28 November 1997

Spray operators take stick for high ipu levels

SPRAYER operators are being unfairly blamed by agrochemical makers for high levels of ipu in surface waters.

Diffuse sources, or leaching of ipu to field drains, are at least as important, maintains Steve White, policy and planning manager for Thames Water Utilities.

"It is easier for the pesticide industry to accept point source is the problem. It takes the blame off the product, and puts it on to operators," he says.

Recent reports from the ipu task force, which includes pesticide manufacturers, have focused on spillages of the concentrated product and poor cleaning of containers, protective clothing and sprayers.

Dry seasons help

The lack of moisture in the last few years has helped that argument, says Dr White. Some field drains have not run for two to three years. Peaks of ipu pollution have tended to follow spraying events instead, suggesting spills and poor rinsing are more likely causes of pollution.

In dry seasons point source contamination may account for 50% of cases, Dr White admits. "But in a wet year it might be a lot less."

Rhône-Poulencs Steve Higginbotham, chairman of the IPU Task Force, defends its position. "It is very difficult to say how much pollution is due to point source contamination and how much comes from diffuse sources.

"German figures suggest point source is responsible for 80% of cases. Whether that compares with the UK is open to question. We are trying to address all aspects of pollution, but it makes sense to tackle those causes that are easiest to resolve first." A poster campaign targeted at sprayer operators is now under way.

That is endorsed by Dr White. "Even if point source is only 10% of the cause on average, it will be worth addressing. Half a cupful of neat ipu is enough to pollute 10km of deep river."

However, tighter controls on field use may also be needed to pacify water companies facing escalating clean up costs.

Ozone is currently used to remove the pesticide, but faces EU pressure since it converts bromide to carcinogenic bromate. Thames Water has recently already invested £400m in plant to remove pesticides from water. Annual running costs are put at £40-50m.

&#8226 Latest figures show ipu pollution as measured by samples exceeding 0.1ppb rose 2% in 1996 compared with the previous year, reaching 19%, according to the Environment Agency. However, ipu use increased in that time by about 10%, industry sources reckon.