Dit rapport beschrijft een model voor het gedrag van toxische stoffen die in bodem gebracht worden door verspreiding van baggerspecie. Regelmatig baggeren is een noodzaak in Nederland. Verontreinigingen in de bagger zorgen daarbij voor een probleem. Waar moet de verontreinigde bagger heen? Momenteel wordt een verspreidingsbeleid gehanteerd dat gebaseerd is op verontreinigingsklassen. Dit systeem voldoet niet meer. In het kader van nieuw bodembeleid moet er anders naar dit probleem worden gekeken. Duurzaam gebruik van de bodem moet centraal staan, en gebiedsspecifiek beleid moet mogelijk worden. De bestaande klassenindeling geeft hier geen mogelijkheden voor. In een onderzoek van RIVM, RIZA en Alterra is gekeken naar de risico's die op een lokatie door verspreiding op land kunnen ontstaan. Hiervoor is een systeembenadering opgesteld: waar komen de stoffen vandaan, waar gaan ze heen, welke organismen worden daadwerkelijk blootgesteld, en wat zijn de lokale risico's na verspreiding nu eigenlijk? Hiernaar wordt in drie samenhangende rapporten gekeken. In dit derde rapport van de serie wordt de risicobenadering technisch-wetenschappelijk beschreven. Er wordt voortgebouwd op gegevens uit het tweede rapport, waarin is beschreven of- en hoe stoffen zich ophopen in de landbodem door het verspreiden van baggerspecie. In dit rapport wordt beschreven hoe dientengevolge de risico's van de stoffenmengsels voor mens, landbouwproducten en ecosystemen kunnen veranderen. In het overzichtsrapport van de serie, het eerste rapport, wordt het ontwikkelde beslismodel als prototype gepresenteerd, en worden de gevolgen van beleidsmatige toepassing van het beslismodel verkend.

Voor het nieuwe bodembeleid is een model ontwikkeld dat ingezet kan worden voor lokale besluitvorming over de verspreiding van licht verontreinigde bagger op de kant. Regelmatig baggeren is een noodzaak in Nederland. Verontreinigingen in de bagger zorgen daarbij voor een probleem. Waar moet de verontreinigde bagger heen? Momenteel wordt een verspreidingsbeleid gehanteerd dat gebaseerd is op verontreinigingsklassen. Dit systeem voldoet niet meer. In het kader van nieuw bodembeleid moet er anders naar dit probleem worden gekeken. Duurzaam gebruik van de bodem moet centraal staan, en gebiedsspecifiek beleid moet mogelijk worden. De bestaande klassenindeling geeft onvoldoende inzicht in lokale landbodemrisico's, en sluit niet aan bij het nieuwe beleid. In een onderzoek van RIVM, RIZA en Alterra is gekeken naar de risico's die op een lokatie door verspreiding op land kunnen ontstaan. Hiervoor is een systeembenadering opgesteld: waar komen de stoffen vandaan, waar gaan ze heen, welke organismen worden daadwerkelijk blootgesteld, en wat zijn de lokatiespecifieke risico's na verspreiding nu eigenlijk? Hiernaar wordt in drie samenhangende rapporten gekeken. In het voorliggende overzichtsrapport van de serie wordt het op basis van de systeembenadering ontwikkelde beslismodel gepresenteerd, en worden de gevolgen van toepassing van het beslismodel verkend. In de twee andere rapporten is de technisch-wetenschappelijke aanpak in detail uiteengezet, respectievelijk voor de modellen gebruikt zijn voor de voorspellingen van de concentratieveranderingen in de landbodem, en voor de daardoor veranderende risiconiveaus voor mens, landbouwproducten en ecosystemen.

