Microplastics found in tap water

21 09 2017

The Guardian, in early September 2017, released a report that microplastic contamination has been found in tap water in countries around the world. What this means for the seven billion people on earth, no one yet knows. All the experts can agree on is that, given the warning signs being given by life in the oceans, the need to find out is urgent.

Scores of tap water samples from more than a dozen nations were analysed by scientists for an investigation by Orb Media .[1] Overall, 83% of the samples were contaminated with plastic fibres. Bottled water may not provide a microplastic-free alternative to tapwater, as the as it was also found in a few samples of commercial bottled water tested in the United States for Orb.

The US had the highest contamination rate, at 94%, with plastic fibres found in tap water sampled at sites including Congress buildings, the US Environmental Protection Agency’s headquarters, and Trump Tower in New York. Lebanon and India had the next highest rates.

Why should you care? Microplastics have been shown to absorb toxic chemicals linked to cancer and other illnesses, and then release them when consumed by fish and mammals. If fibers are in your water, experts say they’re surely in your food as well – baby formula, pasta, soups and sauces whether from the kitchen or the grocery. It gets worse. Plastic is all but indestructible, meaning plastic waste doesn’t biodegrade; rather it only breaks down into smaller pieces of itself, even down to particles in nanometer scale. Studies show that particles of that size can migrate through the intestinal wall and travel to the lymph nodes and other bodily organs.

The new analyses indicate the ubiquitous extent of  microplastic contamination in the global environment. Previous work has been largely focused on plastic pollution in the oceans, which suggests people are eating microplastics via contaminated seafood. But the wholesale pollution of the land was hidden. Tap water is gathered from hills, rivers, lakes and wells, sampling the environment as it goes. It turns out that tiny fibres of plastic are everywhere.

Orb Media

“We have enough data from looking at wildlife, and the impacts that it’s having on wildlife, to be concerned,” said Dr Sherri Mason, a microplastic expert at the State University of New York in Fredonia, who supervised the analyses for Orb. “If it’s impacting [wildlife], then how do we think that it’s not going to somehow impact us?”

Plastics often contain a wide range of chemicals to change their properties or color and many are toxic or are hormone disruptors. Plastics can attract other pollutants too, including dioxins, metals and some pesticides. Microplastics have also been shown to attract microbial pathogens. Research on wild animals shows conditions in animal guts are also known to enhance the release of pollutants from plastics. “Further,” as the review puts is, “there is evidence that particles may even cross the gut wall and be translocated to other body tissues, with unknown consequences”. Prof Richard Thompson, at Plymouth University, UK, told Orb: “It became clear very early on that the plastic would release those chemicals and that actually, the conditions in the gut would facilitate really quite rapid release.” His research has shown microplastics are found in a third of fish caught in the UK.

This planktonic arrow worm, Sagitta setosa, has eaten a blue plastic fibre about 3mm long. Plankton support the entire marine food chain. Photograph: Richard Kirby/Courtesy of Orb Media

Does any of this affect people? The only land animals in which the consumption of microplastic has been closely studied are two species of earthworm and a nematode.[2]

The scale of global microplastic contamination is only starting to become clear, with studies in Germany finding fibers in all of 24 beer brands tested[3] , as well as in honey and sugar .[4] A study revealed a rain of microplastics falling on Paris from the air, dumping between 3 and 10 tons a year on the city.[5] The same team found microplastics in an apartment and hotel room. “We really think that the lakes [and other water bodies] can be contaminated by cumulative atmospheric inputs,” said Johnny Gasperi, at the University Paris-Est Créteil, who did the Paris studies. “What we observed in Paris tends to demonstrate that a huge amount of fibres are present in atmospheric fallout.”

This research led Frank Kelly, professor of environmental health at King’s College London, to tell a UK parliamentary inquiry in 2016: “If we breathe them in they could potentially deliver chemicals to the lower parts of our lungs and maybe even across into our circulation.” Having seen the Orb data, Kelly told the Guardian that research is urgently needed to determine whether ingesting plastic particles is a health risk.[6]

Another huge unanswered question is how microplastics get into our water and food. A report from the UK’s Chartered Institution of Water and Environmental Management[7] says the biggest proportion are fibers shed by synthetic textiles and tire dust from roads, with more from the breakdown of waste plastics. It suggests the plastic being dumped on land in Europe alone each year is between four and 23 times the amount dumped into all the world’s oceans.

