A massive buildup of discarded wet wipes has formed an island that is now physically altering the course of the river Thames. The U.K. government is considering an outright ban on the items because of the environmental havoc they cause when flushed down toilets. “There’s an island the size of two tennis courts and I’ve been and stood on it,” Labour Party MP Fleur Anderson said in the House of Commons. “It’s near Hammersmith Bridge in the Thames and it’s a meter deep or more in places of just wet wipes. It’s actually changed the course of the Thames.” Wet wipes are also said to constitute 90 percent of the material in “fatbergs”—enormous balls of grease and household waste that have blighted British sewers for years.