[Pharmwaste] FW: [hcwh] male fertility and pregnancy rates

[Tenace, Laurie]

Pardon any cross-posting (thanks to Jolie from HCWH for forwarding this to
that list serve). 

 

Laurie 




  _____  

From: Jolie Patterson Rosst [mailto:jprosst at hcwh.org] 
Sent: Wednesday, May 03, 2006 12:43 PM
To: hcwh
Subject: [hcwh] male fertility and pregnancy rates

 

(hcwh at lists.hcwh.org)

Article on www.slate.com <http://www.slate.com/>  by Liza Mundy of the
Washington Post on decreasing fertility - mentions CHE, phthalates,
widespread chemical use, etc... My husband happens to be the organizer of the
National Day to Prevent Teen Pregnancy so this article is of great interest
to us.   

What's Really Behind the Plunge in Teen Pregnancy? 
It's time to look at boys' contributions. 
By Liza Mundy
Posted Wednesday, May 3, 2006, at 10:20 AM ET

Today, May 3-in case you didn't know it-is "National Day To Prevent Teen
Pregnancy." In the past decade, possibly no social program has been as
dramatically effective as the effort to reduce teen pregnancy, and no results
so uniformly celebrated. Between 1990 and 2000 the U.S. teen pregnancy rate
plummeted by 28 percent, dropping from 117 to 84 pregnancies per 1,000 women
aged 15-19. Births to teenagers are also down, as are teen abortion rates.
It's an achievement so profound and so heartening that left and right are
eager to take credit for it, and both can probably do so. Child-health
advocates generally acknowledge that liberal sex education and conservative
abstinence initiatives are both to thank for the fact that fewer teenagers
are ending up in school bathroom stalls sobbing over the results of a home
pregnancy test. 

What, though, if the drop in teen pregnancy isn't a good thing, or not
entirely? What if there's a third explanation, one that has nothing to do
with just-say-no campaigns or safe-sex educational posters? What if teenagers
are less fertile than they used to be?

Not the girls-the boys?  It's a conversation that's taking place among a
different and somewhat less vocal interest group: scientists who study human
and animal reproduction. Like many scientific inquiries, this one is hotly
contested and not likely to be resolved anytime soon. Still, the fact that
it's going on provides a useful reminder that not every social trend is the
sole result of partisan policy initiatives and think-tank-generated outreach
efforts. It reminds us that a drop in something as profound as fertility, in
human creatures of any age, might also have something to do with health,
perhaps even the future of the species.

The great sperm-count debate began in 1992, when a group of Danish scientist
published a study suggesting that sperm counts declined globally by about 1
percent a year between 1938 and 1990. This study postulated that
"environmental influences," particularly widely used chemical compounds with
an impact like that of the female hormone estrogen, might be contributing to
a drop in fertility among males. If true, this was obviously an alarming
development, particularly given that human sperm counts are already
strikingly low compared to almost any other species. "Humans have the worst
sperm except for gorillas and ganders of any animal on the planet," points
out Sherman Silber, a high-profile urologist who attributes this in part to
short-term female monogamy. Since one man's sperm rarely has to race that of
another man to the finish, things like speed and volume are less important in
human sperm than in other animals, permitting a certain amount of atrophy
among humans. 

The Danish study set an argument in motion. Other studies were published
showing that sperm counts were staying the same; still others showed them
going up. In the late 1990s, however, an American reproductive epidemiologist
named Shanna Swan published work confirming the Danish findings. In a
well-respected study published in Environmental Health Perspectives, Swan,
now at the University of Rochester Medical Center, found that sperm counts
are dropping by about 1.5 percent a year in the United States and 3 percent
in Europe and Australia, though they do not appear to be falling in the
less-developed world. This may not sound like a lot, but cumulatively-like
compound interest-a drop of 1 percent has a big effect. Swan showed, further,
that in the United States there appears to be a regional variation in sperm
counts: They tend to be lower in rural sectors and higher in cities,
suggesting the possible impact of chemicals (such as pesticides) particular
to one locality. 

