Drugs in the Water

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What do acetaminophen (Tylenol), codeine, cocaine, ibuprofen, Prozac, erythromycin, caffeine, ethinylestradiol, triclosan, Naproxen, nonylphenol, Metformin and nicotine have in common? They have all been detected in rivers, lakes and coastal waters throughout the United States and Europe (1, 2) in concentrations of parts per billion to parts per trillion. Where do these drugs come from? Are they a threat to the environment? Are they a threat to human health? What can we do about it?

Where Do the Drugs Come From?

Over-the-counter, prescription and recreational drugs ingested by people are typically not completely absorbed or degraded by our bodies before elimination. These drugs are therefore in our waste that is that is flushed down the drain, passed through the sewer system, only partially destroyed in the sewage treatment process, and therefore are still present in wastewater treatment plant effluent. Depending on the location, this effluent stream is discharged to rivers or the ocean. These same water bodies are the source of drinking water for many communities. Drugs also enter the sewer system when unused medications are flushed down the toilet.

Are They a Threat to the Environment?

They can be. In numerous waterways from the Potomac River in Washington, DC to the Brazos River in Texas to Boulder Creek in Colorado to Nevada's Lake Mead to London's Thames River to the ocean waters off Southern California, studies have found changes in the reproductive systems of fish that are linked to pharmaceuticals that can disrupt their endrocrine systems. Fish have been found with both male and female sex tissue and in many cases female fish in areas impacted by wastewater treatment plant discharges greatly outnumbered males. It should be noted that a study and subsequent newspaper article regarding feminization of male fish around a sewage outfall near Los Angeles was subsequently found to be in error. Despite the error, the Southern California scientists said their new peer-reviewed, published research confirms that bottom-dwelling ocean fish are highly exposed to hormone-disrupting chemicals off Los Angeles and Orange counties. Other more subtle signs of altered hormones were confirmed – including reduced estrogen levels in male turbot near the sites where wastewater is discharged. Another study of fish in a San Francisco Bay-Delta estuary indicated that silversides (Menidia audens) collected from an urban beach in Suisun Marsh were more masculinized, but with smaller and less healthy gonads, than were neighboring silversides swimming near a cattle ranch in the marsh, according to a study led by scintists at the University of California, Davis. A potential explanation, the researchers hypothesize, is that exposure to androgens — hormones like testosterone that control the development of male characteristics — reduced the expression of estrogen-dependent genes, which the females need to develop and reproduce successfully. Androgen exposure from endocrine disruptors may also be causing some of the fish that would have been female to become male.

Are They a Threat to Human Health?

At the present time there is no evidence that the presence of pharmaceutical products in the parts per billion to parts per trillion range poses a threat to swimmers or surfers. A more relevant concern is whether these trace levels of pharmaceuticals are making their way into our drinking water and, if so, can they be considered a threat to human health. A recent national study found trace concentrations of a wide variety of drugs in the drinking water supply in many metropolitan areas. A news report from Canada references research that indicates a declining male/female sex ratio in newborns and increasing incidences of sexual abnormalities worldwide. Water district managers typically maintain that their water supply is safe, but the reality is that there are no drinking water standards for these compounds. So, the jury is still out. Water and wastewater treatment facilities can install processes such as reverse osmosis that are effective at removing pharmaceuticals (see below), but the cost is substantial.

It should be noted that:

  • Bottled water is not necessarily safer than tap water. In many cases the source of the water is the same and many treatment processes are ineffective at removing pharmaceuticals.
  • If you are concerned about “toilet to tap” wastewater recycling projects making this problem worse, don't be. The advanced treatment processes, such as reverse osmosis and advanced oxidation (UV light and hydrogen peroxide) used by these facilities is very effective at removing/destroying pharmaceuticals. The Groundwater Replenishment System in Orange County, CA is producing water that is better quality than tap water or local groundwater.

What Can You Do?

The most important thing you can do to reduce the amount of drugs in our waterways is DON'T FLUSH DRUGS DOWN THE DRAIN. This is complicated by the fact that some agencies and pharmacies have previously recommended this practice as a way of preventing misuse of drugs. Also, depending on where you live, there may or may not be established alternative disposal options.

The best options, if available, are to return unused drugs/medications to a pharmacy for proper disposal. Check with your local pharmacy to see if this option is available. In some locations such as in the San Francisco Bay area in California, there are numerous drop-off locations for unused and expired drugs. State, County and City health department Web sites often have information about disposal locations. Here's one for Oregon. There is also a National Take Back Prescription Day.

If these types of options are not available, many Web sites recommend mixing the drugs with an objectionable material such as dirt, kitty litter or coffee grounds, and then placing them in a sturdy, sealed container (double containment if possible) and placing that in the trash.


The presence of drugs in our waterways is a potentially serious environmental and human health issue. The problem can be minimized by disposing of drugs properly and not down the drain.

References and Additional Information Sources

Meds Lurk in Drinking Water

Damming the Flow of Drugs into Drinking Water

Sewage Altering Fish, Study Reports (Los Angeles Times)

New report: Don't blame the pill for estrogen in drinking water

Feminized Fish: A Side Effect Of Emerging Contaminants (OPB/Earthfix)

The Gender-Bending Chemicals in Our Water (The Tyee, British Columbia, Canada)

Polluting The Water With Toothpaste, Shampoo, And Drugs (Investigate West)

Drugs found in Lake Michigan, miles from sewage outfalls (Michigan)

Pharmaceuticals difficult to treat in drinking water (Great Lakes Echo)

Disposal of Unwanted or Unused Pharmaceuticals Fact Sheet (Illinois EPA)

Only 2% of household medicine is safely disposed (Wisconsin)

Proper Medication Disposal (Utah)

No Drugs Down the Drain (CA)

Teleosis Institute

Disposal of Pharmaceuticals (University of Washington)

Proper Disposal of Residential Medications and Pharmaceuticals (City of San Diego)

Safe Medicine Disposal Program (City of Santa Rosa)

Proper Disposal of Pharmaceuticals (City of Columbia, MO)

Save the Bay – Don't Medicate Our Bay

FAQs About Proper Disposal of Drugs (NY Dept of Environmental Conservation)

New Drug Disposal Program a Success (Camarillo, CA)

Endocrine Disruptor Screening Program (U.S. EPA)

This article is part of a series on Clean Water which looks at various threats to the water quality of our oceans, and the negative impacts polluted waters can have on the environment and human health.

For information about laws, policies, programs and conditions impacting water quality in a specific state, please visit Surfrider's State of the Beach report to find the State Report for that state, and click on the "Water Quality" indicator link.