PROFILE Ecotoxicological Effects Assessment in the Netherlands: Recent Developments KEES van LEEOWEN Directorate-General for Environmental Protection Chemical Substances Division P.O. Box 450, 2260 MB Leidschendam, The Netherlands ABSTRACT / In a recently published annex to the National Environmental Policy Plan of the Netherlands (1989), attention was paid to ecotoxicological effects assessment. The pro- posed procedure was based on the advice of the Health Council of the Netherlands (1989) on nsk assessment of toxic chemicals for ecosystems. The various extrapolation methods described by the Health Council are critically discussed in this paper. The extrapolation method of Van Straalen and Denneman (1989) is evaluated for eight chemicals and 11 aquatic species. Conclusions are drawn about the quality and quantity of the ecotoxicological data needed for aquatic effects assessment. For the soil--a compartment that is often at risk--ecotoxicological effects assessment is not possible because suitable ecotoxicological test methods still have to be developed. Environmental risk assessment is becoming an in- creasingly important issue, particularly in view of the large numbers of pollutants that are potentially harmful to the functioning of ecosystems. Lessons from the recent past of several "do-nothing decades" have taught us that prevention of aquatic and terres- trial (including groundwater) pollution is much cheaper than cleanup. The high costs involved in cleanup operations of, e.g., polluted soils, aquatic sedi- ments, or dump sites are painful reminders of the re- cent past in which dilution, adsorption, or leaching were used as an excuse for not taking preventive mea- sures. This "out-of-sight-out-of-mind policy" has led to a grave deterioration of our environment--of our common future (Brundtland 1987)--for in many places restoration is out of the question, whatever our financial possibilities. The risk assessment methodologies and manage- ment philosophies for the protection of human and environmental health in the Netherlands have been published recently (Premises for Risk Management 1989). In the Netherlands the objective for the so- called general environmental quality is to offer protec- tion to 95% of the species in ecosystems. This per- centage has been arbitrarily chosen and implies that 5% of the species may suffer detrimental effects. Fur- thermore, it is assumed that protecting the structure (the qualitative and quantitative distribution of species) will also safeguard the functional characteristics of ecosystems. In nature reserves the preservation of eco- systems and species play a key role. It therefore means that these general risk limits for ecosystems might not offer sufficient protection and that more stringent KEY WORDS: Ecotoxicological effects assessment; Hazard assess- ment; Extrapolation; Safety factors; Test methods limits could be needed to protect certain species. In drawing up the policy for chemicals, no account has yet been taken of these special requirements and char- acteristics of ecosystems (Premises for Risk Manage- ment 1989). It is the intention of the Minister for the Environment in the Netherlands to make optimum use of the still limited knowledge of ecotoxicology (in- cluding the extrapolation procedures) for the protec- tion of ecosystems against chemical pollution (Health Council of the Netherlands, 1989), among other things, to achieve a policy that is founded on sustain- able development (National Environmental Policy Plan 1989). Environmental hazard assessment is a two-compo- nent exercise involving separate exposure (PEC) and effect (NEC) determinations (Van De Meent 1989) (Figure 1). In order to make predictions about envi- ronmental concentrations, models are applied. The various models have recently been summarized by the OECD (1989a). Effects assessment is the process whereby "acceptable" toxicant levels in ecosystems are estimated on tile basis of laboratory determined "no observed effect concentrations" (NOECs), L(E)Cs0 values, or QSAR estimates (quantitative structure-ac- tivity relationships; cf. Hermens 1989) of acute toxicity (USEPA 1984). These "acceptable" toxicant levels are environmental concentrations below which certain ad- verse effects on species in ecosystems (e.g., survival, reproduction, and growth) are unlikely to occur (see Table 1 for definitions). These "acceptable" concentra- tions are obtained by applying safety factors (also called margins of safety, application factors, extrapola- tion factors, or assessment factors) on the laboratory toxicity data, usually in the range of 10 to 10,000 (OECD 1989b). The various stages that can be distinguished in hazard assessment are initial (preliminary), interme- Environmental Management Vol, 14, No. 6, pp. 779-792 9 1990 Springer-Verlag New York inc.