Kaeli WelshHave you ever wondered what happens to a drug after you ingest it? Let’s say you take Tylenol for a fever. In eight hours, it’s worn off and you’re right as rain. But where did the Tylenol go? To put it delicately, it passed through your body and has gone into the sewer system to be filtered out – or has it?
In the last few decades, there’s been growing concern over pharmaceutical pollution. Drugs enter the environment through a variety of ways, such as biological waste from humans or domesticated animals. Drugs can exit our bodies as the original active ingredient or as metabolites, which are broken-down or modified versions of the drug. Some metabolites are generally inactive, but others may still be able to interact with our bodies and cause unintended side effects. Another way drugs enter the environment is through improper disposal. It can be as innocuous as flushing your expired medications down the toilet or as systemic as runoff from drug manufacturers. In one such case, a Swedish researcher, Dr. Joakim Larsson, found that pharmaceutical factories were releasing antibiotic waste into local waterways and cultivating drug-resistant strains. Dr. Larsson spent 17 years researching this issue and lobbying international organizations, leading to new global standards from the World Health Organization.
Active ingredients and metabolites from drugs can persist in the ecosystem and potentially cause harm to local wildlife. Aquatic ecosystems are particularly vulnerable, because these organisms have to live in the contaminated water and are continuously exposed. Hormonal drugs can alter fish physiology and impact reproduction rates. Drug pollution can also impact land animals, with effects as serious as organ damage in vultures. In the 1990s, researchers in India saw startling declines in white-backed vulture populations. They tracked down the culprit to a common pain reliever called diclofenac, which was a popular treatment for domesticated water buffalo. Vultures are particularly sensitive to diclofenac, so one contaminated buffalo carcass could easily harm dozens of vultures . Conservation groups successfully lobbied for diclofenac bans, particularly in locations that have high migration levels and known breeding grounds, which have allowed vulture populations to stabilize.
Organizations around the world are seeking effective ways to understand and prevent drug pollution. Not all organisms are easily monitored, not all effects are easily noticed, and polluted ecosystems contain a complex mixture of pharmaceuticals and metabolites. The United Nations Environment Programme (UNEP) is responding to environmentally persistent pharmaceutical pollutants (EPPPs), which can easily accumulate and have long-lasting effects on local environments. UNEP has been researching EPPPs to understand their life cycles in the environment, identify hotspots, and develop wastewater treatment protocols. The European Union’s Innovative Medicines Initiative developed a tool called ePiE to model where different drugs are accumulating based on changes in medication usage and water treatment protocols across different countries. This tool will allow researchers to virtually monitor over 1500 river basins in Europe, which would otherwise be physically time-consuming and costly.
Scientists are working to curb pharmaceutical pollution by designing drugs to be more eco-friendly in an effort called “benign by design”. A 2022 publication listed a “GREENER” guideline for drug design to be less effective on wildlife, improve drug dosing and delivery methods, and avoid substances that can linger and cause harm in the environment. At the forefront of these approaches, “good practice for patients” is always the most important factor.
Many solutions to drug pollution require systemic changes in water treatment methods and the pharmaceutical industry. However, everyone can contribute to protecting vulnerable ecosystems by disposing of their drugs safely. Instead of flushing old or unused medication, send them to official disposal facilities through take back programs. While the DEA sponsors a National Take Back Day, some pharmacies have medication disposal kiosks or pre-addressed mail-back envelopes. If there aren’t any take-back options near you, there are other resources available. Your medication may have specific disposal instructions. Some drugs, like opioids, are particularly dangerous or often misused, so the FDA compiled a “Flush List” of medications that are best disposed of down the toilet. A subsequent study commissioned by the FDA found that most “flush list” drugs have a negligible effect on the environment, though some require more data. As a last resort, you can dispose of your medications by transferring them to a secondary container filled with unwanted material like dirt or cat litter.
Ultimately, human health and safety will always be the priority when it comes to designing and prescribing medications. Fortunately, there are large-scale efforts underway to make drug design, manufacturing, and disposal a greener process.
Peer Editors: Tiffany Peters & Sophia J. Kennedy