Performance of home compostables misrepresented

A new paper from Francesco Degli-Innocenti, Senior Advisor at Novamont, developer and producer of bioplastics and biochemicals, highlights how citizen science results presented in University College London’s (UCL) recent study ‘The Big Compost Experiment’ have been misinterpreted.

home compostable bagUCL’s report used citizen science to assess the impact and effectiveness of biodegradable and compostable plastics in UK home composting. In his paper, Degli-Innocenti notes the ‘growing practice’ that citizen science has become – its application in both environmental and ecolgoical sciences can span from biodiversity research to marine pollution.

UCL found that its volunteers were ‘confused about the meaning of the labels of compostable and biodegradable plastics’, resulting in plastic waste being disposed of incorrectly. This provides insight into the behaviour of people when it comes to home composting.

Many publications concluded that the problems encountered by the volunteers in disposing of the items through composting were due to the compostability of the products themselves – some of which apparently claimed formal compostable certification. The certification of the products was, however, not checked, resulting in the key conclusion being around participant confusion.

Francesco Degli-Innocenti’s paper (‘The difficult relationship between science, citizen science, and mass communication. A negative example’), explains that UCL’s study has been passed from a field of experts “who can well understand the difference between a qualitative trial based on citizen science and research carried out using a quantitative scientific methodology” to mass media.

In mass media, statements and ‘throw away quotes’ present in the study have been misread as scientifically proven ‘truth’. This, suggests Degli-Innocenti, may be the result of ignorance, or misunderstanding, of citizen science and the study, its data and applied methodology.

UCL’s study, which reports the results of citizen science, is ‘not a scientific study that deals with the interaction between materials and a biological process, but rather it is a scientific study on the attitude and behaviour of a group of volunteers regarding home composting and compostable items’, Degli-Innocenti clarifies.

In support of Francesco Degli-Innocenti’s criticism, David Newman, Managing Director of The Bio-based and Biodegradable Industries Association (BBIA), said: “This is a comprehensive demolition job on the media interpretation of UCL’s study, and of the methodology behind it. 

“A key finding here is that those testing ‘home compostable’ products were not even provided with the same or similar materials. Each citizen participant was left to find their own ‘compostable’ products, without any checks on whether the items tested had even been certified to industry standards. Further research on home composting is underway and will be published in the coming weeks.”

Citizen science

The difference between 'citizen science' and a formal scientific experiment

Using the Oxford English Dictionary definition of citizen science – “scientific work undertaken by members of the general public often in collaboration with or under the direction of professional scientists and scientific institutions" – Degli-Innocenti’s paper highlights that the experiment enters ‘the branch of social science even when applied to waste management’.

Issues of misrepresentation stemmed from journalist misunderstanding of citizen science, as opposed to formal science experiments. “It is not a scientific study that deals with the interaction between materials and a biological process”, Francesco Degli-Innocenti writes, rather “it is a scientific study on the attitude and behavior of a group of volunteers regarding home composting and compostable items.”

No ‘control items’

Compostable items involved in the experiment were not provided to the volunteers – each ‘furnished themselves independently’. As a result, there was no control item in the experiment and the nature of each tested material – whether it was home compostable, industrial compostable, or non-compostable – was indefinite.

Volunteers were not “calibrated”

Within the experiment, there was no 'training course' (“the volunteers were not calibrated”) to educate volunteers on compostable items, to ensure homogenous responses. The volunteer’s results were considered  a "scientific tool", to probe reality and provide data.

Volunteers were not a representative sample

The participants were volunteers rather than a carefully-selected, statistically representative sample. The experiment was a “phenomenological research project focused on the meaning of an experience for a number of individuals”. There was also no respondent validation, a step that occurs during data collection – “when feedback is obtained from the participants about the accuracy of the data they have given.”

What did the UCL report find?

UCL’s study shows that the volunteers ability “to distinguish between compostable and non-compostable products is not very accurate”.

Francesco Degli-Innocenti notes that the results are important as it highlights “a potential generalized problem regarding the ability of citizens to recognize different products”. Simultaneously, it indicates the accuracy of the experiment.

Yet, “nothing can be said about the performance of the certified home compostable products, because the experimental scheme of this test does not allow it.”

It was incorrect to focus on the ‘failure’ of home compostable materials to effectively compost in home composting units.

Degli-Innocenti explores “the passage from scientific journals for experts to mass publication”, during which scientific content loses “all the reservations, the premises, the limits, the weaknesses of the original study to suddenly become apodictic truths.

“Indeed, within many modern articles, the concept of admitting and discussing weaknesses with the science itself has all but been eliminated.”

A 'flawed report'

David Newman explained to Resource that "the failure of UCL to understand the time needed for home composting is at the basis of their flawed report."

Drawing on the fact that "citizens science implies a scientific approach", Newman adds to criticism of the "perverse way" in which UCL undertook research and how it was then then communicated. He highlights, as Degli-Innocenti touched on, that citizens were not monitored, not coached, were told to count anything they put into their compost heaps, had no help on improving their composting performance.

"Citizens were not told to only put in materials certified 'home compostable' and to discard all the rest. They were told to use plastic meshes to view the samples although these naturally slow down any biodegradation process; they were not instructed on retention times but allowed to extract compostable residues after as little as a few months", Newman comments.

However, this contradicts the Royal Horticultural Society (RHS) statement that “garden compost can take between six months and two years to reach maturity". Citizens, and the UCL report, were able to claim that home compostable materials failed after a few months. This, Newman concludes, "falsifies any result".