A novel concept in ground water quality management: Towards function specific screening values.

This paper is meant to initiate and feed the discussion on a more sophisticated procedure for the derivation and use of groundwater screening values (GSVs). To this purpose, the possibilities and tools for the derivation of function specific GSVs, i.e., GSVs that depend on the actual contact of humans and ecosystems with groundwater and groundwater-related mediums, are elaborated in this study. Application of GSVs geared to the specific use and function of specific groundwater volumes could result in a more effective and cost-efficient groundwater quality management, without compromising the protection of human health and the ecosystem. Therefore, a procedure to derive function specific GSVs was developed. For illustrative purposes, risk limits have been derived for human health and ecological protection targets, for arsenic, benzene, methyl tert-butyl ether (MTBE) and vinylchloride. Agriculture and Nature reserves (combined), Residential and Industrial land uses have been considered and two different groundwater management purposes, i.e., curative and sustainable groundwater management. For each of the four contaminants, this results in a series of risks limits for each function and land use combination. It is shown that for all four contaminants higher groundwater screening values are considered appropriate for less sensitive combinations of function and land use. In the process towards (policy) implementation of these function specific GSV, it is recommended to evaluate the selection of protection targets, the scientific basis of the risk assessment procedures applied and the methodology to assess the time factor for groundwater quality assessment, given the fact that groundwater is a dynamic medium. Moreover, protection levels must be harmonized with national or regional groundwater quality standards and correspond with the requirements of the Groundwater Daughter Directive of the European Union Water Framework Directive. Groundwater plumes that are judged as 'no need for remediation' are not compatible with the Water Framework Directive requirement to take actions to prevent or limit inputs of contaminants, even when no receptor is present. However, the European Commission formulated a series of exemptions, to avoid that the "prevent" requirement would imply an onerous and sometimes unfeasible task. The function specific GSVs derived in this study could be used to identify the groundwater volumes that do not result in an unacceptable risk

Guidance on the risk assessment of arsenic in soil for private vegetable gardening

Arseen kan van nature in de grond en het grondwater zitten of daar door activiteiten van de mens in het verleden in terecht gekomen zijn. Wanneer mensen zelf groenten telen, kunnen zij tijdens het tuinieren ongemerkt bodemdeeltjes inslikken. Hierdoor kunnen zij arseen binnenkrijgen. Dat kan ook door de groenten te eten die zijn geteeld op met arseen verontreinigde bodem. Op verzoek van de GGD'en heeft het RIVM een handreiking opgesteld over de beoordeling van de gezondheidsrisico's bij het eten en zelf telen van groenten op bodems die met arseen zijn verontreinigd. Die beoordeling is lastig, omdat onzeker is hoeveel arseen vanuit de bodem in de groenten terechtkomt. Daarnaast is er voor arseen geen actuele waarde voor de 'toelaatbare blootstelling' beschikbaar. De handreiking geeft een indicatie van de waarde die op dit moment het beste als 'toelaatbare blootstelling' voor arseen kan worden gebruikt. De blootstelling aan arseen via het zelf telen en eten van groenten is hierbij hoog ingeschat omdat de opname van arseen door de groenten uit de bodem onvoorspelbaar is. De blootstelling is vervolgens vergeleken met de zogenoemde achtergrondblootstelling aan arseen. Dit is de hoeveelheid arseen waar iedereen aan wordt blootgesteld (namelijk via in de winkel gekochte levensmiddelen als rijst, granen en melk, via drinkwater en mogelijk via andere bronnen), onafhankelijk van lokale bodemverontreiniging. De blootstelling via groenten die men zelf zou kunnen telen, draagt ongeveer 10 procent bij aan de achtergrond-blootstelling; de achtergrondblootstelling via andere levensmiddelen vormt het grootste deel. Ten slotte worden handelingsperspectieven geboden om de blootstelling aan arseen te verminderen bij het moestuinieren. Dat kan bijvoorbeeld voorlichting zijn om de hoeveelheid ingeslikte gronddeeltjes te verminderen.Arsenic is a naturally occurring substance in soil and groundwater, but it can also be present in soil and groundwater through past human activities. When people grow their own vegetables on plots contaminated with arsenic, they may unintentionally ingest soil particles whilst tending their crops and in doing so, they may ingest arsenic. This is also possible when eating vegetables that have been grown on soil contaminated with arsenic. RIVM was requested by the municipal health services (GGDs) to advise on the assessment of the human health risks of growing vegetables in soil contaminated with arsenic. This assessment is difficult because it is uncertain how much of the arsenic in the soil accumulates in vegetables. In addition, a current guideline value for 'tolerable exposure' to arsenic is lacking. This guidance provides an indication of a state-of-art guideline value for 'tolerable exposure' to arsenic. A conservative estimate (based on high exposure) of exposure to arsenic through vegetable consumption was made, because the assessment of the accumulation of arsenic in vegetables is unpredictable cumbersome. Subsequently, the exposure to arsenic through growing vegetables was compared to the so-called background exposure. This is the intake of arsenic by the general public through purchased foods such as rice, cereals and milk, drinking water and possibly other exposure routes, independent of local soil contamination. It was calculated that exposure through the vegetables which people are more likely to grow themselves contributes about 10% to background exposure; the remaining background exposure is predominantly from other food products. Finally, this report offers advice on how to reduce exposure to arsenic for people who grow their own vegetables. This can be done, for example, through information on how to reduce the amount of ingested soil.Programmacollege Gezondheid en Milie

