What
happens when you flush?
Although
often attributed to Sir John Crapper, it was Alexander Cumming who perfected
the design of the flush toilet in 1775, forever changing the way that humans
dispose of their personal waste.
No
longer was waste deposited in the chamber pot or privy. Health and sanitation
improved markedly, but an entirely new problem faced society: what to do with liquid
waste or sewage waters.
In
the developed world, most human waste is now sent to a sewage treatment plant
or through a local septic system to cleanse and renew the waters that carry it.
Sewage
treatment plants and septic systems are designed to take organic wastes and
convert them to carbon dioxide, nitrate and phosphate. We depend on fungi and
bacteria to degrade the waste. In some levels of treatment, bacteria are used
to convert nitrate to nitrogen, which is returned to the atmosphere.
Some
chemicals, such as sorbitol, sodium fluoride in toothpastes and sodium
hypochlorite in bleach, are not unknown in the natural environment and pass
through sewage treatment with little notice.
In
contrast, many of the synthetic chemicals in our daily lives are xenobiotic—that
is, not known in the natural world.
Paraben
is such a synthetic compound that is added to cosmetics as an antibacterial
agent. Silver and copper nanoparticles are added to athletic fabrics to retard
the odor of human perspiration.
For the past 100 years, we have embraced the concept of "better living through chemistry." Chemical manufacturers churn out nearly 80,000 chemicals that keep our farmlands free of weeds and bugs.
Personal
care products color, straighten, or curl our hair, repel biting insects, retard
fires, and cleanse our dishes and laundry.
More
than 10,000 drugs are available to regulate our metabolism and mood, sooth
aches and pains and regulate hormonal urges.
Visit
any local garden store and you will breathe the smell of a plethora of
chemicals designed to give each of us the Green Thumb of victory over nature.
I
looked at the label of a few products around our house, finding C10-16
Alkyldimethylamine oxide (Dawn); N, N-Diethyl-meta-toluamide (Off); Aluminum
zirconium tetrachlorohydrex (Arid Deoderant), tripropylene glycol n-butyl ether
(toilet cleaner), and pyrithione zinc (Head and Shoulders).
A
chemical plant dumping these compounds into local waterways would be subject to
prosecution.
Question
is: what happens to all this exotic stuff when we flush it into the
environment?
It
is a lot to ask the microbial population in a septic system to break down
chemicals that they have never experienced in nature, let alone those designed
to inhibit their activities.
Many
of these chemicals, especially drugs, are designed to be long-lasting in the
environment, so they can do their job well.
The U.S. Geological Survey has recently reported that at least 47 pharmaceuticals were detected in the drinking water at 25 locations across the U.S., apparently unscathed as they pass through our bodies or by microbial degradation in sewage treatment plants.
The U.S. Geological Survey has recently reported that at least 47 pharmaceuticals were detected in the drinking water at 25 locations across the U.S., apparently unscathed as they pass through our bodies or by microbial degradation in sewage treatment plants.
Often,
the fish and other organisms downstream are bathed in a solution of
antidepressants, estrogen, and lithium.
We
think of water pollution as derived from the blatant release of chemicals from
the corporate world into local waterways, but the same compounds are found in
sewage waters that also end up downstream and in groundwater.
What's
in your water?
William
H. Schlesinger is one of the nation's leading ecologists and earth scientists.
He has served as dean of the Nicholas School of the Environment at Duke
University and president of the Cary Institute of Ecosystem Studies. This
article originally ran on Translational Ecology, Schlesinger's
science-based blog offering analysis of current environmental topics.