Water lovers will tell you that not all water tastes the same. However, if your water tastes different when it's in a reusable plastic bottle, a new study finds it may be a cause for worry.
Two scientists, Jan Christensen and Selina Tisler, have undertaken a study about which chemicals （化学物质）in reusable plastic bottles go into the water. They let water sit for 24 hours in new bottles, in used bottles and in bottles that had just come out of a dishwashing machine. After that, they compared what they found in the water in the different bottles.
The results were quite a surprise. More than 400 difierent chemicals had leached （析出） from new plastic bottles into the water. Water stored in used plastic bottles had the highest levels of plastic-related chemicals. Running the bottles through a dishwasher worsened the leaching. After a single washing, more than 3,.500 difierent chemicals ended up in a bottle's water. Many of these were related to dishwasher soap （洗碗皂） and remained even after a second washing with running water. What's more, dishwashing itself also caused more plastic chemicals to leach.
Similar discoveries were also made by Pat Hunt, a biologist at Washington State University. She found that heat can cause chemicals to move out of plastics. Hot water in a dishwasher helps to clean dishes. But plastics can start to break down if they are in hot water repeatedly, "Plastics just shouldn't go in the dishwasher, " she concludes.
Christensen and Tisler5s study found some chemicals that are probably harmful. Future studies could make clear how much of each chemical is there. And that's important. Just because a chemical is in the water doesn't mean it will cause problems. Much of the risk will depend on how much of a chemical actually gets into the body.
Hunt agrees. "This study is a starting point, " she says. It gives researchers ideas about what chemicals from reusable bottles are probably in water. But it doesn't tell us what risks the now-polluted water may bring to us. More research is needed.
Still, lowering exposures （接触）to plastic-related chemicals is probably a good idea. Hunt suggests using non-plastic bottles. "If you do use a plastic bottle, fill it up and use it right away, " Tisler adds. "It's best not to store water in them overnight or for long periods of time. "
