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Wednesday, 4 October, 2000, 18:03 GMT 19:03 UK
Pesticides 'promote dangerous bacteria'
Pesticide spraying
Pesticide spraying may be counter-productive
Pesticides encourage potentially dangerous bacteria to thrive on some crops, say scientists.

They warn that people who eat raw fruit and vegetables such as strawberries, raspberries and lettuce could be at risk.

New Scientist magazine reports that the researchers, from University of Manitoba in Winnipeg, carried out research after a rise in reported cases of food poisoning caused by fresh produce.

This research raises further doubts about the safety of intensive farming

Sandra Bell, Friends of the Earth

They prepared formulations of a range of common herbicides, fungicides and instecticides appproved for use on raw fruit and vegetables.

After diluting each with water, they added strains of bacteria that cause food poisoning.

These included Shigella, Salmonella, Listeria and E. coli O157 which can cause kidney failure.

The researchers found that bacteria thrived in around a third of the pesticides.

The bugs grew most readily in:

  • the fungicide chlorothalonil
  • the weedkiller linuron
  • the insecticides permethrin and chlorpyrifos
Researcher Dr Greg Blank said numbers could increase one-thousandfold.

Salmonella, E. coli and Shigella grew best - particularly on chlorothalonil.


Dr Blank said that when farmers irrigate their crops they may spray on far larger volumes of contaminated water.

However, pesticides could be more of a problem because bacteria multiply in tanks where the solution is stored, and can reach far higher concentrations.

Dr Blank's team is now investigating whether the bugs survive to the point of consumption.

Ross Dyer, technical manager of the Crop Protection Association in Britain, said that dirty water rather than pesticides was more likely to be the cause of any problem.

"If the water supply is contaminated, it's that that's supplying the bacteria in the first place."

Sandra Bell, a food campaigner for the charity Friends of the Earth, said: "This research raises further doubts about the safety of intensive farming, and Sir John Krebs and the Food Standards Agency (FSA) would do well to turn their attention to these reports instead of making unfounded attacks on organic food."

Sir John, who is chairman of the FSA, told the BBC television Countryfile programme last month that he believed organic food to be no safer or more nutritious than conventionally grown crops.

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20 Sep 00 | Health
Tests spark pesticide concerns
16 Sep 99 | Medical notes
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