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November 29, 2019 3 mins

OK, this one is no contest: Your dishwasher can get dishes cleaner, but that doesn't necessarily mean that using one is healthier. Learn about the science behind the suds in this episode of BrainStuff.

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Episode Transcript

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Speaker 1 (00:01):
Welcome to brain Stuff production of iHeart Radio. Hey, brain Stuff,
Lauren Vogel Bomb here, someone needs to erect a statue
of Josephine Cochrane. If it weren't for this American inventor,
all of us might be washing dirty dishes by hand.
Though to be fair, the closest thing we have in
my house too mechanical dishwasher is me. Cochrane lived a

(00:23):
well healed life and loved to entertain her many friends.
Over the course of time, though her household servants had
chipped their fair share of the family's seventeenth century China. Frustrated,
Cochrane began washing the dishes herself, a task she hated.
She wondered why someone hadn't invented a machine to make
it easier. In she took matters into her own dishpan

(00:44):
hands and built the first practical dishwasher, improving on an
eighteen fifty design by one Joel Houghton. Houghton's device was
hand cranked and only splashed water on dirty dishes. Cochranes
washer was more thoughtful. It had a motor that turned
a wheel that pumped hot, soapy water from a boiler
over the dishes. It would take a while for Cochrane's

(01:04):
dishwasher to catch on, but when it did, people loved it.
It was the first commercially successful automatic dishwasher. But what
Cochrane didn't know was that hand washing dishes can be
less sanitary than cycling them through the dishwasher. Today's dishwashers
use scalding hot water, high tech spray nozzles, and other
features to cleanse dishes. Handwashing doesn't even come close. That's

(01:26):
because our hands, as The Washington Post points out, can't
withstand water temperatures that modern dishwashers use up to a
hundred and forty five degrees fahrenheit that's sixty two degrees celsius.
According to the Environmental Protection Agency and the US Department
of Energy, New Energy Star dishwashers use less energy and
water five thousand gallons a year than hand washing does. Moreover,

(01:48):
the sponges that we humans use can harbor lots of germs.
Scientists have found nearly four hundred different species of bacteria
on household kitchen sponges, and the density is astronomical around
forty five billion per square centimeter. However, more sanitary doesn't
necessarily mean healthier Swedish researchers reported the kids living in

(02:08):
households where dishes were hand washed were less susceptible to
allergies compared to children living in households with a dishwasher.
The researchers surmised that handwashing exposed the kids too more microbes,
which jump started their immune systems. If you are someone
in your home is immunocompromised, a dishwasher can be a
great way to help keep everybody healthy. Otherwise, or if

(02:30):
you can't afford one, don't worry about it too much.
It's more of a labor and energy saver than anything else.
And if that sponge thing concerns you, you can sanitize
your sponges by soaking them in diluted bleach, or by
wedding and then microwaving them for about a minute. Oh
and Joseph Cochrane may not have a statue just yet,
but as Romania had the good sense to put her

(02:51):
on one of its postage stamps. Today's episode was written
by John Paratyo and produced by Tyler Clang. Brain Stuff
is a production of I Heart Radios. How Stuff Works
from more on this and lots of other labor saving
topics visit our home planet, how stuff works dot com.
And for more podcasts from my Heart Radio visit i
Heart Radio app, Apple Podcasts, or wherever you listen to

(03:14):
your favorite shows

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Lauren Vogelbaum

Lauren Vogelbaum

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