PRESSURE to control the pollution of drinking water by oestrogen and
compounds that mimic the female sex hormone is growing following two worrying
discoveries.
Last week, Finnish scientists published the most convincing evidence yet that
sperm production by men in industrialised countries is declining. Meanwhile, an
American team has found that an oestrogen mimic that pollutes many rivers, but
which was thought to be relatively benign, can render male rats infertile within
two months.
Previous research into declining male fertility was controversial because the
results relied on sperm counts made on semen samples, which are notoriously
unreliable. But researchers led by Jarkko Parjarinen of the University of
Helsinki avoided the problem by examining tissue from the testes, taken at
postmortem from 528 middle-aged Finnish men who died suddenly in either 1981 or
1991.
Advertisement
Among the men who died in 1981, 56.4 per cent had normal, healthy sperm
production. By 1991, however, this figure had dropped dramatically to 26.9 per
cent. The average weight of the men鈥檚 testes decreased over the decade, while
the proportion of useless, fibrous tissue increased, says a paper from the
Finnish team in the 4 January issue of the British Medical Journal.
Other researchers in the field are impressed with the study. 鈥淭here has been
some doubt about whether sperm counts are falling, and up till a couple of
months ago I鈥檇 have said I wasn鈥檛 sure that it was true,鈥� says Michael Joffe, a
fertility expert at St Mary鈥檚 Hospital in London. 鈥淏ut with results like this
I鈥檇 say there are declines in some areas.鈥�
杏吧原创s are still some way from identifying a clear culprit,
however. 鈥淲e still don鈥檛 know what鈥檚 causing falling male fertility,鈥� says
Joffe. Many believe that oestrogen from women鈥檚 urine in sewage is the most
likely contender (This Week, 16 November 1996, p 7). But the latest research by
Frederic Boockfor and Charles Blake of the University of South Carolina Medical
School in Columbia sounds a fresh alarm about industrial pollution.
Boockfor鈥檚 team injected rats with octylphenol, an organic compound
based on a benzene ring which is a breakdown product of a detergent used in the
manufacture of paper, textiles and plastics. The rats were given 20 milligrams
or 80 milligrams of octylphenol twice a week for one or two months. The lower
dose caused an accumulation of octylphenol in the rats鈥� tissues similar to that
seen in fish from polluted rivers.
鈥淎fter only one month, the rats had a 50 per cent reduction in sperm count
and a fourfold increase in sperm abnormalities,鈥� says Boockfor. After two
months, even at the lower dose, the rats鈥� testes had almost completely
degenerated. 鈥淲e didn鈥檛 expect to see this complete destruction of the
reproductive organs,鈥� says Boockfor. 鈥淲e were a bit shocked.鈥� His and Blake鈥檚
results will be published in a future issue of the journal Biology of
Reproduction.