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31 ELR 10800 | Environmental Law Reporter | copyright © 2001 | All rights reserved Bioavailability: On the Frontiers of Science and Law in Cleanup Methodologies for ContaminationLinda MaloneLinda Malone is the Marshall-Wythe Foundation Professor of Law at the William and Mary Law School. She received her B.A. from Vassar College in 1975, her J.D. from Duke Law School in 1978, and her LL.M. from the University of Illinois College of Law in 1984. How clean is clean? National policy on human health and ecological risk assessment has proceeded for some time on a precautionary approach to remediation requirements. Conservative assumptions on "safe" levels of exposure have created underlying assumptions of "clean up to background" levels of contamination as anything less would not guarantee safety for future residential use. These generic assumptions rather than more site-specific assessments predominated, in large part, due to scientific uncertainty in risk assessment and concern that site-specific analysis necessarily entailed more time and expense. Scientific research on "natural attenuation" (recovery through natural processes) and a more generalized expansion of scientific knowledge has prompted site assessors, responsible parties for cleanup, state agencies, and federal agencies to question the validity of the traditional generic approach in a variety of different contexts. There is more disagreement in these groups over the definition of "bioavailability" than there appears to be in the scientific community as to its overall validity as a scientific precept and methodology for risk assessment. Whatever the precise definition, the essential concept of bioavailability is a site-specific assessment of the risk to human health and the environment from contamination, and remediation to the level necessary to return the site to its actual future use. Assuming sufficient information (a critical assumption), incorporation of bioavailability into the risk assessment process holds the promise of more accurate, cost-effective cleanups with no greater actual risk to human health or ecology than under the traditional generic approach. How Bioavailability Concepts Are Currently Used in Regulation Federal and state environmental regulation and directives take a variety of forms, with differing legal impacts. At the federal level, statutes passed by Congress, such as the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)1 and the Clean Water Act (CWA),2 are binding nationwide on federal and state agencies as well as private parties. Environmental statutes ordinarily designate an agency, often the U.S. Environmental Protection Agency (EPA), to oversee compliance with the statute. As part of this responsibility, Congress may delegate rulemaking authority to the federal agency to regulate in more detail with the benefit of the agency's expertise. Such regulations must be promulgated in accordance with the substantive and procedural requirements of the Administrative Procedure Act (APA),3 ordinarily in the form of "informal rulemaking" following what is known as the "notice-and-comment" procedure—publication in proposed form in the Federal Register, a comment period, publication in final form in the Federal Register, and ultimately inclusion in the Code of Federal Regulations. Assuming that the regulation is promulgated in accordance with the procedural requirements and within the bounds of the authority delegated to the agency, the regulation is legally binding on federal and state agencies as well as private parties. State agencies may administer their own complementary state environmental programs, assist in the administration of a federal environmental program, or assume responsibility for administration of a federal environmental program if the relevant federal criteria are met. As environmental regulation has become increasingly complex, the voluminous and detailed statutes and regulations have lacked the comprehensiveness and detail necessary to put the regulatory requirements into practice. As a result, federal and state agencies have provided more detailed guidance in documents available to the public, but these documents are not promulgated with the formality necessary under the APA to be considered a legally binding rule or regulation. However denominated, these guidance documents are of great practical importance and generally are assumed by regulated parties to state the methodology and criteria that must be followed to meet statutory and regulatory requirements. For example, if EPA, a regional EPA office, or a state environmental agency issues a guidance document on use of bioavailability in making risk assessments, the risk assessor generally assumes that any departure from that guidance will be closely scrutinized and questioned. Similarly, the comments to final regulations in the Federal Register are not per se legally binding, but provide an authoritative interpretation from the regulatory agency of what the relevant regulation requires. As a formal legal requirement, bioavailability currently receives little mention in the federal statutes and regulations governing environmental regulation. The only statutory reference is a brief mention of the bioavailability of restricted metals in CWA § 402's permit requirements for point source discharges into navigable waters.4 In contrast there are 20 or more statutory references to bioavailability and bioequivalence requirements in the pharmacological context of [31 ELR 10801] food and drug regulation under the Federal Food, Drug, and Cosmetic Act.5 Much the same results are obtained from a word search for bioavailability under the federal regulations. Although there are approximately 50 references to bioavailability in the Code of Federal Regulations, the references are concentrated in the regulations enacted under the Toxic Substances Control Act,6 with the exception of a reference to bioavailability of fuel additives under the Clean Air Act.7 Conducting the same word search under the comments to the federal regulations, however, leads to a dramatically different result. The term "bioavailability" appears hundreds of times in the comments to the regulations, including comments to regulations under the major statutory programs outlined below. The incorporation of bioavailability into the more detailed, working guidance provided by the comments to the Code of Federal Regulations suggests the potential for working application of bioavailability far exceeds its formal recognition in the current laws and regulations. Indeed, EPA's only quasi-official recognition of bioavailability in risk assessment of contamination is in an appendix to a Risk Assessment Guidance for Superfund (RAGS),8 and the term "bioavailability" is