PENDUGAAN RISIKO EKOLOGIS

1. MK. METIL KAJIAN LINGKUNGAN PENDUGAAN RISIKO EKOLOGIS smno.psdl.pdkl.ppsub2013

2. LINGKUP & BATASAN Pendugaan risiko ekologis adalah pendekatan konseptual dan metode khusus untuk menduga risiko ekologis ytang ditimbulkan oleh lokasi-lokasi yg tercemar . Lokasi tercemar adalah lokasi-lokasi yang tercemar oleh limbah buangan atau oleh kekeliruan penggunaan bahan kimia atau oleh aktivitas manusia lainnya.

3. Pengertian ini meliputi lahan-lahan yg tercemar oleh pembuangan limbah di permukaan dan bawah-permukaan; air permukaan dan sedimen yang tercemar oleh buangan limbah cair atau penimbunan limbah-padat; serta lahan-lahan dan perairan yang tercemar oleh aktivitas transportasi darat, air/ laut dan udara.

4. PENDUGAAN RISIKO EKOLOGI = Ecological risk assessment (ERA) MERUPAKAN PROSES menghimpun, mengorganisir, dan menganalisis informasi untuk memperkirakan efek-efek yang tidak diinginkan terhadap organisme (nonhuman) , populasi atau ecosystems. Metode ini dikembangkan pada tahun 1980-an untuk memberikan landasan bagi pengambilan keputusan lingkungan, metode ini setara dengan metode “human health risk assessment”. Metode pendugaan ini dikembangkan berdasarkan pengalaman dalam menerapkan metode-metode : Human health risk assessment, Environmental hazard assessment, dan Environmental impact assessment . All varieties of risk assessment are based on the recognition that decisions must be made under conditions of uncertainty and that the desirability of alternative outcomes depends on their likelihood as well as their utility.

5. Tujuan utama dari pendugaan risiko ekologis di lokasi-lokasi yang tercemar adalah untuk menyediakan informasi yang diperlukan bagi pengambilan keputusan tentang rehabilitasi / pemulihan kembali lokasi tercemar tersebut.

6. Ada dua tujuan lain dari pendugaan risiko ekologis, selain yang terkait dengan pengambilan keputusan rehabilitasinya, yaitu: Pertama adalah PENGUNGKAPAN MISTERI Publik ingin mengetahui apa saja dampak yang mungkin ditimbulkan oleh pencemaran lingkungan dan manfaat apa yang dapat diperoleh dari rehabilitasinya. Ke dua adalah pendugaan KERUSAKAN . “Siapa yang menimbulkan pencemaran suatu lokasi berkewajiban memberikan kompensasi atas kerusakan lingkungan yg tidak dapat di-remediasi” atau “di-rehabilitasi” . Paling tidak ada tiga sarana untuk menyatakan risiko ekologis yg lazim digunakan untuk mendukung keputusan-keputusan remediasi / rehabilitasi.

7. 1. Menentukan apakah baku-mutu risiko telah terlampauai Baku mutu risiko ini biasanya dituangkan dalam bentuk peraturan perundangan, mulai dari pusat hingga daerah-daerah, termasuk konvensi yang tidak etertulis. Baku mutu ini ditetapkan “berbasis risiko” dalam arti bahwa mereka ditetapkan sesuai dengan konsentrasi bahan pencemar yang diperkirakan akan menimbulkan dampak minimal terhadap komunitas akuatik di perairan atau lingkungan lain.

8. 2. KELEMAHAN BAKU-MUTU BERBASIS RISIKO Kelemahannya, baru tersedia baku-mutu untuk beberapa jenis bahan kimia, tidak berlaku untuk media lain (selain air) , tidak berkaitan dengan efek-efek khusus, dan hanya mempunyai sedikit sekali dara p[rediktif pada lokasi-lokasi tertentu. Baku mutu untuk air dan media lainnya telah dikembangkan di beberapa negara, seperti Canada, Europe, dan USA. Mengingat penggunaan baku mutu ini relatif cepat, mudah, dan mudah pengamanannya, maka metode ini cepat menjadi populer. Akan tetapi karena kriteria yang tersedia masih terbatas, maka tidak dapat digunakan untuk pendugaan reseptor dan pencemar secara generik.