A lot of the microplastic debris is washed into wastewater treatment plants, where the filtering process does capture many of the plastic fragments. But about half the resulting sludge is ploughed back on to farmland across Europe and the US, according to recent research published in the Journal Environmental Science & Technology[8]. That study estimates that up to 430,000 tons of microplastics could be being added to European fields each year, and 300,000 tons in North America. “It is striking that transfers of microplastics – and the hazardous substances bound to them – from urban wastewater to farmland has not previously been considered by scientists and regulators,” the scientists concluded. “This calls for urgent investigation if we are to safeguard food production,” they say in a related publication.

Plastic fibres may also be flushed into water systems, with a recent study finding that each cycle of a washing machine could release 700,000 fibers into the environment. Tumble dryers are another potential source, with almost 80% of US households having dryers that usually vent to the open air. Rains could also sweep up microplastic pollution, which could explain why the household wells used in Indonesia were found to be contaminated.

A magnified image of clothing microfibres from washing machine effluent. One study found that a fleece jacket can shed as many as 250,000 fibres per wash. Photograph: Courtesy of Rozalia Project

In Beirut, Lebanon, the water supply comes from natural springs but 94% of the samples were contaminated. “This research only scratches the surface, but it seems to be a very itchy one,” said Hussam Hawwa, at the environmental consultancy Difaf,  which collected samples for Orb.

Like so many environmental problems – climate change, pesticides, air pollution – the impacts only become clear years after damage has been done. If we are lucky, the plastic planet we have created will not turn out to be too toxic to life. If not, cleaning it up will be a mighty task. Dealing properly with all waste plastic will be tricky: stopping the unintentional loss of microplastics from clothes and roads even more so.

But above all we need to know if we are all drinking, eating and breathing microplastic every day and what that is doing to us, and we need to know urgently.

[1] https://orbmedia.org/stories/Invisibles_plastics

[2] Carrington, Damian, “We are living on a plastic planet. What does it mean for our health?”, The Guardian, https://www.theguardian.com/environment/2017/sep/06/we-are-living-on-a-plastic-planet-what-does-it-mean-for-our-health

[3] Liebezeit, Gerd; “Synthetic particles as contaminants in German beers”, Journal of Food Additives & Contaminants: Part A, Vol 31, 2014, Issue 9

[4] Liebezeit, Gerd; “Non-pollen particulates in honey and sugar”, Journal of Food Additives & Contaminants: Part A, Vol. 30, 2013, Issue 12

[5] Dris, Rachid, et al., “Microplastic contamination in an urban area: case of greater Paris”, Society of Environmental Toxicology and Chemistry, 2015, https://hal-enpc.archives-ouvertes.fr/hal-01150549v1

[6] Carrington, Damian, “People may be breathing in microplastics, health expert warns”, The Guardian https://www.theguardian.com/environment/2016/may/09/people-may-be-breathing-in-microplastics-health-expert-warns

[7] http://www.ciwem.org/wp-content/uploads/2017/09/Addicted-to-plastic-microplastic-pollution-and-prevention.pdf

[8] Nizzetto, Luca; Futter, Martyn and Langaas, Sindre; “Are agricultural soils dumps for microplastics of urban origin?”; Journal of Envornmental Science & Technology, Sept. 29, 2016, 50 (20), pp 10777-10779

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Nylon 6 and Nylon 6,6

5 06 2012

Nylon is a synthetic polymer called a polyamide  because of the characteristic monomers of amides in the backbone chain.  Polyamides are also naturally occurring – proteins such as wool and silk are also polyamides.

We commonly see two basic types of nylon used in fabrics: nylon 6 and nylon 6,6:

  • Nylon 6,6:  Two different molecules (adipic acid and hexamethylene diamine)  are combined to create repeat units of 6 carbon atoms, thus the name nylon 6,6.
  • Nylon 6:  Only one type of molecule is used in the formation of nylon 6, which also has 6 carbon atoms.  The repeat unit for type 6 nylon is made from caprolactam (also called ε-caprolactam).

Remember polyester is also a polymer (as are lots of naturally occurring things).  And like polyester, the nylon polymers are theoretically unreactive and not particularly harmful, but that’s not true of the monomers:

  • A small % of the monomers escape during production (off gassing or into water), which have environmental consequences.
  • With production expected to be over  4.4 million pounds/year by 2020, burden on water treatment facilities is immense.
  • Monomers are precipitated out during treatment, so they are present in the sludge.

