It’s been a week since my last post and I’m still thinking about salt. Salt mines. Road salt. Sea salt. Waking up in the middle of night and drinking several glasses of water because dinner was too salty. (You also can’t make a batch of lactofermented pickles without some salt.) All aboard the salt train! Salt in cars on train tracks underground in a Carey Lyons salt mine, By undergrounddarkride CC BY-2.0, via Wikimedia Commons https://commons.wikimedia.org/wiki/File%3ASalt_Cars.jpg
I was disappointed to find out that the salt mines under Detroit are not open to the public for tours. However, if you head to Hutchinson, KS (also home to the Kansas Cosmophere), you can check out the tours at Strataca: The Kansas Underground Salt Museum. These Wellington formation salt deposits are the remnants of another inland sea that once covered part of Kansas 275 million year ago during the Permian Era.
I remember learning in 6th grade social studies that salt was a major trade item in the kingdoms of ancient Africa. Check out this National Geographic video from Taoudenni, Mali of salt mining and transportation, similar to the process that took place hundreds of years ago. The workers cut slabs of salt from the beds, which traders load onto camel caravans to transport across the desert to Timbuktu. Salt Selling at Mopti Mali by Robin Young (2003) CC By 2.0 via Wikimedia Commons. https://commons.wikimedia.org/wiki/File:Salt_selling_Mopti_Mali.jpg
The Taoudenni salt deposits are relatively recent Holocene (geologically speaking). Lakes covered this area about 9000-4000 years ago. As the climate changed, the lakes eventually evaporated, leaving salt deposits behind.
One of the challenges of producing modern sea salt is the presence of microplastics left behind by evaporating seawater. Karami et al (2017) tested 17 commercially produced sea salts from 8 countries for microplastic particles. These tiny bits of plastic wash out in our laundry wastewater, or photodegrade from larger pieces of plastic floating around in the ocean. Eventually, ocean circulation brings those tiny plastic bits to even remote locations (like the very bottom of the ocean). From the report, “Due to their low density and slow degradation, plastics are becoming the chief cross-border contaminant that often travels far from their original source. Hence, [microplastics] found in the salt samples of one country could have been produced by another country thousands of miles away. ”
For more about microplastics pollution, check out my posts here and here.
I would be remiss if I failed to mention my interest in the topic (as a clothes-wearer, water-drinker and eater-of-food) started with a series on articles on plastic pollution by science writer Lola Gayle at STEAM Register and Science Crush (Read some of them here, here and here. ) Thanks, Lola!
In addition, outdoor retailers like Patagonia and environmental advocacy organizations such as The Story of Stuff have been generating awareness about how wearing and washing synthetic fabrics can contribute to this pollution stream.
Check out some citizen scientists sampling microfibers from Puget Sound aboard the schooner Adventuress:
Adventuress Microplastics – 090 by Schooner Adventuress (2012) CC BY-NC-ND 2.0 on Flickr. https://flic.kr/p/dgunat
But as a science-educator and a concerned citizen, being informed about the problem isn’t enough. I also want to know how to take action. What can we (both as individuals and society) do to both reduce microplastic pollution and mitigate its effects?
One reader suggested that nudity (ignoring for a moment the issues of frostbite and indecency laws) could solve the problem of washing clothing made from synthetic fabric (It seriously reduces the volume of dirty laundry!) This suggestion would also possibly improve one’s Vitamin D levels by increasing overall skin exposure to sunlight.
Other suggestions have included only purchasing clothing containing natural fibers (i.e. cotton, wool, silk, hemp), whose fibers will biodegrade more readily when discharged with waste water.
But what if you already own a lot of synthetic-fiber based clothing and want to keep wearing it? These fibers seem to be in everything, from yoga pants to t-shirts to wool-blend socks.
Suggestions from Patagonia and researchers at UC-Santa Barbara include washing your fleece outerwear less frequently, and using a front loading washing machine.
Any machine washing will wear down the fiber and cause micro-bits to break off. If you wear your stuff a little schmutzy (as any TEVA educator will attest), you don’t have to wash it as often (ergo, reducing breakage potential in washing machine).
If you use a front loading machine (vs. a top loading machine) it lowers the intensity of the laundry agitation, reducing impact on the fabric and breakage of fibers.
The folks at Plastics Pollution Coalition also add: Washing in cold water (is less tough on the fibers), using liquid detergent instead of powder (ditto) and drying on slower speeds (less impact during tumbling.)