9. Estimate the likelihood of exceeding some risk level that is a threshold for regulatory significance For example, the parties to a remedial decision may agree that remediation is called for if the abundance of fish in a stream contaminated by leachate is reduced by at least 20%. This type of expression of assessment results has been called for by the EPA Office of Solid Waste and Emergency Response (OSWER) (Quality Assurance Management Staff, 1994). The ease of generating this assessment result depends on the magnitude of site effects relative to the threshold. For example, if the fish abundance in the contaminated stream is less than 0.1/m of stream reach and all reference streams have at least 5/m, the level of effect clearly exceeds the 20% threshold.

10. 3. Estimasi Risiko Yaitu estimasi distribusi peluang dari dampak atau tingkat-dampak dengan peluang kejadian tertentu. For example, one might estimate that the most likely (50th percentile) effect is a 10% reduction in fish abundance, but the worst case estimate (90th percentile) is that fish abundance is reduced by as much as 60% relative to an uncontaminated state. This is clearly the most difficult form of output to generate with any confidence. Kalau risiko remediasi harus diseimbangkan dnegan risiko pencemar, atau kalau semua kerusakan akibat pencemaran dikumpulkan, maka tingkat dampak dapat diperkirakan.

11. Tujuan utama dari smeua analisis ini adalah untuk mendukung tindakan-tidakan remediasi. • Alternatif REMEDIASI meliputi: • Pengambilan limbah atau media yang tercemar untuk dibuang atau diolah , • Pengolahan limbah di tempat dengan menerapkan perlakuan-kimiawi • Memacu degradasi biologis, isolation atau redirection (e.g., grout curtains), • Immobilization di tempat(e.g., grout injection), • Kontrol Land-use • Paparan Ekologis, penutupan lokasi tercemar dengan suatu penutup tertentu • No action (remediasi melalui proses-proses degradasi alamiah atau pengenceran alamiah).

12. Untuk dapat mendukung keputusan remediasi, pendugaan risiko harus menyediakan informasi mengenai media apa atau limbah apa saja yang memerlukan remediasi , serta kriteria apa (mis., konsentrasi yg hareus dicapai atau luas daerah yang harus ditutup) yg akan dapat mengurangi risiko hingga tingkat yang telah ditetapkan.

13. KERANGKA ANALISIS ECO-RISK Semua pedoman dan aturan tentang remediasi lokasi tercemar yang berlaku menurut peraturan-perundnagan digunakan sebagai sarana untuk menentukan dampak lingkungan apa saja yang perlu di-remediasi. One of the defining features of ecological risk assessment is the standard framework which has evolved from the National Research Council framework for human health risk assessment (National Research Council, 1983) Kerangka analisis lazimnya terdiri atas: Tahapan perumusan masalah, Tahapan analisis , dan Tahapan karakterisasi Risiko. Apa saja komponen dari Kerangka Analisis ini, sangat beragam. Akan tetapi pedoman umum adalah berikut ini.

14. Kerangka Analisis Pendugaan Risiko Ekologis (EPA, 1998). Perencanaan: Penduga Risiko/ Manajer Risiko/ Stakeholder Mengkomunikasikan hasil-hasil analisis kepada Manager Risiko Manajemen Risiko dan mengkomunikasikan hasil-hasilnya kepada pihak-pihak yg berkepentingan

15. Perumusan masalah : Merupakan fase p[erencanaan dan pembatasan masalah Tahapan ini meliputi: 1. Mengintegrasikan semua informasi yang tersedia — Merangkum semua informasi tentang sumber-sumber, bahan pencemar, pengaruh & dampak, dan lingkungan reseptor dampak. 2. Pendugaan Kondisi-Akhir — Mendefinisikan secara operasional nilai-nilai lingkungan yang harus dilindungi. 3. Penyusunan Model Konseptual — Menyusun deskripsi tentang hubungan hipotetik antara limbah dengan reseptor akhir . 4. Rencana Analysis — Menyusun suatu rencana untuk memperoleh data yang diperluakn dan melakukan pendugaan risiko. Analysis merupakan tahapan dimana dilakukan evaluasi teknis data tentang paparan dan dampaknya

