T he effectiveness of international efforts to protect and improve the marine environment is critically dependent on the reliability of the levels of chemical pollutants. If they are to make good decisions, policy-makers and regulators need reliable, quality environmental monitoring information. However, it is notoriously difficult to establish true comparability between data collected at different test sites. Laboratories commonly produce significantly different measurements from the same samples, even when they use the same test methods. In common with colleagues in other fields, marine scientists have for decades been frustrated by their inability to achieve widespread inter-laboratory agreement.
Inaccurate measurements have the potential to produce large economic and social impacts.
The hypothetical case of a laboratory which tests fish for mercury contamination as the basis for the issue of export certificates illustrates the danger. A false positive may condemn valuable fish stocks and impose crippling and unnecessary losses on the fish producer. A false negative, on the other hand, may allow onto the market fish that constitute a major threat to human health. Though less dramatic, the danger posed by variations in the analytical accuracy of Europe's marine institutes is no less real. Mapping the chemical contamination of the North Sea, for example, will be of value only when there is agreement between the testing laboratories involved.