Measures to reduce pesticides leaching into groundwater-based drinking water resources: An appeal to national and local governments, water boards and farmers.

The purpose of this paper is to show that a number of pesticides is found in groundwater and drinking water resources and to define measures that should reduce the pesticide load in groundwater resources for drinking water in the future. Although the pesticide load that enters groundwater bodies in the Netherlands has gradually decreased over the past ten years, good drinking water quality in the future is not guaranteed. Currently, a number of pesticides ise found in groundwater abstracted for the production of drinking water, worldwide. The most frequently found compounds in the Netherlands are the herbicides BAM (2,6-dichlorobenzonitrile), bentazon and mecoprop. In shallow groundwater, the same compounds are generally found as in deeper groundwater that is abstracted for the production of drinking water, mainly bentazon and mecoprop. Additionally, DEET (N,N-Diethyl-meta-toluamide) is frequently found in shallower groundwater. In order to reduce the pesticide load in groundwater resources for drinking water in the future, 43 measures have been inventoried and ranked based on their scores for 'effectiveness' and for 'practicability'. This paper describes both the most effective measures, with high scores on practicability, and those with limitations regarding practicability. These measures are the most relevant with respect to the frequently found compounds that are still authorised, i.e., bentazon, mecoprop and DEET and, to a lesser extent, glyphosate (due to the presence of its metabolite AMPA (aminomethylphosphonic acid) and glyphosate itself) and isoproturon. The implementation of abstraction-specific 'Drinking Water Protection Files', including the systematic collection of data about the relevant water abstraction and the sources and activities that can negatively affect water quality, is recommended.

Soil-plant transfer models for metals to improve soil screening value guidelines valid for São Paulo, Brazil.

In Brazil, there is a lack of combined soil-plant data attempting to explain the influence of specific climate, soil conditions, and crop management on heavy metal uptake and accumulation by plants. As a consequence, soil-plant relationships to be used in risk assessments or for derivation of soil screening values are not available. Our objective in this study was to develop empirical soil-plant models for Cd, Cu, Pb, Ni, and Zn, in order to derive appropriate soil screening values representative of humid tropical regions such as the state of São Paulo (SP), Brazil. Soil and plant samples from 25 vegetable species in the production areas of SP were collected. The concentrations of metals found in these soil samples were relatively low. Therefore, data from temperate regions were included in our study. The soil-plant relations derived had a good performance for SP conditions for 8 out of 10 combinations of metal and vegetable species. The bioconcentration factor (BCF) values for Cd, Cu, Ni, Pb, and Zn in lettuce and for Cd, Cu, Pb, and Zn in carrot were determined under three exposure scenarios at pH 5 and 6. The application of soil-plant models and the BCFs proposed in this study can be an important tool to derive national soil quality criteria. However, this methodological approach includes data assessed under different climatic conditions and soil types and need to be carefully considered.

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.

Assessment of health risks due to arsenic from iron ore lumps in a beach setting.

In 2011, an artificial hook-shaped peninsula of 128ha beach area was created along the Dutch coast, containing thousands of iron ore lumps, which include arsenic from natural origin. Elemental arsenic and inorganic arsenic induce a range of toxicological effects and has been classified as proven human carcinogens. The combination of easy access to the beach and the presence of arsenic raised concern about possible human health effects by the local authorities. The objective of this study is therefore to investigate human health risks from the presence of arsenic-containing iron ore lumps in a beach setting. The exposure scenarios underlying the human health-based risk limits for contaminated land in The Netherlands, based on soil material ingestion and a residential setting, are not appropriate. Two specific exposure scenarios related to the playing with iron ore lumps on the beach ('sandcastle building') are developed on the basis of expert judgement, relating to children in the age of 2 to 12years, i.e., a worst case exposure scenario and a precautionary scenario. Subsequently, exposure is calculated by the quantification of the following factors: hand loading, soil-mouth transfer effectivity, hand-mouth contact frequency, contact surface, body weight and the relative oral bioavailability factor. By lack of consensus on a universal reference dose for arsenic for use in the stage of risk characterization, three different types of assessments have been evaluated: on the basis of the current Provisional Tolerable Daily Intake (PTWI), on the basis of the Benchmark Dose Lower limit (BMDL), and by a comparison of exposure from the iron ore lumps with background exposure. It is concluded, certainly from the perspective of the conservative exposure assessment, that unacceptable human health risks due to exposure to arsenic from the iron ore lumps are unlikely and there is no need for risk management actions.

Definition and use of Solution-focused Sustainability Assessment: A novel approach to generate, explore and decide on sustainable solutions for wicked problems.

This paper introduces Solution-focused Sustainability Assessment (SfSA), provides practical guidance formatted as a versatile process framework, and illustrates its utility for solving a wicked environmental management problem. Society faces complex and increasingly wicked environmental problems for which sustainable solutions are sought. Wicked problems are multi-faceted, and deriving of a management solution requires an approach that is participative, iterative, innovative, and transparent in its definition of sustainability and translation to sustainability metrics. We suggest to add the use of a solution-focused approach. The SfSA framework is collated from elements from risk assessment, risk governance, adaptive management and sustainability assessment frameworks, expanded with the 'solution-focused' paradigm as recently proposed in the context of risk assessment. The main innovation of this approach is the broad exploration of solutions upfront in assessment projects. The case study concerns the sustainable management of slightly contaminated sediments continuously formed in ditches in rural, agricultural areas. This problem is wicked, as disposal of contaminated sediment on adjacent land is potentially hazardous to humans, ecosystems and agricultural products. Non-removal would however reduce drainage capacity followed by increased risks of flooding, while contaminated sediment removal followed by offsite treatment implies high budget costs and soil subsidence. Application of the steps in the SfSA-framework served in solving this problem. Important elements were early exploration of a wide 'solution-space', stakeholder involvement from the onset of the assessment, clear agreements on the risk and sustainability metrics of the problem and on the interpretation and decision procedures, and adaptive management. Application of the key elements of the SfSA approach eventually resulted in adoption of a novel sediment management policy. The stakeholder participation and the intensive communication throughout the project resulted in broad support for both the scientific approaches and results, as well as for policy implementation.

