Nowadays, microplastics are everywhere, from the Fansipan summit to the sediment of the Mekong River; from salt seeds to fish, shrimp, pebbles, and so on. This makes us wonder, how have microplastics invaded our lives and how will they affect us? Many questions have been raised, and these are urgent issues that have prompted scientists around the world, including Vietnam, to seek solutions.
Statistics show that, globally, about 160,000 plastic bags are produced every second, with almost one million plastic bottles sold every minute and the amount of plastic waste equivalent to the capacity of two trucks is thrown into the ocean. Whether it’s plastic waste or microplastics—plastics in pieces, fibers or particles with a size of no more than 5 mm—they all have one destination: the ocean. However, the difference in size has made microplastics dangerous and difficult to predict. How did they get to the sea? How do they affect the environment? What effect do they have on health?
The microplastic rivers
The story of microplastics has always aroused curiosity for everyone. Obviously, microplastics are human-made products and are associated with social life, i.e. mainly on land, but somehow they have had “border trips” to reach the ocean. Like other pollutants, the pollution pathway of plastic waste and microplastics is a chain of roots rooted in human use and disposal of waste. At that time, they usually flow out of rivers and streams, flowing through urban areas to the coastal coastline and then spilling into the sea, entering sediments or floating along sea streams.
Vietnam has a streamlined river system, with 2,360 rivers more than 10 km long, stretching from north to south and 112 river gates, invisible in the middle, which have created "highways" favorable to the transportation of microplastics. One of the typical examples is the Red River Thunder Valley – the most populous region in Vietnam (nearly 23.4% of the country’s population) with the 1.140 km long Red River system flowing into the sea through the doors of Bạch Đằng, Ba Lạt, Lạch Giang, Tea Li, Đáy... With the divides and subsides, the Hồng River network is extremely complex with forms of water exchange, either taking water from the main flow of the Hồng or supplementing the main stream, after receiving water from ponds and canals. The complexity created by nature has created opportunities for the exchange and rotation of microplastics.
Belonging to the top of the most polluted rivers in the north, the So Cal River flows through the inhabited urban districts of Hanoi and receives almost entirely local wastewater. Later, the water on the So Calendar river flowed to the Thanh Liệt dam to pour into the Nhuệ river, this river received more water from the Hồng river through the Connecticut canopy and then merged with the Dáy river via the Phu Lý canopy before spilling into the sea at the Door of Dáy. During the implementation of the COMPOSE project from 2019-2021, Dr. Emilie Strady and researchers from Vietnam found that every 1 m3 of the So Cal River water contains up to 2,522 microplastics particles (the highest of the rivers surveyed in all three regions, for example, the Korean River with 3.9 particles/m3).
Microplastics – A big question
The new insights that scientists have brought have given us a more detailed picture of microplastics. Wherever they exist, air or land, surface water or sediment, river, lake or sea, they are also divided into two types: primary microplastics and secondary forms. (secondary microplastics). In their primary form, they are manufactured as raw materials for commercial products such as toothpaste, facial milk, fabrics, detergents, wall paint... In their secondary form they are formed from the degradation, decomposition and fermentation process of large plastic products like water bottles, bags, boxes, umbrellas, electronics, fishing tools... The process of fossilization and degradation over time of plastic waste into microplastics, even nanoplastics, is just as complex as the process of transporting them: this process depends heavily on environmental conditions such as solar radiation, temperature, waves, rain, wind...
The most complex problem with plastics and microplastics is that they last for hundreds of years, even longer. Endurance – one of the most proud qualities of plastics – is now its curse, because it means that it will remain in our environment for several hundred years, even longer. Why is the half-life of plastic waste and microplastics so long? Are they not all products of natural origin that are rubber plants? Oh, not that way. Rubber rubber is the main source of raw materials for the production of natural rubber, but it is only a form of polymer of natural origin in many types of synthetic polymer from petroleum today.
