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
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.