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A little over a year ago I wrote a blog about plastics (Signs of Fall 4, 2017). Some key ideas from that post were: Plastics are human manufactured materials, they were invented 110 years ago, and they are large polymers of repeating organic subunits with very high molecular weights.
Humans have, so far, made 8.3 billion tons of plastics. That is enough plastic, according to Roland Geyer (University of California, Santa Barbara) in a recent Science Advances (July 19, 2017) paper, to cover the entire country of Argentina ankle deep in plastic materials. Geyer also notes that almost all of this plastic is non-degradable and will, along with all of the rapidly accelerating yearly production of new plastics, be with us for many hundreds of years. The rate of acceleration of plastic synthesis is staggering! In 1970 global production of plastics was 30 million tons. In 2015, global production had risen to 322 million tons!
Most plastics are used once and then not recycled. In 2012, 26% of disposable plastics were recycled in Europe while only 8.8% of these types of plastics were recycled in the United States. Most plastics end up in landfills but many millions of tons a year pollute our oceans, land masses, and food webs They are even part of the pollution load in our atmosphere! We are conducting an unintentional, unregulated, global experiment in which we are covering the Earth in plastic and feeding it to a wide range of birds, fish and mammals.
Photo by hhach, Pixabay
Plastics out in our environment can be in large, macro-sized forms (like the visible plastic debris I described in the surfing picture at the Carnegie Natural History Museum’s exhibition on the Anthropocene (Signs of Summer 10, 2018), or the ocean-transported, plastic debris that I wrote about that befouls the beaches of the uninhabited Henderson Island out in the middle of the Pacific Ocean (Signs of Fall 4, 2017). Even more insidiously, though, plastics can be suspended and transported in both freshwater and marine systems in the form of microscopic pieces. These particles are coated with algae and attract zooplankton and larger consumers (like sea birds and marine mammals). The surfaces of these plastic particles also attract and accumulate a myriad of extremely toxic pollutants (including heavy metals, dioxins, PCB’s, DDT’s, and PAH’s) which then bioaccumulate in the organisms that ingest the plastic materials.
A very important study recently published in PLOS One (April 11, 2018) looked at drinking water samples from around the world and examined them for microplastic contamination. Researchers at the University of Minnesota School of Public Health and the State University of New York (SUNY) Fredonia sampled tap water from fourteen countries (evenly divided between “More Developed” (MD) and “Less Developed” (LD) nations). A very large percentage of the samples (81%) had microplastic debris. Samples taken from locations in North America had the highest levels of microplastics (9.18 particles per liter) while samples taken from seven E.U. countries had the lowest (3.60 particles per liter). Water samples from MD countries had higher levels of microplastic particles than samples from LD countries in spite of assumed superiority of the MD countries’ water treatment facilities and technologies.
The authors of the paper estimated that, on average, each person in the world ingests over 5000 microplastic particles a year just from their consumption of drinking water.
This PLOS One paper also looked at two other human ingested products and analyzed them for microplastics. The first was sea salt. Sea salt is produced by the evaporation of sea water. Sea salt, like mined rock salt, is primarily sodium chloride but can also have small percentages of other chloride and even sulfate salts of potassium, magnesium and calcium. Sea salts also potentially contain the specific microparticulate debris that were present in the original sea water. All brands of seas salt tested contained microplastic contaminates. There were between 46.7 and 806 microplastic particles per kilogram of tested sea salt.
Water and salt are two vital components of the human diet, and the microplastic materials found in each were very disturbing. Most news articles that reported the results of this study, though, never mentioned either of these very compelling observations. Instead, the third material that the PLOS One paper examined took over all of the headlines and discussion. This third comestible was beer.
Photo by egien, Wikimedia Commons
The PLOS One article built on a study of microplastics in German beer that had been published in 2014 in the journal Food Additives & Contaminants. In this earlier study, microplastics and other contaminants were found in a variety of German beers. The average contaminant loads were 22.6 plastic fibers per liter of beer, 12 to 109 “solid fragments” per liter and 2 to 66 “foreign granules” per liter. The paper described a number of possible sources of this contamination that included atmospheric debris from inside the brewery or from outside air pulled into the brewing facility, gradual decay of materials used directly in the processing and filtration of the beer, or foreign materials associated with the bottles used to package the finished beer. Some of the foreign granules, they suggested, may have been sand particles from the spring water sources used in the brewing processes.
The Minnesota and SUNY researchers looked at beer from twelve breweries arrayed around the Great Lakes of the United States. Three of these breweries used water from Lake Superior, four used Lake Michigan water, one used Lake Huron water, two used Lake Erie water, and two used Lake Ontario water in their brewing. They found, on average, 4.50 plastic fibers per liter of beer but almost none of the solid or granule contaminants reported in the German study. They attributed these lack of coarse contaminants in the United States beers to the more intense filtration methods employed by most large, United States brewers. These extra filtration steps are designed to prolong the shelf-life of finished beer.
The PLOS ONE article stressed that there was no correlation between the levels of plastic fibers in the beers tested and the levels of plastic fibers in the municipal water supplies feeding into the breweries. The plastics, they suggest, came from within the brewing process rather than flowing in with the water.
This study made headlines all over the country: “Great Lakes Beers Contain Microplastics.” These news stories then triggered some energetic outpourings of disgust and outrage from large numbers of beer drinkers. Looking at the numbers, though, there is a very different end-story to this study.
- German beer had five times the load of microplastics in it (and much higher levels of “other” contaminants) than Great Lakes brewed beer.
- Sea salt, like the ocean itself, contains high levels of microplastic contaminants.
- Our tap water contains twice the level of microplastics than our beer!
I can just hear the neighbor at the party in the movie “The Graduate” telling Benjamin the secret to his future success: “plastics!” Were they drinking water or beer at the time?