Chapter 7, Risk Commission Final Report, Vol. 2 (Partial)

Current practices in the use of risk assessment in regulatory programs vary among federal agencies and even among regulatory programs within EPA. Some of the variation is attributable to different requirements among federal laws authorizing regulatory activity, either in the form of explicit methodologic requirements that assessments must follow or as differently mandated regulatory responsibilities that the assessments must support. Some of the variation reflects differences in policy among organizations, adopted as a matter of differing scientific and policy judgment or simply because of the independent establishment of varied precedents, preferences, and objectives. Better coordination among agencies is needed, and there have been several calls for a central organization to coordinate all risk assessment activities.

Previous sections of this report have addressed the larger risk-assessment and risk-management issues that affect environmental health regulatory programs across the federal government. This section narrows those general issues and recommendations to individual agencies and programs and uses them as a basis for specific recommendations. This section is not meant to exhaustively evaluate all the federal agencies that assess and manage risks, but to highlight those that provided testimony to the Commission.

Risk assessment practices are poorly coordinated among and often within regulatory agencies and programs, even among those with overlapping interests and jurisdictions. Inconsistencies and idiosyncratic practices impair the credibility of risk assessment. Nonetheless, the differences among agencies are relatively small considering the complexity and uncertainty of risk assessment.

When two or more agencies or program offices regulate similar health or ecological hazards associated with chronic exposures, they should coordinate their risk assessment methods and assumptions, unless there is a specific statutory requirement for different choices. Scientific disagreements should be explicated.

The primary reason for differening results among agencies is that the function of the risk assessment process—to project possible human health risks associated with the various types and magnitudes of exposures that might arise—outstrips the ability of scientific investigation to give firm answers. The practical need to characterize the risk consequences (including the uncertainty about them) of various potential actions and activities by industries, by government, by individuals, and by society as a whole remains.

There is general agreement on a common framework and structure for risk assessment, but debate continues vigorously about the most appropriate risk assessment approaches, the bearing of various kinds of data on risk projections, the level of risk that is considered negligible, and the degree and appropriateness of conservatism in risk assessment methods. The diversity of methods among federal regulatory agencies makes it difficult to compare risks and any mitigating actions from one regulatory program to another. For example, EPA and CPSC differ on several critical aspects in the performance of a quantitative risk assessment: EPA relies on the "maximally exposed individual" or, now, other upper-end exposure estimates while CPSC uses the average population exposure; EPA uses upper-bound risk estimates while CPSC uses maximum-likelihood estimates; EPA uses pharmacokinetic information for cross-species extrapolation, but CPSC declines doing so.

Defaults and standard methods are necessary in the face of uncertainty and lack of case-specific knowledge, but variation among agencies and programs increases the sense of arbitrariness in risk analyses. In cases where regulatory responsibilities overlap or different groups have occasion to assess the same exposures, differences in assessment outcome can lead to conflict and confusion among the public and the regulated community. When inconsistencies exist among agencies with overlapping regulatory responsibilities, a continuing effort is needed to harmonize methods and assumptions used in risk assessment. In cases where consistency is inappropriate, written justification should be provided. Lorenz Rhomberg’s report to the Commission details the use of risk assessment by federal agencies and indicates where some of the inconsistencies exist (see Appendix A7).

In this global economy, there is and should be increasing efforts to harmonize toxicologic testing, clinical trials, and now risk assessment on an international basis.

EPA has played a critical role in facilitating the substantial improvements in our environment that we have enjoyed over the last 27 years. The major sources of pollution contaminating our air, water, and soil have been greatly mitigated, largely as a result of its programs and private sector and state compliance. The complex problems that remain will require continued creativity and improved efficiency. This section addresses several of EPA’s programs and offers recommendations that are aimed at improving the identification and management of risks.

The 1990 amendments to section 112 of the Clean Air Act established an entirely new program to control hazardous air pollutants from point sources through the promulgation and implementation of technology-based standards. These standards are arrived at by identifying the maximum available control technology (MACT) currently in place. This strategy was mandated because the regulation of hazardous air pollution from point sources using a chemical-by-chemical, risk-based approach was judged ineffective and inefficient. Difficulty in setting new standards was characterized as "paralysis by analysis" by the Natural Resources Defense Council’s David Hawkins, who was assistant administrator for the Office of Air and Radiation in the Carter Administration. The statutory language was interpreted for carcinogens to require an ample margin of safety below the no-effect level, which was assumed to be zero. The agency issued standards for only seven prominent agents, all in the 1970s (see Table 7.1).

**Table 7.1. Air pollutant standards promulgated.**
Section 109 National Ambient Air Quality Standards	Section 112 Hazardous Air Pollutant Standards²

Sulfur dioxide	Vinyl chloride
Particulate matter	Asbestos
Ozone	Benzene
Nitrogen dioxide	Radionuclides
Hydrocarbons¹	Mercury
Carbon monoxide	Arsenic
Lead	Beryllium

¹Deleted in 1983.
²Regulated between 1970 and 1990.

As of January 1997, EPA had promulgated 20 MACT standards for 47 source categories and had proposed three more standards. In all, 174 source categories need MACT standards (see Table 7.2). When the MACT process is complete and the control technologies are in place, EPA must start again with each source category within 8 years to assess residual emissions and residual risks.

This section presents recommendations regarding the assessment and management of residual risks, as the Commission was mandated by Congress, and addresses several related issues. We also address the topic of indoor air pollution.

In the Clean Air Act Amendments of 1990, Congress directed EPA to require industry to improve the technologies they use to reduce emissions from point sources of hazardous air pollutants. Furthermore, Congress mandated that EPA determine whether any unacceptable residual risks to health from hazardous air pollutants remain after MACT has been implemented. EPA needs and wants guidance on how to implement these residual risk provisions.

Section 112 of the Clean Air Act Amendments of 1990 has been so stringently interpreted that if even a single facility within a source category is found to pose a residual cancer risk of 10-6 or more after MACT has been implemented, EPA must consider more stringent new standards for that source category. In the assessment and control of criteria air pollutants (section 109, Table 7.1) and hazardous air pollutants (section 112, Table 7.3), it is noted that the same industrial and utility point sources often contribute pollutants of both types. In addition, motor vehicles are major contributors to ambient levels of the criteria air pollutants ozone, carbon monoxide, and particles, and many hazardous air pollutants, including benzene, 1,3-butadiene, and formaldehyde.

To determine and manage residual risk after implementation of MACT, the Commission proposes that EPA carry out a specific tiered scheme (see Figure 7.1), to be conducted with stakeholder involvement:

1. Problem/Context Characterization. Local, regional, and national levels of air toxics, by pollutant and by source category, must be put in the context of exposures from other air pollutant sources and from environmental pathways other than air. The goal is to build an understanding among stakeholders about the health context of residual emissions from the regulated point sources. Problem characterization, putting a problem in context, and engaging stakeholders are described in detail as part of the Commission’s Risk Management Framework in Section 2.