Regular removal of sediments is a necessity for proper water quantity management in the Netherlands. Sediment contamination causes problems for this. Where can the contaminated sediments be deposited? The New Dutch soil policy aims at the sustainable use of soils, and allows for area-specific regulatory approaches. The current approach, based on sediment classes, does not provide sufficient insight in risks of sediment deposition on land for terrestrial organisms, and does fir the new policy. In a research project of RIVM, RIZA and Alterra, focus was on the site-specific, integrated risk assessment of sediment deposition on land. A systems-approach was designed, so as to model where compounds come from, where they go, and which risks could exist as a consequence. The results of the project are reported in three consecutive reports. In the second report of this series, the systems approach is described, in a basic scientific-technical way. In this third report of the series, the integrated risk assessments for man, agricultural products and ecosystems are described similarly. The first overview report presents the prototype of a decision-support model for sediment deposition on land, including examples of its application.

A methodology based on a tiered (three-step) approach was developed to enable site-specific assessment of risks of soil contamination with asbestos. Along with the presentation of this methodology, we have endeavoured to underpin the Intervention Value for soil remediation for asbestos, which was recently released by the Dutch Ministry of Housing, Spatial Planning and the Environment in its interim policy on asbestos in soil. Because risks to humans after inhalation of asbestos are the most critical, the risk assessment was based on the probability of asbestos fibre emission from soil to air, making a distinction between chrysotile and amphibole asbestos, bound and friable asbestos, and the respirable and non-respirable fraction in soil. Because the behaviour of asbestos in soil is different from the behaviour of any other soil contaminant, the CSOIL exposure model was not used. Instead, use was made of measuring results, i.e. the concentrations of asbestos in soil and air, for deriving the Intervention Value. Guidance on measurement procedures has been incorporated into tiers 2 and 3 of the methodology for determining site-specific human risks.

The Remediation Urgency Method (SUS), a method in the Netherlands to determine the urgency of soil remediation, was introduced in 1994 to prioritise the remediation of contaminated sites in the Netherlands. The methodology is based on human and ecological risk assessment and risks of contaminant migration. Here, the analysis of the restraints in the method are described, focusing on the site-specific risk assessment for humans and contaminant migration. Restraints were established on the basis of interviews with experts and earlier evaluations of the method. Based on the restraints found and estimates on scientific feasibility, options for possible solutions have been prioritised. Besides this, an initial exploration of solutions has been undertaken for some options. For human risk assessment, exploration focused on estimating the oral bioavailability of soil contaminants, and measuring the concentrations in consumption crops and indoor air. A risk assessment framework was developed for risk of contaminant migration, and a tool to assess the leaching of contaminants in the (unsaturated) soil was explored. Studies to improve the site-specific risk assessment of soil contamination are continuing in 2003 and 2004. These focus on overcoming the identified restraints and exploring solutions with a high priority.

The TRIAD approach was tested for its applicability in assessing actual ecological risks on five sites around the zinc factory near the city of Budel, in The Netherlands. The TRIAD method offers the possibility of a tiered approach to actual risks for the local ecosystem. Risk assessment is derived on the basis of three elements, i.e. chemistry, toxicology and ecology. It is meant as an improvement for the present remediation urgency systematics. Three of the five sites were contaminated with zinc and cadmium at different levels, that did not exceed the Dutch 'intervention values'. Besides total soil contents, mobile soil metal fractions and pore-water concentrations were measured during the chemical assessment. Several variants of the toxic pressure calculations were compared. In the toxicological assessment several bioassays were performed, which showed different sensitivities to heavy metals and influence of soil-pH and nutrients. There are still very few tests that can be used for acid sandy field soil. Many soil biological analyses (microbial and soil fauna groups) and a vegetation inventory were used for the ecological assessment. In this field study they showed a larger deviation from the reference site than the chemical and toxicological indicators. From the overall TRIAD assessment it can be concluded, among others, that selection of a non-contaminated reference site is both crucial as well as difficult. Polluted sites generally differ in more aspects from a local reference site than just in the concentration of contaminants. Although the TRIAD approach is relatively time consuming, uniformity and the scientific basis of the actual ecological assessment have improved considerably. Therefore the TRIAD approach is recommended for the future as a standard tool to assess actual ecological risks of contaminated soil.