16. KARAKTERISASI • KOMPONEN PAPARAN • 1. UkuranPaparan — Results of measurements indicating the nature, distribution, and amount of the waste and its components at points of potential contact with receptors • AnalisisPaparan — A process of estimating the spatial and temporal distribution of exposure to the contaminants • ProfilPaparan — A summary of the results of the exposure analysis

17. KARAKTERISASI KOMPONEN DAMPAK 1. UkuranDampak — Results of measurements or observations indicating the responses of assessment endpoints to variation in exposure 2. Analisisresponekologis — A quantitative analysis of the effects data 3. Profil Stressor–respon — The component of the ecological response analysis that specifically deals with defining a relationship between the magnitude and duration of exposure and relevant effects

18. KARAKTERISASI RISIKO merupakan fase dimana hasil-hasil dari fase analisis diintegrasikan untuk memperkirakan dan mendeskripsikan risiko-risiko. Tahapan ini terdiri atas: 1. Estimasi Risiko — The process of using the results of the analysis of exposure to paramaterize and implement the exposure–response model and estimate risks and of analyzing the associated uncertainty 2. Deskripsi Risiko — The process of describing and interpreting the results of the risk estimation for communication to the risk manager

19. MANAJEMEN RISIKO merupakan proses s, in this context, the process of making a decision concerning the need for remediation. Proses ini dilakukan pada dua titik dalam kerangka analisis. 1. Pada awal pendugaan, the risk manager provides policy input to the problem formulation. 2. Pada akhir pendugaan, the risk manager learns the results of the risk analysis and makes a decision. Manajemen risiko adalah proses pengukuran atau penilaian risiko serta pengembangan strategi pengelolaannya. Strategi yang dapat diambil antara lain adalah memindahkan risiko kepada pihak lain, menghindari risiko, mengurangi efek negatif risiko, dan menampung sebagian atau semua konsekuensi risiko tertentu. Manajemen risiko tradisional terfokus pada risiko-risiko yang timbul oleh penyebab fisik atau legal (seperti bencana alam atau kebakaran, kematian, serta tuntutan hukum).

20. PROSES REMEDIASI Pendugaan risiko ekologis merupakan suatu komponen dari prose remediasi yang meliputi beragam kegiatan perencanaan, sampling, analysis, remediation, dan aktivitas rekayasa, semuanya ditujukan untuk mengubah lokasi menjadi kondisi yang normal. Asesor Risiko Ekologis harus terlibat dalam semua tahapan proses remediasi. BIOREMEDIATION TECHNOLOGIES IN SOIL. 1. Criteria for bioremediation 2. Land farming 3. Phytoremediation 4. Bioventing

21. Diagram alir proses pemulihan kembali lokasi yang tercemar Karakterisasi lokasi dan Pelingkupan Perumusan Masalah Rencana Analisis Sampling & Analisis Baseline Pendugaan Risiko EKologis Pendugaan Alternatif Penyembuhan Rencana Kegiatan & Minat Publik Keputusan-keputusan Tindakan2 Penyembuhan/ Pemulihan Pemantauan Pasca Pendugaan Kerusakan Pendugaan Efikasi

22. This diagram does not include identification of candidate sites or the document review and revision processes, which typically occur after the production of each plan or assessment document. Although it is valuable in theory to assure that the assessors are not going off on a wrong course, it is the authors’ experience that risk managers and the staffs of regulatory agencies are overcommitted and often perform few or superficial reviews of intermediate products.

23. Proses remediasi yang bersifat general ini tidak dapat digunakan untuk menangani bencana (emergency responses). If a site is contaminated by a spill of a hazardous material, spending a period of months planning, seeking regulator review comments, gathering ecological data, etc. while the contaminant spreads from the spill site would be inappropriate. Rather, existing emergency response plans should be implemented to contain and remove the material quickly. If there is residual contamination following the emergency response, this process may be used to assess and remediate it.

