Tom C. J. Feijtel

Development of a geography-referenced regional exposure assessment tool for European rivers - great-er contribution to great-er #1

Abstract The objective of the GREAT-ER project is to develop and validate a powerful and accurate aquatic chemical exposure prediction tool for use within the EU environmental risk assessment schemes. Current techniques to estimate regional predicted environmental concentrations (PECs) use a generic multimedia ‘unit world’ approach and do not account for spatial and temporal variability in landscape characteristics, river flows and/or chemical emissions. Hence, the results are merely applicable on a generic screening level since these models do not offer a realistic prediction of actual steady-state background concentrations. A software system will be developed to calculate the distribution of predicted environmental concentrations (PECs) of down-the-drain chemicals in European surface waters on both a river and catchment area level. Data on dissolved oxygen, biological oxygen demand and ammonia will also be used to assess water quality and to provide data for calibration and verification. The system will use a Geographic Information System (GIS) for data storage and visualization, combined with simple mathematical models for the prediction of chemical fate. Hydrological databases and models will be used to determine river flows. This refined exposure assessment tool should significantly enhance the accuracy of current local and regional exposure estimation methods. The new exposure assessment methodology will integrate specific environmental information and be worked out in a geographically-referenced framework, ultimately on a pan-European scale. The initial data collection, collation and model application will be applied to two pilot study areas, representative of different hydrological and climatological situations in Europe. A blueprint of the methodology will be developed and applied to these pilot study areas, which will allow refining, optimization and verification of the system.The ultimate objective is to implement GREAT-ER for the entire European Union.This work will be performed in the second phase of the project, after the initial three years which are limited to the development of the methodology and verification in the pilot study areas.

Biodegradation of [S,S], [R,R] and mixed stereoisomers of Ethylene Diamine Disuccinic Acid (EDDS), a transition metal chelator

An in-depth biodegradation test program was executed on the hexadentate ligand Ethylene Diamine Di Succinate (EDDS). The EDDS structure contains two chiral carbon atoms, and has three stereoisomers ([R,R], [R,S]/[S,R], [S,S]). Our research has focused on the isomer mixture (i.e. 25%[S,S]; 25%[R,R]; 50%[S,R]/[R,S], as produced from the reaction of ethylene diamine with maleic anhydride) and on the single [S,S]- and [R,R]-isomers. Biodegradation screening of the 14C-labelled EDDS isomer mixture in a Batch Activated Sludge (BAS) test with various inocula revealed incomplete mineralization, up to ca. 65% after 28 days. N-(2-aminoethyl) aspartic acid (AEAA), probably the d-isomer, was identified as the major portion of the 14C-material remaining in solution. Further testing revealed that the [S,S]-isomer is rapidly and completely mineralized in all test systems. By contrast, [R,R]-EDDS remained undegraded in a Sturm (OECD 301B) test, but was very slowly biotransformed into the recalcitrant metabolite AEAA in a BAS test. The [S,R]/[R,S] form undergoes biotransformation to AEAA in both high and low biomass systems. In a sewage treatment simulation test (OECD 303) the steady state DOC removal of mixture-EDDS in a CAS test was limited to 25-35%, even after extensive pre-acclimation, while the [S,S]-isomer achieved nearly complete removal (96%). This study illustrates the importance stereospecificity may have on the biodegradation and metabolite formation of a chemical. A biodegradation scheme for the different EDDS stereoisomers is proposed.

Terrestrial risk assessment for linear alkyl benzene sulfonate (LAS) in sludge-amended soils

A comparison of the estimated environmental concentration and the effect concentrations (in the laboratory or field) in the receiving compartment form the basis of environmental risk assessments. This paper reviews processes that critically influence the fate of LAS in the terrestrial environment. Concentrations of LAS in sludge are quite high due to sorption to primary sludge, precipitation of Ca and Mg-salts of LAS, and lack of biodegradation under anaerobic digestion. This implies that when sludge is applied to soil e.g. as a fertilizer, considerable amounts of this important surfactant may enter the terrestrial environment. Influence of aerobic situations on LAS concentrations during sludge storage needs further research to allow incorporation into the risk assessment. Aerobic biodegradation in soil is considered the most important removal mechanism of LAS loading to the terrestrial environment through sludge-amendment. Sorption plays a role in determining the residence time of a chemical in the soil, hereby enabling more time for biodegradation to occur. In addition, sorption may affect the expression of effects of surfactants towards benthic and soil dwelling organisms and plants. Another factor that needs further attention is the form of LAS in the environment, which is not similar to the commercial material applied in detergents. The differential sorption and biodegradation of the LAS components lead to a shift in the alkyl chain length (homologue), and phenylisomer distribution towards increased hydrophobicity. Also, occurrence of Ca/Mg-salts in the environment versus the Na-salt for the commercial material critically impacts the extrapolation of effects data obtained in lab studies (mostly performed with the commercial material) to the field. The literature data were used in combination with strategies and methods provided by the European Union Technical Guidance Document in support of risk assessment of new and notified substances (1996) for the prediction of environmental concentrations of LAS entering the soil system through sludge applications. Soil biodegradation is an essential, necessary element for the PEC-calculations of LAS. The initial realistic worst case assessment presented indicates no human health risks exists with indirect exposure to LAS through either food or drinking water. Also, current LAS use does not pose a risk to terrestrial organisms such as plants and invertebrates.