In this initial step, EPA identifies the priority source categories likely to pose the highest residual risks. The Commission believes that EPA—through the experience gained developing MACT standards—has acquired enough information to identify the source categories most likely to pose significant residual risks, based on whether high priority hazardous air pollutants are present and whether there are highly exposed populations, or "hot spots."

2. Screening Risk Assessments. For these source categories or subcategories, EPA performs screening risk assessments using the Agency’s tier 1 or tier 2 procedures for hazardous air pollutants (EPA 1992d, NRC 1994a), relying on many default assumptions regarding stack heights, distances to fence lines, emission rates, and "lookup tables" to estimate maximum off-site concentrations. The size of the exposed populations should also be considered. Each source category has numerous point sources across the country with different features, operating characteristics, and nearby populations; thus, a screening model must be developed that can be used to generalize risks and likely ranges of risks for each source category. The specific methods, criteria, and assumptions for performing screening risk assessments should be developed by EPA in partnership with state environmental regulatory agencies, with appropriate peer review and stakeholder input in an open and transparent process.

If source categories considered in the screening risk assessment model are found to pose a potential incremental lifetime cancer risk that exceeds one in a million (10^-6) or if a hazard index¹ exceeds one for a hypothetical person exposed to a reasonably representative estimated exposure level, the categories are classified further. If the screening value for cancer risk is > 10^-4 or a hazard index is > 10 (far right in Figure 7.1), the source category is given high priority. More detailed risk assessments are performed first within that category, and regulated parties may voluntarily take steps at this stage to reduce emissions and achieve a lower risk category. If a cancer risk is between 10^-6 and 10^-4 and a hazard index is between 1 and 10, a source category is considered to have "medium" priority (middle of Figure 7.1). Risk assessment results are distributed to the affected industries and other interested parties, accompanied by appropriate caveats regarding the assumption-based, preliminary nature of the results, so that voluntary process changes or other actions may be evaluated to reduce emissions or risks associated with those sources. Some experience with source categories will be needed to see how well these values serve in forming appropriate categories.

Although the 1990 amendments to the Clean Air Act set 10^-6 as the threshold for considering source categories for reduction of residual risk, those categories with screening risk estimates that fall within the 10^-6 to 10^-4 range might not actually require high priority categorization because of the conservative nature of the assumptions used in screening risk assessments. According to testimony received by the Commission from Joann Held and Tad Aburn, who manage air toxics programs in New Jersey and Maryland, respectively, using a flexible 10^-6 to 10^-4 approach is consistent with the permitting strategy already in place in a number of states, where facilities within that range can negotiate their options.

The 1990 amendments do not set a threshold for considering health risks other than cancer, which the Commission believes to be a serious omission. We chose a threshold hazard index of 10 because there are few hazardous air pollutants with RfCs that are within a factor of 10 of their no-observed-adverse-effect levels (NOAELs). Typically, RfCs are one-thousandth of a NOAEL, so a hazard index of 10 in these cases would still leave a margin of exposure of 100. Analogous screening risk assessments that have been performed at Superfund sites might provide useful information about the extent to which screening risk assessments generally identify hazards above and below 10.

3. Detailed Risk Assessments. In cooperation with all stakeholders, EPA and regulated parties perform detailed risk assessments using actual data in place of at least some default assumptions. Actual facilities are evaluated instead of generalized source categories. Options for additional controls or process changes are examined if more detailed risk assessments yield incremental lifetime cancer risks of > 10^-5 or hazard indices of > 1 (bottom right of Figure 7.1). If the more detailed risk assessments yield incremental lifetime cancer risks of < 10^-5 and hazard indices of < 1, no further action is required. To the extent practical, when more than one source category of high priority is found at the same facility, their risks are evaluated together.

The Commission believes that EPA should be able to place the burden of preparing these risk assessments on the regulated parties by issuing appropriate guidance. Current EPA policy prohibits the Agency from requiring regulated parties to participate in the development of regulations that will affect them, although EPA may encourage them to do so. EPA may wish to reexamine this policy. The regulated parties will be the source of essential emissions data and operating parameters in any case. They may welcome the opportunity to find ways to reduce emissions in order to achieve screening model risk estimates that could avoid the need for detailed risk assessment and further controls.

The Commission prefers a 10^-5 flexible bright line for actions to reduce residual cancer risk based on detailed risk assessments. We believe this action level is consistent with Congressional guidance to use 10^-6 for screening purposes and with the 1987 NRDC v. EPA Vinyl Chloride decision about what constitutes an "acceptable" risk "in the world in which we live" (824F.2d at 1165). The choice of this bright line or decision threshold will be better informed after some experience is gained across source categories replacing default assumptions with actual exposure data. Use of a threshold for action more stringent than a 10^-5 lifetime upper-bound incremental cancer risk would continue an outdated practice of giving much greater attention to cancer risks than to all other health and ecological risks. Note that the 10^-5 decision threshold reflects aggregate risks from hazardous air pollutants emitted from a particular source, not just risks from each chemical.

4. Risk Reduction. Identification and implementation of options to reduce risk, where required, are performed as part of a local or regional risk management process conducted within the Commission’s Framework. Risk characterizations serve as starting points for discussions at the state and local levels during the permitting process. Risk estimates stimulate voluntary actions to reduce emissions and risks.

Context must be investigated further at this stage, estimating the contribution of the facility to overall air pollution and specific disease risks. Risk management with full stakeholder participation should address not only the individual facility context, but also the costs, benefits, equity, and values reflected in various risk reduction options (Section 2). In large facilities, there will be multiple sources, often in different MACT source categories. Use of bubble concepts and other techniques should be considered in the facility-wide permitting process.

5. Iteration. After determining the source categories considered to pose the greatest risks, the agency determines the need for proceeding with assessments of medium-priority and low-priority source categories and assesses the decision thresholds proposed here (see Figure 7.1) in light of comparative risks from other air pollutants.

Implementing a tiered or phased approach to assessing risk, such as that recommended here and in Science and Judgment in Risk Assessment (NRC 1994a), could lead to awkward public relations circumstances. Situations might arise in which a community is told that a nearby facility might present a potential health risk, on the basis of a screening risk assessment, and is then assured, after a more detailed risk assessment, that the facility does not pose a threat. Members of the community are likely to remain suspicious and believe that the facility is hazardous despite messages to the contrary. This skepticism will be fueled by knowledge that both the critical data and the detailed risk assessment came from the regulated party. Communicating iterative estimates of risk to the public and the media without loss of credibility is extremely difficult and will require serious consideration in each case.

Early and regular stakeholder participation might reduce the likelihood of conflict; outrage often arises when affected parties are brought into the process late (although there can be additional interested parties at later stages). Open review of the data used in risk assessments and stakeholder guidance for the performance of risk assessments should help.

