Chemical Link Found to Low Sperm Counts
This article was originally printed in the Sunday Times on 29 October 1995. Note the reference to Bisphenol-A which is a consituent of some epoxy resins.
An investigation by the government' s Medical Research Council (MRC) has established that a reduction in sperm counts and testicle size can be caused by consuming tiny quantities of compounds capable of mimicking oestrogen, the female hormone.
The research follows studies showing that European men born between 1955 and 1960 have particularly low sperm production. Investigators have focused on exposure to oestrogenic chemicals in the womb for the first year of life.
Professor Richard Sharpe, who led the study at the MRC's reproductive biology unit in Edinburgh, said: "It is not a chance effect: it is highly consistent. We have accumulated data over two years." Sharpe's researchers fed rats one of three chemicals dissolved in water at concentrations of one part per million. Even at these concentrations, a third of the government-permitted "safe" limit for humans, 15% reductions in sperm count and testicle size were recorded.
The compounds octylphenol, bisphenol A and butylbenzyl pthalate were chosen because laboratory tests bad shown they had strong oestrogenic properties that might suppress male functions such as testicular development and sperm production. They are used in food packaging, cans, babies' dummies and pesticides. Comparisons of testicle size and sperm count were made between hundreds of male rats whose mothers had drunk water containing chemicals and a control group whose mothers had drunk pure water. No diminished sexual function was seen in the control group.
Professor John Sumpter of Brunel University, west London, a leading expert on the effects of environmental oestrogens, believes decline in male fertility may have been caused by a variety of chemicals, some of which are no longer used. He described the MRC results as "an important step forward".
Scientists have long suspected that chemical by-products of petrol and the plastics industry mimic female hormones. There has also been concern that female hormones from contraceptive pills and systems may be reabsorbed by men with harmful effects. Bisphenol A is used to coat the inside of food cans to prevent contamination by metal. This year a Spanish study of tinned vegetables showed that oestrogens from the coatings could migrate into food. Companies involved in producing chemicals and manufacturing cans acknowledge potential problems and are carrying out urgent research. Elizabeth Surkovic, for the Chemical Industries Association, which represents 200 companies, said: "We believe a small but real effect is occurring on the human hormone system. There is definitely something going on."