California Code, Health and Safety Code - HSC § 79270

If currently available scientific data are insufficient to determine the level of a hazardous substance 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 risk assessment prepared in conjunction with a response action taken or approved pursuant to this part shall be based on the level that is protective of public health, with an adequate margin of safety.  This level shall be based exclusively on public health considerations, shall, to the extent scientific data are available, take into account the factors set forth in paragraphs (1) to (5), inclusive, of subdivision (c) of Section 79265, 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, fate and transport analysis, and toxicology.