Environmental contaminants in fish from unmanaged inland UK waterways

There is growing evidence that more people are consuming freshwater fish. This
change is resulting from increased numbers of migrants from Eastern Europe where this
is part of traditional culture, and because of a desire to try new foods encouraged by
celebrity chefs.
2. Fish can bio-accumulate environmental contaminants, and can contribute a signicant
amount to dietary exposure to these chemicals. Rivers are the pathway that many of
these chemicals enter the sea and due to the relatively limited volume of water within
inland waters, can contain higher levels of pollution.
3. This study examines the changing habits of anglers and consumers and characterises a
range of existing and emerging contaminants in freshwater fish species with a view to
determine current levels of occurrence and to allow estimation of consumer exposure.
4. The project was conducted in two stages. The first stage was conducted by ADAS and
consisted of (a) a study that identified freshwater systems that are contaminated either
by anthropogenic activity or as a result of the geology of the area and (b) market
research was conducted in order to assess the consumption habits of the public with
respect of fish and shellfish from unmanaged freshwaters and the possible transfer of
environmental contaminants to these consumers. Regional differences and population
sub-groups were considered, and the habits of unlicensed anglers were included in the
study where possible. This part of the study also identified those species most widely
consumed by anglers and the public.
5. This first stage was followed by evaluation and selection of specific rivers and
waterways that were chosen for investigation, along with the range of contaminants to
be included in the analytical programme. The second stage of the project involved the
collection of samples followed by analysis according to the protocol devised in the first
stage.
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6. A range of fish species from a variety of inland water habitats were obtained,
comprising 46 freshwater fish samples. These were analysed for the following
contaminants:
• Heavy Metals • Chlorinated Dioxins (PCDD/Fs)
• Polybrominated biphenyls (PBBs) • Polychlorinated biphenyls (PCBs)
• Brominated dioxins (PBDD/Fs) • Polychlorinated naphthalenes (PCNs)
• Polybrominated diphenylethers (PBDEs) • OC Pesticides
• Organotin compounds • Organo-fluorine compounds
7. No samples were in breach of legal limits since these only apply to food on retail sale to
the public. Some samples did exceed the existing regulated limits for dioxin and PCBs
that apply to fish that is on retail sale to the public. The maximum detected dioxin and
PCB WHO-TEQ was over 32 ng/kg for a sample of barbel from the River Don, and 6
samples in total exceeded the 8 ng/kg limit.
8. The results of this study confirm the occurrence of a wide range of environmental
contaminants in freshwater fish species and underline the ubiquity and persistence of
these compounds. This is evident from the occurrence of both, legacy contaminants
(PBBs, PCNs and PCBs), as well as more recently introduced chemicals (deca-BDE and
PFCs).
9. This report represents the first study of such a comprehensive set of contaminants in fish
from unmagend inland waterways and as such is unique. The data will allow a
preliminary estimation of dietary intake for consumers of these foods. However,
considerable uncertainty would remain within these estimates, given the limited number
of sites from where samples were taken and also the fact that these were identified as
likely to be most contaminated. The data also provides information on the current
background levels of these emerging and existing contaminants. A parallel study funded
by the Food Standards Agency in Scotland, which investigates a similar range of
contaminants in marine and freshwater fish and shellfish, has recently been completed.
The combined information from these two sets of complementary data may allow more
refined estimates of human exposure.