Most of us have medications that we no longer take, are old, have expired, or were used by someone who died. Many of these unwanted medications contain compounds that are known sometimes as emerging substances of concern. Some of these substances, like synthetic estrogen used in hormone replacement therapy, are considered to be endocrine disruptors that may interfere with or modify hormone processes within an organism. Others, such as sedatives, can affect or modify central nervous system activity. Low levels of antibiotics can lead to the development of antibiotic-resistant strains of harmful bacteria. Emerging substances of concern also include compounds that are used to enhance consumer goods, for example flame retardant coatings on television and computer monitor plastic housings, or to optimize agricultural production, e.g., pesticides.

Emerging substances of concern may be found in very low concentrations in surface water, ground water, domestic wastewater, industrial wastewater, agricultural runoff, reclaimed water, and other waters. It is not surprising that we are finding these compounds since they are associated with human activity and scientists are now actively looking for emerging substances of concern and have the analytical tools to find them at very low concentrations. Many of these compounds are used to enhance our quality of life by protecting human health, enhancing consumer goods, and optimizing agricultural production. It is inevitable that small amounts of these compounds will be released to the environment. It is also likely that these compounds have been there for decades and have remained undetected until the recent development of analytical methods to enable their identification and quantification.

While the concentrations of these substances found in our water bodies are hundreds or thousands of times lower than the therapeutic dosages found in the medications that we take, research has shown that there can be effects on aquatic organisms like fish and frogs. An internal Department working group provides a more technical perspective on the research, analytical methods and effects of these compounds. At this time, no research has shown that concentrations of these substances reported in recent studies pose a threat to drinking water supplies. Research is ongoing, especially on the effects of multiple chemical constituents at low concentrations. A Department report, Emerging Substances of Concern (December 2008), summarizes the conclusions of this workgroup that was formed to evaluate strategies to effectively address a wide variety of potential emerging substances of concern.

We can reduce the amount of these substances by properly disposing of unwanted medications (in Spanish). Expired or unwanted prescription and over-the-counter medications from households are typically disposed of by flushing them down the toilet or a drain. Although this method of disposal prevents immediate accidental ingestion, it can cause contamination in our aquatic environment because wastewater treatment systems, including septic tanks, are not designed to remove many of these medications. You should never flush unwanted medications down the toilet or down a drain. Instead, place them in the household trash after taking precautions (in Spanish) to prevent accidental ingestion by humans or animals.

Disposal of unwanted medications from commercial facilities such as pharmacies, medical facilities and veterinary operations are subject to different regulations than those that apply to medications from household uses. Those facilities should contact the Department's headquarters for guidance.

Remember, never dispose of unwanted medications down the toilet or down the drain (in Spanish).