Anne Hollander

Substance or space? The relative importance of substance properties and environmental characteristics in modeling the fate of chemicals in Europe

The relative influence of substance properties and of environmental characteristics on the variation in the environmental fate of chemicals was studied systematically and comprehensively. This was done by modeling environmental concentrations for 200 sets of substance properties, representative of organic chemicals used, and 137 sets of environmental characteristics, representative of regions in Europe of 250 x 250 km. Since it was expected that the model scale has an influence on the predicted concentration variations, the calculations were repeated for regions with a 100 x 100 km and 50 x 50 km area. Stepwise multiple regression analysis was performed to determine the contribution of each of the individual input parameters on the total concentration variation. Depending on the scenario, the range in predicted environmental concentrations spreads from two up to nine orders of magnitude. In accord with earlier studies, variation in the fate of chemicals in the environment appeared to depend mainly on substance-specific partition coefficients and degradation rates. For the estimation of soil and water concentrations with direct emissions to these compartments, however, the influence of spatial variation in environmental characteristics can mount up to two orders of magnitude, a range that can be significant to account for in certain model applications. Concentration differences in water and soil are predicted to be larger if a smaller region is applied in the model calculations, and the relative influence of environmental characteristics on the total variation increases on a more detailed spatial scale. It is argued that the influence of environmental characteristics as predictors of exposure concentrations of chemicals deserves better attention in comparative risk assessment with conventional nonspatial multimedia box models.

Spatially explicit prioritization of human antibiotics and antineoplastics in Europe

This paper presents a screening tool for the location-specific prioritization of human pharmaceutical emissions in Europe, based on risk quotients for the aquatic environment and human health. The tool provides direction towards either monitoring activities or additional research. Its application is illustrated for a set of 11 human antibiotics and 7 antineoplastics. Risk quotients for the aquatic environment were highest for levofloxacin, doxycycline and ciprofloxacin, located in Northern Italy (Milan region; particularly levofloxacin) and other densely populated areas in Europe (e.g. London, Krakow and the Ruhr area). Risk quotients for human health not only depend on pharmaceutical and location, but also on behavioral characteristics, such as consumption patterns. Infants in eastern Spain that consume locally produced food and conventionally treated drinking water were predicted to run the highest risks. A limited comparison with measured concentrations in surface water showed that predicted and measured concentrations are approximately within one order of magnitude.

Estimating overall persistence and long-range transport potential of persistent organic pollutants: a comparison of seven multimedia mass balance models and atmospheric transport models

Two different approaches to modeling the environmental fate of organic chemicals have been developed in recent years. The first approach is applied in multimedia box models, calculating average concentrations in homogeneous boxes which represent the different environmental media, based on intermedia partitioning, transport, and degradation processes. In the second approach, used in atmospheric transport models, the spatially and temporally variable atmospheric dynamics form the basis for calculating the environmental distribution of chemicals, from which also exchange processes to other environmental media are modeled. The main goal of the present study was to investigate if the multimedia mass balance models CliMoChem, SimpleBox, EVn-BETR, G-CIEMS, OECD Tool and the atmospheric transport models MSCE-POP and ADEPT predict the same rankings of the overall persistence (P(ov)) and long-range transport potential (LRTP) of POPs, and to explain differences and similarities between the rankings by the mass distributions and inter-compartment mass flows. The study was performed for a group of 14 reference chemicals. For P(ov), the models yield consistent results, owing to the large influence of phase partitioning parameters and degradation rate constants, which are used similarly by all models. Concerning LRTP, there are larger differences between the models than for P(ov), due to different LRTP calculation methods and spatial model resolutions. Between atmospheric transport models and multimedia fate models, no large differences in mass distributions and inter-compartment flows can be recognized. Deviations in mass flows are mainly caused by the geometrical design of the models.