Swan is part of a group of scientists whose work suggests that environmental
changes are indeed having a reproductive impact. Under the auspices of a
women's health group at Stanford University and an alliance called the
Collaborative on Health and the Environment
<http://www.healthandenvironment.org/> , some of these scientists met in
February 2005 at a retreat in Menlo Park, Calif., to discuss their findings.
Among the evidence presented are several trends that seem to point to a
subtle feminization of male babies: a worldwide rise in hypospadias, a birth
defect in which the urethral opening is located on the shaft of the penis
rather than at the tip; a rise in cryptorchidism, or undescended testicles;
and experiments Swan has done showing that in male babies with high exposure
to compounds called phthalates, something called the anogenital distance is
decreasing. If you measure the distance from a baby's anus to the genitals,
the distance in these males is shorter, more like that of ... girls.

Wildlife biologists also talked about the fact that alligators living in one
contaminated Florida lake were found to have small phalli and low
testosterone levels, while females in the same lake had problems associated
with abnormally high levels of estrogen. In 1980 the alligators' mothers had
been exposed to a major pesticide dump, which, some believe, was working like
an estrogen on their young, disrupting their natural hormones. A report later
published by this group pointed out that similar disruptions have been found
in a "wide range of species from seagulls to polar bears, seals to salmon,
mollusks to frogs." As evidence that a parent's exposure to toxicants can
powerfully affect the development of offspring, the example of DES, or
diethylstilbestrol, was also, of course, offered. Widely given to pregnant
women beginning in the late 1930s under the mistaken assumption that it would
prevent miscarriage, DES left the women unaffected but profoundly affected
their female fetuses, some of whom would die of cancer, others of whom would
find their reproductive capacity compromised. The consensus was that the
so-called chemical revolution may well be disrupting the development of
reproductive organs in young males, among others. This research is
controversial, certainly, but accepted enough, as a hypothesis, that it
appears in developmental-biology textbooks. 

Tellingly, the U.S. government is also taking this conversation seriously.
Together, the National Institutes of Health and the U.S. Centers for Disease
Control are sponsoring a longitudinal effort to study the effect of
environment on fertility. This study <http://www.lifestudy.us/>  will track
couples living in Texas and Michigan, following their efforts to become
pregnant. The aim is to determine whether toxicants are affecting the
reproductive potential of female and male alike.

It will be welcome information. In the United States, good statistics about
infertility are strikingly hard to come by. There is no government-sponsored
effort to track male fertility rates, even though male-factor problems
account for half of all infertility. Even among women, who are regularly
interrogated about reproductive details, it's difficult to get a good handle
on developments. For years, government researchers included only married
women in the category of "infertility," creating a real problem for
demographers and epidemiologists looking for trends. The National Center for
Health Statistics <http://www.cdc.gov/nchs/>  created a second category
called "impaired fecundity," which includes any woman, of any marital
category, who is trying to get pregnant and not having luck. 

And the "impaired fecundity" category contains findings that may have a
bearing on the are-young-men-more-infertile-than-their-fathers question. In
the United States, "impaired fecundity" among women has seen, over several
decades, a steady rise. And while much attention has focused on older women,
the most striking rise between 1982 and 1995 took place among women under 25.
In that period, impaired fecundity in women under 25 rose by 42 percent, from
4.3 percent of women to 6.1 percent. Recently published data from 2002 show a
continued rise in impaired fecundity among the youngest age cohort.

In a 1999 letter to Family Planning Perspectives, Swan sensibly proposed
"that the role of the male be considered in this equation." If sperm counts
drop each year, then the youngest men will be most acutely affected, and
these will be the men who are having trouble impregnating their partners. In
2002, Danish researchers published an opinion piece in Human Reproduction
noting that teen pregnancy rates (already much lower than in the United
States) fell steadily in Denmark between 1985 and 1999. Unlike in the United
States, in Denmark there have been no changes in outreach efforts to
encourage responsible behavior in teens: no abstinence campaigns, no big new
push for condom distribution. Wider social trends notwithstanding, they note
that "it seems reasonable also to consider widespread poor semen quality
among men as a potential contributing factor to low fertility rates among
teenagers." 

Among other things, the sperm-count debate reminds us that we should not be
smug about the success of teen-pregnancy prevention efforts. We may not want
today's teenagers to become pregnant now, but we certainly want them to
become pregnant in the future, providing they want to be. If nothing else,
the sperm-count hypothesis shows that when it comes to teenagers and sexual
behavior, there's always something new to worry about.

Liza Mundy, a staff writer for the Washington Post, is writing a book about
reproductive technology and its impact that will be published next year.

 

 

 

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