18 August 1995

Pollution is far worse with non- OPdip disposal

By Rebecca Austin

FLOCKMASTERS must consider how they dispose of non-organophosphorus (OP) dips as they are more toxic to aquatic life than OP dips, warns the National Rivers Authority.

Research has proven that synthetic pyrethroid dips are at least a hundred times more polluting in water courses and up to a thousand times more toxic to brown trout than OP dips.

Last month 5km of a tributary of the River Tweed near Hawick in the Borders was polluted and 5000 fish killed by a non-OP dip when it was discharged, it is claimed.

"We are concerned that farmers are increasing use of non-OP dips because they cannot buy an OP dip without a certificate of competence. Many have not got them because they are not prepared to take the test," said Allan Virtue, principal pollution prevention officer with the Tweed River Purification Board. "And because non-OP dips are less toxic to mammals there is a growing, but misplaced, feeling that they are probably less toxic to the environment.

"Farmers must be made aware that they should be extremely careful when disposing of non-OP dips and follow MAFFs Code of Good Agricultural Practice for the Protection of Water to the letter, as well as the manufacturers label recommendations," he says.

MAFFs code of practice states:

&#8226 Dispose of dip as soon as possible after dipping and never empty it into a water course.

&#8226 Soakaways are not suitable in most places as they could pollute groundwater.

&#8226 Spread dip onto land at low application rates in a suitable area.

&#8226 Apply no more than five cubic metres of dip a hectare (450gal/acre).

&#8226 When using a vacuum tanker, dilute the dip before spreading at a rate of one part dip to three parts water or slurry.

&#8226 When there is no suitable land for spreading dip, it should be stored in a holding tank and collected by an approved waste disposal contractor.

&#8226 When in doubt consult the NRA.