not even utilized. Instead, the appendix refers to "adjustments for absorption efficiency." In other words, the guidance opens the door for consideration of information that a substance at a particular cleanup site may be more or less than typically presumed under the standard risk assessment paradigm. There is no agencywide guidance on the data necessary to substantiate such an adjustment, however, leaving that critical determination to EPA regional offices, state environmental agencies, or the judgment of the risk assessors, risk assessment reviewers, remedial project managers, and risk managers to whom the guidance is addressed. Formulation of a general standard is complicated by the fact that bioavailability of any substance is chemical and site-specific. There is potential for incorporation of bioavailability into any federal program utilizing risk assessment to determine an acceptable level of exposure to a contaminant. The focus of this study is incorporation of bioavailability into federal programs that seek to reduce the exposure of any organism to a contaminant in the ambient environment (as opposed to ingestion of a food or drug). The degree of reduction deemed necessary to protect human health or the environment, after calculating the acceptable level of risk, determines the environmentally acceptable endpoint for remediation. The risk assessment paradigm in U.S. environmental regulation assumes generally that the level of a contaminant in soil, air, or water is the level of exposure to humans or other organisms at the point of contact or reception. Other "worst-case" assumptions may also be made, inflating the assessment of risk, e.g., prolonged human exposure and residential land use at a contaminated site at which neither is likely to occur. Bioavailability is site- and chemical-specific and, assuming the availability of perfect information, more scientifically accurate and cost effective as a method of remediation. Absent sufficient supporting data, however, bioavailability may lead to inadequate remediation or at least public perception of inadequate remediation. The principal federal remediation programs that would be affected directly by utilization of bioavailability in risk assessment would be sediment quality assessment under CWA § 404's dredge and fill, CWA § 402's national pollutant discharge elimination system (NPDES), CWA § 303's total maximum daily load, and CWA § 503's sludge disposal programs; the Resource Conservation and Recovery Act (RCRA)9 and CERCLA hazardous waste remediation programs; and state and federal brownfields programs. There is no centralized federal authority for regulating groundwater, although not for lack of federal legislation applicable to groundwater. At least eight federal acts have some coverage of groundwater10 with EPA administering six of the eight statutes. Most of the statutes are directed at remedying contamination after it has occurred rather than protecting the quantity or quality of groundwater. Most groundwater contamination occurs from waste disposed of in landfills, waste that percolates into groundwater from above ground, or waste that is injected into groundwater directly.11 RCRA regulates the generation, transportation, and treatment, storage, and disposal of waste. Both RCRA and the Safe Drinking Water Act (SDWA)12 are designed to curtail the land disposal of untreated waste and to contain releases from any remaining land disposal. CERCLA, and to a more limited extent RCRA, also are directed toward cleanup of existing contamination.13 The regulatory sections of RCRA discussed thus far focus on prevention of contamination. Only RCRA § 7003 addresses the problem of remedying contamination that has already occurred.14 Whenever past or present handling, storage, treatment, transportation, or disposal of any solid or hazardous waste "may present an imminent and substantial endangerment to health or the environment,"15 the Administrator of EPA under RCRA § 7003 may sue in district court any past or present owner or operator of a treatment, storage, or disposal facility, any past or present generator, and any past or present transporter who has contributed or is contributing to such handling, storage, treatment, transportation, or disposal to compel corrective actions.16 The RCRA imminent and substantial endangerment standard requires a different level of risk than the CERCLA requirements, which [31 ELR 10802] allow action upon any showing of evidence to support a conclusion of risk to human health to require remedial action.17 Under EPA's regulations, any significant increase in groundwater contamination by any of a list of designated pollutants, or any hazardous waste at the site, will require cleanup.18 Cleanup must continue until maximum contaminant levels (MCLs) are met, or, if impractical, until alternate concentration levels are met.19 RCRA § 7003 has somewhat lessened in importance since RCRA's regulatory expansion requiring cleanup of contamination and CERCLA's creation of a fund for cleaning up abandoned sites. The purpose of CERCLA is not to prevent groundwater and soil contamination but to remedy contamination after it has occurred. Whenever there is a release of a hazardous substance, or substantial threat of a release of a hazardous substance, or a release or threat of release of a "pollutant or contaminant which may present an imminent and substantial danger to the public health or welfare," EPA may respond under CERCLA § 104 by taking a "removal" action or a "remedial" action.20 Procedures for both response and removal actions are set out in a national contingency plan.21 Both actions are designed to clean up contamination, particularly when no responsible parties can be found or required to do so. In order to finance cleanup, a revolving trust fund (the Superfund) is established through CERCLA, funded by taxes or petrochemical feedstocks, crude oil, general corporate income, and by general revenues.22 The fund may be reimbursed for response costs by "responsible parties" for the contamination. If responsible parties refuse to reimburse the fund, they can be sued by EPA. States, local governments, and private parties that conduct cleanups may also be reimbursed from the Superfund or directly by responsible parties.23 Any person with a known, suspected, or likely release into air, water, soil, or groundwater must give notice to EPA or face criminal penalties.24 A list of sites of which EPA has received notice from states, members of Congress, private citizens, and EPA itself comprise the Comprehensive Environmental Responsibility, Compensation, and Liability Information System (CERCLIS). Each site on the list is reviewed in a preliminary assessment to determine whether EPA has jurisdiction and whether there is a release