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COMMONWEALTH OF PENNSYLVANIA

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Pennsylvania Code



Subchapter F. EXPOSURE AND RISK DETERMINATIONS


Sec.


250.601.    Scope.
250.602.    Risk assessment procedures.
250.603.    Exposure factors for site-specific standards.
250.604.    Fate and transport modeling requirements for exposure assessments.
250.605.    Sources of toxicity information.
250.606.    Development of site-specific standards.

Cross References

   This subchapter cited in 25 Pa. Code §  245.309 (relating to site characterization); 25 Pa. Code §  250.405 (relating to when to perform a risk assessment); 25 Pa. Code §  271.1 (relating to definitions); and 25 Pa. Code §  287.1 (relating to definitions).

§ 250.601. Scope.

 (a)  This subchapter specifies the information and procedures necessary to conduct a risk assessment.

 (b)  A risk assessment shall ensure adequate evaluation of the risks associated with human and ecological receptors exposed to regulated substances at contaminated sites.

 (c)  A risk assessment may include one or more of the following:

   (1)  A baseline risk assessment.

   (2)  A risk assessment to develop site-specific standards.

§ 250.602. Risk assessment procedures.

 (a)  Except as specified in §  250.405 (relating to when to perform a risk assessment), a person shall perform a risk assessment when using a site-specific standard under Subchapter D (relating to site-specific standards) to determine if there are unacceptable exposures to humans or unacceptable exposures to ecological receptors, or both.

 (b)  A person who proposes to perform a risk assessment under the site-specific standard shall use the methodologies used to develop the Statewide health standards contained in Subchapter C (relating to Statewide health standards) to conduct the risk assessment. If methodologies are not specified in Subchapter C or this subchapter, the risk assessment shall be conducted in accordance with the methodology specified in EPA or ASTM guidelines approved by the Department.

 (c)  A risk assessment for human exposure shall include the following components:

   (1)  Data collection, including source characterization and development of a conceptual site model, and evaluation to identify contaminants of concern.

   (2)  Exposure assessment that considers ingestion, inhalation and volatilization pathways and exposure assumptions based on land use.

   (3)  Toxicity assessment that includes the use of toxicity information from sources identified in §  250.605 (relating to sources of toxicity information).

   (4)  Risk characterization that evaluates if the risks meet the human health protection goals and ecological receptor protection specified in §  250.402 (relating to human health and environmental protection goals).

 (d)  An exposure assessment that is based on sampling shall use a data handling methodology that is consistent with the statistical method used to demonstrate attainment.

 (e)  When performing an exposure assessment, a person shall use the appropriate exposure factors identified in §  250.603 (relating to exposure factors for site-specific standards) and meet the requirements of §  250.604 (relating to fate and transport modeling requirements for exposure assessments).

 (f)  The risk assessment report shall discuss the degree of uncertainty associated with the risk assessment.

Cross References

   This section cited in 25 Pa. Code §  250.606 (relating to development of site-specific standards).

§ 250.603. Exposure factors for site-specific standards.

 (a)  A risk assessment for the site-specific standard shall use site-specific exposure factors under the EPA’s Final Guidelines for Exposure Assessment, 1992 (57 FR 22888—22938) or exposure factors used in the development of the Statewide health standards identified in Subchapter C (relating to Statewide health standards).

 (b)  If a person uses site-specific exposure factors that deviate from the standard exposure factors in Subchapter C, the site-specific exposure factors shall be clearly justified by supporting data. The person shall provide the supporting data in the site-specific risk assessment report.

 (c)  The exposure factors shall be selected based on the land use of the site with reference to current and currently planned future land use and the effectiveness of institutional or legal controls placed on the future use of the land.

 (d)  The person shall document in the site-specific risk assessment report the future use of the site.

Cross References

   This section cited in 25 Pa. Code §  250.602 (relating to risk assessment procedures); and 25 Pa. Code §  250.606 (relating to development of site-specific standards).

§ 250.604. Fate and transport modeling requirements for exposureassessments.

 (a)  A person may use the soil-to-groundwater model in §  250.308(a)(2) (relating to soil to groundwater pathway numeric values) to estimate site-specific, soil-to-groundwater leaching potential for organic contaminants if the following conditions are met:

   (1)  Site-specific values of water-filled soil porosity, dry soil bulk density, dilution factors (DF) and fraction organic carbon in soil beneath the source of contamination (that is, not from top soil) are appropriately justified and the person provides supporting data to the Department.

   (2)  Koc values as provided in §  250.308(a)(2) are used or site-specific values which are appropriately justified are used and the person provides supporting data to the Department.

   (3)  There is no identified separate phase liquid contamination at the site.

   (4)  Other processes such as colloidal transport or transport by means of dissolved organic matter (DOM) are not significant at the site.

   (5)  The application of the soil-to-groundwater model shall meet the most current EPA or ASTM quality assurance/quality control criteria approved by the Department.

 (b)  Except for the soil-to-groundwater model in §  250.308(a)(2), a person planning to use other fate and transport models and methods to estimate exposure concentrations and to develop site-specific standards shall use appropriate models or methods approved by the Department. The application of groundwater models shall meet the most current EPA or ASTM quality assurance/quality control criteria approved by the Department.

Cross References

   This section cited in 25 Pa. Code §  250.602 (relating to risk assessment procedures); and 25 Pa. Code §  250.606 (relating to development of site-specific standards).

§ 250.605. Sources of toxicity information.

