Think about what you like to wear on the weekend. There's a good chance that you like to put on a pair of blue jeans(牛仔裤). But according to a new study,our love for jeans may be bad for Earth, especially for sea animals.

In  order to  improve jeans'feel  and  give jeans blue  color, some man-made chemicals(化学品 )are added to denim(牛仔布). Every time we wash our jeans, small bits of denim drop. They come out of our washing machine and into the world's rivers, lakes and oceans. Scientists studied the Great Lakes in America and found denim waste in it. The harmful chemicals in denim have spread far and wide. They might be putting some sea animals in danger.

Scientists also washed jeans to see how many bits of denim each pair would drop for each wash. The answer was worrying:About 50,000 bits. Not all of them come into the environment. Wastewater treatment factories can deal with 99%of them. This may sound pretty good. However, the rest of them still have a bad influence on the environment.

Does this mean we shouldn't wear jeans?Probably not. "We need to buy fewer jeans and only wash them when we truly need to do it,"says Sam Athey, one of the scientists. "You don't need to wash your jeans too often."