In every whale's earwax is a record of their lifetime exposure to pollutants
In addition to the amazing revelation that whales have earwax, we learn that a team of researchers in the US has published a paper detailing a new method that they developed for measuring a whale's lifetime exposure to a wide variety of chemicals – by studying their earwax. In this study, the team examined the earwax plug removed from an individual male blue whale, Balaenoptera musculus, that died after being hit by a ship. The team counted the layers in the earwax and determined the animal's age – just like counting growth rings in the cross section of a tree trunk. The team then chemically analysed the layers of the earwax plug to reconstruct, with a six-month resolution, the fluctuating concentrations of mercury and organic pollutants in the whale's environment. Using their new method, they also measured the hormone levels in the whale's bloodstream. Not only did the team measure the amount of pollutants and hormones transferred to the whale from its mother while it was in utero, and confirm the age of sexual maturity in this species, they also measured the amount of the stress hormone, cortisol, and found that this individual's stress levels doubled over its lifespan. This new technique promises to fundamentally transform scientists' ability to assess human impacts on whales and their ecosystems.
http://www.theguardian.com/science/grrlscientist/2013/sep/17/whale-earwax-pollution-exposure
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