Oregon Administrative Rules › Chapter 340 - DEPARTMENT OF ENVIRONMENTAL QUALITY › Division 122 - HAZARDOUS SUBSTANCE REMEDIAL ACTION RULES › Section 340-122-0084 - Risk Assessment

Current through Register Vol. 63, No. 7, July 1, 2024
This rule establishes a risk protocol for performance of human
				health and ecological risk assessments, including: General requirements for
				risk assessments and specific requirements for baseline human health risk
				assessments, baseline ecological risk assessments, residual risk assessments,
				and probabilistic risk assessments.
(1) General requirements for risk assessments
			 include:
(a) Risks assessments shall consider
			 existing and reasonably likely future human exposures and significant adverse
			 effects to ecological receptors in the locality of the facility.
(b) Risk assessments may be conducted using
			 either deterministic or probabilistic risk assessment methodologies at the
			 discretion of the party conducting the risk assessment, provided the risk
			 assessment requirements of this rule are met.
(c) Sources of toxicity information to be
			 used in a risk assessment may include the following information to the extent
			 it is available and acceptable to the Department at the time a human health or
			 ecological risk assessment is prepared:
(A)
			 For human health risk assessments:
(i) U.S.
			 EPA IRIS Data Base;
(ii) U.S. EPA
			 HEAST Data Base;
(iii) HEAST
			 alternative method;
(iv) U.S.
			 EPA-NCEA Superfund Health Risk Technical Support Center;
(v) Other U.S. EPA documents or
			 databases;
(vi) ATSDR Toxicological
			 Profiles; or
(vii) Other refereed
			 technical publications.
(B) For ecological risk assessments:
(i) U.S. EPA AQUIRE Data Base;
(ii) U.S. EPA IRIS Data Base;
(iii) U.S. EPA HEAST Data Base;
(iv) U.S. EPA ASTER Data Base;
(v) U.S. EPA PHYTOTOX Data Base;
(vi) U.S. EPA Terrestrial Toxicity Data Base
			 (TERRATOX);
(vii) U.S. Fish and
			 Wildlife Service Technical Reports;
(viii) Oak Ridge National Laboratory
			 Toxicological Benchmark Technical Reports;
(ix) Other U.S. EPA documents or
			 databases;
(x) ATSDR Toxicological
			 Profiles; or
(xi) Other refereed
			 technical publications.
(C) In the absence of toxicity information
			 that is available and acceptable to the Department under paragraph (A) or (B),
			 the Department may require the development of acceptable site-specific toxicity
			 information.
(d) Risk
			 assessments may include use of transport and fate models, subject to Department
			 approval of the model and the data to be used for the parameters specified in
			 the model. The Department shall ensure than any transport and fate model
			 approved for use is capable of simulating all site conditions and contaminant
			 properties that might have a significant impact on site-specific contaminant
			 transport or fate.
(e) The
			 Department shall require appropriate sampling approaches and data quality
			 requirements to support the risk assessment and remedy selection
			 processes.
(f) A plausible
			 upper-bound or high-end exposure for both human health and ecological risk
			 assessments is the 90th percentile upper confidence limit on the arithmetic
			 mean of concentrations of hazardous substances that would be contacted by an
			 exposed receptor and reasonable maximum estimates of the exposure factors used
			 in the risk calculations, unless a greater or lesser best estimate is
			 acceptable to the Department.
(g)
			 The central tendency exposure for both human health and ecological risk
			 assessments is the arithmetic mean of concentrations that would be contacted by
			 an exposed receptor and mean estimates of the exposure factors used in the risk
			 calculations. Risk assessments utilizing only deterministic methods shall
			 provide both central tendency and upper-bound estimates of exposure and
			 risk.
(h) The use of population
			 risk estimates in addition to individual risk estimates is provided for as
			 follows:
(A) For human health risk
			 assessments, risk estimates shall be made only at the level of the
			 individual;
(B) For ecological risk
			 assessments, risk estimates shall be made:
(i) At the level of the individual for
			 species present in the locality of the facility if the species is listed as
			 threatened or endangered species pursuant to
			 16
			 U.S.C. 1531 et seq. or ORS
			 496.172;
			 or
(ii) At the level of the
			 population for all other plants or animals in the locality of the
			 facility.
(i)
			 Cumulative risk from multiple hazardous substances will be assessed by assuming
			 additivity of the risk posed separately by individual non-carcinogenic and
			 carcinogenic hazardous substances in the locality of the facility, unless the
			 Department determines that an assumption of synergism, antagonism, or other
			 toxic response is appropriate or it is demonstrated to the satisfaction of the
			 Department that an assumption other than additivity is appropriate.
(j) Appropriate sources of exposure factor
			 information may include, but are not limited to, the following information, to
			 the extent it is available and acceptable to the Department at the time human
			 health and ecological risk assessments are prepared:
(A) U.S. EPA Risk Assessment Guidance for
			 Superfund. Volume 1. Human Health Evaluation Manual, Part A, 1989;
(B) U.S. EPA Risk Assessment Guidance for
			 Superfund Volume 2. Environmental Evaluation Manual, 1989;
(C) U.S. EPA Risk Assessment Guidance for
			 Superfund. Volume 1. Human Health Evaluation Manual, Supplemental Guidance -
			 Standard Default Exposure Factors, 1991;
(D) U.S. EPA Wildlife Exposure Factors
			 Handbook. Volumes 1 and 2, 1993; and
(E) U.S. EPA Exposure Factors Handbook,
			 1990.