Human urine causes high levels of caffeine in Pacific coastal waters

If there was ever a clearer sign that we sure do love our coffee, it's got to be this: A new study from Portland State University has found elevated levels of caffeine at several sites in Pacific waters, off the coast of Oregon. The researchers speculate that, while wastewater treatment plants are effective at removing caffeine, sewer overflows are still flushing the contaminants out to sea.

The study, which was led by Zoe Rodriguez del Rey and Elise Granek, was the first to look for caffeine pollution off the Oregon coast. They targeted several areas near wastewater treatment plants, large population centers, and rivers emptying near the ocean. They had expected to find waste chemicals near the water treatment areas, but their analysis revealed a different source. Writing in Headlight Herald, Samantha Swindler explains more:

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."

The "elevated levels" of caffeine are well below a lethal dose for marine life, but scientists suspect that the contaminants are still affecting organisms. And also, the researchers were only looking for caffeine, but they strongly suspect that the areas are also laden with other waste products. It's worth noting that caffeine breaks up in the water in less than a month, but it's still likely to have an impact on marine life.

Results of the study were published in the July 2012 Marine Pollution Bulletin, "Occurrence and concentration of caffeine in Oregon coastal waters."

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