Data Needed To Implement Section 112 of the Clean Air Act Amendments of 1990

Critical information gaps exist that hinder EPA from reliably determining to what extent MACT standards are reducing health risks and whether significant residual risks remain. There are means to collect needed data and stimulate needed studies in current statutes.

Sufficient toxicity and exposure data should be generated to provide a scientific basis for evaluating residual risks associated with hazardous air pollutants emitted from point sources. Both research programs and data collection efforts are needed. EPA should proceed with TSCA section 4 test rule proposals and with Clean Air Act section 114 emissions surveys.

Congress required that EPA determine through risk-based approaches the need for further control of hazardous air pollutants after implementation of MACT. EPA is poised to start evaluating the residual risks from hazardous air pollutants associated with source categories that have implemented MACT standards, however, data to assess the health risks of most hazardous air pollutants for regulatory purposes are lacking. According to EPA, approximately 40% of the 189 hazardous air pollutants listed in the amendments (one now deleted) cannot be classified as to their cancer hazard, and a noncancer assessment cannot be performed for about 60%. Furthermore, most of the toxicity data that do exist were obtained from experiments that used the oral route of administration, not the inhalation route more appropriate for air pollutants. Despite the fact that these most recent Clean Air Act amendments were passed six years ago, additional toxicity data apparently have not been generated. The existing toxicity data were not compiled until 1996.

The status of exposure data collection is no better. In 1996, EPA tried to perform case studies of potential residual risks after MACT implementation. The agency found that of the 20 source categories for which standards had been promulgated (Table 7.2), adequate data existed to perform even the most preliminary exposure assessments for only seven of them. Those preliminary assessments relied solely on stack heights, distances to fence lines, emission rates, and "lookup tables" to estimate maximum off-site concentrations. This enormous exposure data gap must be filled to perform screening analyses, and estimate residual risks reliably. Perhaps the regulated parties can generate emission estimates from their existing facility-specific (although not necessarily source-specific) TRI reports.

With regard to the Commission’s Risk Management Framework, Congress dictated the Problem/Context stage of the MACT process, so EPA focused entirely on the options stage (i.e., MACT), without stepping back to characterize the problem and its context more fully or to evaluate risks. Congress established rigorous deadlines for EPA to promulgate MACT standards, yet provided limited funding for this major new responsibility, constraining the agency’s ability to collect or generate data. As emphasized in testimony received by the Commission, EPA would be better positioned now had it clarified data gaps and initiated data development efforts.

EPA should explore partnerships with regulated industries to perform the batteries of toxicity tests and collect the emissions and exposure data needed to assess residual risk. EPA’s testing authority under TSCA section 4 is one means for obtaining needed toxicity data for listed chemicals. In fact, EPA has very recently proposed a test rule under TSCA section 4 specifying a battery of toxicity tests for 20 chemicals chosen from the list of 188. Clean Air Act amendments section 114 questionnaires are a means for obtaining needed emissions data. EPA is using this authority to do so. Actual emissions data are often well below the MACT standard-based limits.

By looking at hazardous air pollutants in the larger context of air pollution in particular geographic areas, EPA will be able to make more informed decisions about reducing residual emissions. EPA will give priority to those sources that contribute most to overall risk.

In carrying out its hazardous air pollutant program, EPA has used a decision-making mechanism that involves the regulated parties at the very early stages of the process. This mechanism, referred to as the MACT partnership program, is intended to increase the amount of knowledge, skills, and resources devoted to the development of a MACT standard.

The partnership program should continue and be expanded as a stakeholder-based approach to setting MACT standards, including health and environmental organizations and community representatives. EPA should establish an evaluation process for the partnership program. The Commission recommends a similar approach to facilitate decision-making related to residual risk determinations.

The hazardous air pollutant provisions of the Clean Air Act require EPA to promulgate standards for 174 source categories over a clearly defined timetable (Table 7.2). The goal of EPA’s partnership program is to reach decisions about MACT standards through a consensus-based decision-making process. Participants in this process hope that decisions can be made in a more timely and effective manner, and that points of disagreement can be identified and reduced. The Commission was told that use of the partnership program to facilitate decision-making shows promise in this regard, although a formal evaluation of the program is lacking.

Conceptually, the partnership approach appears to be preferable to other decision-making models that fail to include stakeholders. It is important to determine whether the decision-making mechanism actually is improved, however, both by expediting the promulgation of MACT standards and by yielding starting points for residual risk determinations.

Many emissions sources can be subject to multiple MACT standards, as well as to additional Clean Air Act provisions (such as those addressing control of ozone and particles in ambient air), so the impact of multiple regulatory requirements must be considered.

EPA should continue its efforts to integrate multiple permitting requirements into a workable licensing system. It should consider adopting some regulatory flexibility for sources with multiple compliance schedules. This flexibility should focus on maximizing the cost effectiveness of pollution control measures within a reasonable time frame. It should also focus on the pollution reduction benefit that a more comprehensive regulatory program could achieve.

Control of individual pollutants should not be considered in the absence of an overall regulatory context. Because MACT addresses existing sources, consideration should be given to the effects of multiple control requirements on the sources operating within a facility. Generic pollution standards for individual processes might neglect how the processes interact with other sources within a facility. They might also neglect the logistical problems that can arise when particular processes are modified. More sophisticated policies for determining regulatory compliance are needed to address pollution control issues associated with complex sources. Emphasis should be given to applying MACT throughout a facility, with control technology requirements and time lines set to optimize both the effectiveness and the efficiency of pollution reduction measures. The partnership program should help facilitate an integrated approach.

Compared with extensively regulated outdoor air pollution, indoor air pollution can pose a substantial risk to human health, yet, it receives little attention and remains largely unregulated. Efforts by EPA, Occupational Safety and Health Administration, Consumer Product Safety Commission, and other agencies to develop coordinated strategies for addressing indoor air pollution reportedly have been thwarted by the lack of agreement on the nature of the problems and their solutions, by their lack of statutory authority, and by the fact that jurisdiction over elements of indoor air pollution is shared by several regulatory agencies.

Congress and the administration should develop legislation mandating a coordinated strategy by EPA, OSHA, CPSC, and other federal agencies to address the growing problem of indoor air pollution.

Over the last two decades, public health attention has been drawn increasingly to the problem of indoor air pollution. The energy crises in the 1970s led to a lowering of fresh air ventilation rates recommended by the American Society of Heating, Refrigeration and Air Conditioning Engineers. Many building owners responded by lowering the amount of fresh air circulation through buildings and adding insulation to the walls. Meanwhile, increasing quantities of products containing volatile chemicals were introduced into buildings, such as plywood products and carpeting. A number of studies have shown that the concentrations of many contaminants in air are higher in homes and other buildings than outdoors. NIOSH has reported many complaints, mainly of nonspecific symptoms such as headache, nausea, and eye irritation. The lack of a clearly distinguishable constellation of symptoms and the many causes within indoor environments led to use of the term "sick building syndrome."

