationship between exposure to the contaminant and increased body burden and the degree to which increased body burden levels alter physiological function or structure in a manner that may significantly increase the risk of illness.
      4. (iv) The additive effect of exposure to the contaminant in media other than drinking water, including, but not limited to, exposures to the contaminant in food, and in ambient and indoor air, and the degree to which these exposures may contribute to the overall body burden of the contaminant.
   4. (D) If the Office of Environmental Health Hazard Assessment finds that currently available scientific data are insufficient to determine the level of a contaminant at which no known or anticipated adverse effects on health will occur, with an adequate margin of safety, or the level that poses no significant risk to public health, the public health goal shall be set at a level that is protective of public health, with an adequate margin of safety. This level shall be based exclusively on health considerations and shall, to the extent scientific data is available, take into account the factors set forth in clauses (i) to (iv), inclusive, of subparagraph (C), and shall be based on the most current principles, practices, and methods used by public health professionals who are experienced practitioners in the fields of epidemiology, risk assessment, and toxicology. However, if adequate scientific evidence demonstrates that a safe dose response threshold for a contaminant exists, then the public health goal should be set at that threshold. The state board may set the public health goal at zero if necessary to satisfy the requirements of this subparagraph.
2. (2) The determination of the toxicological endpoints of a contaminant and the publication of its public health goal in a risk assessment prepared by the Office of Environmental Health Hazard Assessment are not subject to the requirements of Chapter 3.5 (commencing with Section 11340) of Part 1 of Division 3 of Title 2 of the Government Code. The Office of Environmental Health Hazard Assessment and the state board shall not impose any mandate on a public water system that requires the public water system to comply with a public health goal. The Legislature finds and declares that the addition of this paragraph by Chapter 777 of the Statutes of 1999 is declaratory of existing law.

3. (3)

   1. (A) The Office of Environmental Health Hazard Assessment shall, at the time it commences preparation of a risk assessment for a contaminant as required by this subdivision, electronically post on its Internet Web site a notice that informs interested persons that it has initiated work on the risk assessment. The notice shall also include a brief description, or a bibliography, of the technical documents or other information the office has identified to date as relevant to the preparation of the risk assessment and inform persons who wish to submit information concerning the contaminant that is the subject of the risk assessment of the name and address of the person in the office to whom the information may be sent, the date by which the information shall be received in order for the office to consider it in the preparation of the risk assessment, and that all information submitted will be made available to any member of the public who requests it.
   2. (B) A draft risk assessment prepared by the Office of Environmental Health Hazard Assessment pursuant to this subdivision shall be made available to the public at least 45 calendar days before the date that public comment and discussion on the risk assessment are solicited at the public workshop required by Section 57003.
   3. (C) At the time the Office of Environmental Health Hazard Assessment publishes the final risk assessment for a contaminant, the office shall respond in writing to significant comments, data, studies, or other written information submitted by interested persons to the office in connection with the preparation of the risk assessment. These comments, data, studies, or other written information submitted to the office shall be made available to any member of the public who requests it.
   4. (D) After the public workshop on the draft risk assessment, as required by Section 57003, is completed, the Office of Environmental Health Hazard Assessment shall submit the draft risk assessment for external scientific peer review using the process set forth in Section 57004 and shall comply with paragraph (2) of subdivision (d) of Section 57004 before publication of the final public health goal.

(e)

1. (1) All public health goals published by the Office of Environmental Health Hazard Assessment shall be established in accordance with the requirements of subdivision (c). The office shall determine, at least once every five years, whether there has been a detection of the corresponding contaminant of each public health goal in the preceding five years in the testing required pursuant to this chapter. Each public health goal shall be reviewed at least once every five years unless the office determines, pursuant to this paragraph, that there has not been a detection of the corresponding contaminant in the preceding five years. Reviewed public health goals shall be revised, pursuant to subdivision (c), as necessary based upon the availability of new scientific data.
2. (2) On or before January 1, 1998, the Office of Environmental Health Hazard Assessment shall publish a public health goal for at least 25 drinking water contaminants for which a primary drinking water standard has been adopted by the state board. The office shall publish a public health goal for 25 additional drinking water contaminants by January 1, 1999, and for all remaining drinking water contaminants for which a primary drinking water standard has been adopted by the state board by no later than December 31, 2001. A public health goal shall be published by the Office of Environmental Health Hazard Assessment at the same time the state board proposes the adoption of a primary drinking water standard for any newly regulated contaminant.

(g) At least once every five years after adoption of a primary drinking water standard, the state board shall review the primary drinking water standard and shall, consistent with the criteria set forth in subdivisions (a) and (b), amend any standard if either of the following occur:

1. (1) Changes in technology or treatment techniques that permit a materially greater protection of public health or attainment of the public health goal.
2. (2) New scientific evidence that indicates that the substance may present a materially different risk to public health than was previously determined.