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Removing the risks of PCBs and PAHs

PCBs are illegally dumped in waste oil.

Trace organic pollutants threaten our environment as they pose potentially dangerous health risks. Their use, regulated through legislation, requires continuous and regular monitoring. For these checks to be accurate and provide data for long term impact assessment, accurate, comparable measurements are necessary. Certified Reference Materials play a vital role in helping laboratories to ensure they are producing quality measurements.


Polychlorobiphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) present great environmental risks. PCBs are persistent and do not decompose easily. They accumulate in the environment, leading eventually to adverse effects on animals at the top of the food chain. PAHs, on the other hand are toxic to aquatic organisms and carcinogenic to mammals, including human beings. Given that there is significant evidence to indicate that even trace amounts of these compounds may be harmful, there is much concern about their use.

There are strict laws to control the occurrence of these compounds which exist in nature and are produced by industry. PAHs are, for example, generated when fossil fuels are burnt and PCBs are used widely in the electrical industry, in capacitors and transformers, as well as in inks, paints and papers in the printing industries. The latter should be destroyed by costly high temperature incineration. To avoid this expense, some companies illegally dissolve the PCBs in waste mineral oil to be buried in landfill sites or disposed in the sea in a container.

The environment is contaminated

In both these instances, the chemicals leach out into the water and soil and both aquatic and land animals are affected by their harmful effects. In order to enforce the law and control the levels of these chemicals and the health risks they impose, regular monitoring is necessary. This requires accurate and reliable measurements that can be compared between laboratories in different countries. Measurements must also be comparable over time so that long term impact studies provide meaningful data from which policy makers can make decisions about the regulation limits.

Discrepancy between laboratories

Currently, the quality of the analyses of environmental samples, such as fresh water sediments, is the subject of much discussion. Everyone realises the importance of obtaining reliable and comparable results, but achieving harmonised results is a different matter. In recent studies, a number of laboratories were given a sample on which to perform their usual measurements. The discrepancy between different laboratories was incredible: the participants simply could not agree on the true content of the harmful chemicals.

The measurements that need to be performed are detailed and involve many steps. Natural materials consist of many different chemicals, many of which are very similar. This makes measuring the levels of PCB and PAH contamination less straightforward than one might think and there are many opportunities for errors to be made.

To improve the quality of measurements, reference materials are often required. Some of these include pure calibration PCBs and PAHs which laboratories can use to check the accuracy of the technique they are using to perform the final detection step. Reference materials that are similar to the actual samples being tested are also required. These are required to test that laboratories are performing all steps of the measurement method correctly. This includes extracting the chemicals from the rest of the sample.

A European effort to solve the problems

Dr Wegener, from the Institute for Environmental Studies in Amsterdam, has coordinated twenty six laboratories from nine European countries to develop fresh water sediment reference materials. These materials have guaranteed levels of PCBs and PAHs and they can be used to reliably check the accuracy of measurements.

To develop the materials and test them for stability and homogeneity, the laboratories performed detailed studies. Because the levels of contaminants in the reference material has to be known, with little uncertainty, the team of laboratories each measured the levels of PCBs and PAHs and then compared their results in technical meetings. Problems and errors were identified and measurements that deviated were removed from the results. However, if there was not significant agreement, the material would not be certified. The group produced hundreds of sediment samples, each with certified levels of contamination.

Most laboratories participating in the certification exercises have been members of "working groups" for PCB and PAH analysis. With most European countries being represented in these groups, the views and expertise of individual organisations is well distributed. The results of the studies involving 28 laboratories all emphasised the importance of open discussion and comparison of results. Only with good communication between the participants could such a valuable interchange of experience realise its full benefits. The laboratories involved can disseminate the results of the studies to colleagues in their own European countries.

Several projects have produced complementary certified reference materials, including contaminated industrial soils, sludges, waste mineral oils and milk. They all provide environmental testing laboratories with useful tools to check their results and techniques for quality and accuracy.

Reference materials in accreditation

The applications of these reference materials is far-reaching: laboratories all over the world will use them to validate their methods for measuring PCBs and PAHs in sediments. The main users are national and regional water authorities, institutes and universities performing environmental research into soil and sediments.

The materials will play a key role in laboratory accreditation. If laboratories want to gain accreditation, they must be able to demonstrate that their results are accurate and reliable and that they follow quality control procedures. Using certified reference materials helps laboratories to demonstrate that they comply with the strict requirements of accreditation.

In order to reduce pollution, measurements must be made on samples taken from the environment. If this monitoring is to be effective, it is imperative that the regular checks provide results that are both meaningful and comparable. In this way, reference materials help the analysts measuring PCB and PAH levels to protect our environment.



Project Title:  The Preparation of a Freshwater Sediment Reference Material Certified for Polychlorobiphenyls

Programmes: Standards, Measurements and Testing
Contract Reference:  

Project Title:   The Preparation of a Freshwater Sediment Reference Material for Polycyclic Aromatic Hydrocarbons

Programmes: Standards, Measurements and Testing
Contract Reference:    

Cordis DatabaseFor more information on this project,
go to the CORDIS Database Record  
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