In addition, specific indoor air pollution problems have been identified or better appreciated over the last two decades. They include the effects of tobacco smoke, radon, asbestos, lead, and indoor allergens (e.g., mold and dust mites). Exposure to those pollutants is associated with clearly defined health effects, such as lung cancer and asthma; indeed, the incidence and severity of asthma has increased markedly in recent years. Unregulated uses of pesticides, cleaning chemicals, deodorants, and emissions from gas and wood stoves generate high concentrations of potentially toxic air pollutants. Legionellae and other infectious agents can live in air conditioning ducts and other indoor, moist niches and cause outbreaks of infections, possibly in combination with chemical exposures.

CPSC has taken an active role in conducting research on indoor air quality in order to protect consumers. CPSC’s accomplishments include: a ban on asbestos in consumer products; a voluntary standard to limit formaldehyde emissions from particleboard and wall paneling; studies of exposures and health effects of biological pollutants in residences, conducted as part of the Harvard Six Cities Study; labeling of methylene chloride-containing products; and many others.

No regulatory framework exists for addressing indoor air pollution concerns, and there are essentially no enforceable standards. Due to their complexity, indoor air pollution problems may not be amenable to tradional command-and-control regulation. EPA’s regulatory attention is focused mainly on outdoor air despite research findings on total exposures. The attention of OSHA is focused mainly on industrial environments, and CPSC addresses materials as consumer products. Meanwhile, many problems in offices, public buildings, and homes remain relatively unrecognized and unaddressed. All of these agencies recognize the growing importance of the problem, but none has the regulatory mandate to address it fully. There is an interagency task force, but it, too, lacks a statutory mandate.

Approaches to indoor air pollution assessment and education are fragmented at both the federal and state levels. EPA’s Office on Radon and Indoor Air Quality provides educational materials, and EPA coordinates indoor air research efforts on an intra-agency and interagency basis. NIOSH continues to be active in surveillance. Much political opposition to the development of a regulatory program remains, however. The Commission was told that recent OSHA public hearings on restricting smoking in the workplace and developing basic ventilation requirements was dominated by the tobacco industry and various building-owner organizations.

Indoor air quality problems are often complex and vary widely from one building to the next. Despite the differences, however, some guidance exists that can help to address these problems. EPA has produced excellent documents that can provide useful information, including a kit called "tools for schools" that provides schools with much needed assistance in addressing indoor air quality problems. The agency could gain valuable risk management expertise in this area as it provides technical assistance to building committees organized to address indoor air quality concerns, especially if the agency conducts evaluations of the effectiveness of these activities.

When Congress enacted the original Superfund statute (Comprehensive Environmental Response, Compensation, and Liability Act, or CERCLA) in 1980, few were aware of the extent of the problem created by years of inappropriate or inadequate hazardous waste disposal practices. Many thought that the program would need to clean up just a few hundred sites, and expected the initial authorization of $1.6 billion plus reasonable expenditures by private companies to be sufficient and the cleanup to be quick. Today, we recognize that we must still address several hundred thousand contaminated sites, a legacy of an earlier industrial era. We also recognize that most of those sites are not so highly contaminated or complex as to require the attention and active management of the federal Superfund program. EPA, states, and others are working together on a range of approaches to address this wide array of contaminated sites. Many states now administer voluntary cleanup programs that can efficiently return contaminated lands to productive reuse. In particular, there is a focus on "brownfields" that can be restored and employed in the local economy.

Over the years, EPA has identified more than 40,000 potentially contaminated sites in its Comprehensive Environmental Response, Compensation, and Liability (CERCLIS) database. The shadow of liability under the Superfund statute hangs over all those sites. In 1996, EPA announced that more than 28,000 of those need no further federal attention—a step that should assist in removing them from the liability shadow. The federal government and the states continue to study, design, and carry out cleanups at the remaining 13,000 sites on the CERCLIS data base. To date, about 1,300 of the 13,000 have been placed on the National Priorities List (NPL) for federal attention, and more than 30% of the 1,300 have completed cleanup. Although each of the last two years has produced more completed cleanups than the entire first decade of the program, progress is slow. With an average cleanup cost of more than $20 million per site, it is also very expensive. As Clean Sites, Inc., president Toby Clark has testified before Congress, usually someone is happy when Congress causes billions of dollars to be spent; almost everyone, however, seems disappointed with Superfund, for diverse reasons.

The 1990 amendments to the Superfund National Contingency Plan (NCP) addressed the competing goals of the 1986 Superfund Amendments and Reauthorization Act (SARA) by establishing a site-specific decision process. Under this process, cleanup options must satisfy the threshold criteria of protecting human health and the environment and comply with the applicable or relevant and appropriate requirements ("ARARs") of other federal and more stringent state environmental laws. Tradeoffs among options that meet the threshold criteria are then balanced with respect to seven additional criteria that reflect the SARA’s mandates to utilize permanent solutions and treatment technologies to the maximum extent practicable and to be cost-effective. Neither SARA nor the NCP prescribes in detail how to ensure "protection" or how to compare or match options for the protection of health and the environment. Indeed, cleanup decisions often have to satisfy competing criteria in the statute and the NCP, such as long-term effectiveness and permanence of remedy; reduction of toxicity, mobility, or volume; short-term risks (especially to workers); and costs. Acceptability to states and communities are two relevant criteria.

In the years since promulgation of the NCP, EPA has put into place several rounds of administrative reforms to achieve a "faster, fairer, more efficient" program and address "worst sites first" under the constraints of the current law. In the last few years, EPA has emphasized the importance of using reasonably anticipated future land use in site-specific risk assessments and cleanup decisions; issued several important ground water guidance statements to implement recommendations of the National Research Council; acted to protect small parties, prospective purchasers, and innocent landowners from liability; instituted a risk-based priority-setting scheme for funding cleanup actions; and accelerated cleanups through, for example, presumptive remedies and the Superfund Accelerated Cleanup Model. It has also initiated the Brownfields Action Agenda and its pilot program, which seeks to empower states, communities, and other stakeholders through economic redevelopment, safe cleanup, and sustainable reuse of contaminated properties. EPA faces the challenge of implementing these improvements and goals consistently in its 10 regions and in states, territories, and tribal jurisdictions and of meeting reasonable expectations for cost effectiveness.

There is also a critical link between Superfund, the cleanup program for hazardous waste sites no longer in use, and the Resource Conservation and Recovery Act (RCRA), for management of wastes currently being generated. Designing Superfund cleanups and corrective actions to comply with applicable requirements for the treatment, storage, and disposal of RCRA hazardous waste has been difficult. Guidance on using treatability variances to comply with land disposal restrictions and more recent regulations governing Corrective Action Management Units (CAMUs) help, but compliance is still too complex.

The Superfund program has struggled with many difficulties. One has been the inconsistent consideration of future land uses and of realistic exposure scenarios. Recently a number of administrative changes have significantly improved the operation of the program. In addition, the highly successful emergency removal actions of Superfund are not well appreciated, despite their timely and major contribution to reduction of public health and ecologic risks.

