Polyvinyl Alcohol: 75% of This ‘Liquid Plastic’ Ends Up in the Environment and Some in Us: Its Toxicity, However, is Considered to Be Low

     Polyvinyl alcohol (PVA or PVOH) is used in lots of products. (I will use PVOH since PVA also refers to polyvinyl acetate). Its uses include the paper, adhesive, textile, and construction industries, as well as in ceramics, packaging, and electronics. Its physical and chemical properties make it versatile. These include “water-solubility, excellent film forming characteristics, high tensile strength, and elasticity, as well as resistance against organic solvents and dispersing power.” It is used for cross-linking and bonding. It is used in cosmetics, for coatings, and for PVC. Its idealized formula is [CH2CH(OH)]n.

     Most synthetic polymers are not water soluble like PVOH. It comes as beads or in solution and can be made into hydrogels. According to Wikipedia:

“It is commonly supplied as beads or as solutions in water. Without an externally added crosslinking agent, PVA solution can be gelled through repeated freezing-thawing, yielding highly strong, ultrapure, biocompatible hydrogels which have been used for a variety of applications such as vascular stents, cartilages, contact lenses, etc.”

It has many uses, including many medical uses. PVOH is commonly used in household sponges that absorb more water than polyurethane sponges. Its extensive use in laundry and dishwasher pods has led to its proliferation in the environment. According to Wikipedia:

“Preparation of polyvinyl butyral is the largest use for polyvinyl alcohol in the US and Western Europe.”

“Worldwide consumption of polyvinyl alcohol was over one million metric tons in 2006.”

     China has about 45% of the world’s PVOH production capacity.

“Polyvinyl alcohol has excellent film-forming, emulsifying and adhesive properties. It is also resistant to oil, grease and solvents. It has high tensile strength and flexibility, as well as high oxygen and aroma barrier properties. However, these properties are dependent on humidity: water absorbed at higher humidity levels acts as a plasticiser, which reduces the polymer's tensile strength, but increases its elongation and tear strength.”

 

Toxicity and Environmental Issues

PVOH comes in different grades depending on the degree of polymerization and hydrolysis, and some are more soluble and biodegradable than others. PVOH used in detergents is considered to be highly biodegradable. According to Wikipedia:

“Orally administered PVA is relatively harmless. The safety of polyvinyl alcohol is based on some of the following observations:

“The acute oral toxicity of polyvinyl alcohol is very low, with LD(50)s in the range of 15-20 g/kg; Orally administered PVA is very poorly absorbed from the gastrointestinal tract; PVA does not accumulate in the body when administered orally; Polyvinyl alcohol is not mutagenic or clastogenic.”

     According to Karuna Eberl in an article for Family Handyman:

“In this country, we use an estimated 20 billion dishwasher and laundry pods and sheets each year. Each one is made with or wrapped in polyvinyl alcohol, or PVA. Although that wrapping seems to magically disappear, a recent study showed 75% of it actually ends up in our waterways.”

The study came from researchers at Arizona State University and was published in the International Journal of Environmental Research and Public Health in 2021.

     At issue is the biodegradability of PVOH, which is affected by different factors including solubility. The researchers first determined how much PVA is breaking down, and in what section of the wastewater treatment plant. Then they compared that to the total use of laundry and dishwasher pods. The issue is that biodegradability differs considerably according to the environment in which PVOH degrades. The study found that 75% of the PVOH was not biodegrading as it went through the typical processes of wastewater treatment plants. This results in about 8000 tons of PVOH being released into waterways and soils (often via land-applied biosolids) each year in the U.S. One of the paper’s authors Varun Kelkar noted:

“…many companies hire outside firms to create specific biological environments suitable for PVA to degrade. By doing so, the company using PVA in its products can claim it’s biodegradable. But, he said, wastewater treatment plants in the U.S. are generally not built to create optimal conditions for this specific polymer. Instead, they are built to treat human waste and other biological matter.”

The figures below are from the paper in the International Journal of Environmental Research and Public Health.

It does biodegrade in warmer environments, but the study shows that companies’ claims of biodegradability are wrong. Distorted is perhaps a better word. However, since its toxicity is relatively low, it will probably not become a public health concern, but rather just something to watch.

     Since PVOH is considered a “liquid plastic” its presence in the environment is not considered to be a microplastic. Also, as mentioned, since its toxicity is not high, it has not received much attention from the EPA and regulators. More research, however, is needed on its potential effects on aquatic organisms, especially as its concentration rises in the environment. The researchers noted one important consideration:

“PVA {PVOH} presence in the environment, regardless of its matrix, is a threat to the ecosystem due to the potential mobilization of heavy metals and other hydrophilic contaminants.”

Perhaps that should be an area of research.

     A 2022 study by Italian researchers in the journal Polymers found that PVOH was present in human breast milk, making up 2% of the plastic content. The abstract explains:

“MP {microplastic} contamination was found in 26 out of 34 samples. The detected microparticles were classified according to their shape, colour, dimensions, and chemical composition. The most abundant MPs were composed of polyethylene, polyvinyl chloride, and polypropylene, with sizes ranging from 2 to 12 µm. MP data were statistically analysed in relation to specific patients’ data (age, use of personal care products containing plastic compounds, and consumption of fish/shellfish, beverages, and food in plastic packaging), but no significant relationship was found, suggesting that the ubiquitous MP presence makes human exposure inevitable.”

The figure below is from the paper:

Thus, it appears PVOH’s share was small compared to other microplastics and added to its low toxicity, I would say that it does not appear to have much potential of becoming a public health threat, although its presence and concentrations should be considered and monitored.

 

 

References:

 

What Is Polyvinyl Alcohol and How Does It Impact the Environment? Karuna Eberl. The Family Handyman. October 16, 2024. What Is Polyvinyl Alcohol and How Does It Impact the Environment?

Raman Microspectroscopy Detection and Characterisation of Microplastics in Human Breastmilk. Antonio Ragusa, Valentina Notarstefano,Alessandro Svelato, Alessia Belloni, Giorgia Gioacchini, Christine Blondeel, Emma Zucchelli, Caterina De Lu, Sara D’Avino, Alessandra Gulotta, Oliana Carnevali, and Elisabetta Giorgini. Polymers 2022, 14(13), 2700; https://doi.org/10.3390/polym14132700.

Kuraray Poval. Products. Polyvinyl Alcohol. Kuraray Poval™ | Kuraray Polyvinyl alcohol (PVOH)

Polyvinyl alcohol. Wikipedia. Polyvinyl alcohol - Wikipedia

Are laundry and dish pods biodegradable? Not exactly, ASU study shows. Arizona State University. Eureka Alert. AAAS. July 27, 2021. Are laundry and dish pods biodegradable? Not | EurekAlert!

Degradation of Polyvinyl Alcohol in US Wastewater Treatment Plants and Subsequent Nationwide Emission Estimate. Charles Rolsky and Varun Kelkar. Int. J. Environ. Res. Public Health 2021, 18(11), 6027; https://doi.org/10.3390/ijerph18116027.