W. Va. Code R. § 60-3-8

Current through Register Vol. XLI, No. 50, December 13, 2024

Section 60-3-8 - Risk Protocol

This section establishes a risk protocol for conducting human health and ecological risk assessments. It describes general requirements for risk assessments and specific requirements for baseline human health and ecological risk assessments, residual risk assessments, and application of probabilistic risk assessment methods.

8.1. General Requirements for Risk Assessments. - Risk assessments shall consider existing and reasonably anticipated future human exposures and significant adverse effects to ecological receptors of concern in accordance with this rule.

8.1.a. Risk assessments may be conducted using either deterministic (single point value) or probabilistic risk assessment methodologies as agreed to in the Voluntary Remediation Agreement.

8.1.b. Risk assessments, to the extent practicable, shall consider the range of probabilities of carcinogenic risks potentially occurring, the nature and magnitude of potential non-carcinogenic health hazards, the range of size of populations likely to be exposed, current and reasonably anticipated future land and water uses, and quantitative and/or qualitative descriptions of uncertainties in accordance with subsections 8.1 and 8.2 of this rule.

8.1.c. Appropriate sources of toxicity information include the following:

8.1.c.1. For human health risk assessments, in order of preference:

8.1.c.1.A. U.S. EPA Integrated Risk Information System (IRIS);

8.1.c.1.B. U.S. EPA Superfund Health Risk Technical Support Center (SHRTSC) provisional peer reviewed toxicity criteria; and

8.1.c.1.C. Other scientifically valid documents or information developed from governmental or non-governmental sources and approved by the Secretary.

8.1.c.2. For ecological risk assessments, in order of preference:

8.1.c.2.A. U.S. EPA Region 3 BTAG Screening Benchmarks;

8.1.c.2.B. U.S. EPA Region 4 Ecological Risk Assessment Supplemental Guidance;

8.1.c.2.C. U.S. EPA ECOTOX Database;

8.1.c.2.D. U.S. EPA IRIS Database;

8.1.c.2.E. U.S. EPA HEAST Database;

8.1.c.2.F. U.S. Fish and Wildlife Service Technical Reports;

8.1.c.2.G. Oak Ridge National Laboratory Toxicological Benchmark Technical Reports;

8.1.c.2.H. ATSDR Toxicological Profiles;

8.1.c.2.I. Other peer-reviewed technical publications;

8.1.c.2.J. National Oceanic and Atmospheric Administration's Screening Quick Reference Tables (SQuiRTs); and

8.1.c.2.K. Other scientifically valid documents or information developed from governmental or non-governmental sources and approved by the Secretary.

8.1.d. Risk assessments may include the use of fate and transport models subject to the Secretary's approval of the model and the data to be used for the parameters specified in the model.

8.1.d.1. The Secretary shall ensure that any fate and transport model approved for use is capable of simulating those site conditions and contaminant properties that might have a significant impact on site-specific contaminant fate or transport.

8.1.d.2. Risk assessments shall include sensitivity analyses of models and data used as model parameters. Sensitivity analyses shall be based on the range of conditions which have historically occurred or may be likely to occur at the site.

8.1.d.3. For models not included in Department guidance documents, risk assessments shall include a description, including published references if available.

8.1.d.4. Where available, the Department shall give preference to the use of peer-reviewed models and data for which on-site validation is demonstrated.

8.1.e. The use of population risk estimates in addition to individual risk assessments is provided for as follows:

8.1.e.1. For human health risk assessments, risk estimates shall initially be made at the level of the individual. A population-based risk assessment may be conducted where the applicant determines it would be practicable and of assistance in evaluating the appropriateness of the remedial action; and

8.1.e.2. For ecological risk assessments, the applicant shall make risk estimates:

(A) at the individual level where any endangered or threatened species is significantly impacted by the proposed activities at the site; and

(B) at the level of the population for all ecological receptors of concern exposed to contaminants at the site.

8.2. Sampling Protocol, Data Requirements, and Sampling Methods. - The applicant shall use sampling approaches, data quality requirements, and statistical methods set forth in the Voluntary Remediation Program Guidance Manual as approved by the Secretary to support the risk assessment and remedy selection process.

8.2.a. Characterization of Site Contamination. - The applicant shall collect and analyze a sufficient number of environmental media samples so as to provide a reasonable characterization of the nature and distribution of site contaminants, horizontally, vertically, and temporally. Therefore, it may be necessary to sample media such as surface water and groundwater on multiple occasions to assess temporal distribution. The number and location of the samples collected shall be of sufficient quantity and quality to calculate the appropriate exposure point concentration as defined in subparagraph 8.4.b.3.B and subdivision 8.5.c of this rule.

