Free compost full of microplastics

Amsterdam, 14 December 2019 – There are 4000 microplastics in one kilo of compost. Wageningen University has been commissioned by the Plastic Soup Foundation and NH Nieuws to research compost that is provided free of charge by municipalities in Noord-Holland. Members of Parliament were shocked by the results and demanded clarity.

Members of parliament from PvdA, GroenLinks, and D66 are wondering whether compost can still be used safely and have announced parliamentary questions, according to NH Nieuws. Gijs van Dijk (PvdA) wants the Minister to take measures quickly: ‘The compost will again be provided by municipalities in the spring. The Minister must clarify before then whether or not municipalities should do so. Environment minister Veldhoven wants to wait for research from the RIVM. However, it is not clear whether RIVM is already investigating the effects of microplastics in compost.

Alarming research results

In Wageningen, a bin containing four kilos of compost from the Purmerend waste processor HVC was examined for the presence of microplastics by Violette Geissen, Professor Soil Degradation & Land Management. First, the sample was sieved to two millimeters, giving it the quality of certified compost A. After that, some 4000 microplastics per kilo were counted. Some of these turned out to be bioplastics, which were not broken down during the industrial composting process.

Existing standards insufficient

You can buy compost with a quality mark (Compost with quality labels A, B or C). That compost may contain a maximum of 2 grams of plastic per kilo. That is the weight of five sandwich bags. The legal norm is a maximum of 5 grams of plastic per kilo (10 sandwich bags). Moreover, this standard does not take into account pieces of plastic of fewer than 2 millimeters. In terms of weight, they do not even count. These are the smallest pieces that are invisible to the consumer and most harmful to the environment. So you get compost for free or you buy it, but you can never see for yourself to what extent it is contaminated with microplastics.

Soil alien material

Plastic penetrates more and more into all types of soil. It is an alien material. A year ago, the standards of the Soil Quality Regulation were tightened up. Since then, only ‘sporadically’ alien to the soil other than stone and wood may occur in dredging spoil. Plastic and polystyrene foam must be removed from the soil and dredged material before they can be used. However, existing microplastics cannot be removed.

Harmen Spek, manager of Innovations & Solutions at the Plastic Soup Foundation: “There is no standard for microplastics in compost, even though those small pieces are the most problematic. We need a stricter standard as soon as possible.”

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