Plastics are useful, and problems with plastic waste solvable

Perjantai 3.5.2024 klo 15.54 - Mikko Nikinmaa

There are an incredible number of good sides in plastics, and another vast number of problems. The first big problem is that they are usually produced from oil, and plastics production is a significant source of carbon dioxide. This problem can be overcome quite easily. The oil-based plastics can be replaced by wood-based plastics, and if they are produced using green energy, they are a carbon dioxide sink for as long as the product has not been broken down.

As a second problem with plastics, their stability is usually taken up. Indeed, they can be stable for hundreds of years, and because of this, plastic waste is considered to be a major problem. Plastic waste is found everywhere, strangling fish and birds. But hey, isn’t this a problem with waste collection and treatment, not of plastics themselves. The real problem has been that people throw plastics everywhere. If that were not done, the problem would be much smaller. If plastics were fully recycled, there would be no plastics problem. Presently, much of the plastics cannot be accepted for recycling. However, also this could be changed. If the plastics were melted in pyrolysis, they could be first changed to their original compounds, and thereafter de novo plastics could be produced, enabling full recycling. The toxic compounds could be distilled out. If you are now saying tha this is impossible, I can just answer you that it is not any more difficult than what is currently done in oil refineries.

If most plastic materials were collected and treated before they were broken down to microplastics, and if microplastics use in cosmetics were discontinued, a major source of micro and nanoplastics would unfortunately still remain: tyre wear particles from cars. It is estimated that about 50 % of all microplastic materials in aquatic environment are tyre wear particles. In air, the proportion is 80 %. What is even worse is that the tyre wear particles contain toxic compounds. In addition, any microplastics may not be very harmful themselves as polyethene or such like, but because they are hydrophobic materials and most toxicants are hydrophobic, the microplastics can act as means for toxicants to enter the body. Diminishing tyre wear particles could best be done by increasing use of public transport and decreasing reliance on private cars.

So, most of the problems with plastic waste could be solved with reasonable cost and time. If the governments are really worried about plastic pollution, and not just saying that they are worried, the solutions should be implemented.

Kommentoi kirjoitusta. Avainsanat: microplastics, tyre wear, wood-based plastics, hydrophobic toxicants

Electric cars - there are all sorts of environmental problems

Perjantai 5.5.2023 klo 14.22 - Mikko Nikinmaa

In the name of combatting climate change, car manufacturing is rapidly changing from producing petrol- and diesel-consuming cars to electric cars. It is reasonable to ask, if electric cars are a sustainable solution. There are several problems, which should mean that one cannot increase the number of cars, even if they are electric. Rather, to combat climate and other environmental changes, the number of cars should be drastically reduced. The paragraphs below indicate the reasoning for this.

First, electric cars are fossil fuel-free only if the electricity used in them is produced not using coal and oil. The overall electricity use increases markedly with increasing number of electric cars. Hitherto the proportion of electricity produced using fossil fuels has not really decreased, even though the electricity produced using renewable sources has increased markedly. This is due to the increase in the total electricity use. So, presently an electric car user may increase the use of fossil fuels in electricity production (naturally depending on the country).

Second, production of cars is using a lot of steel. Steel production is currently one of the most important sources of emitted carbon dioxide. For example, out of the total carbon dioxide emitted by Sweden, steel production accounts for more than 10 %. The steel producers are aware of their large carbon footprint, and companies are currently competing to have carbon-free steel production. Carbon-free steel will undoubtedly be eagerly bought by car manufacturers. However, its production requires a lot of electricity, so fossil fuel-free electricity production is the key also here.

Third, present electric cars are on average bigger and heavier than petrol-fuelled cars. As a consequence, their production needs more steel. Also, their batteries use more of the metals, which must be mined with dire consequences to the environment. Some of the needed metals occur only in low concentrations even in the richest ores. Electric cars must thus become smaller and new types of batteries utilizing commonly occurring compounds developed.

Fourth, almost every day news alerts us about the dangers of microplastics. It is hardly ever mentioned that by far the most important source of them is tyrewear. They cannot be removed in sewage treatment, as they are produced wherever cars are driven. The amount of particles released increases with the weight of the car, so the heavier electric cars are a bigger problem than current petrol cars.

All in all, electric cars have several problems, so we should try to reduce the number of automobiles in use. By doing that, some land now taken up by roads would be free for other uses. Doing it may be required for the wellbeing of environment.

