The findings may offer a clue to one of the most alarming of medical mysteries - an apparent dramatic drop in male fertility over the past 50 years.
Studies in 20 countries have shown men are producing only half as much sperm as in the 1930s and scientists increasingly suspect that pesticides - ubiquitous in a normal diet, but absent from organic food - are partly to blame.
At least one in 20 British couples is infertile because the man's sperm count is too low. Professor Stephen Seager, director of the Fertlity Research Programme at Washington's National Rehabilitation Hospital, who has analysed the sperm of more than 100 different animal species says: 'I believe that the human race will eventually become extinct through our poor performance in procreation.'
The new research, by the Department of Occupational Medicine in Arhus, Denmark, and the Danish National Organic Farmers' Board, showed that consumers of pesticide- free food, tested at a convention this year, had sperm counts twice as high as the average - at about the same level as was normal for everyone before the mysterious decline began.
The findings have yet to be formally presented in a scientific paper, but they have been reported in the Danish media and will appear tomorrow in a joint issue of Living Earth and The Food Magazine.
Other scientists are reluctant to comment without seeing the full study. Professor Niels Skakkebaek, head of Copenhagen University's Department of Growth and Reproduction, says: 'I cannot say that this cannot be true, but it needs to be evaluated scientifically.'
Dr Richard Sharpe, who heads research into the quality of sperm production at the Medical Research Council's Reproductive Biology Unit in Edinburgh, described the research as 'anecdotal'. He says that only about 30 men were tested, too small a sample to give unambiguous results.
He pointed out that organic food enthusiasts were likely to be 'extremely careful' about health in other ways as well, and this might be responsible for their high sperm counts. Or - since recent intercourse lowers the sperm count - they might have been abstemious while at the convention.
Prof Skakkebaek and Dr Sharpe believe that pesticides and other chemicals increasingly present in the environment, such as detergents and food additives, are responsible for the decline in male fertility. But they think they do their damage on the male foetus while it is in the womb. Perhaps the fertile Danes' mothers ate pesticide-free food too . . .Reuse content