Earwax of Dead Blue Whale Reveals High DDT Levels

Earwax of Dead Blue Whale Reveals High DDT Levels

A new study released Monday reveals that earwax build-up in whales is a useful indicator of how much pollution the animal has endured in its life. Since whales certainly aren’t capable of cleaning their ears, the layers of wax pile up and eventually create a reliable record of chemical pollution to which the whale has been subjected. The study began, in fact, when a blue whale carcass began being looked at. The earwax of that particular blue whale, dead for some time, revealed significantly high levels of the chemical DDT.

In the same whale, the accumulated earwax was nearly a foot long in size. The wax was collected by scientists at the Santa Barbara Museum of Natural History.

One of those researchers, Sascha Usenko, was quite surprised by the finding, especially considering how long DDT has been out of use. “It’s been 30-plus years since we’ve stopped using this compound,” Usenko remarks, “but to still see it showing up at such high concentrations — one of the dominant chemicals we see — was surprising.”

DDT was most widely used during the 1940s and 1950s, when it was employed as a treatment for typhus, malaria, and dengue fever, but this was long after the aforementioned diseases had already been successfully dealt with. Even the World Health Organization relied on the chemical in the 50s, a campaign which was largely responsible for creating pesticide-resistant insect strains in those areas where it was used. The compound has since seen bans worldwide. This makes the revealed presence of high DDT levels in a dead blue whale’s earwax all the more striking.

Usenko, who works as environmental scientist at Baylor University, adds that the study doesn’t really indicate whether the analyzed whale was actually harmed by DDT. Still, the presence of chemical pollution data in ear wax alone is a monumental finding, one that Usenko believes will be able to give researchers a greater understanding of how those chemicals have impacted the existence of whales.

In the past, blubber has been attempted to be analyzed for similar reasons. While this method did reveal the types of chemicals a whale had been exposed to, it was still not capable of revealing precisely when the animal was exposed. Now, Usenko and his team have started looking at earwax – another material made of fatty substances – in order to pinpoint the exact time range when a whale endured exposure to chemicals. This particular blue whale, Usenko notes, was found to have been subjected to DDT during its entire life.

“It’s kind of got that icky look to it,” he explains concerning the wax. “It looks kind of like a candle that’s been roughed up a bit. It looks waxy and has got fibers. But it’s pretty rigid — a lot stronger and a lot more stable than one would think.” While wax columns in whales’ ears have long been used as indicators of the animals’ ages – much like tree rings – the new discovery of chemical pollution accumulation adds another dimension to scientists’ understanding.  The presence of high DDT in one dead blue whale’s earwax will certainly not be the only case of such a phenomenon.

Written by Chris Bacavis