After studying 150 fishermen, researchers discovered that exposure to certain pollutants that are a bi-product of industrial and agricultural processes increased the Y chromosome sperm. However, lead researcher, from Lund University in Sweden, Professor Aleksander Giwercman said a larger population sample would be needed to confirm if the effect would lead to more boys being born. The researchers analyzed the effect of exposure to two persistent organochlorine pollutants - DDE and CB-153 - which is most likely to come from eating fatty fish such as salmon. According to the Human Reproduction journal, 20% of men with the highest exposure to DDE compared with the 20% with the lowest exposure had 1.6% more sperm with the Y chromosome. For CB-153 there was a 0.8% increase. Dr. Allan Pacey, a specialist in male fertility at the University of Sheffield and secretary of the British Fertility Society, said, "It is the first time I have heard of pollutants having this effect...if this is so it is possible others could have a similar impact and that could have huge consequences."