I read in BW that metaldyhyde pollution in watercourses is a growing problem for water companies, and that this comes from slug pellets used by farmers to protect oilseed rape. Since oilseed rape is a Hope Farm crop, how is this issue handled?
Sue Everett of Conservation News at British Wildlife magazine tells me that metaldyhyde in water courses at very low levels (EU standard 1ppm) does not harm wildlife. It appears to be a drinking water problem. So I guess if it's only bad for people, that's ok then.
Drinking water standards for all pesticides are set at 1ppm – in essence this is a surrogate for zero that dates back 20-30 years. This reflects an inherently precautionary approach to human health protection. Since then technology has moved on and we can detect pesticides at vanishingly small concentrations but the standard remains unchanged.
So are current concentrations a problem? Well, firstly we should consider that what we’ve learnt about metaldehyde suggests it last longer in the environment and is far more mobile than originally thought. This raises some interesting questions about the tests routinely applied when authorising a pesticide for use. How many other surprises await the environmental chemist in the future?
As for toxicology – Pan-UK have a nice summary of studies that point to concerns for wildlife and pets but l I’m not acutely concerned about my tap water even though I know the source is surrounded by intensive arable crops. That said I’d rather not be drinking this stuff and I’d rather it wasn’t turning up in watercourses at concentrations well in excess of 1ppm.
But what really bothers me is that Government has failed show any kind of strategic leadership on the issue. The farming industry has tried its best through education and advice but if it keeps turning up in drinking water, as I suspect it will, we risk sleep walking into a ban. I fear this will inevitably mean a mass switch to methiocarb (a pesticide with significant risks to wildlife) because apparently safer alternatives based on ferric phosphate struggles to gain farmer acceptance against the marketing power of big agri-industry.
So metaldehyde wouldn’t be the first concern for wildlife or even human health but the fact it is popping up all over the place does suggest the way we regulate and use pesticides is far from perfect.
Rob Cunningham (Head of Water Policy)
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