Speaking at the PCD Congress in Paris this week, Professor of Bio-polymer Science and Engineering Stéphane Guilbert said use of certain materials can be accompanied by unwelcome ethical consequences.
Potential ethical traps
For example, polylactic acid (PLA) is often derived from genetically modified (GM) corn starch and, as a general rule, green consumers tend not to be fans of GM.
Materials used to make bio-plastics such as PLA are also derived from sugarcane and cornstarch that are important sources of food.
Professor Guilbert said by harvesting these crops to make packaging, environmentally-conscious companies could be inflating food prices in developing countries.
Questionable environmental credentials
The head of the Joint Research Unit: “Agropolymers Engineering and Emerging Technologies” in Montpellier, France, also questioned the environmental credentials of certain green packaging materials.
Some so-called biodegradable or compostable plastics are not actually biodegradable in the soil and require specialist treatment that is not widely available. If these materials are not being treated correctly, it makes little sense to use them in the first place.
Guilbert also said telling consumers that packaging is now biodegradable could have perverse consequences. People may take less care to dispose of used packaging, creating littering problems.
These question marks over the environmental and ethical value of green packaging materials led Guilbert to conclude that they should only be used when there is a functional justification.
Inferiority of bio-plastics
But the professor said that many bio-plastics are inferior to conventional materials on all levels.
Due to high water sensitivity they are generally not suitable for direct contact with cosmetic and personal care products. Their sensitivity to temperature changes also presents problems.
PLA begins to lose its shape at over 60 degrees Celsius so a compact case could easily fall out of shape and therefore out of favour if left in a hot car.