Kommentoi kirjoitusta. Avainsanat: climate change, fossil fuels, microplastics, steel production, electricity

Plastics - not an environmental problem as the material but because of consumption habits and waste management

Perjantai 8.7.2022 klo 19.16 - Mikko Nikinmaa

After plastics were invented, they started appearing everywhere from packaging to toys. One can say that since 1970’s we have lived in plastic age. Pretty much everything has been made of plastics or wrapped in plastics. For years we have carried our shopping home in plastic bags, drunk from plastic bottles and used plastic single-use utensils.

A few years back one started noticing the huge amount of plastic waste accumulating in the environment. As the extreme huge plastic gyres have formed in world’s oceans, the Pacific as the worst example. We have all seen pictures of birds and fish getting stuck in plastic bags or fishing gear, and microplastics are found in every aquatic environment. As a result, a movement considering plastics as one of the most important environmental problems has emerged. However, stating that plastics are bad and should be banned does not address the real problems, overconsumption, cost minimization and waste management problems.

Plastics as materials are cheap, durable, malleable, inert and recyclable. Those properties make them ideal for many uses, and are the reason for plastic age. For example, the Lego bricks, which I got 60 years ago have not aged at all. Indeed, it is estimated that no aging occurs for at least 500 years. This durability is invariably said to be a problem, but I would say it is a good thing. In the following, I go through the questions associated with plastics and point out which changes and solutions would be available to us.

Traditionally plastics are made of oil. As our dependency from fossil fuels must be decreased, this requires that oil-based plastic making is reduced and finally stopped. However, since the material is durable, even oil-based plastics have small carbon footprints. Exactly the same plastics can be made using, e.g., wood as starting material: they look the same, are equally durable, and cause similar contamination if thrown in the environment. However, since they are not made from oil, their carbon footprint is smaller than that of oil-based plastics.

The real reason why plastics have become an environmental problem is our overconsumption. As a consequence, plastics, being very cheap, have been added as wrapping materials to everything. Extreme examples are biscuit boxes, which are enclosed in plastic and each individual biscuit is also enclosed in plastic: wouldn’t a single cardboard casing suffice? We have taken plastic bags for granted. Since we consume a lot, every time we go to buy clothes, a lot of plastics follows home with the shopping. If the use of unnecessary plastic were discontinued, a large portion of plastic contamination would disappear.

Much of the plastic is recyclable. Although this is the case, the efficiency of recycling is not more than 50 % even in the best countries. This is far from the 95 % efficiency of glass bottle recycling in Finland. If the efficiency of recycling were improved, plastic pollution would be much decreased. In waste collection, many companies are saving money by transporting plastic waste to poor countries for nominal fee. As a result, plastic contamination in rich countries disappears. However, the treatment of plastic waste in most poor countries is to throw it in the rivers where the float to the oceans, out of sight and out of minds, contributing to the garbage gyres of the oceans. It would be very simple to stop this kind of “saving”. One could make international agreements that transport of plastic waste across national boundaries was forbidden. Burning plastic waste is a much better alternative than its transport and consecutive appearance in garbage gyres. Plastic burning could substitute the use of fossil fuels for heating.

Today most plastics are nontoxic. Earlier toxic components were much more common. The problem is that plastics are hydrophobic, and most toxicants are also hydrophobic. Because of this microplastics can act as carriers of toxicants into animals in the aquatic environment. The toxicants are taken in together with the microplastics. The most effective way of decreasing such toxic impacts would be to decrease the amount of toxic chemicals, such as insecticides and other pesticides, released in the environment. The two major sources of microplastics in the environment are tyre wear particles and cigarette butts. Both contain a plenty of toxic compounds making the microplastics released quite toxic. The tyre wear particles could be decreased by decreasing car and truck traffic. Thus, exactly the same action would combat microplastic pollution and climate change. With regard to cigarette butts all that would be required would be for smokers to use cigarette trays or waste bins to dispose of the cigarettes, not throw them to the environment.

Thus, all the aspects of plastic pollution are solvable. It is only the matter of actions; one could demand that they are done.

Kommentoi kirjoitusta. Avainsanat: microplastics, cigarette butts, overconsumption,

What to Wear?

