Coming to you on land, sea and air

Microplastics have been found in the deep ocean, in the arctic, in our food. What we don’t yet know is how they are affecting our health and lifestyle. Dr Anjani Ganase reports.

Plastic pollution is a known and observable phenomenon with impacts that include the entanglement, choking, smothering and drowning of marine life – turtles, sea birds and even whales. Yet, there is the unseen equivalent problem of microplastics that have managed to pervade not just the natural ecosystem but human life as well. Microplastics are classified as less than 5 mm in size; most are not visible to the naked eye and therefore require special techniques to see them. Microplastics can be anything from the by-products of plastic pellets used in manufacturing – plastic saw dust, microbeads found in scrubs and toiletries, fibres from synthetic cloths and from the wear and tear of tyres on the road. Other forms of microplastics result from the breakdown of large pieces of plastics that have already been discharged into nature. Plastic tends to degrade in the sun, becoming brittle and breaking down into smaller and smaller particles until they’re microscopic. Unfortunately, very little is known about the impacts of these plastics to our health and biology, yet they are invading our ecosystems at alarming amounts.

Microplastics found among grains of sand. Photo by 5Gyres, courtesy of Oregon State University (CC)

As most microplastics originate from land, fine particulates use the same avenues to get into the marine environment via rivers and streams especially surrounding cities and urban areas. Most major cities around the world sit on river systems where the run off from rainfall is deposited immediately into drains that run to the rivers and out to sea. Studies have mapped the transport and the collection of microplastics within river catchment zone adjacent to the large urban and suburban areas. Collection points include beaches, riverbeds that often get washed off to sea by periods of heavy rainfall. When out at sea, the microplastics permeate our marine food chain. Filter feeding invertebrates such as sponges, tunicates, clams and oysters are likely to accumulate fine plastics which move up the food chain to species that we enjoy.

Apart from the microplastics formed from plastics dumped in the environment, more – about two-thirds of any given sample - are released into the ocean from synthetic textiles – polyester, rayon etc - as well as from tyres.  Only about 2 % come from the household toiletries. Of course the origins of microplastic varies significantly with location. In Africa, an equivalent of 22 plastic bags in microbeads are deposited per person per week; India and China account for the equivalent of 33 – 35 plastic bags. The USA however dumps an equivalent of 150 plastic bags per person per week. Trinidad and Tobago would be closer to the global average which is about 46 plastic bag equivalent of microplastics per person per week. The difference in number is related to lifestyles: India and China use more synthetic fabrics, while in the Americas most of the microplastics originate from tyres.

Are the oceans the only places we’re finding microplastics? What about on the mountaintops? A few studies published this year revealed that microplastics can be easily aerosolised and transported far off via air currents. Scientists monitored the amount of microplastics being deposited on the remote Pyrenees Mountains in southwest France. The surges in microplastics appeared to correspond to periods of greater rain, wind and snow. As the wind drives the microplastics into the atmosphere, the snow and rain can then bind to the particles and bring them back down to the earth, sometimes far away from where they originated. The scientists also observed the presence of bronze particles in the snow at certain times of the year, indicative of Saharan dust, in which it is speculated the microplastics may travel similar distances. More revealing were the quantities of certain microplastics originating in neighbouring French cities. The majority of microplastics found were low density polystyrene and polyethylene, both of which are used in lightweight single use packaging, despite the fact that they’re recyclable. Other scientists have reported on microplastics  being deposited in the snow of the Swiss Alps, Bremen and even in the Arctic.

The pervasiveness of microplastics in most natural ecosystems is sobering especially when we consider the consequences on our health and food. The presence of microplastics in the atmosphere implies a much easier and widespread contamination of our food and our bodies even on a remote tropical island. Scientists estimate that the average adult in the USA takes about 100,000 microplastic particles into their body a year from the foods consumed. While the second largest source of microplastics that enter the body comes from seafood, persons who drink bottled water exclusively will ingest about 90,000 microplastic particles compared to those who drink tap water, about a 22 times lower. Bottled water is the largest source of microplastics entering our bodies. Little is known about consumption of plastics through our meats, grain, dairy and vegetables. When we consider inhalation of microplastic particles, the quantities nearly doubles in amount and is likely to be even higher in urban areas. The most common type of plastic is in the form of plastic fibres and fragments. Still, so little is known about the direct impacts of microplastics on our bodies.

Let us think about Trinidad and Tobago: what we put out as well as what is transported on the ocean to our shores, and what rides the winds from distant lands. Much more research needs to be done locally to determine the amount of microplastics in the food we eat, the fish, crabs, oysters, and the impacts on our bodies. Let us think about building confidence in our drinking water and reconsider the amount of bottled water we drink. We may be small rocks in a vast ocean but we can make the effort to reduce and remove plastics from our daily lives.

References:

Allen S, Allen D, Phoenix VR, Le Roux G, Jiménez PD, Simonneau A, Binet S, Galop D. Atmospheric transport and deposition of microplastics in a remote mountain catch

Bergmann M, Mützel S, Primpke S, Tekman MB, Trachsel J, Gerdts G. White and wonderful? Microplastics prevail in snow from the Alps to the Arctic. Science Advances. 2019 Aug 1;5(8):eaax1157.

Boucher J, Friot D. Primary microplastics in the oceans: a global evaluation of sources. Gland, Switzerland: IUCN; 2017.

Cox KD, Covernton GA, Davies HL, Dower JF, Juanes F, Dudas SE. Human Consumption of Microplastics. Environmental science & technology. 2019 Jun 5.