24. KARAKTERISASI LOKASI & PELINGKUPAN Before an ecological risk assessment can be performed, it is necessary to have a basic understanding of the nature and extent of contamination, potential routes of exposure, and ecological resources present at the site. Tinjauan lapangan ke lokasi dan survei pendahuluan (pengenalan) harus dilakukan , dan harus dapat dihimpun informasi tentang kondisi lokasi dan sejarah keberadaan dan dinamika lokasi tersebut.

25. Pengenalan lokasi meliputi kunnjungan lokasi dan mendeskripsikan karakteristik fisik lokasi (topography, geology, hydrology, anthropogenic structures, and other features that would affect transport and fate); Sumber potensial pencemar, seperti drums, lagoons, dan pipes; Tipe-tipe komunitas ekologis , ukuran besarannya, dan kondisi aktual yang sedang berlangsung.

26. In addition to the field reconnaissance, local experts should be consulted, local residents and employees should be interviewed, and information should be collected from existing sources such as aerial photographs, maps such as wetland inventories and endangered species range maps, and prior assessments of the site or nearby sites. Previous remedial actions taken at the site that have affected the environment, such as capping of landfills, should also be described. If data concerning the composition and concentration of the contaminants in site media are unavailable from existing information, reconnaissance sampling and analysis may be performed. Sampling harus difokuskan pada sampel untuk analisis spektrum luas atau sampel lokasi yang paling menderita parah.

27. Alternatively, portable devices such as photoionization detectors (PIDs) may be used to provide rapid, broad-spectrum analytical data. Data yang dihimpunselamastudipendahuluanpengenalanlokasiharusdigunakanuntukmelakukanpelingkupandalammempersiapkanrencanaprosespendugaansecarakeseluruhan Informasi yang tersediadapatdipakaiuntukmenentukanapakahadabahayapotensial yang mengancam. If there is sufficient information concerning the concentrations of contaminants on the site, a screening assessment may be performed, instead of the scoping assessment, to identify the hazard and narrow the scope of the assessment.

28. PROSES PERUMUSAN MASALAH The problem formulation defines the purpose, scope, and goals of the assessment, as well as the methods by which it will be performed. Its products include the assessment endpoints, the conceptual model, and the analysis plan. Perumusan masalah harus dilakukan secara kolaboratif

29. The ultimate arbiter of the scope, methods, and content of the assessment is the decision maker who is responsible for the remedial decision. The other necessary participants in the problem formulation are the technical experts who will prepare the analysis plan and carry out the assessment. Potential additional participants include representatives of the responsible parties, resource agencies, and local citizens. Typically, a screening assessment is performed to determine the nature and scope of the assessment problem • DERAJAT PENTINGNYA DAMPAK • Kriteria Dampak Penting (PP No 27 1999, Pasal 5 ayat 1): • Jumlah manusia yg terkena dampak • Luas wilayah persebraan dampak • Intensitas dan lamanya dampak berlangsung • Banyaknya komponen lingkungan lain yg terkena dampak • Sifat komulatif dampak • Berbalik (reversible) atau tidak berbaliknya (irreversible) dampak • Rentang sekala yang digunakan: • 1 = kurang penting 2 = Cukup penting • 3 = Penting 4 = Lebih penting • 5 = Sangat Penting

30. RENCANA ANALISIS The analysis plan (RI work plan) explains how the decisions made during the problem formulation process will be implemented. A screening ecological risk assessment is typically included in the analysis plan to provide a technical justifi- cation for the scope of ecological sampling, analysis, and assessment activities. The analysis plan is a plan for obtaining the data needed for the baseline assessment, as identified in the problem formulation process, and a plan for using those data to assess ecological risks. KARAKTERISASI RISIKO is the phase in which the results of the analysis phase are integrated to estimate and describe risks. It consists of: 1. Estimasi risiko: The process of using the results of the analysis of exposure to paramaterize and implement the exposure–response model and estimate risks and of analyzing the associated uncertainty 2. Deskripsi Risiko: The process of describing and interpreting the results of the risk estimation for communication to the risk manager

31. ITERASI DALAM PENDUGAAN RISIKO The ecological risk assessor must ensure that the proposed activities will in fact fill the needs of the assessment by consulting with the authors of the sampling and analysis sections and by authoring a plan for performing the baseline ecological risk assessment using that data set. If the site is poorly characterized by existing data, the assessment may be carried out in phases. That is, a Phase 1 sampling and analysis program may be defined and carried out, which provides the basis for planning a more-focused second phase. This sequence requires that the results of the Phase 1 studies be used to conduct a screening assessment, which is used to identify any data gaps that must be filled in Phase 2. Berapapun iterasi yang diperlukan, dapat dilakukan dalam tahapan planning, sampling dan analysis, serta tahapan pendugaan risiko . However, few schedules or budgets permit more than two phases, and few sites are so complex as to require them.

