Concerns over decreasing male fertility rates
Progress Educational Trust10 March 2008
The first study, led by Dr David Glenn at Queen's University Belfast, , treated sperm in vitro with Viagra, and found treated sperm to be more active than untreated sperm, but also that the 'acrosome', which produces enzymes that help the sperm penetrate the egg, was damaged by the drug. Tests in mice showed that sperm treated with Viagra produced 40 per cent less embryos than untreated. Dr Glenn is concerned that the drug is being prescribed to couples seeking help for fertility problems, and says that 'giving male partners something that could make the problem worse is scarcely the right approach'. He has also raised issues with younger males using the drug recreationally, who may be harming their chances of starting a family in the future.
The second study identified another factor thought to influence male fertility rates: pollution from chemicals such as dioxin, released through industrial processes and found in the atmosphere. A chemical explosion in Italy in 1976 exposed people to a cloud of highly toxic dioxin. A study 22 years later of male volunteers who were exposed found that men who were aged under nine at the time of the explosion had 43 per cent lower sperm counts than a control group. Men who were aged between ten and 17 when exposed, however, had sperm counts 62 per cent higher, and men who were over 17 were unaffected. The findings suggest that dioxin is a potential factor responsible for falling sperm counts, and also puts a question mark over other industrial chemicals.
Endocrine-disrupting chemicals are also thought to be affecting fertility rates. Three such chemicals have been investigated by scientists at the National Food Institute, Technical University of Denmark. When the chemicals were administered separately, they were harmless. Concurrent exposure, however, resulted in malformed sexual organs in the fetuses, showing potential cocktail effects of chemicals should be taken into account when investigating their effects on fertility rates. In Denmark, just under five per cent of boys are born with a certain malformation of their sexual organs.
Meanwhile, new hope was given to infertile couples in Australia, where Menevit, the 'first ever drug to for male infertility', has been developed. It contains antioxidants and works by acting on free radicals that fragment sperm, the main cause of infertility. In a preliminary study of 60 infertile men, the rate of pregnancy was increased significantly, but larger clinical trials are required before the drug can be merited.
Reproduced with permission from BioNews, an email and online sources of news, information and comment on assisted reproduction and genetics.