BasinBox: a generic multimedia fate model for predicting the fate of chemicals in river catchments

Multimedia fate models have proven to be very useful tools in chemical risk assessment and management. This paper presents BasinBox, a newly developed steady-state generic multimedia fate model for evaluating risks of new and existing chemicals in river basins. The model concepts, as well as the intermedia processes quantified in the model, are outlined, and an overview of the required input parameters is given. To test the BasinBox model, calculations were carried out for predicting the fate of chemicals in the river Rhine basin. This was done for a set of 3175 hypothetical chemicals and three emission scenarios to air, river water and cropland soils. For each of these hypothetical chemicals and emission scenarios the concentration ratio between the downstream area and the upstream area was calculated for all compartments. From these calculations it appeared that BasinBox predicts significant concentration differences between upstream and downstream areas of the Rhine river basin for certain types of chemicals and emission scenarios. There is a clear trend of increasing chemical concentrations in downstream direction of the river basin. The calculations show that taking into account spatial variability between upstream, midstream and downstream areas of large river basins can be useful in the predictions of environmental concentrations by multimedia fate models.

Modeled and monitored variation in space and time of pcb-153 concentrations in air, sediment, soil and aquatic biota on a european scale

We evaluated various modeling options for estimating concentrations of PCB-153 in the environment and in biota across Europe, using a nested multimedia fate model coupled with a bioaccumulation model. The most detailed model set up estimates concentrations in air, soil, fresh water sediment and fresh water biota with spatially explicit environmental characteristics and spatially explicit emissions to air and water in the period 1930-2005. Model performance was evaluated with the root mean square error (RMSE(log)), based on the difference between estimated and measured concentrations. The RMSE(log) was 5.4 for air, 5.6-6.3 for sediment and biota, and 5.5 for soil in the most detailed model scenario. Generally, model estimations tended to underestimate observed values for all compartments, except air. The decline in observed concentrations was also slightly underestimated by the model for the period where measurements were available (1989-2002). Applying a generic model setup with averaged emissions and averaged environmental characteristics, the RMSE(log) increased to 21 for air and 49 for sediment. For soil the RMSE(log) decreased to 3.5. We found that including spatial variation in emissions was most relevant for all compartments, except soil, while including spatial variation in environmental characteristics was less influential. For improving predictions of concentrations in sediment and aquatic biota, including emissions to water was found to be relevant as well.

Environmental impact assessment of pharmaceutical prescriptions: Does location matter?

A methodology was developed for the assessment and comparison of the environmental impact of two alternative pharmaceutical prescriptions. This methodology provides physicians with the opportunity to include environmental considerations in their choice of prescription. A case study with the two antibiotics ciprofloxacin and levofloxacin at three locations throughout Europe showed that the preference for a pharmaceutical might show spatial variation, i.e. comparison of two pharmaceuticals might yield different results when prescribed at different locations. This holds when the comparison is based on both the impact on the aquatic environment and the impact on human health. The relative impacts of ciprofloxacin and levofloxacin on human health were largely determined by the local handling of secondary sludge, agricultural disposal practices, the extent of secondary sewage treatment, and local food consumption patterns. The relative impacts of ciprofloxacin and levofloxacin on the aquatic environment were mostly explained by the presence of specific sewage treatment techniques, as effluents from sewage treatment plants (STPs) are the most relevant emission pathway for the aquatic environment.

Environmental fate factors and human intake fractions for risk assessment of petroleum products

Petroleum products may contain up to thousands of individual hydrocarbon compounds, which vary widely in environmental behavior and ecotoxicity. Environmental risk assessment of these complex substances is facilitated by use of the hydrocarbon block method (HBM). The HBM assigns similarly behaving hydrocarbons to the same blocks and then relates release rates of petroleum products to environmental concentrations and human intake rates by means of so-called environmental fate factors and human intake fractions of the hydrocarbon blocks. We have derived such fate factors and intake fractions and associated uncertainties with a library of representative hydrocarbon structures. Fate factors and intake fractions of over 1500 individual representative hydrocarbons have been modeled according to the EU Technical Guidance Documents. Fate factors and intake fractions for the chosen hydrocarbon blocks are then estimated from average values obtained for the individual compounds in the blocks. Fate factors and intake fractions of the hydrocarbon blocks vary by up to 10 orders of magnitude for the different emission scenarios and compartments/spatial scales. The highest fate factors are obtained for the exposure scenarios with the highest emission intensity (the local emission scenarios) and for the most direct exposure chain. Uncertainties introduced by the “blocking” method are typically smaller than 30% and rarely larger than a factor of 3. Various hydrocarbon blocking schemes of different resolution were tested, and all schemes investigated appeared to perform satisfactorily. The use of the library-based HBM was illustrated by assessing the aquatic ecological risk of gas oil, emitted to water. The aquatic risk characterization ratio of gas oil hydrocarbons in regional freshwater is estimated to be 6 × 10(−5) per unit of emission (1 kg/d released 1:10:100 to local, regional, and continental scales, respectively), with an uncertainty of 32%. In view of other uncertainties in environmental risk assessment, the precision achieved with the procedure presented here is judged to be reasonable.

