Public discussions around plastics and human health have intensified in recent years. Headlines frequently warn of toxic household plastics, microplastic ingestion, or chemical risks in food packaging. While many of these claims stem from misinterpreted or incomplete scientific data, they continue to shape consumer perceptions. A recent U.S.-Canada study found that up to 40% of shoppers avoid plastic products due to concerns about toxicity and sustainability.
For companies advancing sustainable materials, such as Plastrans Technologies, this raises an important question: how accurate are these claims, particularly when they involve bioplastics?
A widely cited source of recent debate is the Nature Review “Mapping the chemical complexity of plastics”, which summarizes over 16,000 chemicals associated with plastics, from monomers and additives to non-intentionally added substances (NIAS). A supporting PlastChem report categorized a subset of these chemicals by hazards such as persistence, bioaccumulation, mobility, and toxicity. Based on this, the authors suggested that bioplastics and plant-based materials can exhibit toxicity comparable to conventional plastics. While attention-grabbing, this conclusion requires careful contextualization.
One major test method used in the study, the Microtox assay, measures the impact of chemical extracts on the bioluminescence of bacteria. Packaging materials were rinsed, cut, soaked in solvents, and tested on the bacteria. Any decrease in luminescence was labelled “toxic.” This approach has two key limitations:
First, naturally occurring, safe substances were flagged as hazardous. Lactic acid, found in yogurt, baked goods, and human muscles, was identified as a chemical of concern, despite being widely recognized as safe and even beneficial. Lauric acid, a main component of coconut oil and commonly used in food-grade applications, was similarly labelled toxic. In polylactic acid (PLA), 22 of 35 detected molecules were flagged, not because PLA contains hazardous chemicals, but because the toxicity criteria were overly broad and lacked context.
Second, contaminants were often misattributed to bioplastics. Like other polymers, bioplastics can absorb molecules from the products they contain. Ingredients from cosmetics, detergents, beverages, or food, such as UV stabilizers, preservatives, surfactants, or polyphenols, can migrate into packaging. Even after washing, residues may remain and be incorrectly identified as additives from the polymer itself. The Nature Review data did not sufficiently account for this distinction.
Additional uncertainty arose from polymer identification. Many samples were classified as bioplastics based on the generic recycling code “7,” which includes a wide mix of plastics. FTIR analysis, intended to confirm polymer type, sometimes failed to reliably detect PLA, meaning some samples labelled as PLA may not have been PLA at all.
Before attributing toxicity to bioplastics, it is crucial to differentiate between polymer-based additives, environmental contaminants, and ingredients from packaged goods. While the studies provide valuable data, interpretation must consider the origin of detected substances, the limitations of extractive toxicity tests, and the real-world behavior of natural molecules in biobased polymers.
For Plastrans Technologies, this reinforces the importance of evidence-based communication, scientific transparency, and responsible material sourcing. Properly assessed, bioplastics remain a safe, rigorously regulated, and promising class of materials. A more accurate evaluation requires improved testing methods and a clear distinction between polymer chemistry and external contamination. Without this careful approach, conclusions risk overstating potential hazards and could undermine the role of sustainable polymer solutions in the transition to a circular, low-carbon economy.
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