32. BASELINE • ECOLOGICAL RISK ASSESSMENT • In contrast to the screening assessment, which defines the scope of the baseline assessment, the baseline assessment uses new and existing data to evaluate the risk of leaving the site unremediated. • Tujuan kegiatan baseline ini adalah untuk menentukan : • if significant ecological effects are occurring at the site, • the causes of these effects, • the source of the causal agents, and • the potential future risks from leaving the system unremediated.

33. Analisis baseline ini menyediakan informasi ekologis untuk menentukan perlunya remediasi. The baseline risk assessment is part of the remedial investigation. Because the baseline assessment focuses on a smaller number of chemicals and receptors than the screening assessment, it can provide a higher level of characterization of toxicity to the populations and communities at the site. In the baseline ecological risk assessment, a weight-of-evidence approach should be employed to determine if and to what degree ecological effects are occurring or may occur.

34. Most baseline ecological risk assessments focus primarily on current risks. Pendugaan risiko di masa mendatang diperlukan kalau: 1. Paparan bahan pencemar diperkirakan semkain meningkat di masa mendtaang (e.g., a contaminated ground water plume will intersect a stream) 2. Suksesi biologis diperkirakan dapat meningkatkan risiko (e.g., a forest will replace a lawn) 3. Natural processes will result in significant recovery in the near term without remedial actions (i.e., the expense and ecological damage associated with remedial actions may not be justified)

35. ALTERNATIF REMEDIASI If significant risks to humans or ecological receptors are found by the baseline risk assessments, it is necessary to assess the remedial alternatives. This is referred to as the feasibility study. For the no-action alternative and for those alternatives that simply limit human access to and use of the site, the risks are those identified in the baseline ecological risk assessment. Other remedial alternatives actively reduce site contamination but also cause physical disturbances, which have their own ecological risks. These remedial risks include destruction of the biotic communities on the site and on uncontaminated sites for borrow pits, landfills, roads, laydown areas, parking lots, etc.

36. The remedial ecological risk assessment must consider these direct effects, secondary effects such as erosion and habitat fragmentation, and the expected rate and degree of recovery of the disturbed areas given the site management and expected land uses. The importance of assessing remedial risks is demonstrated by the record of decision (ROD), in which contaminant levels that are estimated to constitute a significant risk to shrews and wrens, but not humans, were left in place because the potential remedial actions would result in destruction of riparian forests and wetlands. That is, the remedial risks exceeded the baseline risks. The results of this assessment are used to develop a proposed plan for remediation. That plan is presented to the public for review and comment. The results of this process are used to revise the plan, which is then incorporated into the ROD.

37. PENDUGAAN EFIKASI Pendugaan Risiko EKologis yang dilakukan setelah selesainya kegiatan remediasi biasanya untuk memenuhi persyaratan legal atau untuk tujuan kelestarian lingkungan . Kalau kegiatan remediasi maninggalkan sisa/residu pencemar di tempat, dan bukannya menghilangkannya atau mendegradasikannya , pihak yang berwenang diharuskan memantau lokasi remediasi dan setiap lima tahun melakukan pendugaan efikasi kegiatan remediasi ditinjau dari proteksi kesehatan manusia dan lingkungan, hingga dimungkinkan penggunaan lokasi yang telah diremediasi secara aman.

38. The nature of this monitoring and assessment activity is specified in the ROD. However, the monitoring required is usually minimal and focused on human health risks. Therefore, the site owner must, to meet planning and site-stewardship needs, determine whether additional monitoring is needed to ensure that risks to environmental resources have been sufficiently reduced.