8.2.b. Media to be Sampled. - The applicant shall collect and analyze samples from those media that are reasonably anticipated to have been impacted from contaminants at the site, considering the nature of the site operations and the nature of the contaminants of potential concern at the site.

8.2.c. Contaminants for Analyses. - The applicant may not need to analyze all samples for the same contaminants. The applicant shall analyze collected samples for those contaminants that are reasonably anticipated to be encountered, considering the nature of the site operations and the nature of the substances used or disposed of at the site.

8.2.d. Data Validation. - The applicant shall validate the quality of the analytical data to be used in establishing exposure point concentrations by review of at least ten percent (10%) of the data or some other percentage agreed to by the Secretary in accordance with current EPA protocols and data quality considerations presented in the Voluntary Remediation Program Guidance Manual. Standard EPA protocols for validation may require modification, with the Secretary's approval, depending on the type of analyses performed (e.g., Contract Laboratory Protocol or SW-846).

8.2.e. The 95th percentile upper confidence limit of the most appropriate frequency distribution of the site data as determined by statistical software (e.g., ProUCL) or the maximum value of the site contaminant concentration data shall be a reasonable estimate of a plausible exposure point concentration for this contaminant. If a contaminant can be shown to have dissimilar distributions of concentrations in different areas, then the areas should be subdivided. For example, "hot spots" may be considered separately.

8.3. Quantification of cumulative risks posed by multiple exposure pathways. - The Applicant shall account for the cumulative risks to each receptor via all pathways to which they may be exposed.

8.3.a. Non-Carcinogenic Risk: An upper-bound hazard quotient shall be calculated for each toxicant in each exposure pathway. The hazard quotients in each pathway will be added to calculate an upper-bound hazard index that accounts for cumulative impacts in that pathway. The hazard indices for each pathway to which a receptor may be exposed will be added to calculate the total site hazard index for each receptor. Where multiple systemic toxicants affect the same target organs or act by the same method of toxicity, the upper-bound estimate of hazard index shall be calculated using these same procedures for each pathway and receptor, but only for the toxicants that impact the specific organ or act by the same method.

8.3.b. Carcinogenic Risk: The excess lifetime cancer risks (ELCR) above and beyond background exposures shall be calculated for each toxicant in each exposure pathway. The ELCR in each pathway will be added to estimate the cumulative cancer risks in that pathway. The ELCR for each pathway to which a receptor may be exposed will be added to estimate the cumulative cancer risks for each receptor.

8.4. Baseline Human Health Risk Assessments (BHHRA). - The applicant may use a BHHRA to provide a characterization of the risks to human health posed by contaminants at the site, given a full evaluation of site-specific conditions.

8.4.a. The applicant may use the BHHRA either to:

8.4.a.1. Assess the need for remedial action considering site-specific conditions; or

8.4.a.2. Demonstrate the acceptability of current site conditions with respect to the remediation standards specified in this rule.

8.4.b. BHHRAs shall include, but are not limited to, the following information:

8.4.b.1. A conceptual site model showing contaminant sources, release mechanisms, transport routes and media, potential human receptor populations, and reasonable potential exposure scenarios based on current and reasonably anticipated land and water uses;

8.4.b.2. Data quality objectives for the human health risk assessment based on the conceptual site model;

8.4.b.3. An exposure assessment that evaluates the potential for and magnitude of human exposure, considering both the current and reasonably anticipated future land and water uses at and in close proximity to the site. An exposure assessment shall include:

8.4.b.3.A. An exposure pathway analysis which identifies complete exposure pathways from contaminants to receptor populations, identifying the nature and extent of site contamination, the presence or absence of media that could transport the site contamination, the presence or absence of receptor populations that could be exposed to the contamination, and the likely exposure routes; and

8.4.b.3.B. A quantification of the magnitude of the exposure (in accordance with Department guidance documents) if, following the performance of the exposure pathway analysis, the potential exists for exposure of receptor populations to site contaminants. At a minimum, the applicant shall develop exposure levels that approximate a reasonable upper bound of the exposure distribution. The applicant may also account for the implementation of presumptive institutional and engineering exposure controls that meet the criteria in subdivision 9.8.a. to account for exposure pathways that will be rendered incomplete by the implementation of these controls.

