From sink to Sea: Microplastic release from kitchen sponges and potential environmental effects

• Kitchen sponges lose material during use due to abrasion. If the sponges contain plastics, it is released into the wastewater as microplastics (MP). • Based on citizen science experiments performed in Germany and North America, the total MP release from different sponges ranges between 0.682 ± 0.566 and 4.212 ± 3.039 g of MP per year and person. • A life cycle assessment showed that the damage to ecosystem quality per 100 hours of dishwashing ranges between 6.26 PDF*m2*yr and 9.73 PDF*m2*yr. Most of the damage is caused by the water usage during manual dishwashing rather than by material production or abrasion. • A sponge declared as organic contained the least amount of plastic (15.9 w%), which led to the lowest MP release and lowest damage to the ecosystem compared to a sponge with a higher plastic share (59.3 w%). Therefore, a lower plastic share in kitchen sponges can significantly reduce MP release and related negative effects in the environment. Microplastics (MPs) are released during the extraction, production, usage, or end-of-life stage of plastic products and cause negative effects for organisms and humans. Kitchens have recently been identified as hot spots for MP release, however, only few household items have been analyzed for their MP release quantities and related environmental effects. Here, we determined the MP release of kitchen sponges based on a combination of citizen science and laboratory experiments and performed life cycle assessment (LCA) to evaluate the resulting ecosystem damage. The results show the plastics in the sponges are released into the wastewater as MPs due to abrasion. The total MP release from different sponges into the wastewater stream ranges between 0.682 ± 0.566 and 4.212 ± 3.039 g of MP per year and person. The damage to ecosystem quality per 100 hours of dishwashing ranges between 6.26 PDF*m2*yr and 9.73 PDF*m2*yr. Most of the damage is caused by the water usage during manual dishwashing rather than material production or abrasion. A sponge declared as organic contained the least amount of plastic (15.9 w%), which led to the lowest MP release and lowest damage to the ecosystem compared to a sponge with a higher plastic share (59.3 w%). Therefore, a lower plastic share in kitchen sponges can significantly reduce MP release and related negative effects in the environment.