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Keeping pesticides out of water
PAN UK and the Chartered Institute of Water and Environmental Management (CIWEM) joined forces to host the Keeping Pesticides out of Water conference in London on 7 February. Peter Beaumont reports on key points made by the water industry, users and policy makers concerned with pesticides.
CIWEM is a professional body for engineers, scientists and other qualified personnel engaged in water and environmental management. The conference was chaired jointly by CIWEM’s President Ronnie Falconer and Mark Davis of PAN UK. It highlighted the pollution resulting from the regular and legal use of pesticides, and called for an environmental policy on pesticides.
The main pesticide contaminants
Andy Croxford presented information from the Environment Agency (EA) which monitors freshwater, groundwater, marine water, and sewage and trade effluent – drinking water monitoring is coordinated by the Drinking Water Inspectorate. The testing regime:
- tests for 184 pesticide chemicals, including breakdown products at 3287 sites;
- makes 370,000 analytical determinations;
- and costs £4 million.
The main pesticide contaminants of surface freshwaters and marine waters are the herbicides mecoprop, diuron, isoproturon and MCPA. Most of the recorded Environmental Quality Standard failures are caused by the marine antifoulant TBT, and by sheep dip chemicals (both from dip waste and from wool washing plants) and mothproofing chemicals. The main pesticide contaminant in groundwater is the herbicide atrazine.
Dr Croxford also detailed three cautionary points. Firstly it might appear that few pesticides were being found at levels in excess of drinking water standards or EQSs but this might well be because the Agency was not looking in the right place. Most of the sampling was at points of abstraction in headwaters and major rivers. Pesticides would be more likely to be found in small streams nearer farm sources before they had become diluted by flowing into larger water bodies. Secondly, groundwater monitoring was for the moment concentrated around the Thames area, but steps were being taken to widen the geographical range of monitoring. Finally, pesticide monitoring data needed to be linked with information on biological effects so the impact of pesticides on aquatic ecology could be judged.
How pesticides get to water – the Cherwell Project
Dr Andrée Carter of the Agricultural Development and Advice Service (ADAS) at Rosemaund presented work done at Cherwell Farm, Oxford, showing the importance of point source contamination of a river catchment. The experiment examined how pesticides from point sources travelled from the concrete soakaway in the farmyard to contaminate the River Cherwell catchment. The work observed a spray contractor at work mixing, loading and applying isoproturon (IPU) in the autumn of 1999. Pesticide spillages in the farmyard accounted for considerable quantities of surface water contamination. The sources were:
- glugging and splashing from containers during the loading operation;
- leaking equipment and dripping nozzles;
- upturned containers that leaked rinsate containing pesticides;
- washing down the rear of the tractor and the spray unit after use;
- soil on the sprayer wheels that contained pesticide from trafficking over treated land – this too was washed into drains.
The contribution of the yard washings from all these incidents meant that the level of IPU in the River Cherwell rose to 13µg/l (breaching the drinking water limit of 0.1µg/l) on the day of application. Concentrations of pesticide up to 6µg/l continued to leave the yard 3.5 months after application. Mud containing pesticides that washed into drains caused contamination to the catchment for up to 11 months after the pesticide was applied.
Calculations showed that losses from the farmyard contributed approximately 40% of the total IPU load in the small catchment, despite the observance of good practice by professional spray contractors. It is likely that this will apply to the majority of soluble and mobile pesticides where washing takes place in a farmyard that drains directly to a catchment; and will apply to every such farm.
The water industry’s view
Dr Bob Breach expressed the industry’s frustration that for some particular pesticides, good practice had not achieved a significant reduction in water contamination. He noted that in spite of regulatory controls and good examples of best practice in the UK, including specific local catchment agreements, municipal and railway weed control and stewardship campaigns, some pesticides were still polluting water.
Dr Breach cited as an example high levels of atrazine, from suspected illegal use, that had polluted a Midlands reservoir to such an extent that treatment facilities were overwhelmed and the reservoir had to be taken out of supply for some months while the pesticide degraded naturally.
He trailed a report from the Union of the Water Supply Associations from Countries of the European Communities – to be released in April. It will say a high percentage of lowland European rivers were affected by pesticides, and the most common exceedences were triazines, urons and mecoprop. Up to 10% of groundwater was contaminated, again the most common pesticides were triazines, mecoprop and bentazone.