8.4.b.4. The applicant shall perform a toxicity analysis if he or she identifies and quantifies the potential for human exposure to site contaminants in accordance with subparagraph 8.4.b.3.B of this rule. The toxicity analysis shall include a summary of current information regarding the carcinogenic and non-carcinogenic effects of the identified contaminants of concern, as well as current slope factors, inhalation unit risks, reference doses, reference concentrations, and any other pertinent toxicity values from the sources described in subdivision 8.1.c of this rule.

8.4.b.5. Risk Characterization. - If the potential exists for human exposure to site contaminants, the applicant shall integrate the exposure quantification information with the dose-response assessment (toxicity analysis) to provide a characterization of the potential risks present at the site. The risk characterization shall include a quantification of risks from individual contaminants. The applicant shall include a quantification of cumulative risks posed by multiple contaminants using the most sensitive exposure pathway for each constituent. The risk characterization shall analyze the following:

8.4.b.5.A. Non-Carcinogenic Risk: In quantifying risks from individual toxicants at the site, the applicant shall develop a hazard quotient for each contaminant in each exposure pathway. In quantifying the risks from cumulative exposure to multiple contaminants at the site, the applicant shall develop a hazard index for exposures to multiple contaminants. In developing the hazard index for multiple contaminants, the applicant shall assume additivity, but may account for those contaminants that affect the same target organ or act by the same method of toxicity as outlined in subdivisions 9.2.d, 9.3.g, and 9.4.b; and

8.4.b.5.B. Carcinogenic Risk: In quantifying risks from carcinogens at the site, the applicant shall estimate the excess lifetime cancer risk above and beyond the risk associated with background exposures for individual toxicants as well as the cumulative risks from exposure to multiple toxicants across all pathways. The risk estimates are presumed to be additive unless an alternative mechanism is appropriate.

8.4.b.5.C. The applicant shall include, as appropriate, a discussion of any available facility-specific human health studies and consideration of any other non-quantified (qualitative) risks in the risk characterization described herein.

8.4.b.6. Uncertainty Analysis: As part of performing the site-specific risk assessment under this section, the applicant shall identify the qualitative, and to the extent practicable, the quantitative uncertainty embodied in the analysis. The applicant shall also identify the likelihood of overestimating or underestimating risk for each element of the analysis. At a minimum, this shall include consideration of:

8.4.b.6.A. The analytical characterization of the site;

8.4.b.6.B. The exposure assessment, including the size of the potentially exposed population; and

8.4.b.6.C. The dose-response assessment, including the toxicological criteria used in the analysis and potential synergistic/antagonistic interactions.

8.5. Baseline Ecological Risk Assessment. - The applicant may perform a site-specific de minimis screening ecological evaluation as specified in subsection 9.5 of this rule as part of the site investigation to determine if a complete exposure pathway exists and there are ecological receptors of concern. If, after this evaluation, the applicant identifies a potentially significant complete exposure pathway, then the applicant shall complete the uniform ecological evaluation as specified in subsection 9.6 of this rule to determine if site concentrations exceed benchmark levels. If the applicant proposes remediation goals that exceed benchmark levels, then the Secretary may require, at his or her discretion, a baseline ecological assessment to evaluate potential risks to ecological receptors and to develop appropriate remediation standards based on these risks. If the Secretary requires a baseline ecological risk assessment, it shall address, but not be limited to, the following information:

8.5.a. Problem Formulation. The applicant shall identify the purpose (goals) of the assessment and define the problem. This step includes identification of potential contaminants of concern, potential ecological effects, potential ecological receptors of concern, potential exposure pathways, and initial assessment and measurement endpoints, all with respect to current and reasonably anticipated future land and water uses. The applicant shall develop a conceptual site model to depict how the site conditions might affect ecological components of the natural environment;

8.5.b. Data Quality. The applicant shall develop data quality objectives for the site based on the conceptual site model;

8.5.c. Exposure Analysis. The applicant shall perform an exposure assessment that evaluates the potential for and magnitude of ecological effects to receptors of concern, considering current and reasonably anticipated future conditions at the site. Exposure is analyzed by describing the source and releases, the distribution of the stressor in the environment, and the extent and pattern of contact or co-occurrence. The end product of this analysis is an exposure profile which summarizes the magnitude and spatial and temporal patterns of exposure for the scenarios described in the conceptual site model;

8.5.d. Ecological Response Analysis. If the Exposure Analysis reveals potentially complete pathways for ecological receptors, the applicant shall develop an ecological response analysis that includes a summary of current information regarding the toxicological and ecological effects of the identified contaminants of ecological concern, as well as ecological benchmark values. Appropriate sources of toxicity information are identified in paragraph 8.1.c.2 of this rule;

