Background
Consumers are becoming increasingly concerned with the environmental impact of the products and services they use, and so there is great demand for products which purport to minimise harm to, or benefit, the environment. This focus on sustainability has led to the proliferation of products with various green claims, however, many of which may mislead consumers and/or exaggerate any environmental benefits. Biodegradation-promoting additives (also referred to as enzyme-mediated biodegradable additives) are claimed to make conventional (typically derived from fossil fuels and non-biodegradable) polymers (such as nitrile) attractive to microorganisms and therefore biodegradable (in landfill conditions) when incorporated with the polymer, thus proposing an end of life solution for non-recyclable polymers (including nitrile gloves). The exact mechanism by which these additives supposedly function is yet to be explained or proven in any publicly available peer-reviewed scientific study (1). Polyco Healthline has concerns regarding the lack of evidence for the efficacy and utility of these additives, as explained in the remainder of this article.
Laboratory testing
Polyco Healthline has been provided with several test reports which claim to show additive-mediated biodegradation – all of which originate from the same unaccredited and unaffiliated laboratory. In an effort to verify the results in one such test report, samples of a nitrile glove containing a biodegradable additive were sent to an ISO 17025 accredited laboratory for ASTM D5511 biodegradability testing. The testing was stopped after 90 days, as no biodegradation was observed. This contradicted the results in the test report originally provided, which claimed ~15% biodegradation in a similar time period. The graph to the right shows a comparison between the biodegradation observed in the cellulose positive control (which achieved >80% biodegradation) and the test specimen (which achieved 0% biodegradation).
Publicly available evidence
A peer-reviewed study by Michigan State University in 2015 examined the effects of 5 additives from 5 different manufacturers on the biodegradability of polyethylene (PE) and polyethylene terephthalate (PET) polymers in compost, anaerobic digestion, and soil burial environments. The authors’ testing found no significant effect on biodegradation rate in any of the environments for any of the additives in either PE or PET polymers (2).
In 2014, OWS (Organic Waste Systems) reviewed the websites, available technical data, and other publicly available information for 5 biodegradation-promoting additives from 5 different manufacturers and concluded that there was no evidence to support the biodegradability/compostability claims made by the manufacturers of any of the 5 additives (3).
Polyco Healthline were unable to identify any reliable peer-reviewed studies that supported the claim that additives may confer biodegradability on conventional non-biodegradable polymers.
Advertising Standards Authority ruling regarding biodegradability testing
A recent ruling by the ASA (Advertising Standards Authority) found that ASTM D5511 test results were not sufficient to substantiate claims of landfill biodegradability, despite test results showing significant (>85%) biodegradation in the provided test report under standard conditions allowed under the test method (4). The ASA concluded that the claim was misleading and contended the below:
“Furthermore, we also understood that conditions would vary across a UK landfill, and in different landfills, depending on factors including the waste that had been deposited and compacted in a specific area, the moisture level, the temperature and the types of microorganisms that were present. We accepted that the report showed that the wipes fully biodegraded in the test conditions within 15 days. However, the test was carried out under optimal conditions, and it did not replicate the condition of the wipes at the time of disposal or the conditions of a landfill, including when rubbish first arrived there. We therefore considered the test was not appropriate to substantiate a claim that the wipes would completely biodegrade within 15 days of arriving at a landfill.”
Green Claims Code
Due to the increasing prevalence of misleading green claims, the Competition and Markets Authority (CMA) developed the Green Claims Code, which is based on the requirements of consumer protection law. The Code is a set of principles all environmental claims must follow, and it includes stipulations (amongst others) that claims must be truthful, accurate, clear and unambiguous, and substantiated by robust, credible, up to date evidence (5). No marketing materials examined to date by Polyco Healthline for products incorporating biodegradation-promoting additives have adequately explained how laboratory test conditions relate to real-world conditions, and they often include ambiguous ‘biodegradable’ claims with no mention of required conditions or timeframes. Some products feature ‘biodegradable’ claims based on extrapolation of test results which do not show complete biodegradability. Such claims would appear to be in contravention with the Green Claims Code, and should therefore be considered misleading.
Conventional polymers are typically derived from oil
Even if sufficient evidence were available to prove beyond doubt the efficacy of the additives in conferring biodegradability on conventional polymers, and despite misleading claims in product marketing, biodegradability is not automatically beneficial to the environment. Biodegradation involves the conversion of a material into carbon dioxide (and methane in anaerobic conditions), and the polymers targeted by this technology (such as nitrile) are typically derived from non-renewable fossil fuels (6). It is not realistic to assume that all landfills will have the capability of capturing all carbon dioxide and methane released, so some degree of greenhouse gas emission as a result of biodegradation is inevitable. A biodegradable nitrile glove might therefore have a very similar carbon footprint to conventional nitrile gloves which are incinerated, and a potentially larger carbon footprint than landfilled gloves, which may remain inert for hundreds of years.
For biodegradability to represent an environmental benefit, the carbon footprint must be lower than when compared to the non-biodegradable alternative – this may be achieved, for example, by replacing an oil-derived polymer with a bio-based biodegradable polymer derived from renewable plant sources, which may be regrown to recapture carbon emissions produced during the material’s lifecycle. Simply incorporating an additive to confer biodegradability will not decrease the carbon footprint of the product or benefit the environment, as it does not change the fact that the polymer was derived from non-renewable fossil fuels.
Conclusion
Given that substantive evidence for the efficacy and utility of biodegradation-promoting additives could not be found, and evidence that some additives do not work as claimed, Polyco Healthline has taken the decision not to offer products containing such additives. This position will be kept under review and we will continue to examine any new evidence that comes to light.
References
1. https://docs.european-bioplastics.org/publications/bp/EUBP_BP_Additive-mediated_plastics.pdf
2. https://pubs.acs.org/doi/full/10.1021/es504258u
3. https://www.ows.be/wp-content/uploads/2013/10/Final-Report-DSL-1_Rev02.pdf
4. https://www.asa.org.uk/rulings/q-river-ltd-a21-1116986-q-river-ltd.html
5. https://greenclaims.campaign.gov.uk/
6. https://www.biopak.com/au/resources/biodegradable-plastic-problems
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