An improved model for predicting the fate of consumer product chemicals in wastewater treatment plants

Abstract The WW-TREAT model was developed to predict the fate of consumer product chemicals in primary and activated sludge wastewater treatment plants using independently determined values for the distribution coefficient between sludge solids and liquid, Henrys law constant and biodegradation rate constants. The major difference between this model and previous models is that it assumes the total chemical, not just the dissolved chemical, is available for biodegradation and that sorption to sludge solids increases the time that a chemical is available for biodegradation. The model was validated with monitoring data for four chemicals which possess sorption and biodegradation characteristics that span the range typical of the broader class of consumer product chemicals. Sensitivity analysis revealed that the most important parameters were the plant operating parameter, sludge/solids retention time and the chemical specific parameters, distribution coefficient and biodegradation rate constants. The sludge/solids retention time had its greatest effect when it was less than 9 days and the distribution coefficient had its greatest effect when it was between 100 and 3000 l/kg. The model predicted removal in primary and activated sludge wastewater treatment plants within 5%. Thus, the model can be used as a valuable tool for predicting the fate of consumer product chemicals.

Comparison between three different LCIA methods for aquatic ecotoxicity and a product Environmental Risk Assessment – Insights from a Detergent Case Study within OMNIITOX

Background and ObjectiveIn the OMNIITOX project 11 partners have the common objective to improve environmental management tools for the assessment of (eco)toxicological impacts. The detergent case study aims at: i) comparing three Procter &c Gamble laundry detergent forms (Regular Powder-RP, Compact Powder-CP and Compact Liquid-CL) regarding their potential impacts on aquatic ecotoxicity, ii) providing insights into the differences between various Life Cycle Impact Assessment (LCIA) methods with respect to data needs and results and iii) comparing the results from Life Cycle Assessment (LCA) with results from an Environmental Risk Assessment (ERA).Material and MethodsThe LCIA has been conducted with EDIP97 (chronic aquatic ecotoxicity) [1], USES-LCA (freshwater and marine water aquatic ecotoxicity, sometimes referred to as CML2001) [2, 3] and IMPACT 2002 (covering freshwater aquatic ecotoxicity) [4]. The comparative product ERA is based on the EU Ecolabel approach for detergents [5] and EUSES [6], which is based on the Technical Guidance Document (TGD) of the EU on Environmental Risk Assessment (ERA) of chemicals [7]. Apart from the Eco-label approach, all calculations are based on the same set of physico-chemical and toxicological effect data to enable a better comparison of the methodological differences. For the same reason, the system boundaries were kept the same in all cases, focusing on emissions into water at the disposal stage.Results and DiscussionSignificant differences between the LCIA methods with respect to data needs and results were identified. Most LCIA methods for freshwater ecotoxicity and the ERA see the compact and regular powders as similar, followed by compact liquid. IMPACT 2002 (for freshwater) suggests the liquid is equally as good as the compact powder, while the regular powder comes out worse by a factor of 2. USES-LCA for marine water shows a very different picture seeing the compact liquid as the clear winner over the powders, with the regular powder the least favourable option. Even the LCIA methods which result in die same product ranking, e.g. EDIP97 chronic aquatic ecotoxicity and USES-LCA freshwater ecotoxicity, significantly differ in terms of most contributing substances. Whereas, according to IMPACT 2002 and USES-LCA marine water, results are entirely dominated by inorganic substances, the other LCIA methods and the ERA assign a key role to surfactants. Deviating results are mainly due to differences in the fate and exposure modelling and, to a lesser extent, to differences in the toxicological effect calculations. Only IMPACT 2002 calculates the effects based on a mean value approach, whereas all other LCIA methods and the ERA tend to prefer a PNEC-based approach. In a comparative context like LCA the OMNIITOX project has taken the decision for a combined mean and PNEC-based approach, as it better represents the ‘average’ toxicity while still taking into account more sensitive species. However, the main reason for deviating results remains in the calculation of the residence time of emissions in the water compartments.Conclusion and OutlookThe situation that different LCIA methods result in different answers to the question concerning which detergent type is to be preferred regarding the impact category aquatic ecotoxicity is not satisfactory, unless explicit reasons for the differences are identifiable. This can hamper practical decision support, as LCA practitioners usually will not be in a position to choose the ’right’ LCIA method for their specific case. This puts a challenge to the entire OMNIITOX project to develop a method, which finds common ground regarding fate, exposure and effect modelling to overcome the current situa-tion of diverging results and to reflect most realistic conditions.

Environmental risk assessment of phosphonates, used in domestic laundry and cleaning agents in The Netherlands.

