The Big Compost Experiment – Fact check

Frontiers recently published the results of a UCL study of home composting among a panel of volunteers in the UK. This article was picked up by the press, turning the findings into catchy headlines, which in turn led to doubts about the ability of certified compostable products to actually compost.

While a punchy headline can capture attention, only by examining the content of the study can relevant conclusions be drawn.

The laudable and interesting aim of the UCL study is to check whether home compostable products are actually compostable. And if we analyse the study in detail, we conclude that it is not a scientific study on the compostability of man-made products, certified compostable at home or not, but a social study on the behaviour of composters.

Home composting is an art
Testing is a profession

In 2019, ADEME, the French national government agency for the environment, conducted a large scientific test on different home composting configurations and demonstrated that certified home compostable plastics disappear entirely in a properly maintained compost.

This study highlights the importance of regular stirring to aerate the compost and confirms the good correlation between the lab tests leading to certification and the real conditions.

The major difference between the ADEME study, a quantitative professional science research, and the UCL one, a qualitative citizen science study, is that accurate conclusions can be drawn from the former and very little from the latter because of the imprecision of the instructions and the poor consistency check of the data submitted (only 50 images checked out of the 1307 results submitted). Some examples next page, taken from the study’s photo gallery, illustrate the poor quality/reliability of the information collected.     
In any case, the results of these tests should normally have been excluded from the analysis when reviewing the data which is not the case and we regret it.