ASURGE in the number of boys born with genital abnormalities has been discovered by Cambridge scientists, who are investigating the impact of everyday chemicals in the environment.

Seven per cent of boys are now born with undescended testicles, which can lead to higher rates of infertility and testicular cancer. There has also been an increase in more serious genital abnormalities.

The new research adds to growing concern in the medical community about problems in male reproductive health. Testicular cancer rates have doubled in the past quarter of a century, while a new study in Scotland suggests that one in six men now has a low sperm count.

Scientists are investigating whether phthalates, compounds used to soften plastics and found in packaging, cosmetics and fabrics, suppress sexual development in the womb.

The European Union has become so concerned by the potential impact of modern chemicals on human health that last year it introduced legislation that will see about 30,000 chemicals tested at a cost of £7.5 billion.

Ieuan Hughes, a professor of paediatrics at Cambridge who led the new study, said: “There is a hypothesis that the increase in undescended testes, hypospadias [another genital abnormality], infertility and testicular cancer has a common denominator.

“We are exposed to a soup of up to 1,000 chemicals and it wouldn’t be surprising if it’s having an effect on humans. It’s not something we can just ignore.”

The Cambridge study began in 2001 with the support of a £1.5m EU grant. Doctors and nurses checked 700 boys at birth at Addenbrooke’s hospital, and found that 51 (7%) had undescended testes. In 1992 a study at John Radcliffe hospital, Oxford, found 4% of boys had undescended testicles at birth.

In two-thirds of cases, the boys’ testicles descended of their own accord within two years. The remainder required surgery, although doctors add that the process is not complicated. When testicles are undescended, they remain in the body unlike normal babies where they are already outside the body in the scrotum.

There are far greater concerns, however, over the long-term impact. Boys born with undescended testicles are eight times more likely to develop testicular cancer and up to seven times more likely to be infertile.

Imran Mushtaq, a consultant paediatric urologist at Great Ormond Street hospital, London, said: “There just doesn’t seem to be enough public awareness and enough interest in what is a common condition. The general impression of people who do this form of surgery is that the incidence of undescended testicles is increasing. If the Cambridge people are observing this too then it’s a concern.”

Hughes plans to investigate the extent to which phthalates suppress production of testosterone, curbing the sexual development of babies in the womb.

Previous laboratory tests on pregnant rats and mice have found that exposure to phthalates has resulted in genital abnormalities and a low sperm count, while a US study found women with higher levels of phthalate-related chemicals in their blood were more likely to give birth to babies with undescended, or small testicles and small penises.

Richard Sharpe, a professor of endocrinology at the Medical Research Council’s human reproductive sciences unit, led the studies into rats. “Phthalates are in the air, they are in rainwater, they are ubiquitous. They don’t have any overt toxicity, they don’t give you cancer, but we don’t know what effect they have on human reproductive development,” he said.

Doctors believe hypospadia is also on the rise. It affects nearly one baby boy in every 260, with the opening of the penis in the wrong place, in some cases at the base of the penis or even beneath the scrotum.

One father, whose two-year-old son has severe hypospadia, said: “We first found out shortly after the birth. We were pleased the baby had been born safely, but the genital abnormality came as a shock.

“He has had a normal, happy upbringing but when the surgery happens when he’s three there could be complications.”

Gwynne Lyons, director of Chem Trust, a charity that aims to raise awareness of the damage chemicals do, said: “The government is not adequately controlling these chemicals.”

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