‘Compostable’, ‘biodegradable’, ‘bio-based’? Standards must ensure green claims are true in single-use plastics
ECOS is advocating for strong standards to set clear definitions and test methods based on real-life conditions for compostable and biodegradable plastics. Without robust methods, consumers may be misled into buying harmful products.
Plastics represent more than 90% of the litter collected on European beaches. More than half are single-use plastic items, such as plastic bottles, cups, lids, straws, stirrers and shopping bags. This waste is a serious threat to marine ecosystems, biodiversity and human health, and to activities such as tourism, fisheries and shipping.
In Europe, the amount of disposable plastic littering is expected to be slashed as of July 2021, when the EU will ban several single-use plastic products, such as plastic cutlery, plates and straws, as well as products made from oxo-degradable plastic (that fragment into smaller pieces, microplastics, but not to the molecular or polymer level like biodegradable or compostable plastics) as part of the Single-Use Plastic (SUP) Directive.
More and more of such products are being replaced with single-use alternatives labelled as ‘compostable’, ‘biodegradable’ or ‘bio-based’. Recent industry-driven attempts to develop international standards for compostable drinking straws and biodegradable plastic shopping bags are confirming these trends.
These plastics do not simply disappear in your compositing bin: they require specific conditions to biodegrade in industrial composting plants (such as specific temperature, duration, microorganisms, nutrients, oxygen and moisture). In natural conditions, the plastics may biodegrade slowly or not at all, or fragment into microplastics. On the other hand, ‘bio-based’ plastics may well be sourced from biomass but are not necessarily meant to biodegrade, whether in the open environment or in industrial composting conditions.
To determine the compostability of plastics, several European and international standards are used to assess their environmental safety (i.e. chemical characteristics and ecotoxicity) and degradation (in industrial composting or home composting conditions). Other standards cover plastic material biodegradability in soil or freshwater. Several test methods are also being developed at international level within ISO to determine plastic biodegradation in seawater.
ECOS has been taking an active role in this process to avoid confusion between ‘home composting’ and ‘industrial composting’ conditions, as well as ensure lab testing is performed under realistic conditions. The standards could be improved, for instance by shortening the composting time, in line with common practice, and running ecotoxicity tests on the entire product (not only on the plastic materials to which more chemicals can be added).
In fact, ECOS has recently argued that the international draft standards on the promotion of compostable plastic shopping bags and straws will hardly help solve the problem of plastic pollution. Instead, reusable long-lasting products should be favoured, rather than lightweight and short-lived plastic products, which inevitably end up polluting the environment. It is a crucial aspect to be considered in the upcoming EU policy framework for bio-based plastics and biodegradable or compostable plastics, announced for 2021.
While we do agree that European harmonised rules for compostable and biodegradable plastics might be useful for niche applications, they should not hamper the introduction of the single-use plastic item ban, or the achievement of European recycling targets. They should be used exclusively in applications where prevention and reusable alternatives are not possible, such as composting bags or fruit labels.
Prevention of plastic production and use, but also reuse, are always the best choices.