Dit rapport biedt een bijgewerkt overzicht van de inventarisatie van het Landsdekkend beeld bodemverontreiniging en een raming van de aantallen verontreinigde locaties en spoedlocaties in Nederland. Het RIVM schat het aantal locaties in Nederland waarvan de bodem met spoed moet worden gesaneerd op 6500 tot 7500. Er zijn nog enkele jaren nodig om op basis van bodemonderzoek de exacte aantallen en de precieze spoedlocaties vast te kunnen stellen. Het overzicht is aangevuld met geraamde saneringskosten en risiconiveaus. Nieuw is dat bij de bepaling van de spoedlocaties naast de verontreinigingsbron meer factoren zijn betrokken die de risico's voor de mens bepalen: de manier waarop de bodem wordt gebruikt (huisvesting, industrie, volkstuinen, enzovoort) en de kans op verspreiding van de verontreiniging naar het grondwater (afhankelijk van het bodemtype) Volgens het huidige coalitieakkoord en de prioriteiten van de minister van VROM gelden een aantal gebieden (zoals de veertig wijken in de grote steden, de milieuaandachtsgebieden en de ecologische hoofdstructuur) als aandachtsgebied. Ook voor deze aandachtsgebieden zijn in dit rapport de aantallen locaties bepaald. Er is onderzocht of op de uitvoeringskosten kan worden bespaard door grondwatersaneringen of beheermaatregelen op nabijgelegen locaties te combineren. Het RIVM beveelt aan deze insteek verder te ontwikkelen.

Regular removal of sediments is a necessity for proper water quantity management in the Netherlands. Sediment contamination causes problems for this. Where can the contaminated sediments be deposited? The New Dutch soil policy aims at the sustainable use of soils, and allows for area-specific regulatory approaches. The current approach, based on sediment classes, does not provide sufficient insight in risks of sediment deposition on land for terrestrial organisms, and does fir the new policy. In a research project of RIVM, RIZA and Alterra, focus was on the site-specific, integrated risk assessment of sediment deposition on land. A systems-approach was designed, so as to model where compounds come from, where they go, and which risks could exist as a consequence. The results of the project are reported in three consecutive reports. This overview-report presents the prototype of a decision-support model for sediment deposition on land, including examples of its application. The prototype has not yet been finished, as various regulatory decisions are awaited. In the previous reports, the systems approach is described in a basic scientific-technical way, for the prediction of local concentrations of toxic compounds in soils and the risk levels that will consequently occur for man, agricultural products and ecosystems, respectively.

he human body, the risk assessment of soil contaminants for humans can be improved. Insight into the uptake process is obtained by simulating the human digestion process (in vitro digestion model). In this report a concrete proposal is given for using the knowledge on the uptake of lead in the human body in procedures to assess the soil quality according to the new soil policy (Dutch Soil Protection Act). In addition, risk assessors and policy makers are advised on the situations where performing tests with the in vitro digestion model is desirable. Besides the application in soil policy, the scientific basis of the in vitro digestion model has been described. The experimental results of the experimental model have been compared to human and swine data for the contaminant lead to demonstrate the correctness of the model. In future, international harmonization on the application in soil policy and the methodology to obtain knowledge on the uptake process will become important.

At present, the Remediation Urgency Method can be used in the Netherlands to determine the urgency of remediation for seriously contaminated sites. This methodology includes a site-specific ecological risk assessment based on the presence of contaminants, the sensitivity of the ecosystem with respect to land use, and the dimensions of the contaminated soil surface. A so-called TRIAD to improve ecological risk assessment of soil contamination has recently been developed and validated. Risk assessment with the TRIAD is based on three different angles: 1. the presence of contaminants (chemical angle), 2. results from bioassays using samples from the site (toxicological angle)and 3. ecological field observations (ecological angle). Integration of the results from the three TRIAD angles provides a multiple weight of evidence in the risk assessment, which strongly reduces uncertainties in the ecological risk assessment. The TRIAD, as explained here, is not solely based on chemical soil quality, which overcomes some of the drawbacks of the methodology for determining how urgent remediation is. A preliminary guideline for a simple TRIAD is also presented here. The costs of the assessment and the complexity of the guideline are of the same magnitude as the current methodology to determine the urgency of remediation.