There are good reasons that the Drug Enforcement Agency and local communities are holding a drug drop-off day Saturday, Sept. 25. Besides making a collective effort to keep pharmaceuticals away from addicts and abusers, it likewise benefits public health and the environment.

Expired drugs — antibiotics, narcotics, anti-depressants and aspirin — become useless, or worse, dangerous to the human body. The older they are, the more they alter chemically and lose their effectiveness. Some break down in such ways as to become toxic. The general advice is to throw away all prescription drugs past their expiration date.

But do not throw them in the trash, or toss them down the toilet. They can potentially destroy good bacteria in septic systems; children and pets can get into them in the garbage; and we do not want them to seep into our drinking wells and ponds.

The U.S. Environmental Protection Agency now has a name for these products: Pharmaceuticals and Personal Care Products as Pollutants, or PPCPs. The acronym refers to any product used by individuals for personal health or cosmetic reasons or used by agribusiness to enhance the growth or health of livestock. PPCPs comprise a diverse collection of thousands of chemical substances, including prescription and over-the-counter therapeutic drugs, veterinary drugs, fragrances and cosmetics.

While the DEA and the Maine Bureau of Health are concerned about the growing problem of prescription drug abuse, environmental agencies are worried that prescription drugs and their chemical compounds are leaching into groundwater and the oceans.

An array of pharmaceuticals, including antibiotics, anti-convulsants, mood stabilizers, heart medicine and sex hormones, have been found in the drinking water supplies of at least 41 million Americans, according to the National Community Pharmacists Association. Pharmaceuticals, vitamins and cosmetics, suntan lotion and perfumes contain bioactive chemicals, substances that have an effect on living tissue, according to the EPA. Although they have been around for decades, an explosion of personal hygiene products and drugs has occurred over the last 25 years, and their environmental effect is now subject to research.

It hits home locally; currently, Lincolnville is going door to door in the watershed that feeds Norton Pond to assess sewer systems, not just to trace the origin of a certain type of bacteria, but to determine if phosphates and personal care products, such as toothpaste whitener, are also leaching into the fragile pond.

On Saturday, Sept. 25, there will be a number of local collection spots for outdated or unwanted drugs. The effort is coordinated by the DEA and is part of a national program recognizing that such drugs are a potential source of supply for illegal use and an unacceptable risk to public health and safety. The program is anonymous, and all over-the-counter drugs are accepted. Injectables and illicit substances are not part of the initiative.

To learn more about where to take old drugs, see page A6. We have a big enough public health problem with drug abuse; let’s try to mitigate it environmentally, as well.