Implementation of depth-dependent soil concentrations in multimedia mass balance models

In standard multimedia mass balance models, the soil compartment is modeled as a box with uniform concentrations, which often does not correspond with actual field situations. Therefore, the theoretically expected decrease of soil concentrations with depth was implemented in the multimedia model SimpleBox 3.0. The effects of this implementation on the model outcomes were explored for nine compounds in four environmental compartments. For compounds with a low penetration depth, the new model predicts substantially higher or lower concentrations in the vegetation compartment than the old model. For those compounds, predicted concentrations in surface water and air were higher in the new model, but the deviations from the old model were smaller than in the vegetation compartment. For compounds with a large penetration depth, the model adaptations show little effect. No field study was carried out to validate the results of the model calculations, but we did collect measured data on concentrations in vertical soil profiles from literature. According to those data, we concluded that the implementation of depth dependent soil concentrations might be a useful extension for steady state multimedia mass balance models. More field study has to be carried out to validate the model outcomes.

SimpleBox 4.0: Improving the model while keeping it simple

Chemical behavior in the environment is often modeled with multimedia fate models. SimpleBox is one often-used multimedia fate model, firstly developed in 1986. Since then, two updated versions were published. Based on recent scientific developments and experience with SimpleBox 3.0, a new version of SimpleBox was developed and is made public here: SimpleBox 4.0. In this new model, eight major changes were implemented: removal of the local scale and vegetation compartments, addition of lake compartments and deep ocean compartments (including the thermohaline circulation), implementation of intermittent rain instead of drizzle and of depth dependent soil concentrations, adjustment of the partitioning behavior for organic acids and bases as well as of the value for enthalpy of vaporization. In this paper, the effects of the model changes in SimpleBox 4.0 on the predicted steady-state concentrations of chemical substances were explored for different substance groups (neutral organic substances, acids, bases, metals) in a standard emission scenario. In general, the largest differences between the predicted concentrations in the new and the old model are caused by the implementation of layered ocean compartments. Undesirable high model complexity caused by vegetation compartments and a local scale were removed to enlarge the simplicity and user friendliness of the model.

The flash environmental assessment tool: Worldwide first aid for chemical accidents response, pro action, prevention and preparedness

The United Nations response mechanism to environmental emergencies requested a tool to support disaster assessment and coordination actions by United Nations Disaster Assessment and Coordination (UNDAC) teams. The tool should support on-site decision making when substantial chemical emissions affect human health directly or via the environment and should be suitable for prioritizing impact reduction management options under challenging conditions worldwide. To answer this need, the Flash Environmental Assessment Tool (FEAT) was developed and the scientific and practical underpinning and application of this tool are described in this paper. FEAT consists of a printed decision framework and lookup tables, generated by combining the scientific data on chemicals, exposure pathways and vulnerabilities with the pragmatic needs of emergency field teams. Application of the tool yields information that can help prioritize impact reduction measures. The first years of use illustrated the usefulness of the tool as well as suggesting additional uses and improvements. An additional use is application of the back-office tool (Hazard Identification Tool, HIT), the results of which aid decision-making by the authorities of affected countries and the preparation of field teams for on-site deployment. Another extra use is in disaster pro action and prevention. In this case, the application of the tool supports safe land-use planning and improved technical design of chemical facilities. UNDAC teams are trained to use the tool after large-scale sudden onset natural disasters.