Not a novel story - but a somewhat worrying one

It was only in August that I noted a report that Israeli researchers had found long term decline in human sperm count and quality:

Over the last 10 to 15 years, the concentration of sperm samples collected by the bank dropped 37% from 106 million cells per milliliter to 67 million, according to Dr. Ronit Haimov-Kochman, a leading Israeli infertility researcher at the Hadassah Hebrew University Medical Center.

Now a very similar sounding study in France finds much the same:

New research shows that the concentration of sperm in men's semen has been in steady decline between 1989 and 2005 in France. In addition, there has been a decrease in the number of normally formed sperm.

The study is important because, with over 26,600 men involved, it is probably the largest studied sample in the world and although the results cannot be extrapolated to other countries, it does support other studies from elsewhere that show similar drops in semen concentration and quality in recent years.

They found that over the 17-year period there was a significant and continuous 32.2% decrease in semen concentration (millions of spermatozoa per millilitre of semen), at a rate of about 1.9% per year. The researchers calculated that in men of the average age of 35, semen concentrations declined from an average of 73.6 million/ml in 1989 to 49.9 million/ml in 2005.

In addition, there was a significant 33.4% decrease in the percentage of normally formed sperm over the same period. Changes in the way sperm shape (morphology) was measured during this time may partly explain this decrease and make it difficult to give an estimate for the general population. However, the researchers say that these changes do not account for the total decrease in the quality of sperm morphology observed over the study period.

In their paper, the researchers write: "To our knowledge, it is the first study concluding a severe and general decrease in sperm concentration and morphology at the scale of a whole country over a substantial period. This constitutes a serious public health warning. The link with the environment particularly needs to be determined."

 A few observations:

a.   the Israeli's decline seems to have started from a much higher starting point.  I wonder what the explanation for that might be.

b.  the Israeli report at my first link noted that 20 million per ml and below count as "abnormal" sperm counts, and the French figures indicate that the average is heading that way very rapidly.

c.  As noted at the end of the French report - surely it's most likely that it is something environmental that is causing this, and the figures do sound as if it is something deserving really serious and urgent research.

This deserves greater attention in the media, I reckon.

UPDATE:  the Guardian has a good article looking at this study, and noting the history of controversy over whether declining sperm counts are "real" or just an artefact of changing  laboratory methods.

Certainly, it seems to my amateur scientist eye that the French study goes a long way towards showing that it is real.  The Guardian article notes that there is no detail of socioeconomic factors that might account for why the men in the study had lower sperm counts (such as if they were more likely to be smokers or drinkers), but as the original article I linked to suggested, the men who end up in fertility clinics are probably more likely not to be from the poorer classes, and to have reasonable health if they have been trying to conceive.  The sample, in other words, may be biased for higher than average sperm counts, not lower.