The Dutch groundwater quality monitoring network includes 390 monitoring points. The frequency of sampling is once a year. The objectives of the network are: - to make an inventory of the present quality in relation to soil use, type of soil and hydrogeological conditions ; - to distinguish long term changes in quality ; - to provide data for quality control and groundwater management ; - to indicate the extent of human influence on groundwater quality. This report gives the results of analysis in 1990 from 36 monitoring points in the province of Zuid-Holland.

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A workshop was organized June 10th last by the RIVM and the Directorate-General of Environmental Protection (Ministry of Housing, Physical Planning and Environment) on validation of ecotoxicological derived risk levels for soil ecosystems. The intention of the workschop was to give priorities and to discuss methodological and theoretical possibilities for a research program directed to the validation of risk levels. Several short introductions were given by policy makers and scientists. These introductions are included in this report as separate chapters (2,3,4 and 5). An account of the discussion is given in chapter 6. Reactions received later are incorporated as chapter 7. Conclusions and suggestions are formulated by the organizers of the workshop and presented in chapter 8. The actual procedure used by the ministry for deriving standards for substances in the environment was taken as a departure for discussion. Three aspects to be proved were recognized in this procedure. (1) Field relevance of toxicity data derived in laboratory single species tests. (2) Validation of the assumptions underlying the methodology used for deriving risk levels. (3) Consequences for the ecosystem when the NOEC values for 5 or 50% of the species are exceeded. At short notice validation of all these aspects is unreliable. Since the first aspect was considered as the most basic in the context of the actual procedure and critical for the entire procedure it was advised to direct the limited research potential to this aspect.<br>

This report is one of the background reports of the evaluation report "MINAS en Milieu" It deals with the impact of fertiliser- and manure application in agriculture on the quality of soil (phosphrus) en groundwater (phosphorus/nitrogen). It is based on monitoring data carried out in the period 1984-2000. The report describes the actual status of quality standards with respect to nutrients. The agricultural soils in the Netherlands are in general phosphorus-rich. Nitrate concentrations in groundwater are high in shallow groundwater (in 2000 in sandy areas ca 125 mg/l: more than twice the standard value) but show a decrease since 1995, due to lower N-surpluses in dairy farming. At greater depths, concentrations are lower due to a combination of slow travel time, hydrology and decay (denitrification). In certain areas the abstracted groundwater for public water supply shows an increase of co-products of denitrifiaction e.g. sulphate, metals (nickel) and hardness.<br>

In this report, results are presented of a follow-up study on levels of the seventeen toxic congeners of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (together called 'dioxins') in samples of cow's milk from dairy farms in the vicinity of the municipal waste incinerators (MSWs) at Almaar and Zaandam (the Netherlands). Milk samples were collected at regular intervals over a month's period (27 September - 27 October 1989) and subsequently mixed to time-averaged samples. Levels of dioxins are expressed in picogram 2,3,7,8-TCDD- toxicity equivalents per gram of milk fat (pg TEQ/g). Time-averaged dioxin levels in the milk of five dairy farms in Alkmaar appeared to range between 5.1 and 8.1 pg TEQ/g, 12.1 pg TEQ/g. The dioxin levels in milk of two farms in Alkmaar and of three farms in Zaandam were above the maximum allowable limit of 6 pg TEQ/g. Milk samples (daily milk production) from these farms have been collected on 19 and 20 February 1990. The level in the samples from the farms in Alkmaar were below the 6 pg TEQ/g of September/October. The dioxin level in milk samples from Zaandam were all above the 6 pg-limit and were on average (10.9) not significantly different from the level in time-averaged samples of September/October.<br>

The State Health Inspectorate of the Dutch Ministry of Housing, Spatial Planning and the Environment has commissioned RIVM to develop a method to determine 14C in the waste water of nuclear installations. The report describes the method, measuring both organic and inorganic 14C, and validation.<br>

The economic assessment of priorities for a European environmental policy plan focuses on twelve identified Prominent European Environmental Problems such as climate change, chemical risks and biodiversity. The study, commissioned by the European Commission (DG Environment) to a European consortium led by RIVM, provides a basis for priority setting for European environmental policy planning in support of the sixth Environmental Action Programme as follow-up of the current fifth Environmental Action Plan called 'Towards Sustainability'. The analysis is based on an examination of the cost of avoided damage, environmental expenditures, risk assessment, public opinion, social incidence and sustainability. The study incorporates information on targets, scenario results, and policy options and measures including their costs and benefits. Main findings of the study are the following. Current trends show that if all existing policies are fully implemented and enforced, the European Union will be successful in reducing pressures on the environment. However, damage to human health and ecosystems can be substantially reduced with accelerated policies. The implementation costs of these additional policies will not exceed the environmental benefits and the impact on the economy is manageable. This requires future policies to focus on least-cost solutions and follow an integrated approach. Nevertheless, these policies will not be adequate for achieving all policy objectives. Remaining major problems are the excess load of nitrogen in the ecosystem, exceedance of air quality guidelines (especially particulate matter), noise nuisance and biodiversity loss. This report is one of a series supporting the main report: European Environmental Priorities: an Integrated Economic and Environmental Assessment. The areas discussed in the main report are fully documented in the various Technical reports. A background report is presented for each environmental issue giving an outline of the problem and its relationship to economic sectors and other issues; the benefits and the cost-benefit analysis; and the policy responses. Additional reports outline the benefits methodology, the EU enlargement issue and the macro-economic consequences of the scenarios. This report documents the Nuclear Accidents issue.<br>

The aim of the Substance-Information-System (SIS) project within the RIVM is to reach conformity in the domain of substance-oriented information systems and to gain a clear insight into the status of RIVM with regard to providing substance-oriented information to a third party. In this feasibility study an investigation into the internal situation at the RIVM and the wishes of the clients has been carried out. A growing need for evaluated and reliable information seems to exist with clients. Within this framework the quality of information obtained from the RIVM is highly estimated. In the short term the need for assessment data will increase and integrated risk evaluation will become vital. Clients will want to be able to quickly consult information, preferably on-line and through an intermediary. Within the RIVM no central information system is available. However, a number of laboratories are developing systems locally, that do link up-the task setting of the concerning laboratories as to functionality, though within this framework only partly meet the clients, wishes. Usually clients have free disposal of additional sources of information, however, these sources often do not offer evaluated information. It is recommended to stimulate the development of local data banks with a specific functionality, but at the same time to promote a greater conformity between these data banks. To this end a conceptual data model has to be built. Furthermore, it is recommended to build a central RIVM substance information system, into which selections of data from local RIVM data banks could be recorded and from which data could be made centrally available through an intermediary. Such a system should be managed centrally and a distinct market strategy should be developed. The International Substance-Information-System (SIS) could be chosen as the initial nucleus of such a system. Eventually, a decision has to be made on the mode of handling "confidential" data and how the delineation of the RIVM task setting in providing information to a third party has to be drawn up. In a sequel to the SIS-project recommendations could be further developed and proposals to realise this could be made.

Het Landelijk Meetnet Grondwaterkwaliteit bestaat uit ca. 380 meetpunten die jaarlijks worden bemonsterd. M.b.v. het meetnet wordt inzicht verkregen in de relatie tussen grondwaterkwaliteit en -kwaliteitsveranderingen gerelateerd aan menselijk handelen enerzijds en natuurlijke factoren, zoals bodemgesteldheid en hyrologie anderzijds. De rapportage betreft de analyse resultaten van grondwatermonsters uit 25 meetnetpunten in de provincie Noord-Holland.

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