We can easily see the transition our society has taken in terms of the material that we have chosen to consume, reflected in the changes of the various beach landscapes of the world. What was once a few castaway glass bottles and broken wood planks from ships, has become a colorful array of fishing nets, plastic bottles, and plastic bags, turning our beaches into what some would call a colorful landfill.
At the start of this transition, many people thought of plastic waste as an inert substance that was just an eyesore and did not consider it to be that harmful compared to other types of pollution that has a bigger impact, in terms of effects. However, with so much plastic ending up in the ocean, these discarded plastics end up moving through large scale vortices, called gyres and end up into central convergence zones to create what we now call the Great Pacific Garbage Patch.
Gathered up into these convergence zones, the plastic, as inert as it may be, is weathered down into smaller plastic particles (plasticles) that now make up the dominant type of plastic pollution in our oceans.
These small plastic particles have been given the name Microplastics. Their exact naming is according to the figure below.
This article will cover the possible health risks that this new type of major pollutant can have on not just the marine organisms in the area, but on human health, as many of us are ingesting these plastic particles on a daily basis without ever knowing about their presence.
Identification of the types of MP
The largest contributor of primary MP tends to be the cosmetics industry. This type of MP typically comes in the form of small spherical beads, making them easily recognizable when they are discovered in the natural environment. These primary microplastics are those that have been manufactured to be small, mainly for the use in cosmetics and cleaning agents to provide abrasion and deeper cleaning. Usually made of polyethylene, these MPs will persist in the marine ecosystem much like a plastic bottle, and plastic bags.
Another major source of primary MP comes from industrial feedstock, such as plastic pellets. Although many of the pellets are melted down to form bigger plastic products, the occasional spillage is often unavoidable, resulting in devastating amounts of primary MP entering the local water system. According to a study done in 2017 (Christopher Blair Crawford and Quinn, 2017) about 1050 tons of primary MP were put into the environment through accidental happenings.
Secondary MPs are plastic particles that have gone through the weathering and breakdown of larger plastics that are usually already present in the environment. These secondary MPs are usually found to be PE (polyethylene), PS (polystyrene), PVC (polyvinyl chloride), and PP (polypropylene). These plastics are usually used as single use packaging materials and are discarded right after they serve their purpose.
These plastics, although chemically inert to changes in the environment, will degrade into small particles subject to volatile wave action and constant UV exposure working together to make the plastic brittle, and then causing abrasion as the waves move around. A paper written in 2016 discovered that a 1cm-by-1cm piece of polystyrene was capable of producing 126 million nanoparticles per ml of water, just after a 24 hour exposure to UV light (Lambert and Wagner, 2016).
Problems with these plastic particles
Is microplastic toxic?
The common misconception that we view these MPs with is perhaps lessening what their actual impact on our health might be. Thinking that they are inert particles that cannot harm us might be somewhat true for sterile plastics that have been prepared in a lab under conditions that are food safe but even then we have yet to discover what these plastic particles can do to our body.
The natural environment that the plastic particles exist in is typically not considered food safe.The MPs collected were found to be vectors for POPs (persistent organic pollutants) such as DDT, HCH and PCBs (for more information http://chm.pops.int/TheConvention/ThePOPs/tabid/673/Default.aspx). A study done in 2017 revealed that near a polyethylene production plant, the MP concentration was at 100,000 particles per cubic meter of seawater. The MP in the area showed that the concentration of POPs on the MPs were a million times higher compared to the background concentration in the surrounding water (Christopher Blair Crawford and Quinn, 2017). These MPs, which are capable of carrying these pollutants over long distances in ocean currents and the ability for them to escape many municipal filters in the sewer system, poses a real danger to our ecosystem.
Environmental Impacts of Microplastics
There is little research done in regard to the impact of microplastics on human health when ingested. There are two studies that have gone through testing on human subjects in the late 1980s (Tomlin and Read, 1988) and in late 1990s (McIntyre et al., 1997). These two studies revealed that when the subjects were given 15g of polyethylene MP measuring 1-2 mm in size, there was a significant decrease in the transit time through the gastrointestinal system. This condition, whilst not posing any threatening toxicities, can certainly still be harmful by greatly reducing the absorption of nutrients in the intestines, eventually leading to nutritional deficits.
However, one must note that these two tests were performed with sanitized, pulverized plastic particles that do not represent the toxic vectors that exist in the marine environment. This issue has yet to be tested and clinically proven, but the potential that these MPs carry as vectors into the human system should not be disregarded and caution should be taken with future research. Indeed, a recent study has found that MP is currently being ingested through fish containing plastic, such as the king mackerel. These fish were found containing yellowish MPs, which tend to be contaminated with the highest degree of chemical pollutants (Miranda and de Carvalho-Souza, 2016).
Whilst there are many studies that speculate that the nanoplastics are not likely to pass-through cellular membranes, it is possible and if they do, it is able to cause inflammation of the gut via lymph nodes into the circulatory system (Bouwmeester, Hollman and Peters, 2015). As for the nano plastic particles that can penetrate the cellular membrane and are able to stay for prolonged periods of time in our system, there is hardly any research done and thus cannot be stated that they are or are not a definite problem.
Microplastics can be an avoidable horror, or an ever present nuisance if nothing is done to reduce the amount that we are generating and putting into the natural system. The difficulty and the financial burden of removing the already present microplastics in the oceans make it virtually impossible for a single group to roll up their sleeves and take action. The problem is universal, so the solution should be done as a collective effort, the best being reducing the production of microplastic producing materials. Although the definite health impacts are not very visible to us yet, the thought of having miniscule plastic particles small enough to be embedded into our internal systems should be scary enough to spark a change.
- Bouwmeester, H., Hollman, P.C.H. and Peters, R.J.B. (2015). Potential Health Impact of Environmentally Released Micro- and Nanoplastics in the Human Food Production Chain: Experiences from Nanotoxicology. Environmental Science & Technology, 49(15), pp.8932–8947.
- Christopher Blair Crawford and Quinn, B. (2017). Microplastic pollutants. Amsterdam Etc.: Elsevier, Cop.
- Lambert, S. and Wagner, M. (2016). Characterisation of nanoplastics during the degradation of polystyrene. Chemosphere, [online] 145, pp.265–268. Available at: https://www.sciencedirect.com/science/article/pii/S0045653515304094.
- McIntyre, A., Vincent, R.M., Perkins, A.C. and Spiller, R.C. (1997). Effect of bran, ispaghula, and inert plastic particles on gastric emptying and small bowel transit in humans: the role of physical factors. Gut, 40(2), pp.223–227.
- Miranda, D. de A. and de Carvalho-Souza, G.F. (2016). Are we eating plastic-ingesting fish? Marine Pollution Bulletin, [online] 103(1), pp.109–114. Available at: https://www.sciencedirect.com/science/article/pii/S0025326X15302393 [Accessed 3 Mar. 2020].
- Tomlin, J. and Read, N.W. (1988). Laxative properties of indigestible plastic particles. BMJ, 297(6657), pp.1175–1176.