or substantial threat of a release of a hazardous substance or "imminent and substantial danger" from a contaminant allowing EPA to conduct a cleanup of the site. Based on a site inspection, EPA determines whether a removal or long-term remedial action is necessary. In 1995, the EPA Administrator announced plans to create a National Remedy Review Board to assure cost-effective remedies, along with other reform plans which will shift the remedy selection process to the states.25 If a remedial action is necessary, EPA must first rank the site on the national priorities list (NPL). CERCLA § 105(a)(8)(A) requires the president to develop the criteria for "taking remedial action and, to the extent practicable taking into account the potential urgency of such action, for the purpose of taking removal action."26 President Reagan delegated CERCLA authority to EPA in Executive Order No. 12316.27 For responses financed by the Superfund, the actual cleanup may be done by EPA, by a state or local government by agreement with EPA, or by a private party.28 Remedial actions are broadly authorized and only limited to actions "to prevent or minimize the release of hazardous substances so that they do not migrate to cause substantial danger to present or future public health or welfare or the environment."29 EPA only engages in remedial actions at sites on the NPL and must rank all releases on the list in order of priority.30 To rank sites, EPA must consider their: Relative risk … taking into account to the extent possible the population at risk, the hazard potential of the hazardous substances at such facilities, the potential for contamination of drinking water supplies, the potential for direct human contact, the potential for destruction of sensitive ecosystems, the damage to natural resources which may affect the human food chain and which is associated with any release or threatened release, the contamination or potential contamination of the ambient air which is associated with the release or threatened release, State preparedness to assume State costs and responsibilities, and other appropriate factors.31 A 1995 reform announced by EPA allows interested parties to become involved in designing risk assessments.32 EPA then delineates the techniques for remedial actions.33 In 1986, due to concern that the ranking undervalued the threat from contaminated groundwater, an amendment required EPA to give high priority to health risks from contamination of drinking water.34 The first step in a remedial action consists of two studies: a "remedial investigation" that evaluates the nature of and danger from the contamination and a "feasibility study" that evaluates potential remedies.35 EPA must consult with the state in which a contaminated site is located before selecting the remedy.36 The state must agree to provide at least 10% [31 ELR 10803] (50% for some sites under state ownership) of initial cleanup costs and assume responsibility for maintenance costs except for those of the first 10 years of groundwater treatment.37 A state may also voluntarily assume EPA's role within the state.38 If EPA concludes that the state is financially able to do so, the state may take over and become entitled to reimbursement of its response costs.39 Cleanup must comply with state environmental quality or facility siting standards if stricter than federal requirements.40 EPA must publish notice of its final remedial plan, provide an opportunity for public comment and a public hearing, and public notice of its final plan.41 Among other restrictions, remedial plans are to give preference to on-site treatment over land disposal.42 "The offsite transport and disposal of hazardous substances or contaminated materials without such treatment should be the least favored alternative remedial action where practicable treatment technologies are available."43 CERCLA specifies the factors to be considered in assessing an alternative treatment solution, and provides a general cleanup standard: the remedial action that is "protective of human health and the environment, that is cost effective, and that utilizes permanent solutions and alternative treatment technologies to the maximum extent practicable." If a remedy choice fails to meet these criteria, a detailed explanation is required.44 On-site treatment that is the best demonstrated available treatment technology must be used.45 For groundwater, cleanup must bring the water up to the SDWA's MCLs46 or, if no MCLs have been established, up to standards in any other applicable federal statutes.47 EPA defines brownfields as "abandoned, idled or under used industrial and commercial sites where expansion or redevelopment is complicated by real or perceived environmental contamination that can add cost, time, or uncertainty to a redevelopment project."48 The goal of the brownfields programs is the restoration of brownfields to a state in which they can once again be used as a fruitful resource.49 The program was aimed at implementing policy changes within the context of existing law. States take a wide range of approaches to brownfields. Some states specifically address brownfields through voluntary programs, while others have entirely separate brownfields cleanup and redevelopment programs.50 The number of states with brownfields programs has increased considerably over the last 10 years because states are recognizing that the regulatory programs currently in place will not be able to address all of the contaminated sites. By the end of 1997, just over one-half of the states had implemented brownfields programs.51 This is a 100% increase since 1995 when only 13 states had such programs.52 Now, approximately 40 states and tribes have voluntary cleanup programs.53 While the majority of these programs were established by statute,54 some were established pursuant to the states' voluntary cleanup statutes. Still others are established by means of informal policy. Many states not relying on formal brownfields programs address brownfields through alternative mechanisms. For example, Maine works through its voluntary program with other state agencies to form a "brownfields team" to identify in-state resources to promote redevelopment. Although the criteria for inclusion in brownfields programs vary from state to state, the most common criteria are that the sites be abandoned or underutilized and have potential for redevelopment. Virtually every state uses the same cleanup standards for brownfields sites as for voluntary cleanup sites. The few states that apply a different set of standards to brownfields sites appear to offer additional incentives for brownfields cleanups. Participation in brownfields programs is promoted in almost all states by incentives that fall into two broad categories: liability relief and