Keskiviikko 26.2.2020 klo 11.48 - Mikko Nikinmaa

Virtually all clothing is today made of cotton, polyester or their mixtures. Presently textile industry is one of the biggest causes of environmental contamination and uses a lot of energy largely produced with fossil fuels. One of the problems with clothing is that the life cycle has decreased a lot with increasing GNP. The time that for example trousers are used has decreased to one third of what it was 50 years ago. Thus, one way of decreasing the environmental footprint of clothing is to use them longer. Another is to recycle them, certainly most of us in Europe and North America have nearly unused clothing in our cupboards, which could be recirculated. If a piece of clothing is not in adequate condition to be sold, it could theoretically be recycled to produce new clothing. However, already this presents difficulties, since most clothes are cotton-polyester mixtures, and remaking usable cloth from the mixtures is nearly impossible with present methodology.

However, even though longer use and recycling of clothing decreases the environmental footprint of textile industry, it does not abolish it. New clothes are needed all the time, and both cotton and polyester have significant environmental impacts. Every time one washes polyester-containing clothing, some microfibres, microplastics, end up in spinnova-sustain-20180123-WEB.jpgwastewater. Although modern wastewater treatment plants remove 99 % of the microplastics, some still end up in our rivers, lakes and seas. With recent discussion about microplastics it is hard to realize that the problem with cotton is much worse than that caused by polyester, but it is! First, cotton uses up very much land in subtropical and tropical areas, where land would be needed for food production. Second, cotton is cultivated in semidry areas, where it uses up virtually all water. The water is thus taken away from food production. The problem would be slightly smaller, if the profits from cotton would come to the local people, but this is not the case. Third, cotton cultivation is the most insecticide-intensive branch of agricultural production. In addition to insects, millions of birds are estimated to die every year because of eating the insects dying as a result of pesticide treatment.

In view of the above, an environmentally thinking person is faced with a dilemma: what to wear, since pretty much everything is environmentally unsustainable. The solution to this dilemma may be soon forthcoming. Start using clothes made of wood fibre. The Finnish company Spinnova has, together with Marimekko made the first experimental batches of clothing using wood fibres produced with their method. In addition to removing all the problems with cotton, the production can be carbon neutral. Further, if trees are planted to some of the arid areas, where cotton is presently cultivated, the area may become more moist (it appears that the presence of trees somehow helps to increase rainfall).

So, after a few years of asking for sustainably produced clothing, we may be able to change our rags to new clothes. One may hope that also dyeing them is done in a more environmentally-friendly fashion than is today done with cotton cloth in major producers like India, Pakistan and Bangla Desh, where cloth dyeing is a major source of aquatic pollution.

Kommentoi kirjoitusta. Avainsanat: climate change, land use, microplastics, insecticide, water shortage

Fashion largely determines what is studied in (aquatic) toxicology

Perjantai 18.10.2019 klo 17.37 - Mikko Nikinmaa

I finished as editor-in-chief of Aquatic Toxicology at the end of July after 14 years. During that time, I have handled more than 6000 manuscripts, which makes it possible to evaluate, what the scientists are studying. It also gives an indication about what is funded, since adequate funding is a prerequisite of being able to carry out the research. Overall, I must say that I am disappointed, since it appears that the funders mainly support fashionable topics, and scientists are naturally willing to do what gives them funding. Associated with this is the positive correlation between fashionable topic and the impact factors of journals. If you have many articles in a journal on a fashionable topic, its impact factor increases, even if the real environmental relevance of the work were poor. I present some major problems, which are the result of trying to do fashionable things instead of thinking already at the outset, what the real environmental relevance of the studies is.

First, it seems that using the newest possible methodology enables you to do work, which has little importance, and still get funded. In the past 15 years the -omics methods have increasingly been utilized by environmental toxicologists. Although they give new possibilities, if properly interpreted and utilized, their improper use is common, and many conclusions are faulty. Most studies use a very small number of organisms, typically 3. This is far too small number for any conclusions with natural populations of animals, especially as their environmental responses may involve changes in variability. I suppose everybody accepts that the responses to toxicants depend on the functions of proteins and their disturbances. Yet, most studies forget this, and based on real-time PCR, microarray or RNA-seq data, which show an increase in steady-state mRNA level conclude that the function encoded by the gene studied has increased. However, this need not be so: if the protein activity decreases because of the action of a toxicant, transcription is increased as a compensatory response. Yet, even after the compensatory response, protein activity may be reduced. In fact, some studies have seen this happening, but have not indicated this obvious explanation just being surprised of the finding. While the above concerns the commonly used transcriptomics, one can find problems with proteomics and metabolomics also. Basically, since toxicants can only affect organisms, if they disturb some functions, functional measurements are required. The -omics data help in finding the genes and consecutively functions, which may be affected. The reason why this is seldom done is twofold: functional measurements are time-consuming, and it is hard to make them high-throughput; the methodology is usually classical and does not attract funders as the use of fancy methodology does.