39. Both the legal requirement and the environmental stewardship goals require the collection of data to characterize the post-remedial condition and to estimate levels of effects. All of the techniques that were applied to earlier stages of the assessment could be employed at this stage. However, efficacy assessments are typically based on a minimal monitoring program that is focused on one or a few critical issues. The data analyses are also typically minimal and are focused on clearly defined criteria for acceptable risk.

40. Alternatif Hasil-hasil dari Proses Pendugaan EFIKASI : (1) RISIKO MINIMUM, proses pendugaan dan remediasi dapat berakhir; (2) RISIKO SIGNIFIKAN, diperlukan remediasi lebih lanjut; (3) RISIKO TIDAK MINIMAL, tetapi tidak memerlukan remediasi tambahan, sehingga lanjutkan pemantauan .

41. PENDUGAAN KERUSAKAN The Natural Resource Damage Assessment (NRDA) provisions of CERCLA require that the residual injuries, following remediation, be assessed so that natural resource trustees can be compensated for lost natural resource services. The purpose is to use the funds to restore the environment to provide the lost natural resource services. To be efficient and to ensure that remedial actions are taken which avoid excessive payments of natural resource damages, NRDA should be integrated with the rest of the CERCLA process. Therefore, results of the baseline and remedial alternatives risk assessments are important input to the NRDA, and selection of assessment endpoints which are also “natural resource services” could save assessment costs and damage payments. While this integration is logical and would be cost-effective, it is complicated by the fact that, except for informing the natural resource trustees, the EPA does not participate in NRDA activities. Therefore, NRDA is not explicitly addressed in the EPA Data Quality Objectives (DQO) process or in RI/FS-related documents that are reviewed by the EPA.

42. PELINGKUPAN, PENAPISAN DAN PENDUGAAN DEFINITIF In general, ecological risk assessments are performed in phases or tiers, including scoping assessments, screening assessments, and definitive baseline assessments. The successive tiers each require more time and effort. Scoping assessments determine whether an ecological risk assessment is needed; screening assessments determine what contaminants, media, and receptors need to be assessed; and definitive assessments determine the nature and magnitude of risks. Each tier of risk assessment should include all three phases: problem formulation, analysis, and risk characterization. Even the most hurriedly performed scoping assessment should define the nature of the problem, analyze available information on exposure and effects, and explain how they are potentially related. The purpose of tiers of assessment is to perform the assessment as efficiently as possible by performing only the number of assessment activities needed to reach an informed decision. At any point the assessment process might end because the risks are clearly unacceptable or are clearly negligible. Scoping assessments determine whether a formal ecological risk assessment is needed by ascertaining whether there is a potential for current or future exposure of ecological receptors.

43. There are several questions to be answered. • Is there a source of contaminants? The apparent waste may be innocuous, there may actually be no waste, or the waste may have been removed by prior actions. At one Oak Ridge unit, the waste was merely construction rubble. • (2) Are there currently or might there be in the future ecological receptors on the contaminated site? In some cases, there is no complete pathway from the contaminants to an ecological receptor, because the contamination is limited to an industrial facility or an inactive industrial site that will be returned to industrial use or converted to commercial use (i.e., a brownfield). In those cases the site has little ecological value and is not expected to have significant ecological value under future land uses. There is no complete pathway on the site because there are no significant receptors. • (3) Could movement of the contaminants result in significant exposure of ecological receptors off the site? The principal concern is with contamination of surface waters and wetlands through runoff or lateral groundwater movement. Groundwater contamination is not normally a basis for performing an ecological risk assessment unless the groundwater intersects the surface or the near-surface root zone.

44. Screening assessments go beyond scoping assessments by asking whether the identified pathways from the contaminants to ecological receptors could result in toxicologically significant exposures. Screening allows assessors to focus resources by first applying rapid and conservative assessment techniques to screen out sites, portions of sites, media, or chemicals that clearly pose minimal risks. More time and effort can then be devoted to definitive assessments that provide risk estimates by applying more realistic and site-specific analyses to those hazards that have not been screened out. Chemicals that are retained by the screening process are termed chemicals of potential ecological concern (COPECs). Screening assessments should be conservative and as broad as is reasonably possible so that no potential hazards are overlooked.

