Introduction

Today, authorities responsible for regulating environmental quality in Europe, both at the Union and at the State level, are frequently referring to results from 'new research' in their efforts to regulate or restrict uses of metals and metal-containing materials. This has resulted in an increasing demand for critical, scientifically sound evaluations and compilations - in a transparent and holistic format - of relevant information about metal stocks and fluxes in society and the properties, behaviour and effects of trace metals in the environment.

One of the longest standing international programmes for assessing the effects of chemicals, including metals, on man and the environment, the "Environmental Health Criteria (EHC) Programme", was initiated in 1973. This effort is nowadays an integral part of the "International Programme on Chemical Safety" (IPCS), a cooperative programme of the three United Nations Agencies UNEP, ILO and WHO. While the first EHC monograph (on mercury), published in 1976, focused entirely on human health aspects, later EHCs for metals - at least since 1989 - also treated environmental aspects. For example, the EHCs for nickel (EHC # 108, publ. in 1991), for copper (EHC # 200, publ. in 1998) and for zinc (EHC # 221, publ. in 2001) included comprehensive sections on generic environmental exposure and environmental effects of the metals involved.

The environmental risk assessment of trace metals requires a cautious approach because of the natural occurrence of metals, the great variations in metal speciation, affecting the metal's bioavailability and toxicity and - for some metals such as chromium, copper, nickel and zinc - their essentiality for many organisms. These aspects were emphasized by the IPCS, e.g. in the EHCs for copper and zinc, as summarized by the following conclusions:

• The total concentration of an essential element such as copper or zinc, alone, is not a good predictor of its bioavailability or toxicity.

• The toxicity of copper or zinc will depend on environmental conditions and habitat types, thus any risk assessment of the potential effects of these metals on organisms must take into account local environmental conditions.

• Because copper and zinc are essential elements, procedures to prevent toxic levels in the environment should not incorporate safety factors that result in recommended concentrations being below natural levels or causing deficiency symptoms.

Moreover, under the "Existing Substances Regulation" (793/93) of the European Union, a thorough assessment of the human health and environmental risks associated with production and use of zinc and five zinc compounds is being conducted by Dutch environmental authorities. In parallel with this "mandatory" environmental risk assessment (RA) for zinc, as an industry initiative, a voluntary RA of copper and several copper compounds is underway in cooperation with Italian authorities and the European Commission. These current trace metal environmental RA activities have called for updates of previous compilations of data on exposure and effects of metals in the environment. The new RAs have also directly encouraged important new research programmes, some of which are sponsored by the international metals industry.

Initiated by the Nordic metal industry, three monographs on "Metals in Society and in the Environment", covering copper, zinc and major alloying metals in stainless steel (chromium, nickel and molybdenum), were prepared by the Swedish Environmental Research Group (MFG) in the late 1990s, and were published both in Swedish and in English (Landner and Lindestrom, 1996; 1997; 1998; 1999; Walterson, 1999). The aim was to make a balanced and comprehensive compilation, together with a scientific appraisal, of available data on fluxes and stores of metals in the anthroposphere, on metal flows to and between environmental compartments, and on metal behaviour, exposure and effects in humans and in natural ecosystems. However, the current intense research on metal speciation and the upcoming new methodologies for prediction of metal bioavailability in water, sediments and soils, as a result of important scientific advances, made it urgent to bring this information up-to-date.

For this reason, the Swedish "Metal Information Task Force"1 took an initiative, in the middle of 2002, to engage MFG to prepare an updated monograph on metals. In this follow-up work, special emphasis was given to new scientific advances made in the field of metal speciation in environmental media and to the interpretation of its consequences for the mobility, bioavailability and toxicity of trace metals in water, sediments and soils. Among the highlights that we will present and discuss in this monograph are two metal speciation-based concepts or tools recently developed to improve our understanding of environmental effects of metals,

1 e-mail: [email protected]

the "Acid Volatile Sulphides" (AVS) concept to predict metal bioavailability in sediments and the "Biotic Ligand Model" (BLM) to calculate the availability and toxicity of metals to aquatic biota. The metals included in this updating effort are, primarily, copper, nickel and zinc, and to some extent also chromium.

0 0

Post a comment