Researchers are raising an alarm over recent studies showing that plastic pollution is continuing to spread across the land and into the seas worldwide, threatening the health of humans and other living creatures. 

The studies show that miniscule plastic specks, including microplastics and nanoplastics, are finding their way inside the human body and into the heart, brain, lungs and many other organs via various routes.

Plastics decompose slowly and persist as microplastics and nanoplastics in ecosystems, polluting food and water sources.

Drinking bottled water can also result in the consumption of tiny plastic particles.

STUDIES REVEAL CONTAMINATION

In a U.S. study conducted by Columbia and Rutgers universities, a research team detected 240,000 microscopic plastic particles in an average liter of bottle water it examined.

Of these, 90 percent were nanoplastics, which are pieces of plastic that are usually between 1 and 1,000 nanometers in size. One nanometer is 0.000001 millimeter.

The rest were microplastics, which usually range from 5 millimeters to 1 micrometer, according to the study, published last year in the Proceedings of the National Academy of Sciences. One micrometer is 0.001 mm.

Other ways of ingesting fine plastic particles include the consumption of fishes that have swallowed microplastics and nanoplastics that were released into the sea.

Recent studies also suggest that plastic particles become embedded in the human body as air is inhaled that contains floating microscopic plastic fragments.

The result is that plastics have been found in the heart, brain, lungs, blood, breast milk, semen and feces in humans, among other areas. 

A study by Japanese scientists published last year discovered fine plastic pieces in the blood of four of 11 subjects.

Hideshige Takada, a visiting professor of environmental effects of chemicals at the Tokyo University of Agriculture and Technology who was involved in the study, said an intake of tiny plastic specks will trigger inflammation in one form or another as they are foreign substances to human tissues.

Various chemical additives incorporated into plastics are thought to be the main culprit behind the inflammation.

Additives are used to maintain and enhance plastics’ properties during the production of plastics, which are made from fossil fuels such as oil and natural gas.

Plastics consists of a specific type of polymer, chemical compounds in which molecules are bonded together in long, repeating chains.

Since plastic additives are not covalently bound to a polymer matrix, they can leach out of the polymer over time when they are broken down to microplastics and nanoplastics.

The United Nations Environment Program pointed out in a 2023 report that at least 13,000 chemicals are associated with plastics and plastic production.

Of these, the report continued, more than 3,200 are “of potential concern since they are associated with carcinogenicity, mutagenicity, reproductive toxicity, endocrine disruption, and/or ecotoxicity to aquatic organisms.”

But only 7,000 of the 13,000 plastic-associated chemicals have been screened for hazardous properties, the U.N. report said, adding that not enough is known about the remaining chemicals to assess the threat.

Experiments with animals showed that the release of plastic chemicals can affect their reproductive ability, slow the development of fetuses and disrupt hormone production.

But researchers agree that it is premature to predict that humans would experience similar disruptions from the intake because animals were exposed to high concentrations of plastic chemicals over a short period of time for the experiment. 

Epidemiological surveys show that patients with dementia had higher microplastic levels in their brains than those without the disease.

They also report that people with plastic particles in the plaque of their neck arteries are at an elevated risk of a heart attack, stroke or death.

It is unclear how plastic chemicals contribute to the risk of disease and death.

But Takada said it cannot be ruled out that these chemicals are behind such events, citing other studies reporting similar findings.

ENSURING A SAFER FUTURE

In regulating potentially hazardous chemicals, the central question will be how to secure the usability and safety of plastic products, or how to strike a balance between them.

Shigeharu Nakachi, professor of environmental chemistry with Kumamoto Gakuen University, noted that it will be an enormous technical challenge to come up with non-hazardous additives.

“Additives have been used to bolster the strength, flexibility and durability of plastics so products made from that material will be easier to use,” he said. “It will be preferable to replace the present additives with those made of harmless components, but that will not be easy technologically.”

Regulations concerning chemicals vary from one country to the next.

In Japan, the use of chemicals is regulated under the chemical substances control law and the Food Sanitation Law.

But there are chemicals that are not regulated in Japan due to a lack of scientific evidence definitively pinpointing their negative impact on the environment and humans.

In contrast, EU nations rigorously regulate potentially hazardous chemicals under the principle of taking a precautionary approach even if their harmful effect has yet to be fully understood.

So what can people do to avoid unnecessary risks posed by plastic products?

Some researchers suggest that heating food in a plastic container in a microwave should be avoided due to the potential danger that additives might leach out because plastics degrade under high temperatures.

Takada recommended using a microwave after placing food in heat-resistant glass or ceramic tableware, rather than in a plastic container.

“You do not have to be too concerned with the safety of plastics as long as you live a normal life,” he said. “But you will be better off taking extra precautions whenever you can.”