CHAPTER 8 • Quality Status, Appropriate Monitoring and Legislation of the North Sea
165
8.4.3
An Integrated Approach to Monitoring
While the arguments for and against biological and chemical monitoring have been
considered separately, it is clear that an integrated approach is essential. Chemical analysis of contaminants could no more be expected to give a true impression of their biological impact than biological effects techniques alone could pin point their chemical
causes. Advances in environmental toxicology have combined the relevance and costeffectiveness of using biological techniques, closely allied to chemical analyses that
enable the identification of the chemical causes of toxic effects. Issues of causality, the
generality of biological techniques and their deployment, in an environment where
contaminants become heterogeneously distributed, remain key issues and are considered b'elow.
Establishing causality. In any chemically orientated monitoring, potential causality
between chemical contaminant and its toxic effect is implied by environmental concentrations that are in excess of the EQS. Historically the limitations of techniques to
establish causality have weighed against the wider use of biological techniques for
monitoring. Thus operational techniques depending on weight of evidence, rather than
rigorously demonstrated causality, have been advocated (Stebbing 1992). Such techniques depend on correlative evidence and the relationships between environmental
concentrations, or tissue concentrations, and toxicological threshold concentrations.
In the approach advocated here, the need to establish causality becomes an integral part
of the method.
Recent developments have improved the rigour of relationships between contaminants and biological effects. Thus the toxicological interpretation of tissue burdens of
contaminants using QSARs (quantitative structure activity relationships) is adequate
to identify PAHs and organotins as two important classes of contaminants causing the
depressed scope for growth in mussels along the UK East Coast (Widdows et al. 1995).
Similarly the use of ion exchange resins allied to sensitive water quality bioassays can
be used to demonstrate metal pollution (Stebbing 1979a), or to concentrate contaminants and bioassay the eluate to demonstrate the toxicity of organic contaminants
(Bening et al. 1992). Such extraction and fractionation techniques have considerable
potential for establishing causal relationships between chemical contaminants and their
biological effects.
Several biochemical techniques which measure enzyme activity help to identify their
chemical causes. The induction of Mixed Function Oxygenases (MFOs) identifies the
limited range of organic compounds (including PAHs and PCBs) which induce their
production. Thus the induction of EROD in dab indicates pollution by such organic
compounds (Fig. 8.6). Similarly induction of the metal-binding protein metallothionein
indicates exposure to metals, typically copper, zinc, cadmium and mercury (Hylland
et al. 1992). Acetyl cholinesterase activity (AChE) in freshwater fish is used to indicate
the impact of some pesticides (including organophosphorous and carbamate pesticides). The occurrence of increased activity of AChE in dab in the German Bight follows the same distribution as MFO activity, suggesting that chemicals which induce
AChE have the same distribution as the chlorinated or polynuclear aromatic hydro-
165
8.4.3
An Integrated Approach to Monitoring
While the arguments for and against biological and chemical monitoring have been
considered separately, it is clear that an integrated approach is essential. Chemical analysis of contaminants could no more be expected to give a true impression of their biological impact than biological effects techniques alone could pin point their chemical
causes. Advances in environmental toxicology have combined the relevance and costeffectiveness of using biological techniques, closely allied to chemical analyses that
enable the identification of the chemical causes of toxic effects. Issues of causality, the
generality of biological techniques and their deployment, in an environment where
contaminants become heterogeneously distributed, remain key issues and are considered b'elow.
Establishing causality. In any chemically orientated monitoring, potential causality
between chemical contaminant and its toxic effect is implied by environmental concentrations that are in excess of the EQS. Historically the limitations of techniques to
establish causality have weighed against the wider use of biological techniques for
monitoring. Thus operational techniques depending on weight of evidence, rather than
rigorously demonstrated causality, have been advocated (Stebbing 1992). Such techniques depend on correlative evidence and the relationships between environmental
concentrations, or tissue concentrations, and toxicological threshold concentrations.
In the approach advocated here, the need to establish causality becomes an integral part
of the method.
Recent developments have improved the rigour of relationships between contaminants and biological effects. Thus the toxicological interpretation of tissue burdens of
contaminants using QSARs (quantitative structure activity relationships) is adequate
to identify PAHs and organotins as two important classes of contaminants causing the
depressed scope for growth in mussels along the UK East Coast (Widdows et al. 1995).
Similarly the use of ion exchange resins allied to sensitive water quality bioassays can
be used to demonstrate metal pollution (Stebbing 1979a), or to concentrate contaminants and bioassay the eluate to demonstrate the toxicity of organic contaminants
(Bening et al. 1992). Such extraction and fractionation techniques have considerable
potential for establishing causal relationships between chemical contaminants and their
biological effects.
Several biochemical techniques which measure enzyme activity help to identify their
chemical causes. The induction of Mixed Function Oxygenases (MFOs) identifies the
limited range of organic compounds (including PAHs and PCBs) which induce their
production. Thus the induction of EROD in dab indicates pollution by such organic
compounds (Fig. 8.6). Similarly induction of the metal-binding protein metallothionein
indicates exposure to metals, typically copper, zinc, cadmium and mercury (Hylland
et al. 1992). Acetyl cholinesterase activity (AChE) in freshwater fish is used to indicate
the impact of some pesticides (including organophosphorous and carbamate pesticides). The occurrence of increased activity of AChE in dab in the German Bight follows the same distribution as MFO activity, suggesting that chemicals which induce
AChE have the same distribution as the chlorinated or polynuclear aromatic hydro-