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Title: A Strategic Review Of Sheep Dipping
Author: A Armstrong
Author: K Philpis
Author: Environment Agency
Document Type: Monograph
Annotation: Environment Agency Project ID:EAPRJOUT_436, Representation ID: 128, Object ID: 1775
Control of ectoparasites is necessary for the continuing~health of the UK sheep flock. Sheep Scab is a particular problem;traditionally.controlled by dipping. sheep in a bath containing a diluted solution of a powerful insecticide. Recent surveys have shown that pollution of surface waters by sheep dip is widespread, and that action -needs to be taken to reduce this pollution. This review examines the background and options to reduce-the environmental impact of sheep dipping. 1. Traditional methods of controlling ectoparasites have involved dipping: sheep in .. organophosphate (OP), or more- recently synthetic pyrethroid (SP) chemicals. Alternative pour-ons and injectables ahave recently.: become available, although some of these are less effective for the:treatment of some diseases, notably scab. The usualmeans of disposal of spent sheep dip is by .spreading on the land, where it is sorbed to organic material and subject to microbial and chemical breakdown. by-passes this organic material, or is applied at excessive rates, it moves to surface or ground waters, and presents a direct environmental hazard. 2.. Although only few reported pollution incidents each year are attributable directly to sheep. dip,. this conceals widespread background pollution. In 1995 .only 4 of the 55 substantiated pesticide-pollution-incidents reported involvedsheep dip, although in the same year 5% of all samples analysed for sheep dip chemicals had these chemicals present above the limit of, detection. :In response to this concern and, to assessthe possible impact of such pollution. a survey in Wales conducted by the Agency in 1997 showed a widespread pollution problem.A recent increase in reported incidents in -1997 may be due both to a greater awareness of the problem, and thegreater use and toxicity.of .SP (as opposed to OP) dips. 3. Sheep dip, as waste from~agricultural premises is not a controlled waste. Pollution of water courses by dip is covered by the Water Resources Act 1991, andscriteria for the safe disposal of spent dip to land are contained in the MARP/WOAD Code of Good Agricultural Practice for the Protection of Water (1991). Regulations proposed by DETR to protect groundwaters (and currently.under discussion) will require Agency authorisation of sheep dip disposal sites. It is considered that the effect of this proposed regulation will be to reduce, the frequency of sheep dipping, with an increase in. the :use of non-dipping alternatives. This report argues that- the current legislative framework is too limited, and that more positive control is needed, based on the requirement for agreed dip management.. plans, the licensing of-dip facilities as. well as dip disposal sites, and the notification of dipping operations. 4. Poor dip installation design and siting has been identified as a major problem that needs to be addressed. Other poor practices result from a lack of care, and a lack of awareness of pollution. risks. There. is a need for the development of a code ofa good practice for ectoparasite control in sheep that embraces the ,whole of the dipping operation, from the. management of the flock, the dip installation, the,management of the dipping operation, and the disposal of the spent dip. This code- could be the focus of a programme of farmer education. The role of the mobile dipping contractor has been identified as being particularly crucial-in this respect. R and D Technical Report P170 Vii 5. Positive flock management techniques present the possibility of managing sheep flocks without the use of dips. Alternative methods of disease control can be used in collaboration with the rigorous use of internal quarantine controls, to create and maintain scab free flocks. Such flocks may require no dipping for scab, although dipping for control of other parasites may be required. Such techniques are not, however, likely to be applicable to those flocks grazing common land unless supported by a legislation. 6. Current guidance excludes disposal of spent dip to any area likely to generate direct runoff to water courses. At application rates of up to 5 m3/ha, spent dip presents little risk to groundwater, or to surface water or ifit does not run off or enter groundwaters. Normally the active ingredients in sheep dip remain bound to the soil organic matter and degrade. However, the impact of dip disposal on terrestrial fauna is poorly documented and needs investigation. 7. On-farm treatment of sheep dip offers the prospect of some detoxification before disposal. Addition of high alkali solutions may lead to chemical decomposition of SPs and some OPs. However, the resultant product may have some residual toxicity, and so present a risk to the environment, and therefore still needs careful disposal to land. Addition of spent dip to organic materials (particularly manures) where high rates of biological activity could potentially lead to the rapid degradation of the active ingredients on dip, appears to offer the potential for the safe treatment of used dip, but is untested.. Much further work to evaluate these techniques is needed before they can be advocated. 