Risk assessments and remedy selection should be based on reasonably anticipated current and future uses of a site. As EPA’s Land Use Directive of 1995 states, reasonable assumptions about future land uses should be developed early in a process of seeking consensus with local officials and community representatives. Congress should encourage reuse of brownfields by providing liability protection to prospective purchasers who agree to provide access to the property by government authorities and do not exacerbate or add to the contamination. In addition, prospective purchasers who remediate a site should pay a premium to a fund that would cover the costs of future changes in cleanup standards.

Land use and other resource use assumptions play a critical role in determining how clean a site must be for adequate protection of health and the environment, which is a primary criterion under the Superfund NCP. A playground and an industrial warehouse are associated with very different potential exposure scenarios and therefore need different remedial approaches with potentially differing costs to achieve the same estimated level of health protection. EPA’s administrative actions and pilot projects to promote the reuse of brownfields include guidance documents about early consideration of future use, extensive coordination with communities and other stakeholders, deferral of NPL listing determinations while states oversee response actions, voluntary cleanup programs, and model agreements for purchasers.

Inclusion of affected communities from the start as partners in the investigation and remedy selection processes can improve the likelihood that the choice of remedy will reflect reasonably anticipated uses of the site and the wishes of the community. Involving community members should also reduce the dissonance and long delays that often occur when EPA proposes solutions before discussing goals and costs with stakeholders. Such a process is consistent with the Commission’s Risk Management Framework.

Use of enforceable institutional controls can make it feasible to protect health and the environment reliably into the future at cleanup levels that are less stringent than those mandated for residential levels. For example, thoroughly cleaning up of a former industrial site in an urban area to a standard safe for young children would be unnecessary and might be so expensive as to preclude the re- development that might provide economic de- velopment opportunities in depressed areas and save pristine areas elsewhere. To overcome impediments to waste site cleanup, innovative approaches being developed at the state level should be carefully evaluated. Liability protection for prospective purchasers, with appropriate safeguards for access and exacerbation of contamination, is one approach worth considering. A premium could be levied for a fund that would cover the costs of future changes in cleanup standards. Assurances for non-NPL sites that brownfield development under qualified state programs will protect cooperating prospective purchasers from Superfund liability must be accompanied by a continuing monitoring program so that potentially hazardous migration of contaminants from the sites can be predicted, detected, and remedied. Hazardous on-site exposures due to changes in land use or failure to control access must also be prevented.

EPA needs additional guidance about choosing risk-based cleanup standards. Remedy selection and cleanup standards are sometimes complicated by conflicting relevant and appropriate state or federal requirements.

EPA should continue to use its 10^-6 to 10^-4 risk range as a guide for site-specific risk-based cleanup goals, related to future land use. Site-specific data from the Remedial Investigation/Feasibility Study process should be used to refine default assumptions when available. Because a risk estimate is a result of many assumptions and judgments, it is wise for Congress to eschew setting specific risk levels, leaving that decision to EPA and the states. The Commission prefers qualitative language in legislation, such as "reasonable certainty of no significant harm." The Applicable or Relevant and Appropriate state or other federal Requirements (ARAR) provision of the Superfund law should be amended to delete the "relevant and appropriate" language, because of the wide differences in interpretation that arise.

The risk range is being used productively by EPA. We recommend realistic high-end exposure scenarios for screening assessments and descriptive or probabilistic distributions or ranges of exposure for refined risk assessments (see Exposure Assessment on page 72).

Too much confusion and conflict over the ARAR provision has persisted and consequently the ARAR waiver clause has not been used efficiently. The state and federal regulations that can serve as ARARs were often not written for conditions at Superfund sites and greatly complicate remedy selection and implementation. We support retaining applicable state and federal requirements so long as they do not conflict with the risk-based goals tied to future land use, as recommended in the preceding section.

Many difficulties in implementing the balancing criteria of the National Contingency Plan for Superfund have arisen. For example, the requirements introduced in SARA in 1986 to "utilize permanent solutions and . . . treatment technologies to the maximum extent practicable" have been applied inflexibly at some sites. Interruption of exposure pathways and other controls might be more appropriate than treatment at some sites, particularly non-residential ones.

The mandate to use permanent solutions "to the maximum extent practicable" should be changed to the assurance of long-term reliability of protection of health and the environment. Treatment options to reduce toxicity, mobility, or volume of highly hazardous material should be used to ensure long-term reliability and should be overridden when no effective treatment remedy is available. EPA should continue to develop better coordinated mechanisms for proper compliance with RCRA hazardous waste standards at Superfund and RCRA corrective action sites, such as the Hazardous Waste Identification Rule for contaminated media. A design team approach, including states and responsible parties, should be encouraged to accelerate the remedial design phase of the cleanup. Remedies should be chosen to be most cost-effective in meeting necessary protective cleanup levels.

EPA, the states, potentially responsible parties, and citizens often are timid about applying on-site remedies that reduce toxicity, mobility, or volume of contaminants—incineration, solidification, vapor extraction, and bioremediation—and about restrictions on site use. Remedies involving removal to "elsewhere," usually landfills or off-site incinerators, generally are high cost remedies and often are resisted by local communities anxious about the numerous truck trips needed to haul away contaminated material or fearful of incineration and incineration malfunction. Parties must be encouraged to negotiate phases of cleanup, especially when even expensive remedial actions are inadequate for some aspects of the site. On-site technologies that reduce toxicity, mobility, or volume should be used when appropriate. They should be identified as EPA has begun to do, as "presumptive remedies" for appropriate sites and cleanups. Responsible parties should be given opportunities to propose and select alternative remedies if those remedies can meet overall cleanup objectives—including risk-based or residual contaminant or exposure levels—agreed on through a process open to public scrutiny. Cost effectiveness should be a factor; multiple health and ecologic effects might also need to be balanced, as might community cultural, social, and political factors.

One aspect of the law that makes implementation of Superfund cleanups especially difficult is RCRA land disposal restrictions, which have discouraged intrasite movement of wastes for less intensive—yet efficient—on-site treatment. EPA has taken steps to reduce the problem via its CAMU Rule and will do more through its Hazardous Waste Identification Rule for contaminated environmental media. Enactment in April 1996 of H.R. 2036, the Land Disposal Program Flexibility Act, provides a platform for complementing RCRA remediation reforms.

Better and less expensive remedies are being identified as the Superfund cleanup program progresses. In addition, changing policies on consideration of future land use could make it possible to alter the remedy in favor of less reduction of contamination to reach the same cleanup standard, due to different exposure scenarios.

EPA should expand and implement its new policy directives to allow revisions of selected remedies.