financial incentives. One obstacle confronting continued success of brownfields programs is posed by the risks that accompany cleanup and redevelopment of brownfields sites. Businesses, fearing liability for cleanup costs and remediation costs of previous contamination, are often tentative about purchasing brownfields.55 This fear of unforeseeable liability and lack of future profitability are the two primary uncertainties deterring developers from buying and developing environmentally impaired property. Incorporating bioavailability into state and federal brownfields programs would do much to alleviate these businesses' concern. The purpose of any brownfields program is to restore a site to a state of productive use. In most cases this does not mean restoration to the "highest and best" use of residential use, but rather to commercial development. The advantage of bioavailability in defining cleanup goals is that it sets the cleanup goal (and thereby limits cleanup costs) to the actual use and exposure levels that would occur at the site. The more precisely tailored the future use of the property, the more accurate the assessment of bioavailability can be. In this way, utilizing bioavailability to determine cleanup responsibility and granting clean legal recognition to it as a methodology for determining cleanup has the potential to lower cleanup costs and lessen the potential liability of businesses for prior contamination. In order to determine if, and to what extent, the EPA regional offices were utilizing bioavailability in the federal programs they oversee, the offices were sent a brief questionnaire asking if the region, or the states in that region, had developed any bioavailability default values, guidance material, or policy statements regarding the use of bioavailability in environmental cleanup.56 Each regional office was also asked to identify any site-specific applications of bioavailability factors for metals or organics. The questions were phrased in terms of "bioavailability" specifically, rather than referring to the various processes (such as mobility, leaching, etc.) that might be affected by bioavailability calculations, in order to obtain a sense of more formalized recognition of bioavailability as an overall methodology for assessing cleanup values. Measurements based on bioavailability could at present be used to adjust and refine human health and ecological risk assessments, most readily with the authorization provided in EPA's RAGS for Superfund cleanups.57 Utilization of bioavailability in state and federal cleanup projects thus far is limited at best. The preliminary information collected from the regional offices suggests several possible reasons for this disparity. First, in general the regions are being very cautious in their recognition and utilization of bioavailability—more cautious, perhaps, than necessary from the perspective of scientific validation or legal impediments to its use. In particular, Regions 4 and 6 appear to have at least considered the methodology and for unspecified reasons sharply limited its availability as an optional approach. Secondly, there are wide variations among the regions in receptiveness to the approach: from regions where it appears to have received little or no consideration—Regions 2 and 7; to a region conducting studies for its possible implementation—Region 8; to regions seemingly skeptical of its use—Regions 4 and 6; and to regions actively exploring its use but also with varying levels of acceptability and actual utilization—Regions 1, 3, 5, 9, and 10. The regional differences may only be explained partially by the regional differences in the nature, types, and costs of contaminated site cleanups. Third, hesitancy to utilize bioavailability may reflect agency concern with increased costs for initial implementation, questions about scientific validation for the methodology, anxiety about public and community acceptance of the methodology, and a related concern with any legal impediments or challenges to its use. EPA created a methodology—the Soil Screening Guidance—that can be used to quickly screen soil contamination before doing a full-scale risk assessment.58 The stated intention of the Soil Screening Guidance is to focus resources on sites that pose the greatest risk. Another advantage to using the Soil Screening Guidance is to eliminate low-risk sites containing soil-only contamination from further consideration. The Soil Screening Guidance provides a methodology to calculate risk-based, site-specific soil contaminant concentration levels for a very specific subset of contamination problems. Only contamination problems that are similar to those used in the Soil Screening Guidance can be considered. The guidance assumes an acceptable risk of 10<-6> for carcinogens and a hazard quotient of 1.0 for noncarcinogens, and it encompasses 110 chemicals.59 Only residential land use is considered, and six exposure pathways are specified, including direct ingestion of soil and groundwater contaminated by soil, inhalation of volatiles and dust, dermal absorption, ingestion of produce that has been contaminated by soil, and migration of volatiles in basements.60 These criteria are used to formulate generic soil screening levels (SSLs). Generic risk-based screening levels for soil are also found in two American Society for Testing Materials (ASTM) Risk-Based Corrective Action guidance documents. Table 1 below compares these RBSLs to EPA's generic SSLs, RCRA cleanup criteria, and several state generic screening levels. The table includes soil screening values for a variety of contaminants assuming direct ingestion of soil, residential land use, a carcinogenic risk level of 10<-6>, and a hazard quotient of 1.0. For most of the chemicals, the EPA and the ASTM values are all quite similar. The values for naphthalene and xylene are notable exceptions. Rather than using the default values for soil cleanup, as shown in the following table, states could choose to do a site-specific risk assessment that would incorporate adjustment factors for bioavailability.
