Story from BBC NEWS:
March 27, 2007
Scientists have produced evidence to suggest that Europe was right to ban the beef industry from using growth promoters to increase yield.
A US study has linked use of the chemicals to damage to human sperm.
The University of Rochester found men whose mothers ate a lot of beef during pregnancy had lower sperm counts.
The Human Reproduction study found they were three times more likely to have a sperm count so low they could be classified as sub-fertile.
It confirms that Europe was justified to ban the use of these hormones when they did
Dr Allan Pacey
University of Sheffield
The use of growth promoting chemicals was banned in Europe in 1988.
But although the US banned the use of some growth promoters in 1979, others, such as the sex hormones testosterone and progesterone, are still in use in the beef industry.
The Rochester team examined sperm counts among US men born between 1949 and 1983.
They found those whose mothers ate more than seven beef meals a week had an average sperm concentration of 43.1 million sperm per millimetre of seminal fluid.
In contrast, the sons of mothers who ate less beef had an average of 56.9 million sperm.
Fertility threshold
GROWTH PROMOTERS
Six growth promoters are legally in use in the US:
Natural steroids:
estradiol
testosterone
progesterone
Synthetic hormones:
zeranol
trenbolene acetate
melengestrol acetate
Among sons of mothers who ate a lot of beef, 17.7% had a sperm concentration below the World Health Organization sub-fertility threshold of 20 million sperm per millimetre of seminal fluid. The figure for the sons of lower beef consumers was 5.7%.
Lead researcher Professor Shanna Swan said the findings suggested that exposure to growth promoters contained in the beef eaten by the boys' mothers was to blame.
However, she admitted the research team had no specific data on which chemicals the meat contained, and conceded other possible causes, such as exposure to pesticides, or lifestyle factors could not be ruled out.
She said: "Theoretically, the foetus and young children are particularly sensitive to exposure to sex steroids.
"Therefore, the consumption of residues of steroids in meat by pregnant women and young children is of particular concern."
Professor Swan said to pin down the role of growth promoters the study would have to be repeated in men born in Europe after 1988.
Damaging effects
EU POSITION
Hormonal growth promoters banned in EU in 1988
UK government runs a system of surveillance for residues of such substances in UK cattle to monitor compliance with the ban
EU law bans meat from hormonally treated animals being exported to the EU by non-member countries
Dr Allan Pacey, senior lecturer in andrology at the University of Sheffield, said: "Even though males don't start producing sperm until puberty, it is during the time in their mother's womb, and in the early years of their life as an infant, that the testicles develop their capacity to produce sperm.
"Scientists have been concerned for a number of years that oestrogen mimicking chemicals in water supplies, plastics or make-up can affect the critical stages in the development of young boys' testicles.
"In extreme cases of exposure, this could lead to sperm counts in adult men that are low enough to be the cause of infertility
"That hormones given to cattle might have lowered the sperm counts of adult men because their mothers ate a lot of beef when they were pregnant with them is alarming to say the least.
"But it confirms that Europe was justified to ban the use of these hormones when they did."
Professor Alastair Hay, an expert on environmental toxicology at the University of Leeds, said one weakness of the study was that it relied on women being able accurately to recall how much beef they had eaten during pregnancy - something which may have happened many years earlier.
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