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Bioplastics, a safe alternative or just more plastic waste?

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by / Views 59 / October 28, 2020

Another “natural” substitution goes off the rails.

The concept was creating a non-petrochemical, potentially sustainable approach to manufacturing ecological plastic products. Unfortunately, what happening is just the opposite.

In a recent publication of the journal Environment International, an article questioned the safety of bioplastics. The title “Are bioplastics and plant-based materials safer than conventional plastics? In vitro toxicity and chemical composition” describes how a good idea went off the rails and why consumers need to be on their toes and get the rest of the story to be safe.

The researchers checked commercial products and their starting materials for toxicity.  The bad news, by the time the product was actually made, a ton of toxic chemicals were incorporated into the finished products. They sampled 27 bioplastics with the highest market share, including materials that are bio-based and biodegradable (PLA, PHA), petroleum-based and biodegradable (PBS, PBAT) as well as bio-based and not biodegradable along with 16 plant-based materials made from starch, cellulose, and bamboo.

Definitions:
Let’s explore the issues. First we need to define bioplastics. The problem is there really is no definition because currently the industry can start with many different products from multiple sources and call it a bioplastic. At some point the government will need to address this. Bioplastics can be made from a number of starting elements. They include plants and fungal sources and the list goes on. This study looked at a host of options including renewable feedstocks (bio-based, e.g. Bio-polyethylene, Bio-PE), materials supposed to degrade naturally (biodegradable, e.g. polybutylene succinate, PBS), or both (e.g. polylactic acid, PLA and starch blends).

Types of bioplastics:
For those of you looking at labels, think in terms of polyethylene (Bio-PE), polyethylene terephthalate (Bio-PET), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polylactic acid (PLA), polyhydroxyalkanoates (PHA) and bamboo-based materials.

The problem creation:
The concept is sound, so where is the real problem? Why not use materials other than petroleum for plastic production?

The problem is in the additives and necessary chemistry to make the products viable in terms of their shape, ability to handle heat, and other characteristics. The original materials are mixed with plasticizers, antioxidants, stabilizers, solvents and catalysts, to name a few. The bottom line, these chemicals can migrate to our food when used. So next time you pick up a tray, spoon, cup, bag or even some wine closures that allude to being bio friendly, you may be going the wrong direction.

Findings:
The findings were that two-third (67%) of the samples induced baseline toxicity, 42% oxidative stress, 23% antiandrogenicity and one sample estrogenicity. In English, they were toxic and not a solution to the plastic problem.

One of the most disturbing findings is the inconsistency of the toxicity regardless of the source, including when made from the same starting product. Why is this important? It means you can’t know if one product from say bamboo is any less toxic than another, so even if a “good solution” exists, it is impossible to know what to choose.

So, should you purchase a plastic bio or recyclable product? Probably not.

A great resource is the Plastic Pollution Coalition.

Take home:
Ditch the plastics, including toys
Substitute with glass, stainless, or silicon products
Know your plastic numbers to make a better choice
Avoid any plastics that will come in contact with your food, period!
Ask your grocer and others to minimize their use

Are bioplastics and plant-based materials safer than conventional plastics? In vitro toxicity and chemical composition

Authors: Lisa Zimmermann, Andrea Dombrowski, Carolin Völker, Martin Wagner

Highlights:
Most bioplastics and plant-based materials contain toxic chemicals.
Cellulose and starch-based products induce the strongest in vitro toxicity.
Most samples contain >1000 chemical features; the maximum is 20,000 features.
The material type does not predict toxicity or chemical composition.
Bio-based/biodegradable materials and conventional plastics are similarly toxic.

Abstract:
Plastics contain a complex mixture of known and unknown chemicals; some of which can be toxic. Bioplastics and plant-based materials are marketed as sustainable alternative to conventional plastics. However, little is known with regard to the chemicals they contain and the safety of these compounds. Thus, we extracted 43 everyday bio-based and/or biodegradable products as well as their precursors, covering mostly food contact materials made of nine material types, and characterized these extracts using in vitro bioassays and non-target high-resolution mass spectrometry. Two-third (67%) of the samples induced baseline toxicity, 42% oxidative stress, 23% antiandrogenicity and one sample estrogenicity. In total, we detected 41,395 chemical features with 186–20,965 features present in the individual samples. 80% of the extracts contained >1000 features, most of them unique to one sample. We tentatively identified 343 priority compounds including monomers, oligomers, plastic additives, lubricants and non-intentionally added substances. Extracts from cellulose- and starch-based materials generally triggered a strong in vitro toxicity and contained most chemical features. The toxicological and chemical signatures of polyethylene (Bio-PE), polyethylene terephthalate (Bio-PET), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polylactic acid (PLA), polyhydroxyalkanoates (PHA) and bamboo-based materials varied with the respective product rather than the material. Toxicity was less prevalent and potent in raw materials than in final products. A comparison with conventional plastics indicates that bioplastics and plant-based materials are similarly toxic. This highlights the need to focus more on aspects of chemical safety when designing truly “better” plastic alternatives.

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