1,2,4-trichlorobenzene marine risk assessment with special emphasis on the Osparcom region North Sea.

A risk assessment on 1,2,4-trichlorobenzene was carried out specifically for the marine environment according to the methodology laid down in the EU Risk Assessment Regulation 1488/94 and the Guidance Documents of the EU Existing Substances Regulation 793/93. The study consists of the collection and evaluation of data on effects and environmental concentrations from analytical monitoring programs in large rivers and estuaries in the North Sea area. The risk is indicated by comparing the predicted environmental concentration (PEC) with the predicted no-effect concentrations (PNEC) for the marine aquatic environment. A PNECwater) value of 0.3 microg/l and a PNECsed value of 38 microg/kgdw were derived from the results of toxicological studies in organisms representing three trophic levels, i.e. aquatic plants, invertebrates and fish. Based on monitoring data two situations are distinguished: a typical case and a worst case with a PECwater of <0.047 and 0.1 microg/l, respectively, and a PECsed of 40 and 90 microg/kgdw, respectively. The calculated PEC/PNEC ratios were 0.16 and 0.3 for water and 1 and 2.4 for sediment, respectively. It was concluded that no risks are expected for aquatic organisms. Based on the combination of worst-case assumptions risks to benthic organisms could not be fully excluded, but since all open uses of 1,2,4-trichlorobenzene will be ended following the EU risk assessment outcome of 2001 any potential risk is expected to be reduced accordingly. 1,2,4-trichlorobenzene is not considered toxic according to the EU criteria and the available data on persistence of 1,2,4-trichlorobenzene indicate a half-life in water of a few days and a significant biodegradation potential. The bioaccumulation potential is low to moderate with most BCF ratios for fish ranging from 600 to 1400 and one highest of 2020. Based on an extensive evaluation of persistence, biodegradation and bioaccumulation data it is concluded that 1,2,4-trichlorobenzene is not a PBT, since it does not fulfill any of the EU criteria. Biomagnification in the food chain is not expected due to the relatively high elimination rate constants.

Scientific activities of Euro Chlor in monitoring and assessing naturally and man-made organohalogens.

In this paper a review of the scientific activities and research programmes carried out by Euro Chlor, the European Federation of chlor-alkali producers is presented according to two main axes: marine risk assessments with statistical analysis of monitoring data, temporal trends of emission levels and environmental concentrations. The methodology applied in each field is briefly presented and then illustrated by several practical examples. As a large part of the uncertainties in assessing the risk of a chemical to a given species or ecosystem often comes from the difficulty in evaluating the exposure level, Euro Chlor has chosen to use a monitoring approach, the exposure level being estimated from a statistical analysis of measured concentrations levels in water and sediment from rivers, estuaries and coastal areas. As the modelling approach often used by the authorities to estimate the predicted environmental concentration value is starting from roughly estimated emission levels, Euro Chlor collated emissions data from about 80 production plants in order to reduce the uncertainty associated with the default values introduced in the modelling approach.A brief review of the European emission levels for chlorinated organic substances is given as well as the temporal trends of both emission and environmental levels. A methodology to quantify the trends in measured concentrations at local and regional scales is briefly described. The observed decreasing trends demonstrate the continuous progress made by the Euro Chlor member companies in protecting the environment.Finally, the problems linked to the simultaneous presence in the environment of naturally and man-made chlorinated substances are briefly reviewed. To stimulate further research in the field, two key questions are raised which have not yet found a satisfactory answer: how to quantify natural background levels and how to quantify global persistence in the environment?

Monitoring, modelling and environmental exposure assessment of industrial chemicals in the aquatic environment.

Monitoring and laboratory data play integral roles alongside fate and exposure models in comprehensive risk assessments. The principle in the European Union Technical Guidance Documents for risk assessment is that measured data may take precedence over model results but only after they are judged to be of adequate reliability and to be representative of the particular environmental compartments to which they are applied. In practice, laboratory and field data are used to provide parameters for the models, while monitoring data are used to validate the models' predictions. Thus, comprehensive risk assessments require the integration of laboratory and monitoring data with the model predictions. However, this interplay is often overlooked. Discrepancies between the results of models and monitoring should be investigated in terms of the representativeness of both. Certainly, in the context of the EU risk assessment of existing chemicals, the specific requirements for monitoring data have not been adequately addressed. The resources required for environmental monitoring, both in terms of manpower and equipment, can be very significant. The design of monitoring programmes to optimise the use of resources and the use of models as a cost-effective alternative are increasing in importance. Generic considerations and criteria for the design of new monitoring programmes to generate representative quality data for the aquatic compartment are outlined and the criteria for the use of existing data are discussed. In particular, there is a need to improve the accessibility to data sets, to standardise the data sets, to promote communication and harmonisation of programmes and to incorporate the flexibility to change monitoring protocols to amend the chemicals under investigation in line with changing needs and priorities.

Controlling persistent organic pollutants-what next?

Within the context of current international initiatives on the control of persistent organic pollutants (POPs), an overview is given of the scientific knowledge relating to POP sources, emissions, transport, fate and effects. At the regional scale, improvements in mass balance models for well-characterised POPs are resulting in an ability to estimate their environmental concentrations with sufficient accuracy to be of help for some regulatory purposes. The relevance of the parameters used to define POPs within these international initiatives is considered with an emphasis on mechanisms for adding new substances to the initial lists. A tiered approach is proposed for screening the large number of untested chemical substances according to their long-range transport potential, persistence and bioaccumulative potential prior to more detailed risk assessments. The importance of testing candidate POPs for chronic toxicity (i.e. for immunotoxicity, endocrine disruption and carcinogenicity) is emphasised as is a need for the further development of relevant SAR (structure activity relationship) models and in vitro and in vivo tests for these effects. Where there is a high level of uncertainty at the risk assessment stage, decision-makers may have to rely on expert judgement and weight-of-evidence, taking into account the precautionary principle and the views of relevant stake-holders. Close co-operation between the various international initiatives on POPs will be required to ensure that assessment criteria and procedures are as compatible as possible.