Men who carry their mobiles around their waists may be making themselves less fertile, scientists say Hong Kong men have been warned they may be risking more than their street credibility by wearing mobile phones on their belts: they may also be putting their fertility in jeopardy. A study presented to an international conference in Berlin last week suggested that carrying a handset around all day, particularly in a belt holster or trouser pocket, can reduce sperm counts by up to 30 per cent. Tests found that men who carry a switched-on mobile phone had sperm counts averaging 59 million sperm per millilitre of seminal fluid, compared with 83 million for men who do not carry mobile phones. The study suggests that electromagnetic signals emitted by mobile phones may affect sperm counts - and that the closer the phone is carried to a man's sensitive areas, the higher the risk of a man's fertility being affected. A team of scientists from the University of Szeged in Hungary studied 221 men over a period of 13 months, comparing the sperm of men who carried mobile phones most of the day with those who did not own a phone. The scientists also found that the motility of sperm - its ability to swim - was affected by mobile-phone transmissions. Men who made frequent calls had only 36 per cent of fast-swimming sperm, compared with 51 per cent in men who made no calls. Team leader Dr Imre Fejes said in his report to the European Society of Human Reproduction and Embryology conference: 'The prolonged use of cell phones may have a negative effect on spermatogenesis and male fertility that presumably deteriorates both in concentration and motility.' Hong Kong has one of the world's highest levels of mobile phone ownership, with 7.4 million mobile phone subscriptions for a population of 6.8 million. It also has one of the world's lowest birth rates, with each woman having an average of 1.17 children, compared with 1.33 in Japan and 1.51 in South Korea. But experts have cast doubt on whether the Hungarian report can be taken as evidence of a direct link between mobile-phone use and sperm counts. The lifestyles of people who use mobile phones regularly may be more stressful and less healthy than those of men who never use them, meaning other factors are affecting fertility. A spokesman for the UK National Radiation Protection Board described the findings as unexpected. 'The decline in male fertility has been going on for decades before the widespread use of mobile phones and there can be many reasons for it,' he said. But if the theory is proved, changing fashions and increasingly lighter mobile phones may help spare Hong Kong men from full exposure to any dangerous effects from radiation. Fewer men now carry their phones on their belts, opting instead to carry them around their necks or out of sight in jacket pockets or backpacks. But fashion writer Tim Lim said: 'The only people I've seen wearing mobile phones on their belts these days are truck drivers and mainlanders. It's a bit local to have your phone on a belt where everyone can see it. I'm told the trendiest way to carry your phone is in your back pocket.' Ricky Wong, who sells mobile phones at a Causeway Bay store, said: 'It's mostly older men, those aged 40 to 50, who put their mobile phones in a leather case and wear it on their belt. Younger men usually wear it on their necks, or put the phone in their backpack.'