In the long-term cooperative project Voluntary Plan of Action (1990) between the Dutch Soap and Detergent Association (NVZ) and the Dutch Ministry of Housing, Spatial Planning and the Environment (VROM) environmental risk assessments of several main components of laundry cleaning formulations were completed. As a part of that project the environmental risk assessment of HEDP, ATMP, EDTMP and DTPMP phosphonates used in detergent applications has been carried out according to the EU Technical Guidance Document for Environmental Risk Assessment for New and Existing Chemicals. All PEC/PNEC ratios were well below 1. Results of this assessment based on the total industry volumes from 1995 and 1998 indicate that the environmental risk of these phosphonates is low in The Netherlands with properly functioning sewage treatment plants.

Mode of action and aquatic exposure thresholds of no concern

Threshold concepts of toxicological concern are based on the possibility of establishing an exposure threshold value for chemicals below which no significant risk is to be expected. The objective of the present study is to address environmental thresholds of no toxicological concern for freshwater systems (ETNCaq) for organic chemicals. We analyzed environmental toxicological databases (acute and chronic endpoints) and substance hazard assessments. Lowest numbers and 95th-percentile values were derived using data stratification based on mode of action (MOA; 1 = inert chemicals; 2 = less inert chemicals; 3 = reactive chemicals; 4 = specifically acting chemicals). The ETNCaq values were derived by multiplying the lowest 95th percentile values with appropriate application factors; ETNCaq,MOA1-3 is approximately 0.1 microg/L. A preliminary analysis with complete MOA stratification of the databases shows that in the case of MOA1 or MOA2, the ETNCaq value could be even higher than 0.1 microg/L. A significantly lower ETNCaq,MOA4 value was observed based on the long-term toxicity information in the European Centre for the Ecotoxicology and Toxicology of Chemicals database. Application of the ETNCaq value in a tiered risk-assessment scheme may help chemical producers to set data-generation priorities and to refine or reduce animal use. It also may help to inform downstream users concerning the relative risk associated with their specific uses and be of value in putting environmental monitoring data into a risk-assessment perspective.

Risk assessment and management of new and existing chemicals

An evaluation was made of the recently developed risk assessment methodologies for new and existing chemicals in the European Communities. The evaluation also included the methodologies to prioritize chemicals and procedures for risk management, i.e., the (draft) guidance document for the development of strategies for risk reduction. The way in which chemicals are prioritized is accepted with only very few comments. Clear progress has been made in the development and harmonization of risk assessment methodologies and the application of estimation methodologies. Nevertheless, improvements are necessary for the estimation of consumer and occupational exposure, the derivation, use and transparency of assessment factors for chemicals and classes of chemicals based on the mode of toxic action, environmental exposure models and their validation and relation with monitoring data. As far as risk management is concerned it was recommended to improve the integration of the myriad of directives and regulations, to clarify definitions, to provide clear guidance on the determination and weighing of advantages and implications of risk reduction measures and to develop tools, including voluntary agreements, to speed up the slow chemical-by-chemical approach.

Integration of bioaccumulation in an environmental risk assessment

Abstract The potential of a substance to bioaccumulate in the aquatic environment into an organism depends particularly on its lipophilicity and its metabolism within the organism. Bioaccumulation is an exposure-related parameter and will determine the body burden but it is not an ‘effect’ or hazard in itself. Therefore, when appropriate, bioaccumulation should be included as an exposure related parameter in the environmental risk assessment of substances. The “direct” toxicity assessment should consider “time to steady state” in evaluating PNEC values. Depending on the steady-state criteria used, the duration of a 96h acute fish LC50 test may be insufficient for substances with a log Kow above the range of 3.8–4.5. If exposure and uptake are possible, the BCF is estimated in an iterative approach in order to address the potential for bioaccumulation and resultant “indirect” (dietary) toxicity. When the BCF value is above 1000, a PEC/PNEC assessment for predators is made. A step-wise approach is recommended. In practice, substances which are widely dispersed in the environment, which potentially can be taken up by biota, which are persistent, lipophilic and exhibit negligible metabolism will be selected by this scheme for a more detailed evaluation.

AIS/CESIO Environmental Surfactant Monitoring Programme. Part 1: LAS Monitoring study in "de Meern" sewage treatment plant and receiving river "Leidsche Rijn".

Abstract This manuscript reports on the outcome of a 7-day pilot monitoring study on the anionic surfactant linear alkyl benzene sulfonate (LAS) at the “de Meem” municipal sewage treatment plant. The receiving surface water, the Leidsche Rijn is a straight river — about 20 m wide and 1.5 m deep — and dilutes the sewage discharge by a factor 3. The monitoring study illustrates an effective removal of LAS of 99.9% during dry weather and normal operating conditions. The LAS concentrations in daily composite raw sewage samples varied between 3.1 and 7.2 mg/L, with corresponding effluent concentrations generally under the analytical detection limit of 8.1 ug/L. During this same period, total LAS concentrations in the river varied between