Marine species absorb hazardous chemicals
Causes bad effects on ecosystems, human body


According to newspaper reports, Britain’s Brunel University London announced in 2018 that it investigated shells sold at eight supermarkets across the country and detected microplastics from all varieties of sample shells. Specifically, it found that an estimated 70 microplastics were contained in every 100 grams of mussels. In the same year, a survey team led by Prof. Hideshige Takada of Tokyo University of Agriculture and Technology also detected the substance from sardines and blue mussels harvested from Tokyo Bay.

Microplastics are broadly classified into the primary plastics and secondary plastics. The former, generally called microbeads, are manufactured in microscopic size. Those products include abrasives like facial cleanser and toothpaste. They spill out into the natural environment through water drains and other channels. The latter, produced in larger size, are the ones broken down and fragmented in the natural environment.

Japan’s Ministry of the Environment is concerned that chemical substances contained in or attached to microplastics floating in the sea are taken into the food chain and affect the ecological system and human body. In fact, Philip Schwab, a gastroenterologist at the Medical University of Vienna in Austria told a meeting of the European Society of Gastrointestinal Endoscopy on October 23, 2018 that microplastics were found from the feces of eight persons who cooperated in his team’s preliminary study.

Another study has found that microplastics in the sea, which have a characteristic to adsorb hazardous chemical substances quick to dissolve in oil, can concentrate their toxicity 100 times. Especially, they easily absorb polychlorinated biphenyl (PCB) and dioxins (DDT) dissolved in the sea. These are highly toxic and easy to accumulate in adipose tissues and are known to be carcinogenic. They can cause skin disorders, visceral disorders and hormonal abnormalities. Particularly, plastics containing flame retardants (PBDEs) that make them harder to burn can cause thyroid disruptors and neurotoxicity.

Furthermore, phthalate ester in soft polyvinyl chloride used in synthetic leather, toys and swimming rings are known as an endocrine disruptor that affects female hormones and estrogen. This substance can add to the risk of breast cancer.

However, some scientists think that data currently available are not sufficient enough to elucidate the activity and toxicity of microplastics in the human body. For instance, the European Food Safety Authority (EFSA) has made its view public that “it is still too early to refer to whether microplastics are harmful or not”. A further progress on their study is keenly awaited.

(Written by: Meiku Takeda)









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