Interim report of the HELCOM CORESET project
Interim report of the HELCOM CORESET project
Interim report of the HELCOM CORESET project
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4.26. Acetylcholinesterase (AChE)<br />
General information<br />
General properties<br />
The analysis <strong>of</strong> acetylcholinesterase (AChE; EC 3.1.1.7) activity and its inhibition in marine organisms has<br />
been shown to be a highly suitable method for assessing exposure to neurotoxic contaminants in aquatic<br />
environments. AChE activity method is applicable to a wide range <strong>of</strong> species and has <strong>the</strong> advantage <strong>of</strong><br />
detecting and quantifying exposure to neurotoxic substances without a detailed knowledge <strong>of</strong> <strong>the</strong> contaminants<br />
present. AChE activity is a typical biomarker that can be used in in vitro bioassays and fi eld applications.<br />
Main impacts on <strong>the</strong> environment and human health<br />
AChE has traditionally been used as a specifi c biomarker <strong>of</strong> exposure to organophosphate and carbamate<br />
pesticides. More recently, its responsiveness has been demonstrated to various o<strong>the</strong>r groups <strong>of</strong> chemicals<br />
present in <strong>the</strong> marine environment including heavy metals, detergents and hydrocarbons. Its usefulness as<br />
a general indicator <strong>of</strong> pollution stress in mussels from <strong>the</strong> Baltic Sea has been shown within <strong>the</strong> EU-BEEP<br />
<strong>project</strong>. AChE inhibition mostly agreed well with <strong>the</strong> studied pollution gradients, especially in mussels. Seasonal<br />
differences in activity were notable in fl ounder, eelpout and mussels, possibly resulting from variations<br />
in <strong>the</strong> occurrence <strong>of</strong> affecting substances (e.g., pesticides from river input or run-<strong>of</strong>f from agricultural<br />
sources) during <strong>the</strong> year. Additional fi eld studies and laboratory experiments showed that AChE in Baltic<br />
mussels is infl uenced by temperature and salinity, while also salinity has an effect on <strong>the</strong> uptake (and <strong>the</strong>refore<br />
on toxicity) <strong>of</strong> substances (Lehtonen et al. 2006).<br />
Status <strong>of</strong> a compound on international priority lists and o<strong>the</strong>r policy relevance<br />
OSPAR pre-CEMP, MED POL Phase IV (2º Tier).<br />
ICES SGIMC has recommended AChE in molluscs as biomarker to be included into <strong>the</strong> OSPAR Coordinated<br />
Environmental Monitoring Programme (pre-CEMP).<br />
AChE has been adopted by UNEP as part <strong>of</strong> <strong>the</strong> second tier <strong>of</strong> techniques for assessing harmful impact in<br />
<strong>the</strong> Mediterranean Pollution programme (MEDPOL Phase IV).<br />
GES boundaries and matrix<br />
The existence <strong>of</strong> extremely low thresholds for induction <strong>of</strong> inhibitory effects on AChE suggests that detection<br />
is possible after exposure to low concentrations <strong>of</strong> insecticides (0.1 to 1 μgl-1; ICES 2010).<br />
Standardisation <strong>of</strong> <strong>the</strong> sampling strategy and regular intercalibration exercises on specifi c organisms are still<br />
necessary before using AChE in routine pollution monitoring.<br />
No formal quality assurance programmes are currently run within <strong>the</strong> BEQUALM programme but one major<br />
intercalibration exercise was carried out during <strong>the</strong> BEEP <strong>project</strong>.<br />
Baseline levels <strong>of</strong> AChE in different marine species have been estimated from results derived from in <strong>the</strong><br />
Atlantic Ocean, <strong>the</strong> Mediterranean and <strong>the</strong> Baltic Sea (Table 4.6; ICES 2010) and ongoing studies within<br />
Bonus+ BEAST.<br />
Generally it has been accepted that 20% reduction in AChE activity in fi sh and invertebrates indicates<br />
exposure to neurotoxic compounds. Depression in AChE activity more than 20% up to 50% indicates sublethal<br />
impact. In <strong>the</strong> fi eld, several species have baseline AChE activities within <strong>the</strong> same order <strong>of</strong> magnitude<br />
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