45. The screening phase may itself be performed in tiers. For example, a screening assessment may be performed using a relatively small set of preliminary data for the purpose of determining what sampling and analysis needs to be performed. The new data should then be used in a screening assessment to determine which hazards should be modeled and analyzed in detail in the definitive assessment. In general, data gaps identified in screening assessments should be treated as a basis for including a hazard in the definitive assessment. Receptors that may occur on the site but are unconfirmed and routes of exposure that are credible but have not been investigated should be retained. Treating unknowns in this manner results in a more credible assessment. If screening assessments have identified credible hazards to ecological receptors, a definitive assessment must estimate risks and identify preliminary remedial goals.

46. PENDUGAAN DEFINITIF Definitive assessments should replace conservative assumptions with best estimates of exposures and effects and associated uncertainties. Because previous tiers of assessment will have reduced the scope of the definitive assessment by identifying contaminants, media, and receptors that constitute credible hazards, it should be possible to devote sufficient time and resources to their assessment. In general, additional testing and analysis reduce uncertainties and increase realism, thereby reducing the need to overremediate to ensure protection. Definitive assessments are not normally performed in tiers unless the assessment process reveals potentially significant pathways and receptors that were missed by the screening assessments.

47. The phased assessments performed at contaminated sites require a different logical approach from the tiered assessment schemes developed to assess risks from new chemicals. The latter schemes are based on the performance of brief and inexpensive tests and simple exposure models in the first tier and performance of more expensive and realistic tests in higher tiers if assessments based on lower tiers are inconclusive. However, the acute lethality tests used in the early tiers of those assessment schemes cannot be used to determine acceptability of risks at a contaminated site. For example, if a soil from a contaminated site is acutely lethal to plants, one can conclude that there are potentially significant risks. However, if the soil is not acutely lethal, one cannot conclude that there are no potentially significant risks. The soil may in fact be lethal in longer exposures or may reduce growth or seed production. In hazard assessment schemes, the insensitivity of traditional early tier tests is compensated for by applying safety factors to the test endpoints (e.g., median lethal concentration, LC50s) and by using conservative assumptions in the transport and fate models. However, when testing contaminated media, those techniques are not applicable. Therefore, one must begin with a sensitive test in order to avoid falsely concluding that there are no significant risks.

48. Tiered assessment schemes for ecological risk assessment are more complex than those for human health risk assessment because of the multiple lines of evidence that are available to ecological assessors. Risk Based Corrective Action (RBCA) scheme prescribes that the assessment is performed by comparing modeled or measured exposure levels for individual chemicals in air, soil, and groundwater to defined levels that constitute thresholds for significant human risk. In RBCA, three tiers of exposure values are defined by use of (1) generic values, (2) easily derived sitespecific values, and (3) values derived by complex and extensive site-specific analyses. Ecological risk assessors perform similar analyses but also employ toxicity tests of contaminated media from the site and surveys of biota at the site. Surveys range from analyses of body burdens and biomarkers to surveys of species composition and abundance. Any of these lines of evidence may be employed in any tier of the assessment, depending on the availability of data, the availability of time and resources to obtain data, or the appropriateness to the source and receiving environment.

49. PENDUGAAN RISIKO KESEHATAN MANUSIA Risikoekologisdanrisikokesehatanmanusiadianggapsamapentingnya, sehinggapendugaannyadapatdilakukansecarabersinergis. Some information and data are likely to be relevant for assessing both human and environmental threats. Common data needs identified during problem formulation should be met in such a way as to avoid duplication of effort. Hal yang sangatpentingialahadanyakoordinasi yang efektifantaraasesorrisikoekologisdenganasesorrisikokesehtaanmanusia, sehinggasmeuadtaadnainformasidapatsalingdiaksesdandimanfaatkansecara optimal.

50. DATA & INFORMASI YANG DIPERLUKAN Common data needs for human and ecological risk assessments are determined by the individual characteristics of the site and by the scale of the assessments. In general, the following data are likely to be useful for both human health and ecological risk assessments. Differences between ecological and human health effects data needs are noted in parentheses.