The first study of whale earwax, the hormones in whale earwax, and the relationship to the pollution and the types of pollution a whale may be exposed to was presented by biologists from Baylor University, Santa Barbara Museum of Natural History, and the Smithsonian Institution in the Sept. 16, 2013, edition of the journal Proceedings of the National Academy of Sciences.
Whale earwax gives a lifetime profile of the exposure of a whale to mercury, pesticides, and organic chemical pollutants. The levels of testosterone and the stress chemical cortisol can be used to determine the frequency of pollutant exposure and the severity of a given whale’s reaction to a chemical pollutant or a group of pollutants.
The researchers examined the earwax composition of a beached male blue whale. The ear canal of blue whales and other baleen species is sealed off from the environment. The earwax accumulation is a lifetime record of the whale’s exposure to pollutants and the whale’s hormonal reaction to pollution and other stresses.
Over the 12 years of its life, the subject whale demonstrated high levels of flame retardant and pesticide exposure during the first two years of its life and high levels of mercury exposure during gestation.
Whale earwax can only keep a record of the fat-soluble chemicals that the whale either excretes or is exposed to.
The researchers propose the adoption of this method to track lifetime exposure to pollution in whales that beach or die from other causes.