MTBE = methyl tertiary-butyl ether Bioavailability in Assessing Sediment Contamination EPA has identified a number of programs to which bioavailability testing may be relevant and useful.61 Many federal agencies, including EPA, the U.S. Army Corps of Engineers (the Corps), the National Oceanic and Atmospheric Administration, the U.S. Fish and Wildlife Service, and the U.S. Geological Survey are required to do environmental monitoring and assessment of chemical bioaccumulation in sediments in addition to the hazardous waste remediation under CERCLA and RCRA discussed above. The Office of Water (OW) in EPA is responsible for developing national programs, technical policies, and regulations relating to drinking water, water and sediment quality—including dredged material—and groundwater; establishing environmental and pollution source standards; and providing for the protection of wetlands. In addition, it furnishes technical direction, support, and evaluation of regional water activities; enforces standards; and develops programs for technical assistance and technology transfer. The OW oversees the provision of training in the fields of water quality, economic and long-term environmental analysis, and marine and estuarine protection. The OW and the Corps have developed joint technical guidance for evaluating the potential for contaminant-related impacts associated with the discharge of dredged material in the ocean under the Marine Protection, Research, and Sanctuaries Act (MPRSA).62 Similar guidance has been published for evaluating dredged material discharges in fresh, estuarine, and saline (near-coastal) waters under CWA § 404.63 These documents employ tiered testing in which bioaccumulation figures prominently. Under CWA §§ 301, 304, 306, and 307, the Office of Science and Technology (OST) within the OW promulgates technology-based national effluent limitations guidelines that control the discharge of toxic chemicals and other pollutants by categories of industrial dischargers. According to EPA's report, bioaccumulation data and modeling are used in support of this effort.64 In response to the Water Resources Development Act (WRDA) of 199265 requirement that EPA conduct a national survey of data regarding sediment quality in the United States, the OST prepared The National Sediment Quality Survey.66 For calculations related to bioaccumulation, the survey makes use of fish tissue residue data and models bioaccumulation from sediment using the theoretical bioaccumulation potential approach.67 CWA § 403 requires determination of the quantities of and potential for bioaccumulation of released chemicals, the potential for pollutant transport, potential harm to biological communities, and direct and indirect effects on humans.68 CWA Section 403: Procedural and Monitoring Guidance, developed by the Office of Wetlands, Oceans, and Watersheds (OWOW) within the OW discusses the qualities of target species and methods for assessing bioaccumulation; monitoring program design, including sampling of caged or indigenous indicator species; the type of tissue to be analyzed in invertebrates and fishes; and techniques for extracting and analyzing chemical contaminants.69 Similarly, EPA's National Estuary Program, authorized under CWA § 320, is a national demonstration program that uses a comprehensive watershed management approach to address water quality and habitat problems in designated estuaries on the Atlantic, Gulf, and Pacific coasts and in the Caribbean. The OWOW developed guidance for this program in 1992, which is similar to that for CWA § 403 guidance discussed above and which includes the design and conduct of bioaccumulation monitoring studies to link exposure and effects and to examine risks to target species and humans.70 Under CWA § 402, administered by the Office of Wastewater Management within the OW, bioaccumulation screening methods can be used to identify chemicals of potential concern in the sediments, followed by chemical-specific analysis for confirmatory purposes.71 Until the states adopt numeric criteria into their standards for sediment contaminants based on bioaccumulation, the NPDES program does not require permitting authorities to include in their NPDES permits sediment bioaccumulation-based numeric limits. States do have the discretion to include such limits in permits based on an interpretation of their narrative standards for toxins. To establish such permit limits, it will be necessary for permitting authorities to develop wasteload allocations for the relevant sediment contaminants.72 CWA § 118(c)(2) required EPA to publish proposed and final water quality guidance on minimum water quality standards, antidegradation policies, and implementation procedures for the Great Lakes System.73 In response to these requirements, EPA developed the Final Water Quality Guidance for the Great Lakes System.74 The guidance incorporates bioaccumulation factors into the derivation of criteria and values to protect human health and wildlife. CWA § 118(c)(3) established the Assessment and Remediation of Contaminated Sediments (ARCS) Program to assess the extent of sediment contamination in the Great Lakes and to demonstrate bench- and pilot-scale treatment technologies for contaminated sediment.75 Under the ARCS Program, the [31 ELR 10807] Great Lakes National Program Office used bioaccumulation data and models to estimate comparative human health risks associated with direct and indirect exposures to contaminated sediments in the lower Buffalo River under selected remedial alternatives.76 Section 503 Sludge Disposal Program Disposal of the solid residue that collects in septic systems is regulated through licensing procedures for companies that dispose of the waste products and clean septic tanks.77 Usually state statutes require state health agency sanitary regulations to be met, and require that the disposal companies have access to suitable disposal areas.78 Septic sludge is often disposed of through public treatment works or buried. Attempts to acquire areas in which to bury sludge may run afoul of local zoning or health ordinances. Some states regulate land disposal of septic waste through permit systems, with consideration given to groundwater quality. For states which did not control sludge disposal through their own permit systems, the 1987 amendments to the CWA provided a national permit system.79 Federal sludge management standards were promulgated in 1992, covering sewage sludge that is applied to land, marketed or distributed, placed in a landfill or surface disposal site, or incinerated.80 These regulations are set to protect public health and the environment from "reasonably anticipated" effects, and incorporate a risk/exposure-based approach.81 The regulations contain quite elaborate models for measuring the relative absorption of contaminants by humans, animals, and plants, but without labeling this methodology as measurements of bioavailability or any conclusive definition of bioavailability. Biosolids are the residual material generated by municipal water treatment, and they consist of about 50% organic matter. They are commonly used as a fertilizer and source of organic matter in agricultural and forest soils. In addition, they are used generally at high application rates, to restore or remediate disturbed soils. They contain measurable levels of trace metals, pathogens, and some trace amounts of synthetic organic compounds. As a result of concern over the hazards from biosolids, EPA