Igor Čatić and Aleksandra Mihajlović
University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, Chair for Polymer Processing, Zagreb, Republic of Croatia, Society of Plastics and Rubber Engineers, Belgrade, Republic of Serbia
The diseases of silicosis and asbestosis, caused by particles of silicon dioxide and asbestos, have been already known for many years. In the recent years, the diseases caused by plastics and rubber have been frequently pointed out. For these diseases a general name has been introduced, plastosis. Based on the necessary evaluation criteria, one being the particle size, the names microplastosis and nanoplastosis have been introduced. This is prompted by increasingly strong attacks by radical environmentalists on plastic and rubber microparticles smaller than 5 mm, in the seas and oceans. It is usually stated that about 8 million tons of plastics enter the seas and oceans per year. However, there are no data on how much of that amount falls on microplastics. It accumulates in the sea where their small size makes it easier for the sea creatures to bring them into their bodies. Microplastics can also enter the food chain. Recent research has found microplastics in the air, drinking water and food. However, with unknown effects on human health. For now, the term “microplastics” has not been defined consistently. According to the available data, 368 million tons of plastic and 13.8 million tons of rubber, the basic ingredient of rubber products, were produced in 2019 worldwide. Acrylonitrile butadiene styrene (ABS) printer emission induced in vitro and in vivo toxicity, revealed that the emitted particles during 3D printing.
Plastosis is a common name for all diseases that can occur during the production of plastic materials and products and during their recovery. Plastosis is also defined as “a disease caused by the harmful physical or chemical effects of plastics and rubber on living organisms. Perhaps the most well-known examples of plastosis are associated with the production of poly (vinyl chloride), the popular PVC, half of century ago. These are Minamata disease that has been reported in Japan during the use of the old procedure, in the presence of mercury. Another disease is a rare type of cancer, angiosarcoma, which affects workers who have cleaned autoclaves in PVC production for a long time. But that is now a distant past. Now, PVC is considered as the greenest material.
According Yong Qian, in study “Acrylonitrile butadiene styrene (ABS) printer emission induced in vitro and in vivo toxicity,” revealed that the emitted particles during 3D printing cause moderate toxicity in human lung cells. This disease can be named adiplastosis (from ad-ditive manufacturing).
From an extensive analysis of the term microplastics conducted in the text,1 which served as the basis for this presentation, it can be concluded that there is no single definition of microplastics. That is why only a practical one is mentioned. The particle size of microplastics is between 100 nm and 5 mm.
It is similar with nanoplastics. According to revision of the European Commission Recommendation 2011/696/EU, the definition of nanomaterials is: “Natural, accidentally formed or produced material containing particles, in the unbound state, as an aggregate or as an agglomerate. In this case, 50% or more of the particles have one external dimension or more external dimensions in the size range of 1 nm – 100 nm”.
n REACH, the nanomaterials are treated like other chemicals. As substances, although there is no explicit reference to nanomaterials.
The terms primary and secondary microplastics attract attention. Microplastics appears in two forms, as primary and secondary. Primary microplastics are particles that are released directly into the environment, into the soil or into the water, and make up about 16% of the total microplastics. They may come from: intentionally added fertilizer additives, plant protection products and detergents; microspheres used in cosmetics; industrial abrasives used for sandblasting, etc. According to the European Chemicals Agency and the PlasticsEurope Association, the deliberate production of microplastics thus defined is less than 0.1% of the total plastics production.
Most of the primary microplastics released into the environment in the EU come from: washing textiles and wearing rubber tires. Abrasion wear of rubber tires (about 500 thousand tons per year) could be called a land trace of microparticles. Unlike particles derived from marine coatings intended to protect the hull from fouling and corrosion. This would be a trace of sliding in water, a very important source of microparticle formation.
