The New face of Environmental Pollution

The growing threat of cancers that seemed related to environmental pollution subsided as new tougher regulations ensured that industries and agriculture dealt with their waste safely, cleanly and efficiently.
New chemicals were also screened more rigorously for toxicity. And evidence seemed to suggest that the large increase of certain cancers seen during the mid twentieth century was beginning to slow.
But the effects of synthetic chemicals didn’t only show itself in the form of cancers or obvious physical abnormalities. Synthetic chemicals it seemed could affect biological systems in very subtle yet extremely damaging ways.

 

Low sperm counts: The evidence

Evidence has been gathering that suggests that the levels of sperm produced by males in all industrialized countries have been dropping dramatically over the last 60 years.
For a long while the accepted average value of sperm was considered to be in the region of 100 million sperm per milliliter. This number was confirmed in a huge study done in the 1950’s involving 2000 men. In this study a team of scientists discovered that 44% of men had sperm counts over 100 million.
However, two decades later in the 1970’s a different team discovered that only 7% of men had sperm counts in the range of 100 million. These were very interesting results, but by themselves they were inconclusive. Another more expansive examination was required for more concrete prove.
Another team of scientists looked further into the evidence. They looked at all the studies that had been published since 1938 concerning sperm counts and compiled the most comprehensive report of all the evidence so far.
Statisticians were called upon to look over the numbers. Certain studies were excluded to prevent any risks of selection bias (for example studies taken at fertility clinics were excluded). The final analysis included sixty studies that spanned over 50 years covering a group of almost 15,000 men.

 

Low sperm counts: The conclusion

The results were indisputable. Between the years of 1940 to 1990 the number of sperm per ejaculate had fallen by more than 50%. The average sperm count had dropped from an average of 113 million per milliliter in 1940 to 66 million per milliliter in 1990.
In the same period of time there was a three-fold increase in the number of men whose sperm count had dropped below the 200 million level, the level at which fertility becomes impaired.
To make sure there wasn’t any mistakes in their techniques (possibly sperm counting techniques might have been different in the 1940’s) they checked other cell types such as blood cells. They were counted more or less the same way as sperm and they discovered that there was no change. The number of blood cells is the same as it was 50 years ago.

 

What can we conclude?

The rapidity of the change meant that genetic factors couldn’t have been responsible. The speed of the decline was extremely fast and it seemed to occur at exactly the same time the chemical revolution took hold. The factors that were responsible were undoubtedly external. Lifestyle changes and diet could have an affect but another study crossed out these factors. It seemed from other related studies that the factors responsible were likely to be linked to the various endocrine disruptors that were now becoming regular aspects of our physical make up.