A tiered approach for the human health risk assessment for consumption of vegetables from with cadmium-contaminated land in urban areas.

Consumption of vegetables that are grown in urban areas takes place worldwide. In developing countries, vegetables are traditionally grown in urban areas for cheap food supply. In developing and developed countries, urban gardening is gaining momentum. A problem that arises with urban gardening is the presence of contaminants in soil, which can be taken up by vegetables. In this study, a scientifically-based and practical procedure has been developed for assessing the human health risks from the consumption of vegetables from cadmium-contaminated land. Starting from a contaminated site, the procedure follows a tiered approach which is laid out as follows. In Tier 0, the plausibility of growing vegetables is investigated. In Tier 1 soil concentrations are compared with the human health-based Critical soil concentration. Tier 2 offers the possibility for a detailed site-specific human health risk assessment in which calculated exposure is compared to the toxicological reference dose. In Tier 3, vegetable concentrations are measured and tested following a standardized measurement protocol. To underpin the derivation of the Critical soil concentrations and to develop a tool for site-specific assessment the determination of the representative concentration in vegetables has been evaluated for a range of vegetables. The core of the procedure is based on Freundlich-type plant-soil relations, with the total soil concentration and the soil properties as variables. When a significant plant-soil relation is lacking for a specific vegetable a geometric mean of BioConcentrationFactors (BCF) is used, which is normalized according to soil properties. Subsequently, a 'conservative' vegetable-group-consumption-rate-weighted BioConcentrationFactor is calculated as basis for the Critical soil concentration (Tier 1). The tool to perform site-specific human health risk assessment (Tier 2) includes the calculation of a 'realistic worst case' site-specific vegetable-group-consumption-rate-weighted BioConcentrationFactor.

The possibilities for the EU-wide use of similar ecological risk-based soil contamination assessment tools.

Soil degradation, e.g. due to soil contamination, is a serious problem in Europe. Therefore, the European Commission believes that a comprehensive EU strategy for soil protection is required. With the purpose of supporting the European soil policy, the possibilities for a common approach in the EU-wide use of ecological risks assessment methodologies are explored. For over ten years now, ecological procedures used in different countries have been discussed in international fora. More recently, within the framework of the HERACLES network a review of ecological risk assessment tools was performed, among other things. From this study it can be concluded that the inclusion of ecological risk assessment in soil quality standards shows an increasing interest in many EU Member States. The study also shows that there are many procedures for ecological risk assessment readily available in several EU countries and will be readily available in even more Member States in the nearby future. Besides, this study clearly shows quite some variation in the ecological risk assessment tools and in the resulting soil quality standards in the different countries. Therefore, an effort was made to look for potential harmonisation of these tools within the European Union. Risk assessment tools used in soil quality assessment include both political and scientific elements, which are often interwoven. Insofar differences in the existing tools originate from geographical or cultural differences between Member States or from political choices, harmonisation is not at all regarded an option. Nevertheless, several differences between existing ecological risk assessment tools have been identified, that merely originate from scientific or technical aspects. These tools could be standardized, which means that there could be a uniform tool to be used everywhere throughout the EU. The development of these harmonised risk assessment tools will imply an intensive international cooperation, with the purpose of at least making the existing differences between those tools from the Member States transparent and to investigate the possibilities for coming to similar tools from a scientific/technical perspective.

Insight into the variation in calculated human exposure to soil contaminants using seven different European models.

In order to get insight into the variation in calculated human exposure, the outputs of 7 European exposure models have been compared. Twenty scenarios, differing with respect to land use, soil type, and contaminant, formed the basis for calculating human exposure to soil contaminants. All calculations were performed twice: Once with a standardized set of parameters for all models and once with the own default parameters. This led to the conclusion that the variation in calculated total exposure (combining all exposure pathways) is large (the majority of the outputs is in between a factor of 100 higher and a factor of 100 lower than the scenario medians). In addition, variation for exposure due to indoor air inhalation is also large. The variation for exposure due to crop consumption is substantial (the majority of the outputs is in between a factor of 10 higher and a factor of 10 lower than the scenario medians) and limited for exposure due to soil ingestion (limited = the majority of the outputs is within a factor of 5 higher and a factor of 5 lower than the scenario medians). The variation in calculated exposure increases when a contaminant is more mobile and, particularly, more volatile. The variation due to selection of input parameters does only yield an additional variation over the variation due to model algorithms for exposure due to soil ingestion and, to a lesser extent, for exposure due to crop consumption. The variation in calculated exposure is not dependent on the soil type and hardly dependent (only for exposure due to soil ingestion) on land use. The choice of model is a very significant factor for the absolute value of calculated exposure. For the promotion of uniformity it was recommended to construct a toolbox for the calculation of human exposure, for general use, including standardized tools and flexible tools, the latter to account for region-specific or country-specific (geographical, ethnological, and cultural) elements and national policy decisions.