25356.1.5
. (a) Any response action taken or approved pursuant to
this chapter shall be based upon, and no less stringent than, all of
the following requirements:
(1) The requirements established under federal regulation pursuant
to Subpart E of the National Oil and Hazardous Substances Pollution
Contingency Plan (40 C.F.R. 300.400 et seq.), as amended.
(2) The regulations established pursuant to Division 7 (commencing
with Section 13000) of the Water Code, all applicable water quality
control plans adopted pursuant to Section 13170 of the Water Code and
Article 3 (commencing with Section 13240) of Chapter 4 of Division 7
of the Water Code, and all applicable state policies for water
quality control adopted pursuant to Article 3 (commencing with
Section 13140) of Chapter 3 of Division 7 of the Water Code, to the
extent that the department or the regional board determines that
those regulations, plans, and policies do not require a less
stringent level of remediation than the federal regulations specified
in paragraph (1) and to the degree that those regulations, plans,
and policies do not authorize decisionmaking procedures that may
result in less stringent response action requirements than those
required by the federal regulations specified in paragraph (1).
(3) Any applicable provisions of this chapter, to the extent those
provisions are consistent with the federal regulations specified in
paragraph (1) and do not require a less stringent level of
remediation than, or decisionmaking procedures that are at variance
with, the federal regulations set forth in paragraph (1).
(b) Any health or ecological risk assessment prepared in
conjunction with a response action taken or approved pursuant to this
chapter shall be based upon Subpart E of the National Oil and
Hazardous Substances Pollution Contingency Plan (40 C.F.R. 300.400 et
seq.), the policies, guidelines, and practices of the United States
Environmental Protection Agency developed pursuant to the federal
act, and the most current sound scientific methods, knowledge, and
practices of public health and environmental professionals who are
experienced practitioners in the fields of epidemiology, risk
assessment, environmental contamination, ecological risk, fate and
transport analysis, and toxicology. Risk assessment practices shall
include the most current sound scientific methods for data
evaluation, exposure assessment, toxicity assessment, and risk
characterization, documentation of all assumptions, methods, models,
and calculations used in the assessment, and any health risk
assessment shall include all of the following:
(1) Evaluation of risks posed by acutely toxic hazardous
substances based on levels at which no known or anticipated adverse
effects on health will occur, with an adequate margin of safety.
(2) Evaluation of risks posed by carcinogens or other hazardous
substances that may cause chronic disease based on a level that does
not pose any significant risk to health.
(3) Consideration of possible synergistic effects resulting from
exposure to, or interaction with, two or more hazardous substances.
(4) Consideration of the effect of hazardous substances upon
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 subpopulations, that are identifiable as being at
greater risk of adverse health effects due to exposure to hazardous
substances than the general population.
(5) Consideration of exposure and body burden level that alter
physiological function or structure in a manner that may
significantly increase the risk of illness and of exposure to
hazardous substances in all media, including, but not limited to,
exposures in drinking water, food, ambient and indoor air, and soil.
(c) 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 chapter 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 (b), 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.
(d) The exposure assessment of any risk assessment prepared in
conjunction with a response action taken or approved pursuant to this
chapter shall include the development of reasonable maximum
estimates of exposure for both current land use conditions and
reasonably foreseeable future land use conditions at the site.
(e) The exposure assessment of any risk assessment prepared in
conjunction with a response action taken or approved pursuant to this
chapter shall include the development of reasonable maximum
estimates of exposure to volatile organic compounds that may enter
structures that are on the site or that are proposed to be
constructed on the site and may cause exposure due to accumulation of
those volatile organic compounds in the indoor air of those
structures.