According to research by experts from the German University of Oldenburg, they suggest that microparticles formed by the separation of layers of protective coatings against fouling and corrosion of the ship’s hull could be most prevalent in the seas. It was found that polyethylene and polypropylene microparticles made of packaging plastic are more prevalent in areas near the coast. They made up only a third of the collected particles. The rest, especially those collected in the open ocean, are particles of poly(vinyl chloride), acrylate and polycarbonate. Road paints (<100 thousand tons) and bulk granules during the production of plastics and plastic products, etc. also contribute to the formation of microparticles.
Secondary microplastics makes up 84% of the total microplastics and is formed by the fragmentation and weathering of larger plastic objects (e.g. bags, bottles, etc.), especially in seawater.
More research is needed to improve the understanding of the sources and impacts of microplastics, including the environmental and health effects, and to develop innovative solutions to prevent its spread.
General and special types of diseases caused by particles
The oldest occupational disease is silicosis. Well-known is also the disease caused by microasbestos fibers, and the disease is precisely microasbestosis.
Microplastosis is a type of plastosis caused by microplastics, and nanoplastosis, caused by nanoplastics.
The definition of “microplastosis” precisely determines the content of the term plastosis caused by particles of the order of a micrometer, which also applies to the term “nanoplastosis”.
If the names asbestosis, nanoosis and plastosis are compared, two are made according to the same criterion, and one according to another. Asbestosis and plastosis according to the origin of substances and materials that cause the diseases, and nanoosis according to the particle size. This makes it possible to define two groups of impacts of microparticles on the occurrence of microplastosis.
Plastics is an inert material. The definition of microplastics is not simple. However, there is a wide range of properties that characterize microplastics. Such as size, shape, chemical composition, color, hydrophobicity, etc. that could harm by the impact of particles on cells and tissues.
Adverse effects on all organisms exposed to microplastics can be divided into two groups: physical and chemical impacts. Physical impacts relate to particle size, shape, and concentration of microplastics, and chemical to hazardous chemicals (e.g. monomer residues, polymer additives) associated with microplastics.
Only physical impacts will be considered. For example, nanoplastics and microplastic particles most often enter the human system by ingesting contaminated foodstuffs: food and drink. The human excretory system is expected to remove up to 90% of the ingested microplastics and nanoplastics. It is estimated that up to 90% of the ingested microplastics and nanoplastics will be excreted after consumption. It is considered that nanoplastics would more easily enter the cells than microplastics. The risks to the environment and the human health posed by microplastics are difficult to quantify.
Potential environmental and health risks for human beings caused by microplastics are relatively new areas of research and there is currently high degree of uncertainty about this issue. The risk is a function of hazard and exposure (dose). The dangers that plastics poses to the environment vary depending on the size of the plastic particles and the size of the organism. Discharges of microplastics into the environment take place mainly in three ways: (i) by discharge into the sewer, (ii) by municipal solid waste and (iii) by direct release.
The entry point of microplastics into the human beings can be ingestion of contaminated food (by means of food chain), inhalation, or skin contact.
The extent to which microplastics in certain foods harm human health is a matter of debate. Given the widespread use of plastic materials in everyday life, microplastics from food and beverages is probably only a minor route of exposure of human beings to plastic particles and related chemicals. This is rarely emphasized and creates a distorted picture of human exposure to plastics.
The estimated daily amount of microplastics ingested by food and drink in an adult is 2 µg (WHO). Quantitative data on human exposure to microplastics through diet are not yet available, and there is still no legislation on microplastics and nanoplastics in food. Based on the available data, there are large gaps in the knowledge about the intake and fate of plastic particles of micro dimensions and nano dimensions in humans and their impact on human health.
The presence and effects of plastic residues are being increasingly investigated. Most research has focused on microplastics, but few reports suggest whether plastic fragments in the size range <100 nm (nanoplastics) can be formed in the aquatic environment, and then in humans as well.
In general, there is a lack of the results of in-depth studies of the impact of these particles on human health and the environment. Therefore, the aggressive attack of the environmentalists, emphasizing the impact of plastic particles on the health of human beings, is unjustified. For the moment there is, namely, not enough evidence about their impact on the health of human beings.
Legend: Microplastix (this image was insered by tecnologiademateriais.com.br)