began a process to develop regulations to set standards for metals, toxic organics, and pathogens concentration in the biosolids that would need to be met before beneficial use was permitted. The regulations were developed in stages. At each stage of development, the proposed regulations were open for public comment and review by a Science Advisory Board and the U.S. Department of Agriculture's Cooperative State Research Service Technical Committee W-170.82 As a result of this process, the regulations changed to become progressively more science based. In turn, a great deal of research was carried out to develop the scientific database that was necessary to support this effort.83 The metal limits set out in the final regulations were seen as sufficiently protective based on an examination of the data available from all applicable research efforts. As a result of this method of setting regulatory standards, the bioavailable fraction rather than the total concentration of the compounds of concern formed the basis of the rule. In defining bioavailability for the regulations, a series of pathways were developed to outline the manner in which land application of biosolids could potentially pose a risk to a highly exposed individual. These pathways were included within the regulations. For each of the pathways, a different highly exposed individual was identified. Highly exposed individuals include humans, animals (soil organisms, soil organism predators, and grazing livestock), and plants. As such, the regulations attempted to be ecologically based rather than focusing solely on a human health endpoint. Because of the range of organisms the regulation attempted to protect, as well as the scope of potentially toxic agents detectable in biosolids, the scientists developing the regulations recognized that the mechanism for toxicity of a single compound may vary by individual. This required setting limits for each element or compound of concern for each pathway. The most limiting pathway or concentration was then used to set the regulatory limit.84 The § 503 regulations are unique because they seek to protect a range of individuals from a wide number of potentially toxic agents. The regulations strive to be protective of both chronic and acute toxicity. In developing the regulations, it was understood that, in addition to the risks associated with the use of biosolids, benefits would also be derived. The EPA regulations concerning the beneficial use of biosolids85 were based on the bioavailable, rather than the total concentration of contaminants of concern. They were developed to be exposure risk-based standards designed to protect the highly exposed individual from reasonable risk associated with land application of biosolids. CWA § 404 Dredge and Fill Program CWA § 404 is the principal regulatory protection at the federal level afforded wetlands, particularly inland wetlands. CWA § 404 requires a permit for all discharges by point sources of dredged or fill materials into "navigable waters."86 CWA § 502(7) broadly defines navigable waters as the "waters of the United States including the territorial seas."87 Until 1983, the regulations of the Corps limited § 404 coverage to truly navigable waters traditionally regulated under the Rivers and Harbors Act of 1899.88 The Corps' limited definition was invalidated as too restrictive, however, and currently the Corps and EPA accept the following broad definition of navigable waters as: (1) All waters which are currently used, or were used in the past, or may be susceptible to use in interstate or foreign commerce, including all waters which are subject to the ebb and flow of the tide; [31 ELR 10808] (3) All other waters such as intrastate lakes, rivers, streams (including intermittent streams), mudflats, sandflats, wetlands, sloughs, prairie potholes, wet meadows, playa lakes, or natural ponds the use, degradation or destruction of which could affect interstate or foreign commerce including any such waters: (i) Which are or could be used by interstate or foreign travelers for recreational or other purposes; or (ii) From which fish or shellfish are or could be taken and sold in interstate or foreign commerce; or (iii) Which are used or could be used for industrial purposes by industries in interstate commerce; (4) All impoundments of waters otherwise defined as waters of the United States under this definition; (5) Tributaries of waters identified in paragraphs (a)(1) through (4) of this section; (6) The territorial seas; (7) Wetlands adjacent to waters (other than waters that are themselves wetlands) identified in paragraphs (a)(1) through (6) of this section. (8) Waters of the United States do not include prior converted cropland. Notwithstanding the determination of an area's status as prior converted cropland by any other Federal agency, for the purposes of the Clean Water Act, the final authority regarding Clean Water Act jurisdiction remains with EPA.89 The Corps in addition to its navigation dredging does assist in cleanup dredging with governmental remediation projects, as well as engaging in studies and investigations in its support of military-related cleanup and remediation.90 The contaminated sediments are disposed of in EPA-designated ocean disposal sites, in keeping with the 1972 London Convention on the Prevention of Marine Pollution by Dumping of Wastes.91 The International Maritime Organization provides guidelines that do not themselves mention bioavailability, but are open to such application. Similarly, the regulations implementing MPRSA § 10392 do not mention bioavailability, but have been interpreted in EPA/Corps' guidance documents93 to equate "bioaccumulation" with bioavailability for purposes of determining which materials are environmentally acceptable for ocean dumping: Materials shall be deemed environmentally acceptable for ocean dumping only when … procedures approved for bioassays … provide reasonable assurance, based on considerations of statistical significance of effects at the 95 percent confidence level, that, when the materials are dumped, no significant undesirable effects will occur due either to chronic toxicity or to bioaccumulation …."94 Aside from disposal, re-use of dredged materials for beneficial use can include restoration of wetland areas. Total Maximum Daily Loads (TMDLs) Once a state has set its water qualitystandards, they must then be translated into specific limits on individual dischargers.95 The first step is to set the TMDL of each criteria pollutant for a given body of water and then to determine the numerical pollutant limits necessary in the dischargers' NPDES permits to stay within the TMDL.96 States must set TMDLs for all waters in their jurisdiction that will not meet water quality standards even after