EPA should establish procedures to provide appropriate and efficient redress of remedial actions in existing RODs in certain limited cases, such as land use restrictions, development of important new scientific information, or technologic advances. Companies and communities that invested in cleanup of NPL sites during the first 15 years of a steep learning curve for EPA and the nation should receive the benefits new information and new technology can bring. For example, reassessment of 30 to 50 years of pumping and treating of groundwater after initial reduction in contamination levels seems appropriate for reopening RODs. The Commission is encouraged by EPA’s "remedy update" reform currently being implemented administratively. This effort is targeted primarily at bringing older groundwater RODs up to date with current science and technology regarding appropriate cleanup objectives for different types of contamination problems. Revising a ROD should not become an excuse for stopping or slowing down cleanup action.

There is a continuing need for information and education on the toxicity of various chemicals, physicochemical characteristics of contaminants, sources of exposure, and effectiveness of remedies.

Congress should continue to support essential support programs for Superfund—the Agency for Toxic Substances and Disease Registry (ATSDR), the National Institute of Environmental Health Sciences (NIEHS) Superfund Basic Research Program at universities, NIEHS programs for training hazardous waste workers, and applicable EPA research and demonstration activities. The Superfund program should make greater use of EPA’s own Science Advisory Board. If, as expected, more responsibility and funding for site-specific decision-making are delegated to the states, research and public health assessment functions should continue to have high federal priority.

Despite extremely challenging deadlines and inadequate data at many sites, ATSDR has made a valuable contribution to the Superfund program through its toxicological profiles of various common contaminants at Superfund sites, its public health advisories (in collaboration with local and state health departments), and its establishment of several exposure registries. That work should continue. The Superfund basic research program administered by NIEHS under the Superfund appropriation has mobilized highly relevant interdisciplinary research at 17 universities. If Congress and citizens want risk estimates and remedies that are based on sound science, not just default assumptions, support for research programs is critical and is a federal responsibility. Good science does not of itself lead to application; Congress must also support EPA’s research activities. Similarly, worker training and worker protection for the relatively high risks involved in the cleanup of sites are continuing responsibilities.

EPA’s Technology Innovation Office has a private-public partnership program coordinated by Clean Sites, Inc., involving major companies with Superfund responsibilities, vendor companies with new or not widely used technologies, DOE or Department of Defense facilities, and state regulators. The program’s demonstrations provide objective comparative assessments in real world circumstances. They should be expanded, and their findings should be widely disseminated.

The authority and mandates of the Office of Prevention, Pesticides and Toxic Substances (OPPTS) are included in the Pollution Prevention Act, the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), the Federal Food, Drug and Cosmetic Act (FFDCA), and the Toxic Substances Control Act (TSCA). The subject of pollution prevention is discussed in Risk Management Options: Alternatives to Command and Control on page 49 of this report. This section focuses on issues related to the toxicity and registration of pesticides and on toxic substances.

In August 1996, Congress passed the Food Quality Protection Act, modifying the pesticide residue provisions of the Delaney Clause. Other applications of the Delaney Clause were not modified (see Food and Drug Administration on page 136). The standard of protection specified in section 408 of FFDCA was changed from zero risk to "reasonable certainty of no harm" in keeping with the Food and Drug Administration’s well established statutory language. At the same time, the safety standard was improved to allow for advances in scientific understanding and by requiring explicit consideration of potential risk for highly exposed populations, particularly young children. These changes are wholly consistent with the Commission’s recommendations in our June 1996 Draft Report.

None. The Commission appreciates Congress’ responsiveness to the recommendations included in our June 1996 Draft Report. We note, however, that because the new statute was effective immediately, EPA was allowed no transition time for making the adjustment to the new procedures and has experienced a difficult time, especially with so many pesticides already in the middle of the approval process.

Historically, EPA has made its regulatory decisions chemical by chemical, including pesticide registration decisions. That approach does not accommodate consideration of the potential effects of exposures to several chemically different pesticides with similar effects or of multiple exposures to chemically similar pesticides. EPA considers multiple exposures and multiple risks when it evaluates pesticides for the purpose of reregistering them, but it does not yet do so during the evaluation of new pesticides.

EPA should establish an integrated approach to the registration process to evaluate multiple risks and exposures to multiple agents. Risks and benefits associated with alternatives should also be compared. Furthermore, to encourage development of safer pesticides and reduce the use of more hazardous alternatives while avoiding market disruption, EPA should expand its accelerated registration program for the products that meet rigorous and well-defined criteria for high human health and environmental safety standards. Products that meet the high standards should be permitted to carry EPA-approved labels to communicate to the user that they meet high safety standards.

EPA has avoided using an integrated approach to registration, because of the potential for serious disruption of market forces, such as shortages due to the loss of minor use labels important to fruit and vegetable growers and pesticide resistance problems as the number of pesticide products on the market is reduced. Instead, the agency has encouraged the substitution of biologic pesticides for more hazardous chemicals and the use of formulation changes and equipment modifications to decrease exposure. It has canceled some of the uses of pesticides that are particularly hazardous, such as parathion. And it has established a restricted use category for needed but highly toxic pesticides to ensure that they will be used only by pest control operators and agricultural workers qualified by training and experience to use them properly. To improve the rational use of pesticides and minimize their adverse effects by establishing an integrated approach to evaluation of multiple risks and of exposures to multiple agents, the agency should introduce the new approach on a demonstration basis, to avoid disruption.

EPA has a longstanding commitment to developing safer pesticides and alternatives to chemical pesticides. By creating a safer pesticide registration and pesticide labeling program, EPA can encourage development of safer alternatives and elimination of highly hazardous materials. A pesticide registration and labeling policy would give manufacturers an incentive to develop safer alternatives and and give consumers information on which to base informed choices. The marketplace can operate to reduce or eliminate exposures without the disruption and spot shortages that can be caused by an integrated approach.

In recent years, toxicologic testing and review requirements for new chemicals have made important contributions to a lower incidence of findings of carcinogenicity and other adverse effects among new chemicals marketed. The Toxic Substances Control Act (TSCA) has not been reauthorized since its enactment in 1976, although it has been subjected to numerous court interpretations, primarily over the process EPA must follow in order to request or require testing by companies. EPA and several consumer and environmental organizations consider the provisions of the law and the judicial interpretations of those provisions as constraining. Industry, on the other hand, believes that much of the information already requested is of little relevance.

TSCA should be updated to reflect advances in toxicology and regulation over the past 20 years. Given the differences in views among key parties, the Commission recommends a focused stakeholder process to review the act and its implementation and to seek consensus on the the best ways for EPA to obtain and interpret needed toxicologic data, especially as related to sections 4 and 8.

TSCA occupies an important position among the numerous health and environmental statutes. It is the only law that provides EPA with the authority to regulate new and existing chemical substances not otherwise regulated by other statutes (such as the laws governing regulation of pesticides, drugs, foods, and cosmetics). It authorizes EPA to gather chemical use, exposure, and toxicologic information; require testing; and regulate unreasonable risks.

