APPENDIX 19
Evidence submitted by English Nature (B
20)
INTRODUCTION
1. English Nature is the statutory body
responsible for advising both central and local government on
nature conservation and for promoting the wildlife and natural
features of England. In fulfilling its duties, English Nature:
— advises Ministers on the development
and implementation of policies for nature conservation;
— advises Ministers on other policies
affecting nature conservation;
— identifies, notifies and safeguards
Sites of Special Scientific Interest (SSSIs);
— establishes, maintains and manages
National Nature Reserves;
— provides guidance and advice on the
principles and practice of nature conservation to a wide constituency;
— commissions and supports research
and other projects relevant to nature conservation.
2. Through the Joint Nature Conservation
Committee, English Nature works with sister organisations in Scotland,
Wales and Northern Ireland to advise Government on UK and international
nature conservation issues. English Nature has a lead agency role
on pesticides and toxic substances on behalf of the other conservation
agencies. This response also represents the views of the Countryside
Council for Wales.
BACKGROUND
3. An environmentally sustainable sheep
farming industry is an important component of the maintenance
of both upland and lowland habitats of importance for nature conservation.
The safety and well-being of the sheep flock is a vital part of
this, and the effective control of parasites is an essential component
of good flock management. Serious environmental problems have
arisen from current methods of parasite control. Any future proposals
which lead to changes to the management of parasites in sheep
flocks will need to take account of the consequential environmental
risks, and must also consider the need to maintain the structure
of sheep farming on which nature conservation depends.
4. English Nature wishes to stress the nature
of the environmental risks associated with the sheep dipping,
and particularly the implications for nature conservation. The
environmental risks differ for organophosphate (OP) dips and the
synthetic pyrethroid (SP) dips which are used as alternatives,
and in particular there is evidence that the aquatic risks are
significantly greater where some of the SP dips are used.
TOXICITY OF
DIP ACTIVE
INGREDIENTS
5. Cypermethrin, one of the widely used
SP dips, has a toxicity to the freshwater crustacean Daphnia
magna some 100 times greater than the OP diazinon at the concentrations
used in dip solutions. The Environmental Quality Standard (that
is the concentration in surface waters below which it is thought
not to harm aquatic life) for cypermethrin is 100 times lower
than that for diazinon. The toxicity of cypermethrin to other
aquatic crustacea and insects can be several orders of magnitude
greater than its toxicity to daphnia. Other SPs such as flumethrin
are less toxic to daphnia than cypermethrin or diazinon, but aquatic
insects may again be more sensitive, due to the general sensitivity
of insects to the synthetic pyrethroid insecticides.
6. Dips may be disposed of onto land, where
they can pose a risk to terrestrial invertebrates and to vertebrates,
such as wildfowl, grazing on treated vegetation. Earlier work
has shown the toxicity of the organophosphate dip propetamphos
to some groups of terrestrial invertebrates when applied to land
(Coulson and Goodyer 1990), whilst there have been poisoning incidents
involving wildfowl grazing areas used for the disposal of OP dip.
Unlike the OP dips, SP dips are less likely to cause avian wildlife
incidents due to their lower avian toxicity. However, their likely
effects on terrestrial invertebrate populations, and hence indirectly
on bird populations through affecting their invertebrate food
supply, are less well understood. English Nature is undertaking
a joint research project with the Countryside Council for Wales
and the Environment Agency to determine more accurately the risks
to birds and invertebrates through disposal of both OP and SP
dips to land.
7. In summary, due to their intrinsic toxicity
to invertebrates, the SP dips pose serious risks to aquatic life.
In the case of cypermethrin this risk is several orders of magnitude
greater than the OPs. At present, the relative risks to terrestrial
invertebrates are less clear cut, although the SPs are likely
to present a lower risk to grazing birds.
INCIDENTS OF
DAMAGE TO
AQUATIC WILDLIFE
DUE TO
SHEEP DIP
8. Problems of aquatic pollution incidents
involving sheep dip have been occurring for many years. An increase
in the number of pollution incidents was recorded in 1997 (Environment
Agency 1998), and there were then several serious incidents involving
SP dips, although some incidents also involved OP dips. Typically,
stretches of river 5-10 km long may be affected by declines in
invertebrate populations following an incident, but much larger
effects have been recorded and recovery, where it has been measured,
has been variable. In Wales, it was estimated during the 1998
survey that up to 1,200 km of upland water courses could potentially
be affected, and it was concluded that sheep dip is the largest
single known cause of impoverishment of fauna in upland rivers
due to pollution (Environment Agency 1999a). During that survey,
all but one of the substantiated incidents confirmed as being
due to sheep dip were due to synthetic pyrethroids.
9. The effects of dip incidents have been
most marked on the highly sensitive groups of aquatic insects.
However, there have also been serious incidents involving other
invertebrates, such as white-clawed crayfish which is a species
listed under Annex II of the Habitats Directive, and for which
a recovery programme exists under the UK Biodiversity Action Plan.
Such incidents have affected a number of Sites of Special Scientific
Interest (SSSIs) such as the rivers Wye and Eden. These rivers
have also been selected under the Habitats Directive as Special
Areas of Conservation (SACs) for this species, as well as for
Annex II fish such as salmon which depend on healthy invertebrate
populations for their survival. Other rive SACs affected by incidents
involving SP sheep dip include the River Ehen in Cumbria, which
is the only SAC selected in England for the freshwater pearl mussel.
There has been a severe impact on invertebrates in this river,
and some impact on juvenile pearl mussels; the implications for
recovery of populations of this very long-lived species are uncertain.
10. The increase in incidents involving
SP sheep dip coincides with a major shift from the use of OP to
SP based dips after the mid 1990s. One of the factors which may
have contributed to this shift is the widespread concern over
health risks to users of OP pesticides (Environment Agency 1999b).
An earlier report (Environment Agency 1998) suggested that one
of the major reasons for the environmental problems arising from
sheep dipping arises from a lack of farmer awareness, and the
need for improved standards of dip installation and sheep management.
The implementation of the 1998 Groundwater Regulations, and the
requirement for authorisation of dip disposal routes is likely
to raise awareness of the environmental risks involved during
dip disposal. However, incidents have been attributed to both
disposal and use of dip, including dripping from sheep into watercourses
after treatment. There is currently no legal requirement for all
those involved in dipping to hold a certificate of competence.
CONCLUSIONS
11. The current restrictions on the use
of OP sheep dip products, pending further action on container
design, will clearly lead to greater use of alternatives including
SP products. Rather less is known about the environmental risks
associated with the widescale use of other treatments such as
pour-on and injectable products, but some of these may also enter
the environment and affect wildlife through residues in dung.
It is very important that where action is taken on the grounds
of protection of human health, users are not misled into a false
appreciation of the relative environmental safety of alternative
methods of parasite control. English Nature urges the Agriculture
Committee to recommend wider user education and suitable training
on the environmental risks associated with parasite control, and
in particular with dipping practice, as a part of any recommendation
it may make on human safety grounds.
REFERENCES
Coulson JC and Goodyer S (1990). The effects
of the insecticide propetamphos on invertebrates of grassland.
Report by Durham University to the Nature Conservancy Council.
Environment Agency (1998). A Strategic Review
of Sheep Dipping. ADAS report to Environment Agency. R&D Technical
Report P170.
Environment Agency (1999a). Welsh Sheep Dip
Monitoring Programme, 1998. Report from the Environment Agency
Wales and Midlands Regions.
Environment Agency (1999b). Sheep Dip Strategy.
Environment Agency R&D technical report p237.
28 March 2000
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