Avoiding Fish for 5 Years Before Pregnancy

Avoiding Fish for 5 Years Before Pregnancy

August 12, 2019 65 By William Morgan


“Avoiding Fish for 5 Years
Before Pregnancy” If you intentionally
expose people to mercury by feeding them fish like
tuna for 14 weeks and then stop, this is what happens to the level
of mercury in their bloodstream: it goes up, up, up, and then
as soon as you stop the fish, it drops back down, such that you can detox down half in about 100 days. So, the half-life of total mercury
in your blood is approximately 100 days. So, even if you eat a lot of fish,
within a few months of stopping you can clear much of
it out of your blood. But what about
out of your brain? Modelling studies are
all over the place, suggesting half-lives
similar to blood at 69 days all the
way up to 22 years. But when you put it to the test, autopsy studies suggest it
may even be longer still. Once mercury gets into your
brain it can be decades before your body can
get rid of even half of it. So, better than detoxing, is to
not “tox” in the first place. That’s the problem with
these fish advisories, where they tell pregnant
women to cut down on fish. For pollutants with long
half-lives like PCBs and dioxins, temporary decreases in fish
consumption, daily contaminant intake, will not necessarily
translate to appreciable decreases in maternal persistent
organic pollutant body burden, which is what helps determine
the dose that the baby gets. For example, here’s how
much exposure an infant gets to a tumor-promoting pollutant called PCB 153 if their mom ate fish. But if, for one year, mom ate only
half the fish, or no fish at all, it wouldn’t budge levels much. Only if mom cut out all
fish for five years before do you see a really substantial
drop in infant levels. So, that’s the fish
consumption caveat. “The only scenarios that
produced a significant impact on children’s exposures required
mothers to eliminate fish from their diets
completely for 5 years before their children
were conceived.” Substituting plant foods instead
of fish would reduce prenatal and breastfeeding exposures
by 37 percent each and subsequent childhood
exposures by 23 percent. So, “a complete ban on fish consumption may be preferable to targeted, life stage–based fish
consumption advisories…”. But if you are going
to eat fish, which is less polluted— wild-caught or farmed fish? In this recent study, researchers
measured the levels of pesticides like DDT, PCBs, polycyclic aromatic
hydrocarbons, and toxic elements like mercury and
lead in a large sample of farmed and wild-
caught seafood. And, in general, they
found farmed was worse. Think of the suspect as
“farmed and dangerous.” The measured levels of most organic
and many inorganic pollutants were higher in the
farmed seafood products, and consequently intake
levels for the consumer, if such products were consumed. So, for example, this is
for polycyclic hydrocarbons, persistent pesticides, and PCBs:
significantly more contamination in all the farmed fish
samples for all the contaminants; the salmon and seabass, though it
didn’t seem to matter for crayfish, and the wild-caught
mussels were actually worse. And, if you split adult
and child consumers into only eating farmed seafood or only eating wild-caught seafoods,
the level of pollutant exposure would be significantly worse
from the farmed seafood. Overall, they investigated
a total of 59 pollutants and toxic elements and taking
all these data as a whole, and based on the rates
of consumption of fish and seafood in the population in Spain where the researchers hailed from, the results indicate that
a theoretical consumer who chose to consume only
farmed fish would be exposed to levels of pollutants
about twice as high than if they would have chosen
instead wild-caught fish. So, you could eat twice the
amount if you stuck to wild-caught. Easier said than done, though. Mislabeling rates for fish
and other seafood in the U.S. is between 30 and 38 percent; so, the average fraud rate
is like one in three.