I wrote:

> This comment's only tangential to the protein post you made, but I recall
> some studies noting the geographic variation of and possible decline of
> sperm counts over time: http://www.pmac.net/rachels2.htm (That cites a New

Tom wrote:
>I believe this is no longer considered true, later studies invalidated
the original, which had design flaws.<

Both studies cited themselves cite refutations of certain past studies, so I
wonder if you were referring to those instead?

The first study I noted includes this:
"Toward the end of 1997, a re-analysis of sperm counts in the U.S., Europe,
and the rest of the world concluded that sperm counts among men in the U.S.
and Europe really have declined steadily for 50 years.[9] In 1992, Elisabeth
Carlsen and co-workers had analyzed 61 separate studies of sperm counts and
reported a 50% average decline in sperm count in Europe, the U.S., and
elsewhere over the last 50 years. (See REHW #343, #369, #372, #432, #446,
#448, and #492). Carlesen's study was criticized from various viewpoints
(though not by anyone who had actually reviewed the 61 studies that formed
the basis of the British report). In 1996 new studies revealed that enormous
differences existed in sperm counts in geographic regions. After that,
skeptics concluded that the whole decline in sperm counts was an artifact of
statistical modeling and had no basis in reality. The NEW YORK TIMES favored
the skeptics, leaving the impression that the whole dispute resulted from
math errors.[10]

Now Shanna H. Swan, chief of the reproductive epidemiology section of the
California Department of Health Services, has re-examined the original 61
studies. Swan conducted straightforward statistical analyses that took
account of regional variations (which are, indeed, large --sperm counts in
New York are 131 million sperm per milliliter vs. 72 million per milliliter
in California.) Swan's conclusion: AVERAGE sperm counts in the U.S. and
Europe during the past 50 years have declined more steeply than the British
first reported, but no decline was found in less-industrialized countries of
Asia and Latin America. In the U.S., sperm counts have declined 1.5% each
year and in Europe the annual decline has been twice as great. Dr. Swan's
study was published in ENVIRONMENTAL HEALTH PERSPECTIVES (a U.S. government
scientific journal) in November.[9] Swan told the LOS ANGELES DAILY NEWS,
"My hope is, this study will change the question of concern from if there is
a decline, to why there is a decline. I think it's time we looked at
that."[11] (The NEW YORK TIMES has so far ignored Dr. Swan's new study.)"


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