Saturday, September 03, 2016

The case against antibacterial soap

Yesterday's big environmental news was the FDA ban on triclosan, triclocarban and 17 other toxic chemicals commonly added to soaps.  Scientists' reactions ranged between "Huzzah!" to "Why did it take 40 years for the FDA to listen to us?"

Bad Dad and I both earned BSs in chemistry so we are familiar with the issue.  However, I realize that most families don't have even one BS in chemistry, especially because chemistry is one of the least popular majors in the United States.  (Which is a shame, because chemistry is truly the "central science" that bridges the life and physical sciences, and gives people a great foundation for understanding the world.)

Here's some stuff to think about and discuss around your dinner table.  OK, we are comfortable discussing bioreactors and biosolids around the dinner table, but maybe you want to wait until after everyone has finished eating in your home.  ;-)

Any soap or body wash that says "antibacterial" probably contains one of the newly-banned substances.

For these to work effectively, you have to wash with them much, much longer than most people do.  You know how long surgeons and surgical nurses scrub their hands (until they are red and raw?); that's how long.  That means, outside of hospitals, antibacterial soaps are not doing anything but going down the drain.

What happens to stuff that goes down the drain?  Glad you asked!  I wrote a series of posts about that.

Think about all the stuff you send down the drain (kitchens, bathrooms, laundry).  Think about everything you ingest and then excrete.  BTW, waste water is a great way to find out how much and what type of drugs/pharmaceuticals people are ingesting.

Your sewage is sent through a screen to separate solids from liquid. The solids are often sent through a bioreactor with bacteria that breaks down the solids. The biosolids (with or without the bioreactor step) are spread on agricultural fields as fertilizer, landfilled or incinerated.

This can be a good thing. Incineration reduces waste AND produces energy. Biosolids are cheaper for farmers (about 1/4 the cost of petrochemical fertilizers) and reduce our reliance on fossil fuels.

The problem is us. We send too much non-necessary chemicals down the drain.

ASU Professor Rolf Halden gave a plenary talk last month at the American Chemical Society's meeting in which he showed that just two chemicals, triclosan and triclocarban, make up 60% of the pharmaceuticals found in municipal biosolids.

This chart is a screen shot from his article in Nature. Note that the horizontal axis is logarithmic so a difference of one tick mark is a factor of ten.  Click to make the graph bigger.

The US produces (and we presume, use) about 2,000 metric tonnes each of triclocarban and triclosan.  4.8-48.2% of the triclocarban ends up in biosolids.  The rest probably remains in the water.  1.8-18% of triclosan ends up in biosolids; more of it remains in the water than triclocarban.

Excerpt from Pharmaceuticals and Personal Care Products in Archived U.S. Biosolids from the 2001 EPA National Sewage Sludge Survey:
Of the more than 7 million tons of sewage sludge produced in the United States in 2004, about 50% was applied to land as fertilizer or soil amendment, and 45% was disposed of in landfills or as landfill cover.
 I've already written about how triclosan can photo-degrade into dioxin under UV light. ("Dioxins are highly toxic and can cause reproductive and developmental problems, damage the immune system, interfere with hormones and also cause cancer.") It doesn't matter whether the triclosan is applied through biosolids or irrigation water. This finding has now been replicated in labs around the world and is accepted scientific fact.

But, incinerating triclosan is also extremely risky.  Excerpt from Halden's research home page:
In addition to toxins in wastewater, Halden’s team is researching the emission of toxic dioxin into U.S. air from incineration of triclosan-laden municipal sludge, or biosolids
Furthermore, these newly-banned substances have all been found to bio-accumulate, not just in earth worms and frogs but in you and me.  These are hazardous chemicals that should not be in our ecosystem.

Antibacterial soaps have their uses--in hospitals--but should not be in widespread use in homes.  They do nothing beneficial under normal home use, but cumulatively do great environmental and health harm.

 Read more:


  1. Great post! It formulated clearly and with details my intuitive conclusions. I think "bacteria" became a new scary word for kids and grownup, like "witches" and "curses" were before: people don't know (or wish to understand) much about them, but boy they are scary! So let's kill the witch!

    1. Thanks. I added a link about triclosan resistance increasing w/ exposure. I was hoping microbiologist bloggers would cover that. But, I added the link just for completeness b/c that is a major concern as well.

  2. Thanks for putting into words what my non-scientific brain always suspected. I think antibacterial is overused much like antibiotics out of some desire to try and control our seemingly out of control world. I've never been an antibacterial fan...just clean up yourself and practice food safety has always been my approach. SO glad that this change is being made.

  3. I was really excited at that news, even though I don't have a degree in chemistry. Well, I still think chemistry is fun. When we had full-time caregivers in the house during my late husbands illness they all wanted antibacterial everything, which they promptly misused, and they would have fits if I didn't have it and would act like I was creating a public health hazard.

  4. The ban makes me happy, especially since normal soaps are just as effective. Aren't these in some toothpastes as well? I find it interesting that for all the concern over keeping kids in as sterile environment as possible for the last few decades, now they are thinking it's childhood exposure to the microbes that may prevent things like asthma and allergies. There may be a place for the antibacterial cleaners, but every home in the nation is not it.

  5. I just thought of a question - were the antibacterials put in soaps and such to protect the product during manufacture and storage, and then promoted as better than regular soaps? Or were they put in as being better cleaners from the start as part of the whole "oooh all bacterial scarey bad!" movement?

    1. @JustGail No, these antibacterials are not the preservatives used to inhibit bacterial growth. They serve no useful purpose under ordinary home use.

      Oddly, the ban is only for the use of these chemicals in soap. That ban does not apply to toothpaste containing triclosan. Why anyone would want to put these chemicals in their mouth is beyond me.


Comments are open for recent posts, but require moderation for posts older than 14 days.