Dear Mark: Swimming Pool Chemicals, Washing Veggies, and Carb Blockers
by
Mark Sisson
Mark’s Daily Apple
Recently
by Mark Sisson: Caveman
Breath
Who doesn't
like a lovely day at the pool? Unless you can't swim, there's no
reason not to love the cool water, the bright sun, the ping pong
(every swimming club worth a dime has a ping pong table, or several
of them), the face dunking, the high dive, and the chicken fights.
But what if something sinister churned within the depths of the
chlorinated water? What if by entering that pool you were risking
life, limb, and the pristine alabaster of your eyeball? In today's
edition of Dear
Mark, I've gone back to the roundup format. I begin with the
question of swimming pool chemical safety, follow with a query about
washing vegetables, and I finish the post with a short section on
carb blocking agents. Sound good?
Let's go:
Dear Mark,
I was wondering
about possible negative effects of pool water. I enjoy a good
sprint workout in the pool, especially when traveling and staying
in a hotel. Could the chlorine or other chemicals be harmful since
they do sometimes make me itch a little afterwards and burns my
eyes (especially if I open them underwater)?
Thanks and
Grok on,
Andrew
I hate to be
the bearer of potentially bad news, but there's probably something
to this. Most pools use chlorine as a disinfectant, to keep the
water clear of bacteria and other microbes, and it's darn good at
that. Reason? Chlorine, in its pure form, is toxic. The chlorine
in the pool is obviously diluted, so it's not going to burn or kill
you outright, nor are you a microbe, but toxicity concerns remain.
Your first clues that it might be doing something untoward, of course,
are the burning eyes and itching skin. That's pretty normal, albeit
disconcerting. As a kid, I used to get red, burning eyes when I'd
spend the day at the pool. Nowadays, I think back to that and wonder…
Anyway, red
eyes clear up and itchiness subsides, but could other problems be
lurking beneath the surface? Maybe. Chlorine reacts with other substances,
including bodily fluids and various organic matter, to form disinfection
byproducts (DBPs), which may have novel – and unwanted – health
effects. Let's take a look at some evidence:
- When
chlorinated pool water meets dimethylamine
(found in urine and sweat), nitrosamine carcinogens (the same
type of compound that forms when we overcook bacon) form, and
appear in pools at concentrations up to 500-fold higher than drinking
water. Though it's unclear whether or not these particular nitrosamines
are absorbed by pool users, some nitrosamines
are absorbed through (rat) skin. Why should you care? Well,
nitrosamines are used to induce bladder
cancer in rodents, and chlorinated pool and bathing water
usage have
been linked to bladder cancer in humans (though it's just
observational).
- Chloramine,
another DBP, has
been linked to asthma in pool workers and elite
swimmers.
- A recent
study
found over 100 chemical byproducts in swimming pools, many of
them toxic. Before and after 40 minutes of swimming laps in such
a pool, healthy subjects' biomarkers were tracked and recorded.
One marker suggested increased lung permeability and inflammation,
while another marker indicated a kind of DNA damage that, if unchecked,
might lead to cancer. Subjects had also accumulated elevated levels
of four of the most common DBPs after 40 minutes in the pool.
The good news
is that you're probably okay. Problems may arise when we absorb
and uptake these DBPs (like chloroform) via inhalation, dermal
absorption, and the ingestion of affected water on a regular basis.
The populations that seem to suffer most from pool-related maladies
are the ones who spend significant amounts of time at, in and around
the pool – competitive swimmers (with their infamously long daily
workouts), lifeguards, and other pool workers – and it doesn't sound
like you're living in the water. If you stick to short, intense
sprints, performed only when you have access to a pool on business
or vacation, I wouldn't worry.
Read
the rest of the article
Listen
to Lew's recent podcast with Mark Sisson
June 5, 2012
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