application of technology-based limits.97 The TMDLs must be set at a level to meet water quality standards "with seasonal variations and a margin of safety which takes into account any lack of knowledge concerning the relationship between effluent limitations and water quality."98 States are basically free to allocate the total load as they wish among the dischargers on the given water source.99 Review of the state standards by EPA involves determinations of whether the designated water uses are consistent with the CWA, whether the criteria protect those uses, whether the standards have been legally adopted, whether uses not specified in CWA § 101 are based on appropriate scientific and technical data, and whether the standards meet the other minimum criteria established by EPA, such as inclusion of an antidegradation policy.100 CWA § 303(d) was amended in 1987 to prohibit revisions of TMDLs for water segments not meeting water quality standards unless the revision will assure attainment, or a designated use not being attained has been removed in accordance with the regulations with respect to downgrading of uses.101 Also, there may be no revisions for waters meeting or exceeding standards unless the revision is consistent with EPA's antidegradation policy.102 It is not clear the extent to which Congress intended to codify EPA's regulations on antidegradation and downgrading of existing uses. The revision of CWA § 303(d) must be read in conjunction with the "antibacksliding" provisions added in 1987 as CWA § 402(o).103 Generally, § 402(o) prohibits issuance of new permits that are less stringent than existing permits for the same facilities, with limited exceptions.104 As to water quality-based permit limitations specifically, they may not be relaxed unless several conditions are met.105 However, § 402(o)(1) indicates that a water quality-based permit may also be relaxed if the revision is in keeping with EPA's [31 ELR 10809] antidegradation policy.106 It would appear that CWA § 402(o)(1) and (2) provide alternative avenues for backsliding, that is, both the conditions and the antidegradation policy need not be met.107 The problem of contaminated sediments is critically relevant to CWA § 303(d). According to the 1998 § 303(d) lists of impaired waters, over 10,964,402 acres are impaired due to sediment contamination, excluding the Great Lakes, and 195.611 shoreline miles are impaired, including the Great Lakes and estuarine shoreline. The water quality itself may be meeting the standards, but the designated uses are not being met due to the sediment contamination. National sediment and source inventories indicate approximately 10% are sufficiently contaminated to pose a risk to human health. Fish advisories indicate the majority are linked to sediment contamination. The absorption by plants and animals of substances from soils, sediments, and water is a complex process that renders ecological risk assessment even more difficult than human health risk assessment. Different routes of exposure involve different mechanisms and therefore different measures of bioavailability. The correlation between bioavailability and state water quality standards is indirect but significant. Many waters are impaired specifically by contaminated sediments for which bioavailability measurements might mean the difference between in-site remediation or removal. [SEE ILLUSTRATION IN ORIGINAL] 1998 303(d) listed Impairments [] 10,964,402 acres impaired due to sediment contamination (not including Great Lakes) [] 195,611 shoreline miles impaired due to sediment contamination (including Great Lakes and estuarine shoreline) Conclusion Measurements of contamination based on bioavailability in the field exceed formal legal recognition of bioavailability as an appropriate methodology. Its acceptance as a scientifically validated process of natural remediation merits additional investment in scientific studies to facilitate its utilization in risk assessment. Explicit recognition of the methodology in regulatory contexts in which it has been utilized and is being utilized would eliminate at least some of the hesitancy on the part of assessors and managers of contaminated sites to consider a measurement technique that may be more site-specific, scientifically accurate, and in many instances less costly. The lower cleanup costs from bioavailability measurements need not be recovered solely by the responsible parties for contamination. In their environmental management roles, state and federal agencies could benefit from lower costs and reinvest those resources in remediation or monitoring. Similarly, responsible parties would have more resources available for long-term monitoring for continued assurance that a site is "clean." With additional scientific information, bioavailability does not have to be more costly or time-consuming than utilization of generic assumptions for risk assessment. As a tool that holds at least some promise of greater accuracy in risk assessment, there is a need for the scientific community to educate the lawmakers and policymakers on the legal recognition it deserves. 1. 42 U.S.C. §§ 9601-9675, ELR STAT. CERCLA §§ 101-405. 2. 33 U.S.C. §§ 1251-1387, ELR STAT. FWPCA §§ 101-607. 3. 5 U.S.C. §§ 500-596, available in ELR STAT. ADMIN. PROC. 4. 33 U.S.C. § 1342, ELR STAT. FWPCA § 402. 5. 21 U.S.C. §§ 301-397. 6. 15 U.S.C. §§ 2601-2692, ELR STAT. TSCA §§ 2-412. 7. 42 U.S.C. §§ 7401-7671q, ELR STAT. CAA §§ 101-618. 8. OFFICE OF EMERGENCY AND REMEDIAL RESPONSE, U.S. EPA, RISK ASSESSMENT GUIDANCE FOR SUPERFUND: VOLUME I—HUMAN HEALTH EVALUATION MANUAL (PART A) app. A (1989) [hereinafter RISK ASSESSMENT GUIDANCE FORSUPERFUND: VOLUME I]. 9. 42 U.S.C. §§ 6901-6992k, ELR STAT. RCRA §§ 1001-11011. 10. G. Marks, Toward a National Groundwater Act: Current Contamination and Future Courses of Action, 61 FLA. B.J. 10, 11 (1987). 11. DAN TARLOCK, LAW OF WATER RIGHTS AND RESOURCES § 4.08(5) (1998). 12. 42 U.S.C. §§ 300f-300j-26, ELR STAT. SDWA §§ 1401-1465. 13. See generally R.G. Stoll, The New RCRA Cleanup Regime: Comparisons and Contrasts With CERCLA, 44 SW. L.J. 1299 (1991). 14. 42 U.S.C. § 6973, ELR STAT. RCRA § 7003. 15. Id. § 6973(a), ELR STAT. RCRA § 7003(a). 16. Id. 17. LINDA MALONE, ENVIRONMENTAL, REGULATION OF LAND USE ch. 9 (2000). 18. SHELDON NOVICK ET AL., LAW OF ENVIRONMENTAL PROTECTION § 13.05(4)(a) (1994). 19. Id. 20. 42 U.S.C. § 9604, ELR STAT. CERCLA § 104(a). 21. Id. § 9605, ELR STAT. CERCLA § 105. 22. Id. § 9611, ELR STAT. CERCLA § 111. 23. Id. § 9612, ELR STAT. CERCLA § 112. 24. Id. § 9603(a), ELR STAT. CERCLA § 103(a). 25. OFFICE OF SOLID WASTE AND EMERGENCY RESPONSE, U.S. EPA, DIRECTIVE NO. 9375.6-11 (1995); see also Guidance on Prospective Purchase, State Role Included in Major Reforms Announced by EPA, 26 Env't Rep. (BNA) 267 (June 2, 1995). 