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Traces of medicines are showing up in streams and drinking water supplies. Where are they coming from and what is the risk? More....

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More than four out of every ten people in the U.S. take at least one prescription drug; one in six takes more than three. (Source: CDC, 2004.)  Commonly prescribed medicines include hormones, antibiotics, pain killers, mood-stabilizers, and drugs to reduce cholesterol or high-blood pressure. Since all of these drugs are not absorbed by the human body, a fraction is excreted into the toilet.  Some people and institutions also flush unused or expired medications down the toilet.  In addition, pharmaceuticals may be discharged from agribusiness, veterinary and manufacturing processes.  Eventually traces of these chemicals can end up in water supplies.

Drugs dumped down the toilet can end up n drinking water. Photo by Bet Zimmerman.
Drugs dumped down the toilet can end up in your tap water.  Photo by Bet Zimmerman.  (No actual water was polluted during this simulation.)

Pharmaceutical residues have been found in drinking water supplies used by at least 41 million Americans in 24 major metropolitan areas (Source: Associated Press, 2008). The U.S. Geological Survey did a study of surface water downstream of urban and agricultural areas.  At least one of the 95 drugs they were looking for showed up in 80% of the samples tested from 139 streams in 30 states. (CT water was not sampled in that study.)

The quantities detected in streams and drinking water are miniscule. They have been found in the parts per million/billion/trillion levels, which are thousands, to hundreds of thousands, of times lower than therapeutic doses.  However, these drugs are deliberately designed to interact with the body at low concentrations.  While traces in drinking water are not likely to pose an immediate health risk to humans, it is impossible to say there is no impact at all, particularly to sensitive populations.  Scientists are concerned about the effects of long-term exposure at low levels.  So far, very few human health assessments of environmental exposure to pharmaceuticals have been conducted.  Such studies are expensive and tremendously difficult to design and draw firm conclusions from.  There are too many variables, including the combined effects of multiple medications and the dynamics that happen to chemicals after they reach the environment.

Aquatic organisms are most vulnerable because they are born and live in the water. They simply can not get away from pollutants.  Some limited studies do show that aquatic organisms can be negatively impacted by pharmaceuticals in surface water.  Antidepressants can affect shellfish spawning.  Endocrine disruption, reproductive effects (e.g., feminimization), and renal deterioration have been seen in exposed fish.  
Sewage and drinking water treatment systems are not equipped to remove all pharmaceuticals. Operators are not required to monitor for them.  The federal government has not established regulatory safety limits for them in drinking water, in part because the consequences are unknown.  There are no federal regulations applicable to the disposal of drugs from households, or even from businesses unless they qualify as hazardous waste.

While this situation is not cause for widespread panic, it is a concern.  A 2008 report by the George Washington University School of Public Health and Health Services recommends:

  • more research on effects and treatment technologies,
  • public education to encourage consumers and health care providers to dispose of medications properly,
  • altering agricultural practices that release antibiotics and steroids into water supplies,
  • controlling discharge of contaminated water at the source,
  • evaluating regulatory approaches, and
  • upgrading drinking and wastewater technology to address water quality issues.

On an individual level, you can take advantage of pharmaceutical take back and household hazardous waste collection programs, ask your doctor to give you a sample or smaller amount of a drug you are taking for the first time to see if it will work, avoid flushing unused pet or people medications down the toilet or drain (instead put them in the trash), and follow the disposal instructions on pamphlets that come with prescriptions. 

Originally published in the Villager newspapers on July 20, 2008

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