At a 1996 conference marking the 20th anniversary of TSCA a divergence of views emerged about how well the processes of testing new chemicals, reporting findings of toxicity and potential risks, and making information available to the public were working. Lynn Goldman, EPA Assistant Administrator for Prevention, Pesticides and Toxic Substances, informed the Commission that judicial interpretations in response to suits over the 20-year history of TSCA have severely limited the agency in issuing requirements for minimal data sets. The agency faces a "catch-22" in that the courts require EPA to have extensive information to justify a testing request, yet EPA can only obtain such information by issuing a testing request.

The Environmental Defense Fund (EDF) has been evaluating the extent to which information is available for quantitative risk assessments of the approximately 2,900 chemicals in the TSCA high-production inventory; apparently not more than a few percent have adequate data for such assessments. INFORM (1996) has performed a study of information publicly available through the Substantial Risk reporting program of section 8(e), which requires chemical manufacturers, processors, and distributors to submit information to EPA concerning "substantial risks" posed by substances used in commerce within 15 days of learning of such risks. Since 1977 EPA has received 13,000 such notices. According to INFORM (1996), such findings are not submitted in a standard reporting format, are often protected very broadly by Confidential Business Information provisions, lack information on uses and exposures, and are not readily available to the public. EDF objects to the presumption that chemicals for which data are not available should be considered free of risks.

The Chemical Manufacturers Association provided testimony to the Commission, in response to our Draft Report proposal that Congress consider amending TSCA, that no fundamental flaws exist in the law, that it provides EPA with the authority and flexibility needed to protect human health and the environment from unreasonable risk, and that problems in its administration and implementation are being addressed regularly by the agency, industry, and other stakeholders.

The underlying problem is that section 8(e) does not require companies to conduct tests, only to report risks that they do discover through their own testing programs. The result, as noted by David Sigman of Exxon Chemical, representing the Chemical Manufacturers Association, is that there are disincentives to conducting tests, especially exploratory tests. Those companies that do not test avoid reporting, while those that do extensive tests run the risk that any adverse data reported will be given undue weight when the overall "weight of the evidence" should indicate that such adverse findings are unlikely to be correct or plausible.

EPA would like to clarify under both TSCA 8(e) and FIFRA 6(a)(2) what studies and human adverse-event reports must be submitted to the agency. Also, EPA is awaiting results from voluntary participation by U.S. chemical manufacturers in an OECD exercise aimed at testing and reviewing test results for some 500 high-production chemicals, as part of a screening inventory. OECD has recommended a basic set of testing requirements, intended to facilitate decisions about testing in member countries and to generate comparable data for various chemicals. The Commission endorses timely completion of this cooperative effort. Such lists of tests will need to be amended as additional and better tests are developed.

OPPTS and EPA’s Office of Research and Development should work together to define criteria for scientifically sound weight-of-evidence reviews of old and new data submitted under sections 8(e) and 8(d). These agencies are cooperatiing in addressing the 1996 Congressional mandate to develop testing protocols and requirements for detecting the effects of chemicals on endocrine functions. At the first meeting of this Commission in May 1994, Theo Colburn discussed observations in wildlife, fish, and humans of changes in reproduction, gender-specific behaviors, sperm count, and incidence of anomalies of the genitalia. The terms "endocrine disrupters" and "endocrine modulators" have emerged as descriptive of a wide range of such effects (Davis and Bradlow 1995, McLachlan and Korach 1995, Colburn et al. 1996), although the National Academy of Sciences committee that is evaluating these effects (see below) uses the term "hormonally active agents." Some, but certainly not all, are mediated by or attributed to compounds that bind to estrogen receptors. Some are chlorinated compounds, but many others, such as alkylphenolic ethoxylate plasticizers, are not.

A recent study of combinations of chemicals with estrogenic activity performed using cultured yeast cells containing the human estrogen receptor reported synergistic interactions at low concentrations in vitro (Arnold et al. 1996). A great deal of scientific, regulatory, and public concern about the potential adverse environmental and human health impacts from synergistic estrogen responses ensued. More recent studies conducted at four different institutions have attempted to reproduce those results in the yeast cell system, in human cells, and in mice (a total of ten different estrogen-responsive assays) (Ramamoorthy et al. 1997a,b). All of the studies failed to reproduce the original results, detecting only an additive response, which suggests that the public attention was premature.

Many scientific issues related to hormonally active agents are just being framed. This topic stands at the hazard identification stage of the Risk Assessment Framework (Section 1) and the Problem/Context stage of the Commission’s Risk Management Framework (Section 2): How do agonists (estrogens) and antagonists(antiestrogens) interact? How predictive are the complex endocrine assays? How do we estimate risks associated with exposure to very low doses of environmental estrogenic chemicals when dietary doses of naturally occurring estrogenic compounds (phytoestrogens, such as flavonoids) are so much higher? Still higher doses of estrogenic chemicals are ingested in the form of oral contraceptives and post-menopausal hormone replacement therapy. The National Research Council has established a Committee on Hormone-Related Toxicants in the Environment to assess their known and suspected modes of action and their potential impacts on wildlife and humans. EPA’s Health Effects Research Laboratory has been working to identify those modes of action for some years, and the Chemical Industry Institute of Toxicology has announced that a portion of their budget has been reallocated to initiate a program of research on endocrine effects. The Commission supports giving priority to the scientific assessment of the potential toxicity of this class of chemicals.

Given the divergent views about the situation, the history of litigation, the advances in the world of testing and toxicologic interpretation, and the willingness of all parties to engage in dialogue, the Commission recommends that EPA, industry, academia, and worker, consumer, and environmental organizations be convened in a sustained stakeholder process to review TSCA and its implementation, to propose criteria for developing test batteries, to seek consensus on making weight-of-evidence judgments about such data, to define criteria for making data more accessible to the public, and to consider analogies to the FDA adverse drug reaction reporting scheme.

The EPA Office of Water has responsibility for protecting the nation’s surface water and ground water and ensuring the supply of safe drinking water for the public. The Clean Water Act was enacted in 1972, soon after the dramatic incident in which the Cuyahoga River in Ohio caught fire because it was so polluted. Water quality has improved substantially since then; nevertheless, about 35% of America’s surveyed rivers, lakes, and streams still do not meet standards for their designated uses (OECD 1996). Point sources of pollution have been controlled to a great extent; now state water quality managers have identified nonpoint sources, such as urban and agricultural runoff, as the largest contributors to water quality problems.

The Clean Water Act regulates point-source and nonpoint-source discharges of pollutants to the waters of the United States. States establish water quality standards based on the designated use of a water body—such as providing fish for consumption, agriculture, or drinking water—and on the quantitative or narrative water quality criteria that are required to support a particular use. Point sources obtain permits for discharges based on available treatment technologies and on the quality of the water receiving the discharge and its designated use. Effluent guidelines for a particular point source are based either on available technology or on water quality. Technology-based effluent guidelines set a consistent, industrywide level of control and are imposed at the point of discharge; if they prove to be inadequate to meet the water quality standards for a particular body of water, additional controls are implemented to meet effluent limits based on water quality. Effluent limits have been established for over 100 pollutants discharged by 51 categories of industry and are based on the best available technology that is economically achievable. For nonpoint sources of water pollution, states use grants from EPA to develop control programs, usually providing for implementation of best management practices.