The manufacture of both nylon 6,6 and nylon 6 uses cyclohexane as a precursor [1] – and cyclohexane is made from benzene, “one of the most challenging processes in the chemical industry”.[2]  Benzene is listed as a human carcinogen by the US Department of Health and Human Services.  It is associated with acute myeloid leukemia (AML), aplastic anemia, myleodysplastic syndrome (MDS), acute lymphoblastic leukemia (ALL), and chronic myeloid leukemia (CML)[3]  The American Petroleum Institute (API) stated in 1948 that “it is generally considered that the only absolutely safe concentration for benzene is zero.” [[4]

But the real culprits are the generation of unwanted by-products of nylon manufacture:  ammonium sulfate [5] in the case of nylon 6 and nitrous oxide in the case of nylon 6,6.

For nylon 6, the conventional synthesis route to caprolactam uses toxic hydroxylamine (NH2OH) and, in the last two steps, concentrated sulfuric acid. Every metric ton of caprolactam produces up to 4.5 tons of ammonium sulfate as a by-product [6].  As with many chemicals now in use, there is no data to evaluate ammonium sulfate as to toxicity to humans, though it has been shown to affect development, growth and mortality in amphibians, crustaceans, fish, insects, mollusks, and other organisms.[7]

In addition, waste water generated during production of nylon-6 contains the unreacted monomer, caprolactam. Owing to the polluting and toxic nature of ε-caprolactam, “its removal from waste streams is necessary”[8]

In evaluating the chief components of nylon 6,6  (hexamethlylenediamine and adipic acid), we find a darker situation.   Hexamethlylenediamine is a  petroleum derivative,  with the usual consequences of petroleum processing. It is considered “mildly toxic”[9] (though in one study, ten administrations of 700 mg/kg to mice killed 3 of 20[10]).   But the production of the other monomer,  adipic acid,  requires the oxidation of cyclohexanol or cyclohexanone by nitric acid, a process which produces nitrous oxide (N2O) –  a greenhouse gas 300 times more potent than CO2.[11]  A study published in 1991 credits the production of nylon – and the concurrent by-product of nitrous oxide – as contributing as much as 10% to the increased observance of atmospheric N2O.[12]  And this is a great concern, so much so that there is increased talk of our “nitrogen footprint”.

Nitrogen is one of the 5 elements (the others are carbon, hydrogen, oxygen, and phosphorus) that make life possible. It is essential for the creation of DNA, amino acids and proteins. 79% of the earth’s atmosphere is made up of nitrogen, but living things can’t use it in this form called dinitrogen (N2).  So in the nitrogen cycle, lightning  converts N2 into nitrate, which is carried to Earth by rain, where it enters the food chain.  When organisms die, bacteria recycles the nitrogen in them and it returns to the atmosphere.  Pretty elegant, isn’t it?

From: Nitrous Oxide Focus Group

But we have disrupted this nitrogen cycle.  A study by University of Virginia environmental scientist James Galloway and colleagues reported that from 1970 to 2008, world population increased by 78% and reactive nitrogen creation grew 120%.[13] The turning point, according to the International Nitrogen Initiative, came in 1909 when humans figured out how to combine hydrogen with N2 to create ammonia – which was used to produce fertilizer. Humans have introduced additional reactive nitrogen into the environment by expanding the production of soybeans, peanuts and alfalfa, (leguminous) crops which host nitrogen-fixing bacteria that convert N2 into reactive nitrogen. We use ammonia to manufacture nylon, plastics, resins, animal and fish feed supplements, and explosives. Fossil fuel burning industries and vehicles produce nitrogen emissions, and nitrogen is a component of the electronics, steel, drug, missile and refrigerant industries.

A single nitrogen molecule can cascade through the environment affecting air and water quality, human health and global warming in numerous ways(click here for a summary):

  • Runoff from agriculture—from fertilized crops fed to animals, from manure, and from biofuel and crops—enters rivers and streams and can contaminate groundwater. When nitrogen-loaded runoff makes its way to the ocean, it can result in eutrophication, where algae bloom, then die, depleting the oxygen and suffocating plants and animals. Runoff from urban areas, sewage treatment plants, and industrial wastewater also contribute to eutrophication.
  • Nitrogen is also a component of acid rain, which can acidify soils, lakes and streams. While some trees may utilize the extra nitrogen to grow, others experience foliage damage and have reduced tolerance for stress.
  • Our air quality is affected by nitrogen emissions from vehicles, fossil fuel burning industries (like coal), and the ammonia from agriculture, which cause ground-level ozone. High concentrations of ozone affect human respiratory and cardiovascular health and disrupt photosynthesis in plants.
  • Climate change is both influenced by and exacerbated by nitrogen. For example, nitrogen may stimulate plant growth, resulting in more carbon dioxide uptake in some forests.