8. Off-site disposal of spent dip to currently licensed premises is not a practicable option. being prohibitively expensive. Few sites in the UK are able to offer disposal facilities, and the prospect of transporting large quantities of dip by road to these sites presents another environmental hazard, 9. The textile industry can also represent a localised source of sheep dip chemicals. Discharges from wool washing and processing plants may lead to exceedence of Environmental Quality Standards, even after treatment. Because much wool is imported, not all the chemicals found have marketing authorisation as a sheep dip product in the UK. A three stage solution to reduce pollution from this source has been suggested: reducing the amount of pesticide in wool; developing a market for pesticide free wool; and the adoption of better effluent treatment. lO.The indicative annual costs associated with the introduction of site authorisation for sheep dip disposal under proposed groundwater regulations are roughly equivalent to the annual costs of dipping a 500-ewe flock using OP chemical ( and 28O/annum). The cost of using nondipping alternatives (pour-ons and injectables) is much higher, at up to andllOO/annum. However, these costs need to be put in the context of the suggested potential loss of income of 22000 per annum from a 500-ewe flock, if ectoparasitic diseases are not controlled. 11.This review has identified a number of significant weaknesses in current knowledge. There is still much that we do not know about the effects of sheep dip, and in particular research is needed to identify the possible effects of the disposed sheep dip on terrestrial ecosystems. Equally, further research is needed to assessthe efficacy of methods of treating spent dip, to render it less harmful to the environment. Recommendation: A national strategy for sheep dip. R and D Technical Report P170 .. Vlll. A national strategy for sheep dip must achieve a balance between the requirements of the agricultural industry and the need to protect the environment. Sheep dipping should remain a component of. good- flock management, ensuring animal welfare at both the individual and national flock levels. Consequently there is a need to develop strategies to achieve two parallel aims: the safe use of dipping is carried out; and the reduction in the overall need to dip by the use of alternative flock management strategies. These can perhaps be best achieved by the following action points which present,a pattern of education and development, in which the farming industry and the Environment Agency can. work in collaboration, to address the very real risks to the environment posed by the necessary continued use of sheep dip. 1. Developing and promoting positive flock management methods to reduce the need to dip, including- the use of alternatives to dipping (pour-ons and injectables) for disease control where practical. 2. Increasing of farmer awareness and education by the production, and dissemination of a code of good practice for disease control in sheep, to include .all aspects of the siting, construction;- and use of dipping facilities, the correct storage and disposal of spent ,dip;-the management of sheep to reduce .the need for dipping; and the codes ashould be promoted though a positive campaign of farmer education. 3. Requiring .the certificate of competence for all (both farmers and contractors) purchase, use and dispose of sheep dip chemicals; who 4. Extending the ban on the movement of animals infected with sheep scab to the transport of all animals, even to slaughter.. 5. Strengthening the legislative framework for the control of dipping, for example by requiring the collaboration between farmer and the agency in the preparation of a dip management. :> plans for each farm involved in dipping sheep. 6. Developing a national register and licensing of mobile dip contractors; an increased dialogue withthe dipping contractors, including both a clarification of responsibilities regarding spent dip disposal and the adoption of acceptable dipping practices. 7. Developing methods to reduce dip chemicals in effluent from the wool treatment industry. 8. Research into the effects and methods of disposal of spent. dip. .,The main areas where research are needed include: A. Examination of the impact of spent dip on terrestrial ecosystems B. A scientific review of. the current recommendations dip dilution before spreading. C. Examination of the effectiveness of on-farm treatments for detoxification of spent-dip. D. Risk evaluation of the movement of spent dip to surface and ground waters.. E. Evaluation of biobeds and reed-beds as means of disposal of spent dip. : F. Investigation of the environmental hazards of dipping of sheep prior to market. G. Examination of the role of stream chemistry in buffering of toxicity effects. H. Investigation of the extent to which dip components wash off sheep. R and D Technical Report P170 ix
Publisher: Environment Agency
Subject Keywords: Pesticides; Groundwater pollution; Agriculture; Sheep; Freshwater pollution; Synthetic pyrethroid; Agricultural waste management; Textile industry.; Organophosphate
Extent: 71
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