미세플라스틱이란 무엇인가? What Are Microplastics?

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Microplastics are plastic fragments smaller than 5 mm (about 1/16 of an inch) that result from breakdown of plastic litter in the environment.

Plastics are synthetic materials that contain various chemicals. More than 13 000 chemicals are associated with plastics, including about 4200 chemicals of concern and 10 chemical groups identified as highly toxic substances.¹ These chemicals, such as per- and polyfluoroalkyl substances (PFASs) found in nonstick cookware and other products, may be released from plastics into the environment. Plastics production has increased from 234 million tons in 2000 to 435 million tons in 2020.

Microplastics have a unique surface area that allows absorption of contaminants, including microorganisms (bacteria, fungi, and viruses) and heavy metals. After plastic has degraded into smaller fragments, people may inhale or ingest microplastics. Inhaled particles can deposit in the lung, enter the bloodstream, and spread to tissues and organs throughout the body. Microplastics can also enter the body when people drink liquids in plastic containers, including bottled drinking water, soft drinks, cold tea, beer, and energy drinks. In addition, people can be exposed to microplastics through use of cosmetics and other personal-use products such as facial scrubs.

Microplastics have been identified in many human organs and tissues, including the lungs, brain, blood, liver, kidneys, heart, spleen, colon, testes, ovaries, and placenta. Microplastics also have been found in human breast milk and infants’ first stools. Concentrations of microplastics in human tissue have increased over the past several decades, in parallel with the increase in worldwide plastic production.

Experiments performed on human tissues and in animals reveal that microplastics cause inflammation and damage to cells and to DNA. Observational studies have reported that after surgical removal of cholesterol and fatty deposits (plaque) inside arteries carrying blood to the brain (carotid arteries), rates of heart attack, stroke, and death from any cause approximately 3 years later were substantially higher among patients who had plaque containing microplastics compared with those without microplastics. A small autopsy study reported that patients with dementia had higher levels of microplastics in their brains compared with individuals without dementia. However, these findings are associations and do not prove that microplastics caused these adverse health outcomes.

To reduce exposure to microplastics through ingestion, people can avoid food packaged in plastic pouches, avoid microwaving food in plastic, and use reusable stainless steel water bottles. Despite many local and national policies that curb plastic pollution, only a few international agreements exist to reduce plastic pollution. Recent agreements are the 2019 Basel Convention Plastic Waste Amendments, which regulate shipments of plastic scrap and waste to countries with limited means of recycling, and the MARPOL Annex V, an agreement signed by more than 150 countries that prohibits ships from dumping plastic waste into the ocean.