Estrogens in the environment:
Some years ago I was chatting with a friend about the falling fertility in many countries.  That fall has pretty much leveled off.  I interpret this to mean that the pre-zygotic infertility of excess outbreeding reaches a saturation point.  That means it produces infertility to a certain degree and not beyond.  Post-zygotic infertility, the infertility of the offspring, is a different story.  It does not appear to saturate but it takes another generation for the effect to manifest.  In support of this I note that over about a generation a lot of countries have had their fertility decline and then stabilize with a simultaneous start of an increase in age at first marriage.  Biological clocks are stopping.  That may continue for another generation, at which point let’s hope something different happens. 

My friend said, “Of course fertility is down.  Men are feminized.  It’s because of estrogens in the meat.  They give estrogens to cattle, which makes them fatten up faster and makes them easier of manage.  And the estrogens are still in there when you eat the meat.”

I argued against that, but without much enthusiasm.  After all, they castrate young bulls for some reason, and estrogens would simply follow the same logic. 

But I rather doubt it is important.  If it were it should be very easy to measure estrogens in meat and get the word out; regulations would swiftly follow and be easy to enforce.  Still the question gnaws at me.

So I was happy to see an article (Richard Owen and Susan Jobling The Hidden Costs of Flexible Fertility NATURE vol. 485 no. 7399 May 24, 2012 page 441) with the blurb “It’s time we faced up to the problem of environmental oestrogen pollution.” 

“Aha,” think I.  “The truth at last.  Somebody has taken a look at estrogens in our environment and thinks the level is significant.”  The more fool I.

As it turns out the “problem” is not one of people eating meat that contains estrogens.  The problem is that people take contraceptive pills and their sewage contains so much estrogen from the pills that it escapes into the environment and affect animals.  The levels are sufficient to cause at least some fish populations to collapse.

So I return to my cave to lick my wounds.  It isn’t that animals are a hazard to people; people are a hazard to animals.  I guess that’s important, too.  And it’s being addressed.  And I suppose silence in this case means that there is no problem in the other direction although the level needed to destroy fish stocks is a about 5 parts per trillion and they are talking about an acceptable level being .035 parts per trillion.  So good for the fish.  I would like somebody to assure me that humans are exposed to contamination at least an order of magnitude lower. 

Let’s see.  If a woman gets a therapeutic dose of 50 micrograms, then presumably a steer gets treated with 500 micrograms, which is sustained.  Assuming it doesn’t all pool in fat, which wouldn’t matter since people eat fat as well, a 1000 kilogram steer (which would be very big) carries a tissue level of .5 micrograms per kilogram or .5 parts per billion.  If meat constitutes 10% of a person’s diet including water, that person lives with .05 parts per billion or 50 parts per trillion. 

Figure it another way.  A 50 kilogram woman takes 50 micrograms or 1 microgram per kilogram.  That’s one part per billion.  If a steer has the same level then a diet of 10% steak (8 ounces out of a five pound diet) should give a human a tissue level of 100 parts per trillion. 

You see why I’d like a little reassurance?  Check my arithmetic.  I often get such things wrong. 

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