Microplastics (MPs) are emerging environmental contaminants. A significant number of articles have been published recently on this particular topic. Based on the current knowledge, what would you tell in 2-3 points about the importance of research on MPs?
I would say we need to do research on microplastics in the environment because we know almost nothing about it.
We don't know the scale of the problem (water, air, soil, food, biota). We do not know all the potential sources of MP in the environment, routes of movement/ transformations in the environment and impact on living organisms. We do not have uniform research procedures. Generally speaking, knowledge about MP is still low. Hence, MP is an important area of research.
Plastics are composed of polymers and additives that modify the transparency, colour and other properties of the polymer. Polymers are brittle and not very useful. Plastifiers are additives added to the polymers to enhance their hardness, flexibility and resistence. Additives are not chemically linked to the matrix of the polymer, so they can difusse from plastics to the environment. They can diffuse to liquids and solids that are in contact with the surface of the plastic. Microplasticts have a large surface to volume ratio, so it is very likely that any additive present in the plastic microparticles difusses more easily to the environment. Among plastifiers, phthalates are present almost in all plastics that we use (for example, last year the EU refused to ban the addition of phthalates to plastics used in the food industry). It has been shown that phthalates are potent endocrine disruptors and interfere with the gonadal development of organisms. Since 1950, 9.5 billion tonnes of plastic have been produced and only a minor fraction of them has been recycled, other fraction has been burned, but most of it is stored as waste somewhere or has been released to the environment. This is about 1 plastic ton per person inhabiting the Earth. More than one million tonnes of phtalates are produced annualy, mostly as additives for plastics that end stored as waste or in the environment. I don't know of any estimate of the total amount of phtalates in the environment, but given these figures, I assume that the amount could be high (about a few grams per person inhabiting the earth). There are also indications of unexplained endocrine changes in human populations. Since the last two decades, a decline in the fertility and quality of human sperm has been documented. Although the causes of this fertility decline are unknown, the most likely cause is environmental, because a genetical change leading to lower sperm production in only two decades is not possible. Low fertility and low quality of esperm are compatible with a chronic exposure to low phthalate concentrations, given the results of toxicity experiments with various organisms. So, because our dependence on plastics could have an impact on human reproduction and because microplastics are present everywhere, including our food and drinking water, research on microplastic is important or, I think more properly, urgent.
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