It’s a hot summer night. Your AC is on full blast, your fans are on, but you still are sweating. Your pillow is hot no matter how much you turn it over; sweat trickles down the sides of your face, beads your forehead and makes your hair stick to your neck. So you head to your kitchen, hoping to find an oasis in the middle of this heat. You grab a cool bottle of water and ravenously open it. The icy water hits the back of your tongue and is the most flavorful thing you have ever drank.

When you think about all the available water on Earth, you might feel grateful for access to it. But when you get into the logistics of wastewater treatment and realize that you might be drinking the same water as you flushed down the toilet two weeks ago…that might not be appetizing. 

Luckily, that wastewater has gone through numerous cleaning cycles and is pristine enough for you to drink. To be considered for human consumption, effluent water from wastewater treatment plants must go through another cleansing treatment. But what about the environment? Though the soil and trees act as natural purifiers for the air and water, there are some substances that even they cannot tweak out – namely, pharmaceuticals. 

Municipal wastewater is treated with several physical and biochemical cleansing treatments, sometimes going up to tertiary treatment. In primary treatment, the cycle is physical; debris is removed and the influent enters a grit chamber and clarifier, where sludge exits. During secondary treatment, biochemical treatment occurs where bacteria break down compounds in an aeration tank; after going through the secondary clarifier, the wastewater is treated with disinfectant and is released as effluent. Pharmaceuticals can enter the environment through human waste – excrement can contain drug-induced hormones, improper disposal of over-the-counter drugs and prescription drugs, and cleaning supplies. Numerous studies have shown the prevalence of pharmaceuticals in treated effluent and others have analyzed the effects on fish downstream. A 2009 study conducted by EPA aimed to measure the occurrence of Contaminants of Emerging Concern (CEC) at nine publicly owned wastewater treatment plants (POTWs). The study reported several analytes above the laboratory-reported detection limit, including Personal and Pharmaceutical Care Products (PPCPs) and sterols and hormones. 441 detected results contained PPCPs (54%) and 240 detected results reported sterols and hormones (58%) (EPA, 2009). 72 PPCPs were outlined in the study, with 44 being detected in “at least one sample of POTW influent collected; in effluent samples, “33 PPCPs were detected in at least one sample” (EPA, 2009). The inability of wastewater treatment plants to remove pharmaceuticals from effluent can have adverse effects on aquatic wildlife as the natural composition of waterways is disrupted by the influx of various compounds.

Pharmaceuticals present in effluent can have alarming effects on aquatic life and ecosystem balance. Chemically induced estrogen environments can feminize male fish, changing population numbers as reproduction is interfered with. EE2 is an estrogen medication with a wide variety of usages, from relieving menopausal symptoms to birth control to certain hormone and gynecological treatments. Hormone medications like EE2 that are improperly disposed of down the drain have potential to change sex-ratios and ultimately, population dynamics. A 2015 study conducted on fathead minnow populations in southeastern New York reveals that plasma vitellogenin (Vtg) levels in male fathead minnows were highly correlated with 17a-ethinylestradiol (EE2) concentrations (Baldigo et al., 2015).Vtg is trigged by estrogens and is a protein precursor to the egg yolk, which eventually develops into an ooctye. The biodiversity and community health of two of the ten study sites were seriously affected by reduced population density and biomass: 79%-89% of species populations were reduced downstream in one such stream (Baldigo et al., 2015). When male fish are feminized due to excess estrogen in their environment and body, intrasex competition is reduced and reproduction decreases, lowering population numbers. On a larger scale, when many males are feminized in a population, trophic cascades can occur as prey populations dwindle, starving out predators. 

Bioaccumulation can also occur in fish and can bioaccumulate up the food chain. Some pharmaceuticals are not easily biodegradable and build up in fat tissues of fish, chemically interfering with body systems. A 2020 study analysis of the bioaccumulation of pharmaceuticals in fish populations that are downstream of wastewater treatment plants reports that 56% of detected pharmaceuticals in water were cardiovascular drugs; almost 50% of pharmaceuticals in sediment were psychoactive drugs (Grabicová et. al, 2020). Moreover, concentrations of several pharmaceuticals were found in various parts of prey and predators, indicating that biomagnification was occurring in the ecosystem. The common carp had the largest bioaccumulation of pharmaceuticals in its liver, constituting but not limited to metoprolol acid, telmisartan, N-DesmethylCIT, atenolol, and carbamazepine; in the kidney, N-DesmethylCIT constituted the majority of detected pharmaceuticals: in the brain, sertraline and carbamazepine (Grabicová et al., 2020). Compounds such as N-DesmethylCIT and sertraline can overwork the body. While N-DesmethylCIT is a cardiovascular drug aiming to improve blood flow and raise the heart rate, sertraline is a depressive drug that relaxes the nervous system. With a variety of pharmaceuticals in their bodies with differing effects, fish can experience a lowered quality of life. Starting from prey and ending at the apex predator in the food chain, these pharmaceuticals can magnify in quantity and effect, dramatically changing ecosystem dynamics.

So the question arises. How do we combat this? We cannot stop delivering pharmaceuticals: the industry is the backbone of modern healthcare. The common person, on their part, can become more educated on proper waste disposal. But that will not suffice. Although a challenging process, modern-day technology can combat the crisis of pharmaceuticals in aquatic environments. Such technologies are being assessed for their cost-effectiveness, availability, and sustainability. Constructed wetlands and algal systems can be potent biofiltration systems for effluent discharge. Coagulation-adsorption technologies are being tested as well as chemical processes such as ozonation, ultraviolet radiation cleansing, and ferrate processes (Radovic et al., 2023). 

The future is the now. Even with hi-tech developments and cutting-edge research working to boost human quality of life, the side effects cannot come at the cost of aquatic ecosystems. Water is the nourishing force of life, and if we firmly believe that our recycled water must be disinfected and purified to drink it again, the community downstream from the wastewater treatment plant deserves the same.

Citations:

Baldigo, B.P., George, S.D., Phillips, P.J., Hemming, J.D.C., Denslow, N.D. and Kroll, K.J. (2015), Potential estrogenic effects of wastewaters on gene expression in Pimephales promelas and fish assemblages in streams of southeastern New York. Environ Toxicol Chem, 34: 2803-2815.

Grabicová, Kateřina, et al. "Water Reuse and Aquaculture: Pharmaceutical Bioaccumulation by Fish during Tertiary Treatment in a Wastewater Stabilization Pond." Environmental Pollution, vol. 267, 2020, p. 115593, doi.org/10.1016/j.envpol.2020.115593. Accessed 19 Jul. 2024.

Radovic, Sanja, et al. "A Review on Sustainable Technologies for Pharmaceutical Elimination in Wastewaters — A Ubiquitous Problem of Modern Society." Journal of Molecular Liquids, vol. 383, 2023, p. 122121, doi.org/10.1016/j.molliq.2023.122121. Accessed 19 Jul. 2024.

United States Environmental Protection Agency. (2009, August). Occurrence of Contaminants of Emerging Concern in Wastewater From Nine Publicly Owned Treatment Works . Accessed 19 Jul. 2024