Fibers Shed by Your Clothes Could Cause Trouble for Plants

Those fleece sweaters in your washing machine may be doing more than clogging the lint trap—they could be slowing down your tomatoes. A new study from Cornell University and the University of Toronto finds that polyester microfibers in soil can hinder the growth of cherry tomato plants, raising questions about how laundry-linked microplastic pollution might affect crops in general. Researchers say household washing machines release millions of microscopic fibers each load, many of which survive sewage treatment and end up in farmland via treated sludge used as fertilizer, per the Washington Post. In some countries, 75% of cropland is treated this way, according to the study published in PLOS One.

In greenhouse experiments, cherry tomato plants grown in microfiber-contaminated soil were 11% less likely to sprout, grew smaller, and took several extra days to flower and ripen compared with plants in clean soil. The polluted soil also held less water, which may have contributed to weaker growth. Lead author Natasha Djuric says tomatoes were chosen because they grow quickly and matter for food production, but she cautions that the findings don't yet translate directly to real-world agriculture.

Some scientists are wary of how far to take the results. Environmental toxicologist Willie Peijnenburg of Leiden University argues the microfiber concentrations in the study exceed what's typically measured in fields and says it's "very difficult to get real effects on plants" in soil-based tests. Others point out that some crops, including corn in one Kansas State University experiment, have shown higher protein levels when grown with microplastics—though that may come with the risk of increased heavy metals. While policymakers debate regulations and engineers test washing-machine filters that can capture shed fibers, experts say consumers can cut their own contribution by favoring natural fabrics, buying secondhand clothing, and washing in cold water.