 (a)  For site-specific standards, the person shall use appropriate reference doses, reference concentrations, cancer slope factors and unit risk factors identified in Subchapter C (relating to Statewide health standards), unless the person can demonstrate that published data, available from one of the following sources, provides more current reference doses, reference concentrations, cancer slope factors or unit risk factors:

   (1)  Integrated Risk Information System (IRIS).

   (2)  United States Environmental Protection Agency, National Center for Environmental Assessment (NCEA) Provisional Peer-Reviewed Toxicity Values (PPRTV).

   (3)  Other sources

     (i)   Health Effects Assessment Summary Tables (HEAST)

     (ii)   Agency for Toxic Substances and Disease Registry (ATSDR) Toxicological Profiles.

     (iii)   California EPA, California Cancer Potency Factors and Chronic Reference Exposure Levels.

     (iv)   EPA criteria documents, including drinking water criteria documents, drinking water health advisory summaries, ambient water quality criteria documents and air quality criteria documents.

 (b)  If no toxicity values are available from sources identified in subsection (a), the person may use the background standard or meet one of the following:

   (1)  Develop for the Department’s review in the risk assessment report one of the following:

     (i)   Chemical-specific toxicity values in accordance with the methods in the most current EPA guidelines or protocols, approved by the Department, using corroborated peer-reviewed data published in a scientific journal, if they exist.

     (ii)   Toxicity values developed from appropriately justified surrogates.

   (2)  Use the minimum threshold medium-specific concentration, as the site-specific standard, with an assumed risk of 1 x 10-5 for purposes of calculating cumulative risk for the regulated substances identified in Appendix A, Table 6.

Authority

   The provisions of this §  250.605 issued under sections 104(a) and 303(a) of the Land Recycling and Environmental Remediation Standards Act (35 P. S. § §  6026.104(a) and 6026.303(a)).

Source

   The provisions of this §  250.605 amended January 7, 2011, effective January 8, 2011, 41 Pa.B. 230; corrected March 19, 2011, effective March 5, 2011, 41 Pa.B. 1458. Immediately preceding text appears at serial pages (355309) to (355310).

Cross References

   This section cited in 25 Pa. Code §  250.602 (relating to risk assessment procedures); and 25 Pa. Code §  250.606 (relating to development of site-specific standards).

§ 250.606. Development of site-specific standards.

 (a)  If an unacceptable risk is identified by the assessments described in §  250.602 (relating to risk assessment procedures), a person shall perform one of the following:

   (1)  A remediation that eliminates all current and probable future exposure pathways.

   (2)  A remediation utilizing a standard developed under a site-specific risk assessment that is protective of human health and the environment.

 (b)  A person who chooses to use a standard developed under a site-specific risk assessment shall meet the human health and environmental protection requirements identified in §  250.402 (relating to human health and environmental protection goals).

 (c)  The development of site-specific standards shall be based on the standard in §  250.605(b)(2) (relating to sources of toxicity information) or the components of risk assessment in §  250.602, the appropriate exposure factors identified in §  250.603 (relating to exposure factors for site-specific standards), the fate and transport modeling requirements of §  250.604 (relating to fate and transport modeling requirements for exposure assessments) and the toxicity values of §  250.605 (relating to sources of toxicity information).

 (d)  The following factors shall be considered in the development of the risk assessment and in the development of site-specific standards:

   (1)  Groundwater in aquifers.

     (i)   Natural environmental conditions that affect the fate and transport of contaminants, such as natural attenuation, shall be determined.

     (ii)   The person shall identify routes of exposure for aquifer groundwater such as human exposure to groundwater by ingestion, human inhalation of regulated substances from volatilization and migration of these substances into buildings or other areas where humans could be exposed, human ingestion of regulated substances in surface water or other site-specific surface water exposure pathways with respect to groundwater discharges or releases to surface water, human inhalation of regulated substances in air, or other site-specific air exposure pathways with respect to release of regulated substances from groundwater to air.

   (2)  Nonaquifer groundwater. The persons shall consider current and probable future exposure scenarios, such as human exposure as described in paragraph (1)(ii).

   (3)  The person shall consider current and probable future exposure scenarios, such as:

     (i)   Human ingestion of soil when direct contact exposure to the soil may reasonably occur.

     (ii)   Exposure to groundwater by ingestion with respect to leaching of regulated substances from soils to groundwater.

     (iii)   Human inhalation of regulated substances from volatilization and migration of these substances into below grade occupied space.

     (iv)   Human ingestion of regulated substances in surface water or other site-specific surface water exposure pathways with respect to regulated substances migration from soil to surface water.

     (v)   Human inhalation of regulated substances in air or other site-specific air exposure pathways with respect to the release of regulated substances from soil to air.

   (4)  If ecological receptors have been identified under §  250.311 (relating to evaluation of ecological receptors) or §  250.402, and are impacted, a remedial activity that eliminates current or future exposure pathways, or a standard, shall be developed to protect the receptors from the direct impacts.

 (e)  In determining soil and groundwater site-specific standards, the person shall identify the land use of the site with reference to current and currently planned future land use and the effectiveness of institutional or legal controls placed on the future use of the land.

 (f)  In determining soil and groundwater site-specific standards, the person shall use appropriate statistical techniques, including Monte Carlo simulations as appropriate, to establish statistically valid cleanup standards. The report for a risk assessment to develop site-specific standards shall discuss the degree of uncertainty associated with the risk assessment.



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