Another strategy is improving filtration of the washing machine water to remove as much of the microfibers as possible before the effluent is released down the drain.
Some filters, like this one, are installed on the washing machine itself to catch microfibers from the water. The filters must be periodically cleaned out and have the microfiber clogs disposed of in the trash. These were originally designed with septic systems in mind, because plastic microfibers don’t break down in a septic system’s biological digestion process and clog up equipment.
If you can’t modify your washing machine, the folks at GuppyFriend have developed a wash bag (like a lingerie bag) that will catch synthetic fibers coming off your clothes. Users put laundry in the bag before putting it in the machine. Then after you remove your laundry, you clean out the bag after each wash and dispose of fibers in the trash. GuppyFriend bags started with a crowdfunding campaign, and do not yet appear to be available to the general public for purchase. Will keep you posted.
3. Bioremediation
Since we’ve been washing synthetic fabrics for awhile, a lot of plastic microfibers have ended up in our bodies of water, as well as in our farm fields (fertilizers made from treated municipal sewage sludge may contain laundry-borne plastic microfibers). The plastic microfibers are out there in the world.
Some organisms may be adapting to consuming and breaking down plastic fibers in our soil and water. For example, researchers have discovered that mealworms (darkling beetle larvae) appear to be able to eat styrofoam (polystyrene) due the special Exiguobacterium sp. of bacteria that live in their digestive tract.
A team in Japan discovered a species of bacteria, Ideonella sakainesis, in wastewater and sediment samples at a recycling plant. These bacteria can eat a thin film of polyethelene (PET)- the same plastic used in water bottles and polyester fleece- given enough time and the proper temperature.
It is still too early to tell if any of these organisms (or others like them) will be able to tackle the massive amount of plastics humans have dumped into the environment. The fact that these critters exist gives me hope that microfibers may not be floating around forever. However, it is still better to try to keep microplastics out of water in the first place.
It’s a laundry day again (an occasion usually determined by running out of clean socks and/or underwear). I dutifully sort out my pile of dirty garments into hot, warm and cold washes. Bras and fine fabrics on delicate cycle. Add some bleach to my gunk-stained kitchen towels.
Here is a cute picture of a toddler captivated by a washing machine:
Jasper And The Washing Machine by Henry Burrows, (2011) CC BY-SA 2.0 on Flickr https://flic.kr/p/9HEw5k
Normally, my focus is on whether or not the washing machine in my apartment building is being used by another resident. (It’s not – Check!) But today, I’m thinking about washing machine waste water, specifically the laundry fuzz in the water that shakes loose during the washing cycle, and where it ultimately ends up.
This is not the first time I have been concerned about the issue of wastewater treatment.
Where Does it Go? by PPJ (2015) CC BY-SA 2.0
This is the cover of my 7th grade research paper on wastewater treatment, circa 1994. Found while cleaning out my childhood bedroom. The colored things are supposed to be pipes.
Back to laundry. So from my particular washing machine usage, the waste water (which often contains little fuzzy bits of lint that come off of synthetic fabric in the wash) goes to the Downriver Wastewater Treatment Plant, which discharges treated effluent into the Detroit River. The Detroit River continues flowing into Lake Erie, and then Lake Erie water continues to flow throughout the Great Lakes.
That water flowing from my washing machine to River to Great Lakes still contains tiny, tiny particles of plastic fibers shed from the fuzz of my polyester fleece sweaters and other synthetic fabrics. Hoffman & Hittinger model this flow of microplastics into the Great Lakes in the December 2016 Marine Pollution Bulletin. (Note: Not all the microplastics come from washing machine discharge.)
These microscopic plastic fibers might look something like this:
The problem with these synthetic microscopic fibers is that they’re … plastic. They’re really, really small, so they are impossible to remove from the water after the fact. They don’t biodegrade in the water (though they might break down into even smaller particles.) These fibers can absorb (and concentrate) other pollutants that are present in the water. And then these plastic fibers get eaten by plankton, and then work their way up the food chain into the bodies of fish and other wildlife, including humans.
As an environmental educator, most of my “outdoor” clothing (i.e. Teva Pants, long underwear, and outer layers, including socks) contain synthetic fibers. Every time I come out of the garden or woods to wash my mud-caked clothes, I’m contributing to this pollution problem.
Protopian Pickle Jar 