Compared to natural rubber, new synthetic polymers are “champions” with the properties that industrial or civilian products desire. Polymer polyethylene terephthalate (PET) is used in fabric fibers, liquid and food containers, plastic casting molds and in combination with technical plastic manufacturing glass fibers; polymer polymer thermal plastic (PE) for plastic tubes, hard suction, plastic bags; polyvinyl chloride thermal plastics (PVC) for thermal stabilizers, lubricants, additives in water pipes, ventilation equipment or metal anti-corrosion... A new study by Dr. Nguyen Minh Kỳ - one of the world's first works on microplastics in mud sediments sampled at a depth of 15 cm in the dams in the districts of Thanghai, Tân Thạnh and Đức Huệ (Long An) has identified 15 types of polymers, the most common of which are PVC (46.2%), PE (20.9%) and PP (9.2%) - the main result of the degradation of packaging, nylon bags, pesticides, chemical fertilizers...
As well as the predominance of coal thermal power in energy, no material can compete with plastic in terms of flexibility, stability, lightweight in volume, durability in many types of environments and especially low production costs. As a result, the world of plastics is surrounding humans in a difficult process to reverse.
The silent spring of plastic
When it is invented, a new substance is beautiful from every angle, and almost only its advantages are seen, only time gives us the left side. In the history of industrial chemistry, there is no shortage of such examples. The pesticide DDT, a high-molecular organic compound containing chlorine, was first synthesized by Austrian chemist Othmar Zeidler in 1874 and subsequently discovered by Swiss chemist Hermann Müller in 1939. Nearly 10 years later, Hermann Müller was awarded the Nobel Prize in Biomedicine for DDT being widely used to protect the crops and prevent epidemics. No one expected that 15 years later, researcher Rachel Carson, despite the threat to her life, published Silent Spring, a book that demonstrates the environmental abomination of insecticide use, which later became an environmental chemist’s “bedbag.” Next, it will take five decades for the scientific community to provide scientific evidence for the link between DDT exposure and breast cancer. So do microplastics harm the environment and human health like examples in history?
If you look at plastic waste, large-scale objects, there are countless instances where they make organisms stuck in the respiratory tract, the digestive tract, trapped in bags, ropes... Images of sea turtles in broken nets, dead fish, birds dying from plastic bite in the stomach give us the clearest view of the death of plastic waste. But what about plastic? Are they potentially harmful to ecosystems and humans? And if so, to what extent? It is too difficult for scientists, whether international or Vietnamese, to come to an immediate conclusion. It’s all too fresh and with the rest of this question, it’s easier to say than to do. It’s a process where everything has just left the starting line. Initially, scientists argued that microplastics are too small to cause something to the ecosystem, but there is more and more evidence of the impact of microplastic. Scientists have used the term “plastic sphere” to refer to ecosystems that have evolved to live in man-made plastic environments, especially marine ecosystem and bottom living organisms. One of them is Professor Robert C. Hale (Virginia Institute of Marine Sciences), who published a paper in Nature Communications in 2020 describing the effects of microplastics on the nitrogen cycle — a process of nitrogen biochemical transformation between its compound forms in marine sediments as well as affecting the bottom microbial community.
In Vietnam, scientists are also struggling to find their way because microplastics research is very complex and requires large investments. So, mostly new microplastics studies have only stopped in determining the initial morphology, size, distribution... of microplastic in nature, rather than in-depth studies of toxic by-absorption mechanisms or the impact of microplastics on the ecosystem. In addition, insufficient funding prevents scientists from interdisciplinary collaboration or conducting large-scale research to provide more comprehensive and meaningful information. However, scientists are still trying to fill the gaps in the picture of microplastics. Surveys by scientists in Huế, Nam Định, Bình Định and Thanh Hóa on blue parrot, the two-piece male shell, show that these species contain fibrous microplastics and its density ranges from 1 to 1,7 or 2.6 grams of wet.
In particular, by the end of 2022, the public was also upset when a study published that the salt samples surveyed also contained microplastics. Eating salt or aquatic species accumulate microplastics that can transmit microplastic to humans through the food chain. But what then? There are several ideas that international scientists are pursuing: diseases caused by exposure to microplastics can be associated with many factors, including pathogen/toxic and polymer/additive absorption; many organic/inorganic toxins in plastic products can account for many percent of the total plastic weight; the morphological properties of microplastic (shape, structure, size) can affect ecotoxicity such as controlling transport in tissue, obstructing the digestive tract, or irritating/harming tissues, leading to abnormalities or increased susceptibility to infectious diseases. The question of the effects of microplastic exposure is still in the minds of scientists and they hope to be able to answer it someday.
