A blue whale surfacing (Credit: Michael L. Baird, via Wikimedia Commons)
Whale earwax records the contaminants that the mammals are exposed throughout their lives, according to a study published in the Proceedings for the National Academy of Science.
Scientists from Baylor University, the Smithsonian Institution and the Santa Barbara Museum of Natural History analyzed earwax from a 21-meter blue whale hit by a ship in 2007.
They found that earwax logged lifetime contaminant exposure over six-month intervals.
The wax showed strong signals for legacy contaminants like DDT and PCBs. Mercury concentrations were also found in increasing levels as the whale aged.
Concentration levels detected for DDT and PCBs in the whales blubber were similar to those found during earwax analysis, but blubber lacked any indication of the time of exposure.