Today, a significant number of personal care products such as scrubs and toothpastes are known to contain thousands of minuscule balls of plastic called microplastics, or more specifically, microbeads. Over the years, microbeads have replaced traditional, biodegradable alternatives such as ground nut shells, and salt crystals.
The microbeads used in personal care products are mainly made of polyethylene (PE), but can be also be made of polypropylene (PP), polyethylene terephthalate (PET), polymethyl methacrylate (PMMA) and nylon. Where products are washed down the drain after use, microbeads flow through sewer systems around the world before making their way into rivers and canals and ultimately, straight into the seas and oceans, where they contribute to the plastic soup. Typically, microplastics are defined as: plastic pieces or fibres measuring less than 5 mm. The microbeads found in personal care products are almost always smaller than 1 mm.
In 2004, the findings of a research programme led by Professor Richard Thompson (University of Plymouth) were published in Science and detailed the distribution of microplastic pollution. The article was the first to conclude the spread of microplastics and plastic fibres throughout the entire marine environment. And since larger pieces of plastic break down into smaller pieces and do not biodegrade, the amount of microplastics is accumulating.I Plastic degrades into ever smaller pieces upon exposure to UV radiation and as a result of abrasive wave action.II The concentration of marine microplastics is accumulating rapidly.III
In addition to these indirect, secondary sources of microplastics, there are several direct sources of microplastics – including the flushing of microbeads used in personal care products. Hundreds, if not thousands, of different personal care products use microbeads as abrasive scrubbers and for cleansing purposes. In 2009, Fendall and Sewell (University of Auckland) published their observations that microbeads pass into household waste water streams directly and are too small to be retained by the standard filters used at sewage treatment plants and therefore enter the marine environment. Not only do they enter the sea, they can also enter the food chain.IV
Although the full extent and consequences is hard to quantify, the accumulation of plastic, including microplastics, in the marine environment is today recognised as a serious, global environmental issue.V As scientists and policymakers alike start to question the full extent of the problem in terms of impacts to marine biodiversity and associated implications for human health, the number of research programs studying microplastics is increasing consequentially.
Some scientific findings:
Marine species are unable to distinguish between food and microplastics and therefore indiscriminately feed on microplastics. In an overview published for the Convention on Biological Diversity, it was shown that over 663 different species were negatively impacted by marine debris with approximately 11% of reported cases specifically related to the ingestion of microplastics.VI Some species of fish excrete plastic easily, but others do not and so accumulate plastic internally. To cite one study: around 35% of 670 fish examined (total of 6 species) had microplastics in their stomachs. The highest number of fragments found in one fish was 83.VII
The surface of microplastics has been proven to attract and absorb persistent organic pollutants (POPs) such as PCBs and DDT from the marine environment. Relatively high concentrations of POPs have been found on the surface of microplastics.VIII The International Pellet Watch, led by Professor Takada at the University of Tokyo, is conducting research to this effect. Takada’s research indicates that certain POPs found in bird tissue were ingested together with their plastic hosts.IX In theory, ingested POPs could remain on the surface of ingested microplastics and could be egested.X However, fish and seafood regularly consumed by humans have been recorded with plastic fragments inside their guts and body tissues. Scientists hypothesise that over time, POPs will start accumulating in the food chain, transferring from species to species, with consequences ultimately for humans.XI
Toxic chemicals added to plastic during the manufacturing process (such as plasticisers and flame retardants) leach out of plastic in the marine environment and pose serious threats to marine fauna.XII The most common plasticisers have been recorded in fish, marine mammals and molluscs.XIII The smallest particles of plastic are ingested and retained by filter feeders such as mussels. Belgian toxicologist Colin Janssen (University of Ghent) found that on average, each gram of mussel flesh contains one particle of plastic.XIV Species of plankton are also found to ingest and retain plastic particles.XV
Once microbeads reach the marine environment, it is impossible to pinpoint the source of origin. German researchers Liebezeit and Dubaish (University of Oldenburg) hypothesise that cosmetics, and especially peelings, make up most of the microplastics they found in the Wadden Sea.XVI
In terms of relative contributions to microplastic pollution, a range of studies have looked at the number or concentration of microbeads in individual products. The American non-governmental organisation (NGO) 5Gyres, found a large number of microplastics in the Great Lakes and estimates that one single care product (Neutrogena's Deep Clean) contains 360,000 microbeads.XVII Dr. Leslie (Free University, Amsterdam) found that microplastics made up 10.6% of one scrub (Exofonic scrub of L'Oreal).XVIII
Water treatment plants are not designed to filter out microbeads. A number of studies have found that water treatment plants do not filter all microbeads from the waste water.XIX Moreover, not all waste water gets purified. Following heavy rain, waste water with microbeads can overflow directly into surface waters. Some countries lack the infrastructure to treat waste water completely.
As scientific understanding of the effects of microplastics on the environment continues to grow, the fate of microplastics has become an extremely important question. Increasingly, sources and impacts of microplastic pollution are being questioned and considered closely by scientists and policymakers alike. For instance, within the framework of the CleanSea European research project, seventeen European research institutes are conducting interdisciplinary investigations into the effects of microplastics.
Research into the quantity and consequences of microplastics in the environment is important. In light of growing evidence confirming the seriousness of this issue, there is a pressing need to address direct sources of microplastic pollution – something that is both avoidable and highly unnecessary.
Producers have been asked to act responsibly and stop adding microplastics to cosmetics.
III M.C. Goldstein et al., ‘Increased oceanic microplastic debris enhances oviposition in an endemic pelagic insect’, in: Biology Letters published on line 9 May 2012; C.J. Moore, ‘Synthetic polymers in the marine environment: A rapidly increasing, long-term threat’, in: Environmental Research108 (2008), pp. 131-139.
VI Secretariat of the Convention on Biological Diversity and the Scientific and Technical Advisory Panel—GEF (2012). Impacts of Marine Debris on Biodiversity: Current Status and Potential Solutions, Montreal, Technical Series No. 67.
XIII STAP. Marine Debris as a Global Environmental Problem: Introducing a solutions based framework focused on plastic. In A STAP Information Document, p. 40. Washington, DC: Global Environment Facility, 2011.
XIV L. Van Cauwenberghe, ‘Occurrence of microplastics in mussels (Mytilus edulis) and lugworms (Arenicola marina) collected along the French-Belgian-Dutch coast, in: J. Mees, et al. (ed.), Book of abstracts - VLIZ Young Marine Scientists' Day. Brugge, Belgium, 24 February 2012. VLIZ Special Publication, 55.
XIXM.A. Browne et al., ‘Accumulations of microplastic on shorelines worldwide: sources and sinks’, in: Environmental Science &Technology 45 (2011), pp. 9175/9179; H.A. Leslie et al., ‘Verkennende studie naar lozing van microplastics door rwzi’s’ in: H2O 14/15 (juli 2012), pp. 45-47.