Finding Dulcinea summarized the Italian results as:-
During the 1970s, Italian men averaged 71 million spermatoza per millimeter. But today, they average 60 million, according to a study of 10,000 healthy men conducted by Fabrizio Menchini Fabris of Pisa University.
Fabris also found that today, fewer than 30 percent of the sperm are ‘active’ in Italian men, while 50 percent were active in the 1970s. Taken together, these number mean that Italian men today have 50 percent fewer active sperm than they did thirty years ago.
It is a common observation across the whole of Europe and North America – but at differing rates. In 2004 the Canadian National Review of Medicine summarized the then current knowledge as:-
The rate of decline is similar to reports from France and other European countries, although sperm counts among British men are even below the European average. It’s generally agreed that sperm counts are falling twice as fast in Europe as in North America.
The primary suspects are endocrine disruptor chemicals, especially pesticides. There are many other suspects from smoking to tight underpants. However the use of agricultural pesticides explain the demographic distributions far better than other suspects.
The prime suspect is the insecticide DDT (dicophane). At the end of WWII it was hailed as a wonder weapon against a range of diseases, especially malaria. A chemical in the insecticide called p,p’-DDE has strong estrogenic and anti-androgenic properties. Wherever it is found in high concentrations, there is evidence of demasculinisation. Florida’s Lake Apopka, with extremely high levels of DDT pollution, is swimming with androgynous alligators.
Other problematic chemicals are alkyl phenol ethoxylates and nonylphenol ethoxylates widely used in industrial detergents, paints and pesticides as surfactants. Agricultural pesticides are clearly implicated and go a long way to explain the geographical variation of male fertility. Within Europe it is isolated Finland, with its minimal agriculture, that has the highest sperm counts.
Although DDT has been banned or restricted for two decades in the developed world, its persistence means that it can still be traced in all humans. It is still in widespread use in many malarial zones, from where it can be exported via food or the atmosphere. Little or no action has been taken to restrict other estrogenic compounds in the environment. The problem of falling sperm counts is bound to get worse before it gets better.
Recently other common pesticides in current common usage have also been implicated in studies in the USA.The general characteristic is that the chemicals are endocrine disruptors. What has been puzzling is that they appear to cause little damage to mammal biology or DNS except in large quantities.
In 2005, a study on rats showed the type of effect required to explain what has been observed in human populations.
Pregnant rats exposed to fungicide sprayed on vineyards and pesticide sprayed on crops had male offspring with a sperm count reduced by 20 per cent.
If confirmed by further experiments, the findings could help explain the decline in human male fertility over the past 50 years.
The timing of the exposure turns out to be critical, which is probably why the effect has not been observed previously, and it also has an unexpected damage path.
The scientists exposed pregnant rats to the chemicals at the crucial moment in gestation when the sex of the offspring is determined. The result was that male offspring suffered a 20 per cent decline in sperm counts, and sperm motility – its ability to swim – fell by up to 35 per cent.
What was surprising was that these traits were also seen in 90 per cent of the male offspring born to three more subsequent generations yet the scientists found no obvious mutations in the DNA of the animals.
One possibility is that the toxic substances altered the natural chemicals, called methyl groups, that normally surround the DNA molecule and these subtle changes were inherited by the male offspring.
“We are mostly describing a new phenomenon… The hazards of environmental toxins are much more pronounced that we realised,” Dr Skinner said.
If this result is confirmed, then we could soon have generations of human males shooting blanks. However it is unlikely to slow down the Italian males that my female friends complain about – I suspect that is cultural.
However it does indicate that perhaps we should be investing in learning about how to store sperm for longer. The pesticides and other agricultural chemicals are required to produce the level of food required for the burgeoning world populations. Consequently their use has been spreading throughout all of the world farming areas. If the male fertility levels in other areas follow what has happened in Europe and the USA over the last 50 years, then the problem will self-correct as the population drops.
The issue is that we might get overshoot into the world of P.D.James in her novel The Children of Men. I watched the movie adaption last night – excellent movie. That started me looking at the material on the net.
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