Plastics and Water Don’t Mix

No matter how hard we try, it’s not easy to avoid using plastic. Think of the number of times you may have used and reused a plastic water bottle. I almost always accept a bottle of water if offered, and don’t think twice about it.

Plastic pollution is a growing problem. Plastics break down over time and can create smaller particles called microplastics. These are 5 mm or less long, which is tinier than a sesame seed. Microplastics can further degrade into smaller pieces called nanoplastics which are under 1 um in size. The tiny plastics are small enough to be absorbed into the body’s cells and tissues.

Research from the past has found proof of plastic particles in human blood, lungs, gut, feces, and reproductive tissues including the placenta and testes. The possible health impacts of these small plastics are yet proven and unknown. The tiny size of nanoparticles makes them difficult to find and study.

To understand the role of nanoplastics, a research team led by Drs. Wei Min and Beizhan Yan of Columbia University altered an imagining technique that Min co-designed 15 years prior with NIH support. This technique, known as stimulated Raman scattering (SRS) microscopy, is currently widely used to identify small particles in living cells. This technique works by focusing two laser beams on samples to encourage certain molecules to release unique detectable signals of light. SRS microscopy doesn’t depend on labeling specific molecules to locate them as other methods do.

In the new study, which the NIH funded, the researchers designed a novel SRS method to find micro- and nanoplastics at the single particle level. Once they confirmed that the method could quickly find plastic particles smaller than 1 um, they created a machine learning-based algorithm to identify seven common plastic types.

The team evaluated the micro- and nanoplastics in three popular bottled water brands to test their new high-throughput imaging platform. Results were published in the Proceedings of the National Academy of Science in January 2024.

The researchers discovered that a liter of bottled water, on average, had roughly 240,000 tiny pieces of plastic. Nearly 90% of these plastic fragments were nanoplastics. The amount was 10 to 100 times more plastic particles than noted in previous studies, which primarily focused on bigger microplastics.

Particles of all seven types of plastic were identified in the water. Polyamide, a type of nylon frequently used to help filter and purify water was the most commonly seen. A high level of polyethylene terephthalate (PET) was also found. This is not surprising, as PET is utilized to make bottles for water, soda, and several other drinks and foods.

Other plastics found included polyvinyl chloride, polymethyl methacrylate, and polystyrene, which is commonly used in water purification. The technique discovered millions of additional particles that didn’t match the seven plastic categories. It’s unclear if these small particles are nanoplastics or something else.

The researchers note that this new method will help to improve their understanding of human exposure to nanoplastics. Yan notes, “This opens a window where we can look into a plastic world that was not exposed to us before”.

Future research will use this approach to evaluate other environmental samples including tap water, indoor and outdoor air samples, and biological tissues. They also designed filters to reduce plastic pollution from laundry wastewater, as several fabrics include nylon, PET, and other plastic types.

Below are tips to reduce your plastic exposure:

·        Don’t buy bottled water or other drinks in plastic bottles.

·        Use a reusable, stainless steel bottle or mug for hot or cold drinks.

·        Don’t reheat food in plastic containers.

·        Store only cold food (such as salad or prepped vegetables) in plastic containers.

·        Allow hot food to cool before storing and use glass containers for storage.

·        Do not freeze food in plastic containers or bags.

·        Recycle plastic bottles and containers when possible.

·        Limit the use of plastic storage bags.

·        Bring recyclable bags to the grocery store.

·        Lather, rinse, repeat! Teach your children the same.

Lisa Andrews, MEd, RD, LD

Reference: Rapid single-particle chemical imaging of nanoplastics by SRS microscopy. Qian N, Gao X, Lang X, Deng H, Bratu TM, Chen Q, Stapleton P, Yan B, Min W. Proc Natl Acad Sci U S A. 2024 Jan 16;121(3):e2300582121. doi: 10.1073/pnas.2300582121. Epub 2024 Jan 8. PMID: 38190543.