|
Posted to uk.d-i-y
|
|
|
What Are Sperm Telling Us?
On Wed, 24 Feb 2021 22:27:23 -0800, David P wrote:
What Are Sperm Telling Us?
By Nicholas Kristof, 2/20/21, NY Times
Something alarming is happening between our legs.
Sperm counts have been dropping; infant boys are developing more genital
abnormalities; more girls are experiencing early puberty; and adult
women appear to be suffering declining egg quality and more
miscarriages.
Its not just humans. Scientists report genital anomalies in a range of
species, including unusually small penises in alligators, otters and
minks. In some areas, significant numbers of fish, frogs and turtles
have exhibited both male and female organs.
Four years ago, a leading scholar of reproductive health,
Shanna H. Swan, calculated that from 1973-2011, the sperm count of
average men in Western countries had fallen by 59%.
Inevitably, there were headlines about Spermageddon and the risk that
humans would disappear, but then we moved on to chase other shiny
objects.
Now Swan, an epidemiologist at Mt Sinai Medical Center in New York, has
written a book, Count Down, that will be published on Tuesday and
sounds a warning bell. Her subtitle is blunt: How our modern world is
threatening sperm counts,
altering male and female reproductive development, and imperiling the
future of the human race.
Swan & other experts say the problem is a class of chemicals called
endocrine disruptors, which mimic the bodys hormones & thus fool our
cells. This is a particular problem for fetuses as they sexually
differentiate early in pregnancy.
Endocrine disruptors can wreak reproductive havoc.
These endocrine disruptors are everywhe plastics, shampoos,
cosmetics, cushions, pesticides, canned foods and A.T.M.
receipts. They often arent on labels and can be difficult to avoid.
In some ways, the sperm-count decline is akin to where global warming
was 40 years ago, Swan writes. The climate crisis has been accepted
at least by most people as a real threat.
My hope is that the same will happen with the reproductive turmoil
thats upon us.
Chemical companies are as reckless as tobacco companies were a
generation ago, or as opioid manufacturers were a decade ago. They lobby
against even safety testing of endocrine disruptors, so that we have
little idea if products we use each day are damaging our bodies or our
children. Were all guinea pigs.
Aside from the decline in sperm counts, growing numbers of sperm appear
defective theres a boom in two-headed sperm
while others loll aimlessly in circles, rather than furiously swimming
in pursuit of an egg. And infants who have had greater exposures to a
kind of endocrine disruptor called phthalates have smaller penises, Swan
found.
Uncertainty remains, research sometimes conflicts & biological pathways
arent always clear. There are competing theories about whether the
sperm count decline is real and what might cause it and about why girls
appear to be reaching puberty earlier, and its sometimes unclear
whether an increase in male genital abnormalities reflects actual rising
numbers or just better reporting.
Still, the Endocrine Society, the Pediatric Endocrine Society,
the Presidents Cancer Panel and the World Health Org have all warned
about endocrine disruptors, and Europe and Canada have moved to regulate
them. But in the US, Congress and the Trump admin seemed to listen more
to industry lobbyists than to independent scientists.
Patricia Ann Hunt, a reproductive geneticist at Washington State Univ,
has conducted experiments on mice showing that the impact of endocrine
disruptors is cumulative, generation after generation. When infant mice
were exposed for just a few days to endocrine disrupting chemicals,
their testes as adults produced fewer sperm, & this incapacity was
transmitted to their offspring. While findings from animal studies cant
necessarily be extended to humans, after three generations of these
exposures, one-fifth of the male mice were infertile.
I find this particularly troubling, Professor Hunt told me.
From the standpoint of human exposures, you could argue we are hitting
the third generation just about now.
What if anything does all this mean for the future of humanity?
I do not see humans becoming extinct, but I do see family lines ending
for a subset of people who are infertile, Andrea Gore, a prof of
neuroendocrinology at the UT Austin, told me.
People with impaired sperm or egg quality cannot exercise their right
to choose to have a child. That may not devastate our species, but it is
certainly devastating to these infertile couples.
More research is necessary, & govt regulation & corporate responsibility
are crucial to manage risks, but Swan offers practical suggestions for
daily life for those with the resources. Store food in glass containers,
not plastic. Above all, dont microwave foods in plastic or with plastic
wrap on top. Avoid pesticides. Buy organic produce if possible. Avoid
tobacco or marijuana. Use a cotton or linen shower curtain,
not one made of vinyl. Dont use air fresheners. Prevent dust buildup.
Vet consumer products you use with an online guide like that of the
Environmental Working Group.
Many issues in headlines today wont much matter in a decade,
let alone in a century. Climate change is one exception, and another may
be the risks to our capacity to reproduce.
The epitome of a low blow is a kick to the crotch. And that,
friends, may be what we as a species are doing to ourselves.
https://www.nytimes.com/2021/02/20/o...ne-disruptors-
sperm.html
Nature is telling us the earth is over populated.
|