Risk-Based Waste Classification in California (1999) / Chapter Skim
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1 Introduction
1 Introduction
Pages 14-35
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proposed approach for the classification of hazardous wastes that are not subject to the Federal Resource Conservation and Recovery Act (RCRA) program.
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and soluble or extractable regulatory thresholds (SERTs) , including the documentation for the CalTOX mode} and its modifications, the lead risk-assessment spreadsheet, the modified preliminary endangerment assessment model, the ecological risk assessments, and several sections on the use of the federal toxicity characteristic leaching procedure in place of the California waste extraction test.
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; ramifications for other California regulatory agencies; and the appropriateness of disposal requirements, predisposal management requirements, or regulation of discharges to sanitary sewers. Instead, the focus of this report is on the scientific validity of DTSC's waste classification methodology.
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Chapter 4 also compares the use of the two analytical extraction methods for leachates from solid waste (toxicity characteristic leaching procedure (TCLP) and waste extraction test (VVET)
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In subtitle D, RCRA also set forth a framework for the management of nonhazardous wastes, including disposal in subtitle D landfi~Is. Under RCRA, states have primary responsibility for the implementation of hazardous-waste regulations.
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Hazardous wastes must be disposed to landfi~Is that have double composite liners and leachate collection systems (class I) .i Nonhazardous wastes may be disposed to municipal solid-waste (class ITI)
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In addition to STLCs, which address leachable contaminants, the waste is analyzed to determine whether the concentration of any chemical exceeds the total threshold limit concentrations (TTLC)
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The 16 carcinogens are those identified in the California Occupational Carcinogens Control Act of 1976 (California Labor Code § 90041. Under the existing waste-cIassification system, DTSC regulates hazardous wastes that pose a low risk to human health or the env~ronment in the same way it regulates wastes that pose a high risk; mitigating information on potential exposures is not factored into the cIassification of waste containing the chemicals.
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· Do not provide a defined mechanism for regulating additional chemicals. Proposed Waste-CIassification System The DTSC has proposed changes to its current approach to incorporate recent advances in exposure assessment, toxicology, and risk assessment.
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special wastes with reduced regulatory requirements, and (3) nonhazardous wastes with no regulatory requirements imposed by DTSC.
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If the \ Lower TTLC ( > 500 mg/kg Proposed Non-RCRA Waste Classification System Note: To be classified as a "Califomia Special Waste" the waste must not exceed any of the catena for-Califomia Hazardous Waste" \ _>Lower .~ . ~ Low;r500 mg/kg ~ ~ ~< 30 mg/kg '°' 7400 mg/kg O 1 1: 1' ~ 500 mg/1 ~LC50 <30 m9/1 ' ~1 it:: :- :: : :: ::Not regulated by ~D~ venom- cl-~8o._d ~ .
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The lower TTLC (i.e., separating special and nonhazardous wastes) is derived to be protective of humans and ecological receptors if the waste is used as a soil amendment (i.e., the land conversion scenario)
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~DTSC has proposed the removal of silver from the list of TTECs due to its low toxicity. to residents living near the landfi~!
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TABLE ~ -] Models Used for the Various Exposure Scenarios Exposure Scenario Upper TTLC Lower TTLC Waste Residents Living Waste Residents on Ecological Constituents NearLandfill Workers Converted Land Concerns Organic CalTOX PEA worker CalTOX Multi-tiered Chemicals process Inorganic LeadSpread LeadSpread LeadSpread Multi-tiered Lead process Inorganic PEA PEA worker PEA Multi-tiered Chemicals process Source: Adapted from DTSC E 1 99Sal.
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For carcinogens, California cancer potency factors are used to derive the human-health-based levels of a chemical corresponding to a risk of ] 0-5 for an exposure scenario that appears to correspond to drinking the groundwater for the typical time that a person stays in a single residence.
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For the derivation of the SERT values, DTSC is proposing to rescind the use of the California WET for determining the extractable constituents of a waste. In lieu of the WET, DTSC is proposing the use of the TCEP that is currently used by the EPA to identify soluble toxic constituents of RCRA hazardous wastes.
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As for acute oral toxicity, the upper threshold is based on adult contact with waste and the lower threshold is based on a child's exposure, with dermal contact rates derived from the dermal contact rate parameters used in the CalTOX model, and uncertainty factors of 100 applied to acute toxicity values. For both oral and dermal toxicity classification, the LD50 values are either directly measured for the whole wastes, or they may be calculated from constituents of the waste.
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This latter value is the current aquatic toxicity threshold of 500 mg/L divided by the tenth percentile estimate of the liner protection factor (~) and rounded to one significant digit.
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The mode! examines the distribution of organic chemicals in the environment and the resulting exposures of human populations via all routes and through multiple exposure pathways (including air, drinking water, food, and soil (ingestion or dermal exposures.
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The principal difference between the lead risk-assessment spreadsheet and the PEA mode! is that the spreadsheet uses empirical ratios between exposure media concentrations and blood lead concentrations and adds the incremental contribution from each of the five exposure pathway to arrive at a ninetieth percentile estimate of total blood lead concentration.
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The proposed DTSC method might result in some waste previously classified as non-RCRA hazardous requiring further consideration by the waste generator to determine whether the waste meets the SWRCB definition of designated waste, thus requiring disposal in class II disposal facilities. IWMB provides for solid-waste planning and implementation and oversees local agencies that manage solid waste.
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and Inventories Hazardous Material Release Response Plans and Inventories Risk Management and Prevention Program Uniform Fire Code Hazardous Materials Management Plans The proposed DISC waste-classification system will affect several of the CUPA programs and require adjustments not only by the local agencies but also by the waste generators themselves, particularly if their wastes are reclassified and subject to different management and disposal requirements. EPA also developed a risk-based approach for the national hazardous-waste program under RCRA to identify wastes that no longer warrant being placed in the hazardous category.
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