Scientists have stressed the need to reduce fossil fuel emissions, improve wastewater treatment, restore natural nitrogen sinks in wetlands, and both reduce the use and increase the efficiency of nitrogen fertilizers. Galloway’s study also underscores the importance of better management of animal waste from the concentrated animal feeding operations that produce most of our meat today.

Another concern of using nylon is that all nylons break down in fire and form hazardous smoke.  Also smoke from burning nylon at a landfill emits the same chemicals,  typically containing  hydrogen cyanide, nitrous oxide (N2O) and dioxins[14].

Because nylon 6,6 is made from two different molecules, it is very difficult to recycle and/or repurpose.  Trying to separate and re-use them is like “trying to unbake a cake”.  However, nylon 6, because it is made from only one molecule, can easily be re-polymerized, and therin lies it’s claims to environmental superiority.  But  nylon production uses a lot of energy – about double that of polyester.  If recycling it uses about half the energy as is needed to produce virgin nylon, then recycled nylon and virgin polyester use about the same amount of energy.

Nylon 6 is becoming the new green darling of designers – but unless the recyling process captures all emissions, treats wastewater and sludge and also recaptures the energy used, the claim is tepid at best.  And nylon, unlike polyester, does degrade,  but slowly[15], giving it plenty of time to release its chemical load into our groundwater

I couldn’t find any data on the toxicity of nylon as fabric, but the government of Canada has evaluated nylon 6,6 because it is also used in cosmetics, and classified it as a “medium human health priority”; it is also on the Environment Canada Domestic Substance List.[16]  Another study found that some of the chemicals in nylon kitchen utensils migrated into food.[17]


[1] The remaining less than five percent of installed caprolactam capacity is via the cyclohexane photonitrozation process of Toray, which goes directly from cyclohexane to the oxime, or the SNIA Viscosa process, which utilizes toluene as feedstock and proceeds via oxidation-hydrogenation-nitrozation.  http://www.chemsystems.com/about/cs/news/items/PERP%200910_1_Caprolactam.cfm

[2] Villaluenga, J.P. Garcia, Tabe-Mohammadi, A., “A review on the separation of benzene/cyclohexane mixtures by pervaporation processes, Journal of Membrane Science, Vol 169, issue 2, pp. 159-174, May 2000.

[3] Smith, Martyn T. (2010). “Advances in understanding benzene health effects and susceptibility”. Ann Rev Pub Health 31: 133–48. DOI:10.1146/annurev.publhealth.012809.103646.

[4] American Petroleum Institute, API Toxicological Review, Benzene, September 1948, Agency for Toxic Substances and Disease Registry, Department of Health and Human Services

[6] Hoelderich, Wolfgang and Dahlhoff, Gerd, “The Greening of Nylon”, Chemical Innovation, February 2001, Vol 31, ppg. 29-40 and Weston, Charles et al, “Ammonium Compounds”, Encyclopedia of Chemical Technology, June 20, 2003, http://onlinelibrary.wiley.com/doi/10.1002/0471238961.0113131523051920.a01.pub2/abstract

[8] Kulkarni, Rahul and Kanekar, Pradnya, “Bioremediation of e-Caprolactum from Nylon 6 waste water…” MICROBIOLOGY, Vol 37, Number 3 1997

[10] “Handbook of Toxic Properties of Monomers and Additives”, Victor O. Sheffel, CRC Press, Inc., 1995

[11] 2007 IPCC Fourth Assessment Report (AR4) by Working Group 1 (WG1), Chapter 2 “Changes in Atmospheric Constituents and in Radiative Forcing” which contains information on global warming potential (GWP) of greenhouse gases

[12] Thiemens, Mark and Trogler, William, “Nylon Production: An unknown source of atmospheric nitrous oxide”, Science, February 1991, vol 251, pp 932-934

[13] Galloway, JN, and Gruber,  “An Earth-system perspective of the global nitrogen cycle.” Nature 451, 2008, 293-296.

[15] For nylon fabric, current estimates are 30 – 40 years.