Sarah Sajedi was visiting Phi Phi Island, Thailand, when she was dazzled by the beautiful scenery of the Andaman Sea. However, when she looked down at her feet, she saw that the white sandy beach was covered with plastic debris, most of which was from plastic bottles.

After many years in the business world as the cofounder of an environmental software company, the experience inspired Sajedi to become a researcher. She had always had a passion for waste reduction, but she realized that the problem was consumption itself.

Thus, as a doctoral student at Concordia University in Canada, Sajedi reviewed over 140 scientific papers to determine the effects of plastic bottles on the human body. She found that people ingest an average of 39,000 to 52,000 microplastic particles per year from food and drinking water, and those who use bottled water on a daily basis ingest nearly 90,000 more microplastic particles into their bodies.

“Drinking water from plastic bottles is fine in an emergency, but it is not something that should be used in daily life,” Sajedi explains. “Even if there are no immediate effects on the human body, we need to understand the potential for chronic harm.”

Long-Term Effects Remain a Mystery

Microplastics are plastic particles ranging in size from 1 micrometer (1/1,000 of a millimeter) to 5 mm. Nanoplastics are even smaller, less than one micrometer. These particles are invisible to the naked eye, but are constantly being generated during the manufacturing, storage, transportation, and decomposition of bottles.

Low-quality plastics, in particular, are prone to release microscopic debris due to sunlight, temperature changes, and physical manipulation. Unlike other plastic particles that enter the body through the food chain, those derived from plastic bottles are of concern because they are ingested directly with drinking water.

Once in the body, microscopic plastics can enter the bloodstream and reach vital organs. This triggers a chronic inflammatory response and exposes cells to oxidative stress, which can lead to hormone system disturbances, impaired reproductive function, and damage to the nervous system. It has also been linked to various types of cancer. On the other hand, the long-term effects on health remain unclear, due to the lack of extensive testing and standardized measurement methods.

Several analytical methods exist for detecting micro- and nanoplastics, but each has its own advantages and weaknesses. Some methods can detect extremely small particles but cannot determine their chemical composition, while others can analyze composition but miss the smallest particles.