Second, nanotoxicology was in fashion a couple of years back. Between 2010 and 2015 one could publish virtually anything showing that nanomaterials can be toxic. In most cases, the amount of nanomaterial used has little bearing to what the environmental levels are or may be in future. Yet, relating the toxic actions to nanoparticles to their environmental occurrence is virtually undone. I fear that the same is happening with the new fashionable topic: microplastics. Horror stories are told about the effects of microplastics. Yet, virtually nothing is known about the effects of environmentally occurring levels of microplastics on the function of organisms.

Third, climate change and interactions of toxicants with temperature or oxygen level, or other environmental variables has hitherto been understudied. This knowledge gap is presently being filled. However, a significant problem remains, and most studies do not even indicate its existence. The studies are typically short, often 1-20 days, and the temperature, carbon dioxide or oxygen level change are typically imposed with virtually no lag time using values expected to occur a hundred years from now. This means that the stress levels in the studies are completely different from naturally occurring ones.

Finally, we are suffering from the tyranny of the mean. Virtually always a toxicological response is considered to be a change in the mean of a parameter. Changes in variance are virtually never considered as a toxicological endpoint. One is considering the heterogeneity of data only as determining if data transformation is needed for statistical testing. Yet, when I went over many toxicological studies, I observed that in most of them variability changed without a change in mean. In those cases, variability is undoubtedly a more sensitive indicator of a toxicological response than the mean. We have pointed out the possible importance of variability as a toxicological end point (Nikinmaa, M., Anttila, K. Individual variation in aquatic toxicology: not only unwanted noise. Aquatic Toxicology 207, 29-33; open access)

Kommentoi kirjoitusta. Avainsanat: nanotoxicology, microplastics, omics

Can we get rid of plastics - or is it really needed?

Lauantai 20.1.2018 klo 13.08 - Mikko Nikinmaa

When I was a child there was practically no plastic material. Fruit and other foods were placed in paper bags. Water was carried in metal buckets. Now everything is put is plastics - all the clothes are in plastic covers, candies are first in plastic bags and then in individual plastic covers. It can actually be said that we have moved from iron age to plastic age. Plastics are oil-based, cheap, light and durable materials. Further, they are good insulating material. Therefore, when I look around, covers of computers, printers, TVs, phones etc. are made of plastics. The same is true of wastewater pipes. For this reason, replacing plastics in manufacturing is very challenging. Or is it really needed?

The real problem with plastic waste is the material that is thrown in the environment. That is the material generating the big marine garbage gyres. Most of their material is plastic waste thrown to the environment. It is funny that people picknicking in parks do not collect their plastic cups, plates and utensils and put them in garbage bins. If that were always done - all the plastic wastes placed in the collected carbage, there would not be any garbage gyres, and the sea and the coasts would be beautiful and trash-free. I have sometimes wondered if people, who throw the wastes around in the environmentIMG_20170727_0010.jpg do that also in their homes.

So what to do with the plastics? The first thing is that they have to be collected. Thereafter much could be recycled, used for new plastic products. Currently only a few percent of plastics are recycled largely because recycling containers are quite rare. If societies really want to solve the plastics pollution problem, the collection of plastics must be improved - the percentage of plastics that is recycled  could easily be increased to over 50%. For the rest, energy use is probably the best. Since plastics are made of oil, burning them for heat production of towns instead of oil, which continues to be used for a long period of time, would be advisable. Instead of burning oil, one could first carry shoppings home in a plastic bag, thereafter use the bag in collecting trash, whereafter it would be burned. Since the same material would be used for several times, the carbon dioxide footprint of the bag would become smaller. This is more or less the same as instead of using wood to produce energy, it is used to produce paper for a newspaper which is afterwards burned in a fireplace.

