A report published in November by the UK
Marine Pollution Monitoring Management Group (MPMMG) collates the first results
of the National Monitoring Programme (NMP) intended to establish the
distribution of contaminants in marine waters and define their biological
status.
A survey of 87 estuarine, intermediate
and offshore sites was carried out between 1992 and 1995 to determine the
distribution of metal and organic contaminants (including organochlorine,
organophosphate and organotin pesticides) in water, sediments, shellfish and
fish. The authors of the report generally paint a rosy picture of the quality of
UK coastal waters.
One area of concern involves the contamination with the
anti-fouling paint tributyl tin (TBT) causing imposex in dog whelks. Imposex is
an abnormality in which male sexual characteristics are imposed on the genital
systems of females. The female develops a penis, which may block the genital
opening so that egg capsules cannot be laid, causing reproductive failure and
ultimately death. The relationship between imposex and the presence of TBT
associated with antifouling paints, which are used to discourage the settlement
of marine organisms on boats, has been established since the late 1980s. This
study confirms that imposex still exists off Northern Ireland and the British
Isles.
The report recommends that future monitoring on NMP sites
should include dog whelk imposex bioassays and TBT determination.
The NMP programme sought a number of organochlorines in
marine fish liver, including dieldrin, aldrin, endrin and DDT. Dieldrin was
detected in more than 90% of the stations for which data were reported. Highest
average levels were found in the Thames Estuary (50 mg/kg) and Moray Firth off
Scotland (72 mg/kg). DDT and its breakdown components DDE and TDE were also
found. The highest average concentrations were detected off the north west coast
of England with average levels of 15-91 mg/kg for DDE, 23-130 mg/kg for TDE and
13-28 mg/kg for DDT.
Claire Vincent, Chair of the NMPWG said: "There are no
standards for pesticides in fish liver. However, according to World Health
Organisation maximum residue levels, these results are within 'expected
values'."
Previous studies have identified organochlorines such as
toxaphene and chlordane in UK fish (see PN21 p.15, CRM41 p.5). This report,
however, does not include analysis of such chemicals because adequate analytical
techniques and quality control procedures have yet to be established.
NMP: Survey of the Quality of UK Coastal
Waters, MPMMG, Scottish Environmental Protection Agency, Clearwater House,
Heriot Watt Research Park, Avenue North, Edinburgh, EH14 4AP, 1998, 80pp.
[This
article first appeared in Pesticides News No. 42,
December 1998, page 16]