Microplastics a potential public health issue

A study on the presence of microplastics in salt from 12 salt-producing sites in the Cox's Bazar and Chattogram districts came up with results that are concerning. Plastics are manmade polymeric materials of organic origin with the property that it can be moulded into different shapes. Common sense dictates that since the substance is not part of the natural environment, it should not be allowed to pollute the air, water and the land. The study was conducted by the researchers from the Noakhali Science and Technology University (NSTU). They found that there were 560 to 1,253 particles of plastic in every kilogramme (kg) of salt produced from the sites in question. The problem is that the plastic particles will in the end find their place in the table salt at our dining table. The study further found out that the offshore salt contained more plastic particles than that produced onshore. 

Now what is the risk involved in microplastics so far as public health is concerned? In fact, the answer till now is ambiguous. More to the point, what harm plastic microparticles exactly causes to human health is still unknown. But as microplastics are foreign to human body, their presence in a person's bloodstream and other vital organs, including lungs, gut, colon, liver, breastmilk, the placenta in a pregnant woman's uterus, etc., as detected by researchers in Belgium, Netherlands, UK, USA and other countries, should be brought under scrutiny and control. But not only in humans, microplastics have long been an issue of concern for their presence in the guts of shellfish and different other aquatic creatures that humans eat. Scientists in Belgium, six years ago, warned that people who eat mussels might be ingesting some 11,000 plastic particles every year.

Assuming that the average weight of a Belgium person is between 66.7 kilogrammes (kg) and 79 kg, then, the yearly consumption of microplastics by a Belgian man will be around 139 microparticles of plastic per kg of his body, while that in a Belgian woman will be 165 particles. From the study by the NSTU researchers, it could be learnt that there are between 560 and 1,253 plastic particles per kg of raw salt from the sites under study. So, it comes to 9.5 to 21.25 plastic microparticles in 17 gm of salt that an average Bangladeshi consumes a day.  In a year a Bangladeshi man will be ingesting around 63 to 140 microplastic particles per kg of his body assuming that his average weight is about 55 kg. Similarly, a Bangladeshi woman will be consuming slightly more plastic microparticles per kg of her body as she is lighter (by, on an average, 5kg) than her male counterpart. Here it is assumed that both of them are taking equal amounts of dietary salt every day. That amount of microplastic in his or her body is coming only from the dietary salt they consume. In this regard, researchers have no clue about what amount of plastic particles Bangladeshis are taking in their body every day from other plastic contaminated sources including food and water. In the South and Southeast Asian region, the presence of plastic microparticles in salt varies in amount from country to country with its lowest found in India and the highest in Sri Lanka.

Evidently, the researches being done in this field are worthwhile. The World Health Organization, too, has been reporting on the issue since 2019. Based on the data made available from researches, the WHO only keeps people aware of the issue. But nothing more about its public health consequences is reported. However, some scientists working with microplastics, for example, Dick Vethaak, a professor of ecotoxicology at VirjeUniversiteit in Amsterdam, Netherlands, would like to call the microplastic particles a 'plastic time bomb'. The concern here is about the plastic in our environment that has not been recycled and that is about 91 per cent of all the plastics produced since the material was created more than a century back. That is about 9.0 billion tons of plastic in the planet's ecosystems including landfills and oceans.

The problem with plastic is that it does not melt into the environment. If anything, it breaks down into smaller parts and contaminates wherever it goes. Micro and nanoplastics belong to this category of plastic particles. The size of the microplastics ranges from 5.0 milimetres to 100 nanometres(a nanometre is one billionth of a metre) in diameter. In other words, the size of a microplastic particle may be as large as a pencil eraser or as small as one-tenth the thickness of a human hair. Obviously, the nanoplastics are far smaller than microplastics. The dangers of microplastics lie in the fact that a large number of different chemicals, some 10,000 of them, are added to plastic to change its physical characteristics for use in different products including toiletries, cosmetics and so on. Some of these chemicals (about 2,400 in number) are potentially hazardous for human health.  Researchers have found that microplastics in human body leach those chemical into the body's tissues.  Due to their being in trace amounts in the blood, human body may mistake them for hormones, which are also present in very small quantities in the bloodstream. In that case the human body may wrongly respond to these chemicals taking those for hormones leading to unknown consequences. In any case, those are toxic for human health. Researchers are working to find what body functions and organs these chemicals from microplastics affect adversely. More research will be required to know the harmful effect of microplastics on the bodies of humans as well as other animals. Until then, alertness should be raised to reduce the intake of microplastics in a human body.

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