The daily routine of washing your clothes could be polluting the ocean at the same time. A new study finds household washing machines are a major source of plastic pollution in the water and on the shoreline. Scientists have found that miniscule threads of plastic from clothing like fleece jackets can seep through filters and enter the environment. The microplastics are able to penetrate the cells of organisms, affecting the health of sea creatures and the people who eat them.

A team of researchers at the University of Dublin tested 18 beaches across six continents and found evidence of lint fibers at every one. Scientists say the highest concentrations are found on shores in densely populated areas and identified wastewater from household washing machines as a major source. The study also quantified the number of fibers lost in the laundry. Just one polyester blanket or fleece sweater can lose hundreds to thousands of fibers per wash. Fibers lost in washing machines and dryers can travel through the sewer systems and end up in the oceans.

Lead author and ecologist Mark Browne says work is now urgently needed to determine if microplastic can transfer from the environment and accumulate in food webs through ingestion which could cause lung and skin problems. He says as the human population grows and people use more synthetic textiles, the contamination of habitats and animals is likely to increase.