ASU KEDtalk: What soap leaves behind

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August 23, 2017
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ASU KEDtalk: What soap leaves behind

Some soaps leave a residue that reaches far beyond your shower door. Rolf Halden tells us about the unexpected consequences of our obsession with antimicrobials and where we go from here.


Full transcript

Rold Halden, director, Biodesign Center for Environmental Security: Thank you. Hello, everybody, and welcome. What happens to the germ-killing chemicals that are added by the millions of pounds to antimicrobial and antibacterial consumer products; the worst-case scenario, in the spirit of Murphy’s Law, where we have a chemical, we design it, we think it’s awesome. We make millions of pounds of it and then we add it to thousands of consumer products only to find out, after the fact, that the chemical did not serve the purpose it was added for and it turned out to be persistent and contaminating our environment, our wildlife and our cells, causing toxic effects.

My team studied and found not only one such chemical but two such chemicals. The chemicals are called triclosan and triclocarban. I see a bland look so you probably don’t know what that means but even if you have not heard the names of these chemicals they are the chemicals that make our consumer products antimicrobial and antibacterial. So if you have ever picked up a product that said it’s antimicrobial, whether it is a tent, a sock, a shoe, a detergent, a deodorant, then you are guilty as charged. So, when we wash our hands, if we wash them at all, it takes about six seconds. In that amount of time, on average, is just too short in order to give us a benefit if antimicrobials are present in our soap.

So, the chemicals are rendered useless and are flushed down the drains in our kitchens and in our bathrooms. And there they go on their merry way towards the wastewater treatment plant. But sadly, in the environment, once the chemicals were out there animals were exposed for very long periods of time, even life-long and for generations we found. This we found out by looking at surface water sediments. And so, by going down into the sediment, we were able to do some time travel. We found that organisms had been bathing in antimicrobials ever since we started producing them in the late 1950s and 1960s.

Microbials don’t really like water and they like to seek shelter. And they seek shelter in living organisms so it looks like we have contaminated everything. What about outer space? We had an opportunity to analyze water from the International Space Station, and guess what we found in the water loop? Antimicrobial chemicals. So you see we have an omnipresence of antimicrobial chemicals. We cannot escape them anymore. They are in our water, in our air, in our soil, in our food. They are in the wildlife. They are in us. But ironically, they much more effective in killing things other than microorganisms. We should call them anti-algal agents, or anti-planktonic agents or fish killers. All of these names would be better than the name that we use today.

So if we want to understand the life cycle of the chemicals and the toxicity we have to look at the beginning. When we synthesized them we already make super toxic, carcinogenic dioxins - they are part of the antimicrobials. And then at the end of the life cycle of the chemical when they fall apart one single molecule can make two carcinogens if it falls apart. But the chemicals also are toxic by themselves in their own right. Among the many effects that antimicrobials can have the one thing we are really concerned about is endocrine disruption. This is a scrambling of the messaging system in living organisms. Animal studies have shown that small concentrations of antimicrobials can lead to malformation of reproductive organs, lowered sperm count, spontaneous abortion, an increase in allergies, and changes in metabolism that can lead to obesity. And when microorganisms are exposed to antimicrobials and survive it they can become tough. They can become super bugs. And so some studies have shown that if a pathogen is exposed to triclosan the organism gets resistant not only to the antimicrobial but also to antibiotics and not just one but six – half a dozen antibiotics that are used in clinics and hospitals around the world to prevent people from losing their limbs and lives from microbial infections.

Why didn’t we ban the chemical in the first place? Turns out in the 1950s and 60s we didn’t have the right tools to fully understand the impact of these chemicals on our physiology and on the environment. And things like genome sequencing or epigenetics or even endocrine disruption weren’t understood or discovered at the time. It’s also true that in America we do a limited amount of testing of chemicals before they reach the market. Often times the assumption is that the chemical is safe until proven harmful.

In Europe people typically do more safety testing and they have something that’s called the precautionary principle which says that if something could be potentially really bad but we don’t have enough information we much rather not use it. But on both sides of the Atlantic there is a legislative back door that allowed triclosan and triclocarban to slip into consumer products and ultimately into our bodies. That door is the “grandfathering process.” Once we make chemicals for a long time we don’t have to test them again when new regulations come out. So they are grandfathered in and they circumvent the testing that might have revealed some of their effects.

How long does it take to ban a chemical? On September 2 of 2016, the United States Food and Drug Administration announced a ban of triclosan, triclocarban and many other antimicrobial chemicals. It has taken 14 years between our discovery of triclocarban in urban streams in Baltimore to the ban of antimicrobials that will take effect in 2017. Today, triclosan and triclocarban are the top 10 pollutants of our drinking water resources. So soon the dark cloud of antimicrobial pollution should lift from the United States. But what about other countries? Over 200 scientists have signed our call to action, the Florence Statement on Triclosan and Triclocarban, and it calls for removal of these chemicals from all consumer products where they don’t have the benefit around the world.

Unfortunately, my students and I, by helping to get these chemicals banned worked ourselves out of our job. So, that is not exactly entirely true. Because there are a lot of chemicals in commercial use. In fact, 70,000 or so in America alone and every year we introduce 2,000 more. So there’s plenty of work to be done to scan the ever-expanding chemical horizons to look for among this very useful and life-saving convenient chemistry the few bad players that might do us in. So this is our job and we try to keep you safe and healthy. And so with this, I hope I didn’t scare you too much but I give you a little bit of appreciation of chemistry. So remember, next time when you enjoy a delicious meal, great company and maybe even love it’s all about good chemistry. Thanks for listening.