‘Stewardship campaigns by agrochemical manufacturers and farmers in respect of diuron and IPU have not been noticeably effective’ said Dr Breach, and he is concerned that effective good practice is not achievable. He called for tougher regulatory action for those pesticides still causing problems.
The future of regulation
Steven Reeves, Policy Advisor at DETR’s Water Quality Division, introduced the newly agreed EU Water Framework Directive 2000/60 that entered into force in December 2000.
It will establish a priority list of hazardous substances – the Commission has proposed a list of 32 substances, 11 of which are pesticides: lindane has been proposed as a priority hazardous pesticide with the intention that all releases to water must cease within 20 years; atrazine, chlorfenvinphos, chlorpyrifos, endosulfan, pentachlorobenzene and trifluralin will be subject to examination by 2003 to judge if they should be additional priority hazardous substances; and alachlor, diuron, isoproturon and simazine are also listed.
Monitoring programmes will include catchment management plans to be drawn up during the coming 15 years to improve or prevent the deterioration of water quality status.
Pollution prevention
Richard Garnett of Wisdom Systems saw the way forward as returnable multi-trip packs, direct chemical injection, closed transfer systems (CTS) and precision pesticide application. He presented the case for CTS, arguing that typically 90% of exposures occur at the stage of opening, measuring and pouring of the concentrate and rinsing the container. CTS was a closed mechanical system governed by British Standards performance criteria that prevented the operator and the environment from coming into contact with the pesticide concentrate. Trials had shown that a reduction in contamination of 90% could be achieved. Systems could be supplied both for agricultural and amenity users.
The potential of CTS was welcomed; but the drawbacks were:
- the lack of standardisation of mechanical couplings;
- the need for agrochemical companies to standardise their packs and make more formulations available;
- the cost and maintenance of the equipment (up to £30,000 for a large spray unit);
- lack of flexibility to load up relatively small amounts of product.
Lower input agriculture
Chris Wise of the National Farmers Union gave the view from the farming side. He suggested there were 20,000 sprayers that covered between 75-80% of the cultivated acreage. There were probably another 30,000 sprayers covering the remainder. In addition there might be 20,000 sprayers lying by hedges! He emphasised that possibly 60% of pesticide applications would be at repeated low doses. The tendency was now for farmers to use low dose applications, lower than label recommendations, and repeat these – although this still resulted in less product being used than if full rate label rates were observed.
Lower input farming systems were being developed and were showing good results for farmers who wanted to go down that route. The Integrated Arable Crops Partnership Alliance (IACPA) has publicised results from such systems. CWS Farms had demonstrated they could reduce costs and increase profitability – trials had cut pesticide use by 40%.
No pesticides in parks
Shaun Faulkner, Head of Service at Brent Parks Service, is responsible for the day to day management and development of over 1,000 acres of public open space in the London Borough of Brent.
Brent provides a range of facilities including parks, sports facilities and consultancy services. Through the use of ISO 14001 environmental management standards Brent has assessed the environmental impacts of all its services provided by the Parks Service. This has resulted in a pesticide reduction strategy, the elements of which are:
- a policy on pesticide usage based on the use of alternatives if available or practical, and prescribing both the uses and the pesticides that can in any event be used;
- maintaining membership of PAN UK’s Local Action on Pesticides (LAP) scheme;
- organising an annual alternatives to pesticides conference with other authorities to share experiences and develop benchmarking;
- trialing and researching the latest machinery products and equipment to assist in developing best practice;
- providing a comprehensive training programme to enable all staff to obtain a clear understanding of the requirements needed for the safe use of pesticides and their alternatives.
In practice this means the Service only uses some herbicides (but not selective products), and in general does not use insecticides, fungicides, turf products or moss killers. Weeds on park paths are cleared by mechanical sweepers. Roses and shrub beds are not sprayed. Worm killers are not used. Generally organic methods are used wherever possible, and the largest open space in the Borough, Fryent Country Park has attained organic status. More of Brent’s parks will try for Green Flag Park awards.
Conclusions
Although problems had been revisited, some solutions had been found, but they needed to be more widely adopted. Water pollution remains on the public agenda but removal of pesticides at the point of supply is not sufficient. It is not certain that good practice will ever be able to prevent pesticides from reaching water. And what incentives can be offered to farmers to invest in less polluting technology and lower input systems?