26. Id. § 9605(a)(8)(A), ELR STAT. CERCLA § 105(a)(8)(A). 27. Exec. Order No. 12316, 46 Fed. Reg. 42237 (Aug. 20, 1981), revoked by Exec. Order No. 12580, 52 Fed. Reg. 2923 (Jan. 29, 1987), ADMIN. MAT. 42237; see also DONALD STEVER, LAW OF CHEMICAL REGULATION AND HAZARDOUS WASTE § 6.06(2)(c)(i) n.282 (1986). 28. 42 U.S.C. §§ 9604, 9606, ELR STAT. CERCLA §§ 104, 106. 29. Id. § 9601(24), ELR STAT. CERCLA § 101(24). 30. Id. § 9605(a), ELR STAT. CERCLA § 105(a). 31. Id. § 9605(a)(8)(A), ELR STAT. CERCLA § 105(a)(8)(A). 32. Cost Review Board, More State Responsibility Among Administrative Reforms Announced by EPA, 26 Env't Rep. (BNA) 1012 (Oct. 6, 1995). 33. 42 U.S.C. § 9605, ELR STAT. CERCLA § 105. 34. Id. § 9604(i), ELR STAT. CERCLA § 104(i). 35. 40 C.F.R. § 300.68(d). 36. 42 U.S.C. § 9604(c)(2), (3), ELR STAT. CERCLA § 104(c)(2), (3). 37. Id. § 9604(c)(6), ELR STAT. CERCLA § 104(c)(6). 38. Id. § 9604(c), ELR STAT. CERCLA § 104(c). 39. Id. 40. Id. § 9621(d)(2)(A)(ii), ELR STAT. CERCLA § 121(d)(2)(A)(ii). 41. Id. § 9617, ELR STAT. CERCLA § 117. 42. Id. § 9621(b)(1), ELR STAT. CERCLA § 121(b)(1). 43. Id. 44. STEVER, supra note 27, § 6.06(2)(d)(iii)(B). 45. 42 U.S.C. § 9621(b)(1), ELR STAT. CERCLA § 121(b)(1). 46. Id. § 9621(d)(2)(B)(ii), ELR STAT. CERCLA § 121(d)(2)(B)(ii). 47. Id. § 9621(d)(2)(A)(i), ELR STAT. CERCLA § 121(d)(2)(A)(i). 48. OFFICE OF PUBLIC AFFAIRS, U.S. EPA REGION 5, BASIC BROWNFIELDS FACT SHEET (1996) [hereinafter BASIC BROWNFIELDS FACT SHEET]. 49. See CHARLES BARTSCH & ELIZABETH COLLATON, INDUSTRIAL SITE REUSE, CONTAMINATION, AND URBAN REDEVELOPMENT. COPING WITH THE CHALLENGES OF BROWNFIELDS (1994). 50. OFFICE OF TECHNOLOGY ASSESSMENT, U.S. CONGRESS, STATE OF THE STATES ON BROWNFIELDS: PROGRAMS FOR CLEANUP AND REUSE OF CONTAMINATED SITES (1995). 51. BASIC BROWNFIELDS FACT SHEET, supra note 48. 52. Id. 53. Id. 54. See ARIZ. REV. STAT. §§ 49-153-157 (1999). 55. See CERCLA and its liability provisions, 42 U.S.C. §§ 9601-9675, ELR STAT. CERCLA §§ 101-405. 56. Questionnaire to theU.S. EPA Regional Offices (on file with author). 57. RISK ASSESSMENT GUIDANCE FOR SUPERFUND: VOLUME I, supra note 8. 58. OFFICE OF EMERGENCY AND REMEDIAL RESPONSE, U.S. EPA, SOIL SCREENING GUIDANCE: TECHNICAL BACKGROUND DOCUMENT (1996); OFFICE OF EMERGENCY AND REMEDIAL RESPONSE, U.S. EPA, SOIL SCREENING GUIDANCE: USER'S GUIDE (1996). 59. Id. 60. Id. a American Society for Testing and Materials, Standard Guide for Risk-Based Corrective Action Applied at Petroleum Release Sites, in ANNUAL BOOK OF ASTM STANDARDS E 1739-95 (1995). b American Society for Testing and Materials, Standard Provisional Guide for Risk-Based Corrective Action, in ANNUAL BOOK OF ASTM STANDARDS PS 104-98 (1998). c U.S. EPA, SOIL SCREENING GUIDANCE: TECHNICAL BACKGROUND DOCUMENT (1996) (EPA 540/R-95/128). d Appendix A—Examples of Concentrations Meeting Criteria for Action Levels, 55 Fed. Reg. 30865-67 (July 27, 1990). e C. Judge, P. Kostecki, & E. Calabrese, State Summaries of Soil Cleanup Standards, SOIL AND GROUNDWATER CLEANUP 10-34 (Nov. 1997). f Michigan Department of Natural Resources, 1998. g Concentrations capped at the soil saturation limit. Different states used different limits for the same compound. h New Jersey standards for toluene and ethyl benzene were capped at 1000 due to concerns over inhalation of these compounds. 61. OFFICE OF WATER AND SOLID WASTE, U.S. EPA, BIOACCUMULATION TESTING AND INTERPRETATION FOR THE PURPOSE OF SEDIMENT QUALITY ASSESSMENT; STATUS AND NEEDS (2000) [hereinafter BIOACCUMULATION TESTING]. 62. 33 U.S.C. §§ 1401-1445; see also U.S. EPA & U.S. ARMY CORPS OF ENG'RS, EVALUATION OF DREDGED MATERIAL PROPOSED FOR OCEAN DISPOSAL (1991). 63. U.S. EPA & U.S. ARMY CORPS OF ENG'RS, EVALUATION OF DREDGED MATERIAL PROPOSED FOR DISCHARGE IN WATERS OF THE UNITED STATES (1998). 64. BIOACCUMULATION TESTING, supra note 61, at 4. 65. Pub. L. No. 102-580, 106 Stat. 4797. 66. U.S. EPA, THE NATIONAL SEDIMENT QUALITY SURVEY (1997). 67. BIOACCUMULATION TESTING, supra note 61, at 4. 68. 33 U.S.C. § 1343, ELR STAT. FWPCA § 403. 69. OFFICE OF WETLANDS, U.S. EPA, OCEANS AND WATERSHEDS, CWA SECTION 403: PROCEDURAL AND MONITORING GUIDANCE (1994). 70. BIOACCUMULATION TESTING, supra note 61, at 4. 71. 33 U.S.C. § 1342, ELR STAT. FWPCA § 402. 72. BIOACCUMULATION TESTING, supra note 61, at 4. 73. 33 U.S.C. § 1268(c)(2), ELR STAT. FWPCA § 118(c)(2); see also Great Lakes Critical Programs Act of 1990, Pub. L. No. 101-596, 104 Stat. 3000 (codified in part in 33 U.S.C. §§ 1268-1270, 1324 ELR STAT. FWPCA §§ 118-120, 314). 74. U.S. EPA, FINAL WATER QUALITY GUIDANCE FOR THE GREAT LAKES SYSTEM (1995). 75. 33 U.S.C. § 1268, ELR STAT. FWPCA § 118. 76. BIOACCUMULATION TESTING, supra note 61, at 5. 77. MALONE, supra note 17, § 8.054. 78. E.g., KY. REV. STAT. ANN. §§ 211.970 (Michie 1999). 79. 33 U.S.C. § 1345(d), ELR STAT. FWPCA § 405(d); see also 42 U.S.C. §§ 6901-6992k, ELR STAT. RCRA §§ 1001-11011. 80. 40 C.F.R. § 503. 81. Id. 82. See generally 58 Fed. Reg. 9387 (Feb. 19, 1993). 83. Id. 84. R.L. Chaney, S.L. Brown & J.S. Angle, Soil-Root Interface: Ecosystem Health and Human Food-Chain Protection, in CHEMISTRY AND ECOSYSTEM HEALTH 279-312 (P.M. Huang ed., 1998). 85. 40 C.F.R. § 503. 86. 33 U.S.C. § 1344, ELR STAT. FWPCA § 404. 87. Id. § 1362, ELR STAT. FWPCA § 502. 88. 33 U.S.C. §§ 401-413. 89. 33 C.F.R. § 328.3(a). It was this reach of wetlands regulation in the CWA that was limited in the U.S. Supreme Court's recent decision in Solid Waste Agency of N. Cook County v. Corps of Eng'rs, 531 U.S. 159, 31 ELR 20382 (2001). 90. See U.S. ARMY CORPS OF ENG'RS, THE FINAL GUIDE FOR INCORPORATING BIOAVAILABILITY ADJUSTMENTS INTO HUMAN HEALTH AND ECOLOGICAL RISK ASSESSMENTS AT U.S. NAVY AND MARINE CORPS FACILITIES (2000). 91. Convention of the Prevention of Marine Pollution by Dumping Wastes and Other Matter, Dec. 29, 1972, 26 U.S.T. 2403 (known as the London Convention). 92. MPRSA § 103 requires evaluation of effects on "marine life including … changes in marine ecosystem diversity, productivity, and stability; and species and community population changes." 33 U.S.C. § 1413. 93. U.S. EPA & U.S. ARMY CORPS OF ENG'RS, THE OCEAN AND INLAND TESTING MANUALS (1998). 94. 40 C.F.R. § 227.6(c)(3). 95. See generally MALONE, supra note 17. 96. Id. 97. 33 U.S.C. § 1313(d)(1)(C), ELR STAT. FWPCA § 303(d)(1)(C). 98. Id. 99. 40 C.F.R. § 130. 100. Id. § 131.5 101. 33 U.S.C. § 1313(d), ELR STAT. FWPCA § 303(d). 102. Id. § 1313(d)(4), ELR STAT. FWPCA § 303(d)(4). 103. Id. § 1342(o), ELR STAT. FWPCA § 402(o). 104. Id. 105. Id. § 1342(o)(2), ELR STAT. FWPCA § 402(o)(2). 106. Id. § 1342(o), ELR STAT. FWPCA § 402(o)(1). 107. H.R. CONF. REP. No. 99-1004, at 156 (1986). 31 ELR 10800 | Environmental Law Reporter | copyright © 2001 | All rights reserved |