A new study has found elevated levels of caffeine at several sites in waters off the coast of Oregon—though not necessarily where researchers expected. Of 14 coastal locations sampled, Cape Lookout had the highest caffeine levels, leading researchers to conclude that possibly septic systems, not wastewater treatment plants, are the source of the pollution.
The study is the first to look at caffeine pollution off the Oregon coast. It was developed and conducted by Portland State University master’s student Zoe Rodriguez del Rey and her faculty adviser Elise Granek, assistant professor of Environmental Science and Management, in collaboration with Steve Sylvester of Washington State University.
Granek said the study focused on caffeine because it “is a pretty easy to look at, you don’t need a lot of permits... but it’s also a really good tracer of wastewater. If we see caffeine, we have a really good idea that it’s coming from a human wastewater source because caffeine is naturally produced by a number of plants, but there are no known plants in the temperate zone that produce caffeine.”
Caffeine is found in many food and beverage products as well as some pharmaceuticals.
“If we are seeing caffeine, then it’s likely that there are other contaminants accompanying it,” Granek said.
In spring 2010, Rodriguez del Rey and Granek collected and analyzed samples from coastal locations and adjacent water bodies from Astoria to Brookings. Of the coastal sampling sites, Cape Lookout had the highest presence of caffeine with 45 nanograms per liter. That was followed by Carl Washburne in Florence, with 30 nanograms/liter; Lincoln City and Newport, each with 18 nanograms per liter, and Seaside/Gearhart with 9 nanograms per liter. High levels were also found following a late-season storm of wind and rain that triggered sewer overflows.
Yet large population centers such as Astoria/Warrenton and Coos Bay had low traces of caffeine, below the mean reporting level.
The results suggest that wastewater treatment plants are effective at removing caffeine, but that high rainfall and combined sewer overflows flush the contaminants out to sea. The results also suggest that septic tanks, such as those used at the state parks, may be less effective at containing pollution. Granek noted that there’s “very little regulation or monitoring” of septic systems once installed, “and possibly because of that there’s not much tracking of whether septic systems are functioning well.”
Even “elevated levels” of caffeine that were measured are well below a lethal dose for marine life. However, an earlier study by Rodriguez del Rey and Granek on intertidal mussels showed that caffeine could have an effect on marine life. In that study, researchers found reactions to “cellular stress” at the lowest amount tested – 50 nanograms per liter. That’s close to the levels found in Cape Lookout.
“We humans drink caffeinated beverages because caffeine has a biological effect on us—so it isn’t too surprising that caffeine affects other animals, too,” says Granek.
She added that while caffeine breaks down in sea water in less than a month, “other contaminants may build up in muscle tissue.” The next step is to determine what other wastewater contaminants may be present and what impacts they may have on marine organisms.
The project was funded in part by an Oregon Sea Grant Program Development Grant and the National Oceanographic and Atmospheric Administration. Granek has submitted a grant to further study septic tanks in coastal areas, which could help identify the extent to which these systems are sources of contamination to Oregon’s marine waters. View the full study online at http://www.pdx.edu/news/CoastalCaffeineWaters.
– Samantha Swindler contributed to this report