New Study Suggests Pacific Ocean is Polluted With… Coffee?

by , 08/08/12

Coffee, Close-Up, Bubbles

People aren’t the only ones getting a jolt from caffeine these days; in a new study published in Marine Pollution Bulletin, scientists found elevated concentrations of caffeine in the Pacific Ocean in areas off the coast of Oregon. With all those coffee drinkers in the Pacific Northwest, it should be no surprise that human waste containing caffeine would ultimately make its way through municipal water systems and out to sea – but how will the presence of caffeine in our oceans affect human health and natural ecosystems?

Plastic Garbage, Underwater, Great Pacific Garbage Patch

The precise impacts that exposure to caffeinated seas may have on humans are not well known. However, related research indicates that evidence of caffeine contamination serves as a good indicator for the presence of other potentially harmful pollutants that have found their way into our waterways, such as prescription medication and hormones. The effects on aquatic life are also not well understood, but lab studies have already demonstrated that higher levels of caffeine in the water have been shown to produce cellular stress in intertidal mussels.

The study showing abnormal levels of caffeine in the waters off the Oregon coast also suggested that the contaminants were predominantly coming from small-scale waste treatment systems such as household septic tanks, as opposed to large-scale wastewater treatment plants, which are regulated with much greater scrutiny. Such massive facilities are well-equipped to process the waste originating from cities in Oregon, which are comparatively smaller than major metropolitan hubs that have much more waste to contend with. For example, in Massachusetts, high levels of caffeine have been detected in Boston Harbor, likely the result of significantly greater quantities of wastewater that require treatment than those present in Oregon.

With so much uncertainty surrounding the effects of caffeine pollution on an ocean already marred by the presence of plastic garbage islands, how much research needs to be conducted before cities decide to embark upon ambitious ocean-cleansing efforts? Hopefully, leaders won’t need to convene over coffee to figure out the right course of action.

+ Marine Pollution Bulletin

Via Grist

Images: Wikimedia Commons

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  1. Alfredo Guillen December 10, 2014 at 6:55 pm

    Are people not drinking coffee in the rest of the US? By comparison The oceans around Italy would be surrounded by a sea of espresso!

  2. 星海 譚 September 6, 2014 at 9:47 am


  3. johnbshannon August 26, 2012 at 1:42 am

    Last time I was out on the water, I noticed the fish were a little ‘jumpy’ — too much caffeine?

    John Brian Shannon

  4. dtpennington August 11, 2012 at 1:22 pm

    Kind of an odd form of pollution. Are we doing similar studies on the other drugs and compounds that get flushed out with human waste? This makes for a cute headline, but I doubt it is the worst thing that is going into our water.

  5. hbergeronx August 9, 2012 at 6:43 pm

    One nanogram per liter is the equivalent of a single cup of coffee diluted into ~100 million (1×10^8) liters, or ~422 million cups of water. The study measured the samples days after a rainstorm, when pollution from storm drain and septic runoff was at its maximum. There’s no doubt that it is man-made pollution, but if pollution on that scale “matters”, then coffee will have to be disposed of as hazardous waste. Even a cup of coffee casually tossed overboard on a ship should make a measurable “plume” of “contamination” at those levels.

    But the science behind this paper ( is extremely hazy. They cite another paper ( which measured North Sea concentrations of caffeine between 5 and 15 ng/l. Without scale, it is impossible to tell what that means. The North sea has an area and average depth of 7.5×10^5 km^2 and 0.095 km respectively- about 7×10^4 cubic kilometers, or 7×10^16 liters. At 10 ng/l, that’s 7×10^6 grams, equivalent to about 7×10^5 kilograms of coffee poured directly into the ocean. The whole world produces 8×10^9 kilos of coffee (along with 4×10^9 kg of tea) every year, so it’s entirely conceivable that such an amount could be discharged. However, the study does not take into account for the rate at which, if at all, it is biodegraded. Clearly, from coffee and tea alone, the amount going into our drains (and toilets) is far larger than what is measured.

    Furthermore, they measured up to 8 ng/l in their *control* samples. Rather than attempting to more aggressively control for contamination (or method error, a much more plausible reason) they simply report values under this level as “not detected”. I personally would argue that they may have a contamination problem on their GCMS injector port before I made the field samplers wear moonsuits to work.

    I would agree that the bioaccumulation of waste products of our lifestyle will always present an environmental challenge- but that challenge is a factor of the large numbers of people on the planet. It’s not as simple as “chemicals in” meaning the same thing as pollution. The extent to which coffee is or is not biodegradable needs to be factored.

    We are not “caffeinating the oceans” as the title implies- we just have a poor idea of the scale of human impact on the planet. Caffeine is exceptionally easy to detect, not least of which because it is a digestion product of DNA in the coffee and tea plant, and DNA bases and their metabolites are easily detected. There’s no doubt that it has an impact on our world. But we’ve been “caffeinating” our streams and lakes for hundreds, if not thousands of years. It’s worth noting that scientists can detect evidence of our behavior, but we need much more research to figure out what that has meant in the past, and what it means today.

    -Matt Harbowy

  6. vikimaui August 9, 2012 at 5:54 pm

    I doubt that coffee is the primary source for all this caffeine. What about caffeinated sodas, snacks and over the counter pill products?

  7. bugmenot August 7, 2012 at 2:00 am

    Would this have anything to do with people using old coffee grounds as compost in their gardens? (Starbucks will even give you theirs for free.)

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