"Even something as fun as baking for the holiday season has an environmental effect," said Rick Keil, an associate professor of chemical oceanography. "When we bake and change the way we eat, it has an impact on what the environment sees. To me it shows the connectedness."
Keil and UW researcher Jacquelyn Neibauer's weekly tests of treated sewage sent into the sound from the West Point treatment plant in Magnolia showed cinnamon, vanilla and artificial vanilla levels rose between Nov. 14 and Dec. 9, with the biggest spike right after Thanksgiving.
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Natural vanilla showed the largest increase, "perhaps indicative of more home baking using natural vanilla," Keil and Neibauer wrote.
"This conjecture is weakly supported by a verbal communication between Rick Keil and an employee of the Wallingford QFC (supermarket) who felt that natural vanilla peaked during the holiday seasons," the scientists' preliminary report says. "This will be investigated more thoroughly."
So far, the research has turned up no evidence that snickerdoodles are harming sea creatures, but their research does lead to some serious environmental questions.
Fish rely heavily on their sense of smell to locate food, for example, and, in the case of salmon, to find their way back to their home stream to spawn.
"All the spices have odors associated with them, so it's interesting to ask whether they are there in sufficient concentration [for fish] to smell them," Keil said.
Using benchmarks from a published scientific study, they were able to estimate that people in Seattle and a few outlying areas served by the sewage plant scarfed down the daily equivalent of about 160,000 butter- or chocolate-chip-type cookies and about 80,000 cookies containing cinnamon during the Thanksgiving weekend.
The county did not spend any money on the study, but officials at King County's Wastewater Treatment Division said they were happy to cooperate because they expected the results to reinforce their message: What goes down the drain has to come out somewhere.
That goes both for pesticides and industrial chemicals as well as vanilla and cinnamon.
"It's an ability to look at a whole population's behavior through one pipe," said Randy Schuman, a county science and technical support manager who helped arrange the wastewater testing.
Keil's findings present a light side of what scientists say is potentially a serious situation.
Scientists at the U.S. Geological Survey and other agencies have documented that antibiotics, contraceptives, perfumes, painkillers, antidepressants and other substances pass through the sewage system into waterways.
King County researchers several years took caffeine measurements to try to learn whether the city's coffee drinking habits had any effect on the sound.
Caffeine was found in more than 160 of 216 samples in water as deep as 640 feet.
"It was everywhere," Schuman said. "There's an effect [from] humans on the sound and it's almost ubiquitous. It's not just at the end of the [discharge] pipe."