Handreiking voor de risicobeoordeling van arseen in de bodem voor de particuliere groenteteelt

Arseen kan van nature in de grond en het grondwater zitten of daar door activiteiten van de mens in het verleden in terecht gekomen zijn. Wanneer mensen zelf groenten telen, kunnen zij tijdens het tuinieren ongemerkt bodemdeeltjes inslikken. Hierdoor kunnen zij arseen binnenkrijgen. Dat kan ook door de groenten te eten die zijn geteeld op met arseen verontreinigde bodem. Op verzoek van de GGD'en heeft het RIVM een handreiking opgesteld over de beoordeling van de gezondheidsrisico's bij het eten en zelf telen van groenten op bodems die met arseen zijn verontreinigd. Die beoordeling is lastig, omdat onzeker is hoeveel arseen vanuit de bodem in de groenten terechtkomt. Daarnaast is er voor arseen geen actuele waarde voor de 'toelaatbare blootstelling' beschikbaar. De handreiking geeft een indicatie van de waarde die op dit moment het beste als 'toelaatbare blootstelling' voor arseen kan worden gebruikt. De blootstelling aan arseen via het zelf telen en eten van groenten is hierbij hoog ingeschat omdat de opname van arseen door de groenten uit de bodem onvoorspelbaar is. De blootstelling is vervolgens vergeleken met de zogenoemde achtergrondblootstelling aan arseen. Dit is de hoeveelheid arseen waar iedereen aan wordt blootgesteld (namelijk via in de winkel gekochte levensmiddelen als rijst, granen en melk, via drinkwater en mogelijk via andere bronnen), onafhankelijk van lokale bodemverontreiniging. De blootstelling via groenten die men zelf zou kunnen telen, draagt ongeveer 10 procent bij aan de achtergrond-blootstelling; de achtergrondblootstelling via andere levensmiddelen vormt het grootste deel. Ten slotte worden handelingsperspectieven geboden om de blootstelling aan arseen te verminderen bij het moestuinieren. Dat kan bijvoorbeeld voorlichting zijn om de hoeveelheid ingeslikte gronddeeltjes te verminderen

Vapour intrusion from the vadose zone—seven algorithms compared

Background, aim and scope: Vapours of volatile organic compounds (VOCs) emanating from contaminated soils may move through the unsaturated zone to the subsurface. VOC in the subsurface can be transported to the indoor air by convective air movement through openings in the foundation and basement. Once they have entered the building, they may cause adverse human health effects. Screening-level algorithms have been developed, which predict indoor air concentrations as a result of soil (vadose zone) contamination. The present study evaluates seven currently used screening-level algorithms, predicting vapour intrusion into buildings as a result of vadose zone contamination, regarding the accuracy of their predictions and their usefulness for screening purpose. Screening aims at identifying contaminated soils that should be further investigated as to the need of remediation and/or the presence of an intolerable human health risk. To be useful in this respect, screening-level algorithms should be sufficiently conservative so that they produce very few false-negative predictions but they should not be overly conservative because they might have insufficient discriminatory power. Materials and methods: For this purpose, a comparison is made between observed and predicted soil air and indoor air concentrations from seven reasonably well-documented sites, where the vadose zone was contaminated with aromatic or chlorinated VOCs. The seven screening-level algorithms considered were: Vlier-Humaan (Be), Johnson and Ettinger model (USA), VolaSoil (NL), CSoil (NL), Risc (UK) and the dilution factor models from Norway and Sweden. Calculations are presented in two scatter plots (soil air and indoor air), each containing the predictions versus the observations. Differences between predicted and observed VOCs concentrations were evaluated on the basis of three statistical criteria to establish their accurateness and the usefulness for screening purposes. Results from the applied criteria are presented in a table and figures. Results: It was found that the screening-level algorithms investigated tended to overestimate soil air concentrations more than indoor air concentrations. Differences between predictions and observations were up to three orders of magnitude. The algorithms with the highest accuracy for predicting the soil air concentration are in ascending order the Johnson and Ettinger model (JEM), Vlier-Humaan and VolaSoil algorithms. For the indoor air, it is concluded that all algorithms have a tendency to overestimate the predicted indoor air concentrations, except for the JEM and Vlier-Humaan algorithms, which produced frequent underestimations. Discussion: Several earlier studies have investigated the accuracy of some of the screening-level algorithms for vapour intrusion and the results presented in the present study agree with the findings. However, the present study presents the accuracy of vapour intrusion algorithms via three statistical criteria that allow their ranking. The present study also determines the suitability of screening-level algorithms as screening tool. It is found that algorithms may rank differently as to accuracy and suitability as a screening tool. Conclusions: The algorithms with the highest accuracy for predicting the indoor air concentration are the JEM and Vlier-Humaan algorithms. The most suitable algorithms to serve for screening purposes are CSoil, VolaSoil and Risc, since they are sufficiently conservative, have fewer false-negative predictions and still have sufficient discriminatory power. Recommendations and perspectives: Given the over-predictions and under-predictions of the algorithms considered, a combination of modelling and measurements will often be required to produce multiple lines of evidence for the presence of an intolerable human health risk or the need for remedial actions at a site. Integrated programmes of modelling and field observations can reduce the uncertainty of predicted soil air and indoor air concentrations, and a tiered approach is presented in this study

Risicobeoordeling cadmium. Evaluatie van enkele recente studies voor de lokale situatie in Nederland

VWSGGD Zuid Limbur

Risicobeoordeling cadmium. Evaluatie van enkele recente studies voor de lokale situatie in Nederland

VW