If plastics were either recycled or burned for energy production, most of plastic pollution would disappear. The remaining problem would be microplastics. Much of it, which is caused by the slow breakdown of big plastic materials to microplastics as a result of mechanic tear, solar radiation and oxygen, would disappear with the collection of plastics. The remaining sources are plastic microbeads of cleaning liquids, tooth pastes and cosmetics, the small fibres given up whe washing clothing containing synthetic materials, and the dust from tyres, paved roads, artificial turfs etc. The first of these could be avoided already today, since there are more and more products, which do not contain plastic microbeads. The choice is the consumer's: he/she only needs to read the contents or ask the shop assistant, and buy products without plastic beads - if products with plastic beads were left unsold, the manufacturer would soon change their contents.The fibres from washing clothes containing synthetic materials is a more difficult problem, as most pieces of clothing have some synthetic fibres. Fleece clothing has recently gained a lot of attention, but actually most shirts, trousers, Goretex clothing, other outdoor apparel  etc. contain synthetic material, and are thus a source of microplastics. The problem with replacing clothing with synthetic materials by cotton actually causes as big environmental (and social) problems as it solves. Water and pesticide  use of cotton production is unacceptable. Further, the use of child labour in different stages of making cotton clothing is also unacceptable. The third major source of microplastics: the tear of tyres, dust from roads, and dust from artificial turfs is probably quantitatively the most important. There are no easy ways to decrease the amount released from traffic, unless people give up cars, and use rail traffic instead.

Thus, I think that the use of plastics can continue, if measures are taken not to allow the release of plastics to the environment. For a large part this can already be done, but requires actions both from the consumers and the society.

Kommentoi kirjoitusta. Avainsanat: garbage gyres, microplastics, climate change, energy production, marine pollution

Can we wear any clothes?

Sunnuntai 17.12.2017 klo 17.38

As the "most unneeded product of the year" the nature conservation magazine Finland's Nature chose fleece clothing, because washing them liberates microplastics in water. This got me thinking, which clothes we can wear, because environmental arguments for the discontinued use of virtually everything are strong. Below I go through them in detail:

1. Fleece clothing, but also virtually all other synthetic clothing should not be used, since they inevitably cause the release of microplastics in the environment.

2. Cotton clothing should not be used because of several reasons. It is very likely that the cotton from which the clothes are made is from genetically modified plants (GMO). The use of different pesticides in cotton fields is greater than anywhere else. As a result, the number of dead birds is great because they eat insecticide-affected insects, and the toxicant also affects them. In the semiarid areas, where cotton is produced, cotton production uses up water, which would be needed for food production and human consumption. Further, it is quite likely that the cotton clothing we wear has been produced using child labour, at least if we want to have cheap models.

3. Wool products should not be used, because wool clothing is produced by taking advantage of sheep. If one is protecting the rights of animals, that is not acceptable.

4. For the same reason as for banning wool products, everything containing leather or fur should not be used, because they can only be produced, if animal rights are not respected.

So what can we wear? Presently only linen clothing, but if it becomes popular, it is likely that many of the problems associated with cotton will also take place in linen production. Wood fibres could be a solution, but many hard-core environmentalists are also against the use of wood products. I suppose I shall start to look what the real environmentalists wear to see, if they follow their principles. - Or maybe we should walk around naked? It would also be difficult here in the north, when temperatures are close to or below freezing.

Kommentoi kirjoitusta. Avainsanat: microplastics, GMO, pesticides, child labour, animal protection

Plastics removal by micro-organisms

Sunnuntai 24.9.2017 klo 17.50 - Mikko Nikinma

Plastic garbage is a huge problem everywhere in the world. The most visible collections of mainly plastic trash are the Pacific Garbage Gyre and similar smaller ones in the Atlantic and Indian Oceans, but all the aquatic environments have plastic waste and non-visible microplastics. Plastic trash is a highly visible problem also in terrestrial environments.

In the light of the huge plastic pollution problem, two major solutions to alleviate it have been envisioned. The first involves diminishing the use of plastics markedly, collecting plastic trash for reuse, and if the material cannot be reused, burning it. Burning plastic is virtually the same as burning oil, since currently virtually all plastics are made of oil. Thus, burning the plastic trash diminishes the need for oil and thus diminishes its consumption. This way of addressing the plastics problem is tedious, demands a lot of work and time, and requires a change in our daily behaviour. 

The other solution is much simpler. Let's just find a micro-organism, which uses the plastics as an energy source. The evolution of micro-organisms is rapid as a result of their short generation interval. There are both some bacteria which use oil as food and some fungi which decompose plastics. An example of the latter has recently been described in the journal Environmental Pollution (Khan et al. 2017 Environmental Pollution 225, 469-480). Notably, oil-eating bacteria have successfully been used to clean up oil-contaminated soil, so what is simply needed is to have plastic-eating micro-organism placed within plastic trash, and the microbe does the rest. Simple and effective, right?