The Safe Drinking Water Act of 1974, most recently amended in August 1996, requires EPA to set drinking water standards to protect human health from both naturally occurring and anthropogenic contaminants, and it specifies requirements for water treatment. Standards have been formulated for more than 80 contaminants. As a result of the 1996 amendments, EPA must establish a priority list of unregulated contaminants and gather information on the magnitude of their risks and their occurrence in the water supply. Every five years, EPA must set standards for at least five of the unregulated contaminants that have been listed and studied. The new law also requires the agency to prepare a benefit-cost analysis, and benefits of new standards must justify their costs unless the agency determines that the risk to human health outweighs the cost justification. As recommended in the Commission’s testimony to the Senate and citied in the Senate Committee report accompanying the 1996 amendments, the act also recognizes that cost and risk are not the only factors that need to be considered in evaluating environmental programs and that other factors, including values and equity, must also be considered. The importance of safe drinking water was brought home to the general public in April 1993 when Cryptosporidia in the Milwaukee water supply caused an epidemic, resulting in deaths and severe intestinal disorders throughout the city.

The following recommendations are intended to build on the important improvements of the last 25 years in surface water, groundwater, and drinking water.

The Clean Water Act regulates sources of pollution in a manner that has resulted in fragmented programs that do not adequately address the health of the watershed ecosystem or sufficiently involve communities, states, and others in multijurisdictional management and protection of water quality.

The Clean Water Act should be amended to establish a comprehensive, integrated watershed management approach to provide for the development of state watershed programs. The state programs should be subject to EPA approval and oversight and have substantial involvement by stakeholders and other appropriate federal, state, and local agencies.

Over the last 25 years, pollutant discharges into the nation’s rivers, lakes, estuaries, coastal waters, and wetlands have been greatly reduced. Much of the success has been achieved through the control of municipal and industrial point-source discharges into water bodies under programs established by the Clean Water Act. The health of an aquatic ecosystem can be affected not only by point sources of pollution but also by nonpoint sources such as urban and agricultural runoff, as well as by activities that disturb the land, including logging and grazing, construction (especially of dams and reservoirs), diversion of surface water and ground water flows for domestic and agricultural uses, overfishing, introduction of exotic species into water bodies, and deposition of air pollutants. Russell Jim of the Yakama Indian Nation spoke to the Commission about the contribution of several of such phenomena to the decline of salmon populations in the Pacific Northwest. The clean water programs take a fragmented approach to those problems and do not provide for integrated environmental management of the watershed ecosystem. As noted in comments to the Commission from Michael Evans, general counsel for the Senate Environment and Public Works Committee, a multimedia approach to watershed management has been a priority of Senator Max Baucus (D-MT). With a watershed management approach, ecosystems and human health could be better protected from the cumulative effects of a multitude of natural and human activities.

The watershed management approach is a comprehensive, geographically based approach that recognizes all resources within a hydrologically defined watershed as parts of an interconnected system that depends on the health of the parts to sustain the healthy functioning of the ecosystem. Ecological risk assessment and the index of biotic integrity (see page 77) can be important tools in identifying stressors of the watershed and characterizing their impact on various plant and animal species. For example, ecological risk assessment case studies being examined by the Office of Water include a wide array of ecological organizations, such as individuals, communities, habitats, landscapes, and ecosystems. The watersheds examined include the Snake River, the Middle Platte River, Waquoit Bay, and Big Darby Creek.

Watershed management should focus on identifying priorities and tailoring solutions to the specific set of problems found in a watershed. The estuary programs in Tampa Bay and Galveston Bay are good examples of government and citizen participation in a process that identifies high-priority environmental problems for the estuaries and institutes action to ameliorate the problems. Those two programs are also good examples of a multimedia approach to environmental problems, as atmospheric deposition was found to be an important source of potential water pollution in both locations.

Achieving greater efficiency and effectiveness through watershed management will depend on building partnerships and integrating federal, regional, state, tribal, territorial, local, and private programs within the watershed.

Regulation of water pollution under the Clean Water Act is generally implemented through effluent limits based on technology and water quality. Ecologic and human health risk assessments provide information that is used to help set effluent limits based on water quality and criteria for receiving water quality. Risk assessments are also used to set regulatory priorities.

EPA and the states should continue to use receiving water quality and risk assessment results (and other considerations) to set priorities for the development of various water pollution control programs. Risk assessment should also be used, where appropriate, to establish water quality criteria and effluent limits based on water quality. Risk-based effluent limits should not yet supplant technology and water quality based approaches for reducing water pollutant discharges and protecting water quality, however.

Risk assessment provides useful information for making decisions about the best ways to control water pollution. EPA uses human health risk assessment to derive water quality criteria intended to protect human health. In contrast, ecologic risk assessment is not yet likely to afford adequate descriptions of risks to complex aquatic systems (see Ecological Risk Assessment on page 77). The impacts of endocrine "disruptors" on fish and on the offspring of fish-eating animals, for example, have not been fully assessed. As an emerging tool, ecological risk assessment has not yet reached the level of sophistication and reliability necessary to support its use as the primary determinant of effluent limits based on water quality.

Methods to assess microbial risks associated with drinking water are too limited for general use, and data on risks associated with microorganisms, disinfectants, and disinfection byproducts are sparse.

EPA should give a higher priority to the improvement and application of methods for assessing waterborne microbial risks. The development of data for assessing the occurrence of and risks from microbial contamination and the relationships to the use of disinfectants that form potentially hazardous disinfection byproducts must also be given priority.

Evaluating drinking water quality includes assessing both microbiologic risks and risks associated with disinfectants and disinfection byproducts. Microbiologic contamination of drinking water supplies poses a clear threat to public health when treatment is inadequate. In response to the threat, EPA is developing a risk assessment paradigm for evaluating human risks associated with waterborne pathogens. Efforts to reduce potential health risks associated with disinfection byproducts must not compromise the microbiologic quality of drinking water.

A 1992 regulatory negotiation effort recently produced the Information Collection Rule, which establishes monitoring and data reporting requirements for large public water systems for EPA to use in setting various drinking water standards. Implementation of the rule is hoped to lead to greater understanding and better characterization of the risks associated with microorganisms, disinfectants, and disinfection byproducts. Additional data and analysis of those risks are needed for the next generation of drinking water standards. Because implementing new standards is expensive and because a large proportion of the United States population is exposed, research should be focused on characterizing risks related to different disinfectants and disinfection byproducts and comparing them with microbial risks so that the agency can target its activities toward the greatest net risk reduction.