科学美国人60秒 SSS 2013-09-24（在线收听）

 Cerumenis a lovely word especially considering that is means earwax.And we're nothingonly species that produces the stuff.Some whales built up waxes along withlipids and charaten protein into what's called earplugs.And now researchers nowknow that examining this plugs tells them about whale's lifetime exposure topollution.Alternating layers of dark and light in the plugs correlate toseasons of feeding migration.So the plugs have been used to determine a whale'sage,think tree rings.In the lasted study scientist analysed an earplug from anendangered blue well killed by a ship in California.They found that levels ofstress hormones doubled of the whale's life.They also found evidence that thewhale has been exposed to pesticide such as DDT with the highest levels turnsthe whale's first six month of life.Whale was likely exposed to the pesticidesin its mother's milk.They also found a couple of peeks of exposure tomercury.The study is in the proceedings of the national academy ofsciences.Future earplug should offer additional clues of whale lives,so look for researchers to get new attention to leviathan cerement.