However, the solution is not so clearcut beneficial. Our world today uses plastics in virtually everything. Already in the beginning of 1972 a book with the name Mutant 59: The Plastic Eaters was written by Kit Pedler and Gerry Davis. In the book, a mutant bacterium was generated (to remove plastic contamination), but it got loose and started eating up, e.g., the plastic covers of electrical wires with the consequence that electrical appliances short-circuited, planes crashed etc. No one can guarantee that the plastic eating micro-organism cannot spread outside of where it is wanted, unless the evolution of organism is directed so that it cannot live anywhere but its wanted target. For example, one could generate the plastic-eating micro-organism so that it is strictly anaerobic, whereby it would die immediately upon contact with air.

However, for developing the plastic-eating anaerobic organism time is needed. Thus, we must primarily use the tedious first alternative.

Kommentoi kirjoitusta. Avainsanat: microplastics, garbage gyres, environmental pollution, plastic waste

Blue Economies - The Seas Affect Our Lives in Many Ways

Keskiviikko 14.6.2017 klo 10.21 - Mikko Nikinmaa

Blue economies are another recent catchword, which indicates economical activity associated mainly with marine environments. From the environmental point of view there are a couple of things that need to be realized.

First, marine pollution is a huge problem. It is probably the biggest single factor behind climate change. Because of the large sea area, algae, largely unicellular microalgae, contribute 40-50 % of the total photosynthesis of the earth. Although in certain areas microalgal growth has increased, it has been estimated that owing to marine pollution the overall amount of carbon dioxide fixed by algae has decreased 10-20 %. This decrease of carbon dioxide sink is greater than that caused by recent rainforest cuts. An important component of marine pollution which has recently got much attention is plastic pollution. A lot has been talked about microplastics, but the weathering of plastics generates even smaller components, nanoplastics, which affect phyto and zooplankton. Their effects can be direct, but additionally they can result in hydrophobic environmental pollutants to become concentrated and available to organisms.

Second, world's seas are overfished. Environmentally, the use of cultured fish would be better than supporting fishing that can cause extinction of the most popular food species within 100 years. However, the problems with aquaculture are the present marked use of antibiotics and pesticides. Both should be diminished. Also, at present the feed is mainly fish flour, which means that overexploitation of natural fish is not reduced by aquaculturing, only changed to species with less human consumption. So, environmentally friendly aquaculture would require development of feeds that are not based on fish flour.

These are two things that need to be considered when developing blue economies. 

Kommentoi kirjoitusta. Avainsanat: climate change, marine pollution, microplastics, fisheries

Plastic waste in the seas

Tiistai 3.1.2017 klo 17.39 - Mikko Nikinmaa

One of the biggest news items on contamination has been the presence of huge amounts of plastics in many areas of world's oceans. One of the greatest sources of plastics are plastic bags - carelessly handled by people. Eighty to ninety % of plastic contamination in the seas comes from coastal areas. Plastics in the coast float up to several thousand kilometers from the disposal point in sea currents.

Plastics are very stable. That is the major reason, why they have become so intensively used. However, abiotically they are slowly degraded to small plastic particles, microplastics, in sunlight and the presence of oxygen. Biologically, bacteria, which are able to use plastics as food source, have evolved. Plastics are made from oil. Thus, oil-eating bacteria have developed to plastic-eating bacteria. They are much more effective at tropical temperatures than in cold. Thus, both oil and plastic pollution are a longer-lasting problem in the arctic than tropical areas.

Although the toxic compounds of oils are also those of many plastics, the major biological effects of plastics are caused by the influence of plastic particles on digestion. Microplastics are virtually undigestible and often clog the digestive tract of animals which eat them. (And this is what most animals do, as plankton-eating animals do either not recognize the difference between real edible animals and undigestible plastic particles or eat animals with digestive tract filled with plastic particles). As the real food cannot then be digested the animals cannot get energy required for living. Consequently, it is presently estimated that millions of birds and fish die annually because of the disturbances in digestion caused by the plastics, and the number of dead invertebrates is much greater.

Kommentoi kirjoitusta. Avainsanat: microplastics, plastic pollution, marine contamination