8.5.e. Ecological Risk Characterization. If the potential exists for significant ecological risks due to exposure to site contaminants, the applicant shall integrate the exposure quantification information in subdivision 8.5.c of this rule with the ecological response analysis to provide a characterization of the risks presented at the site, considering current and reasonably anticipated future land and water uses. The risk characterization shall include a quantitative evaluation of ecological risks potentially associated with the site, a weight-of-evidence analysis of risk, a discussion of available site-specific ecological studies, and consideration of the non-quantified (qualitative) risks as appropriate; and

8.5.f. Uncertainty Analysis. The applicant shall use, as appropriate, qualitative and/or quantitative uncertainty analyses for each element of the risk assessment.

8.6. Residual Risk Assessments (RRA). - The applicant shall consider, in residual human health and ecological risk assessments, conditions that will be present at the site following implementation of the proposed remedy, should one be needed.

8.6.a. In a situation where the applicant has conducted a baseline risk assessment and found that no further action is necessary, the baseline risk assessment may serve as the residual risk assessment.

8.6.b. A RRA shall include an assessment of the risks under current and reasonably anticipated future land and water use scenarios, given:

8.6.b.1. The exposure conditions that will be present following remediation and the concentrations of untreated constituents or treatment residuals remaining at the conclusion of any excavation, treatment, or off-site disposal; and/or

8.6.b.2. The exposure conditions that will result following implementation of any institutional or engineering controls necessary to manage risks from treatment residuals or untreated hazardous constituents.

8.6.c. The applicant shall conduct the RRA following the same basic steps outlined in subsections 8.4 and 8.5 of this rule, except that the conditions used to define the site shall reflect post-remediation conditions, including site-specific numeric remediation standards and site-specific exposure conditions that incorporate any engineering and institutional controls proposed as part of the remedial action.

8.7. Probabilistic Assessment: The applicant may apply probabilistic techniques to human health and ecological risk assessments. At a minimum, before the commencement of a probabilistic risk assessment, the applicant shall discuss with the Secretary the sources and characteristics of the distributions proposed for use in the assessment. The probabilistic risk assessment shall include, but not be limited to, information regarding:

8.7.a. All formulae used to estimate exposure point values, toxicity (e.g., cancer slope factor, reference dose) values, ecological benchmark values, hazard indices, and incremental lifetime cancer risks;

8.7.b. A combination of input parameters expressed as either point estimates or distributions. For each input parameter expressed as a distribution, the applicant shall provide the following information:

8.7.b.1. The shape of the full distribution;

8.7.b.2. To the extent practicable, the mean, standard deviation, minimum, 5th percentile, 10th percentile, median, 90th percentile, 95th percentile, and maximum of the specified distribution;

8.7.b.3. Justification for the use of each distribution clearly explaining the rationale for its use and the rejection of other relevant distributions; and

8.7.b.4. The extent to which input distributions and their parameters capture and separately represent both stochastic variability and knowledge uncertainty. This information shall comprise a portion of, but not be a replacement for, a comprehensive discussion in the body of the baseline risk assessment of the qualitative and quantitative sources of uncertainty.

8.7.c. A description of any correlations between or among input variables that are known or expected to have the practical effect of significantly affecting the risk assessment;

8.7.d. For each output distribution resulting from the probabilistic risk assessment, the following information:

8.7.d.1. The shape of the full distribution and location of the acceptable risk level; and

8.7.d.2. To the extent practicable, the mean, standard deviation, minimum, 5th percentile, 10th percentile, median, 90th percentile, 95th percentile, and maximum of the specified distribution.

8.7.e. A probabilistic sensitivity analysis for all key input distributions conducted so as to distinguish, to the extent possible, the effects of variability from the effects of uncertainty in the input variables;

8.7.f. Justification for the selection of any point estimate value incorporated into the probabilistic assessment and the rationale for its selection and for the rejection of other relevant point estimate values;

8.7.g. Probabilistic methods may be applied to:

8.7.g.1. Environmental media contaminant concentration data;

8.7.g.2. Transport and fate modeling;

8.7.g.3. Exposure estimation;

8.7.g.4. Ecological response estimation; and/or

8.7.g.5. Risk characterization.

8.7.h. The plausible upper-bound exposure condition is equal to approximately the 90th percentile of the exposure distribution. The central-tendency exposure case is the 50th percentile of the exposure distribution. Risk assessments utilizing only deterministic (single point value) methods shall provide both central tendency and plausible upper-bound estimates of exposures and risk.

W. Va. Code R. § 60-3-8