Effluent treatment plants such as the Gold Bar Wastewater Treatment Plant in Edmonton, Alberta, from which the effluent stream can be seen above as a dark color in the North Saskatchewan River water, need to deal with an expanding range of compounds. Photo: City of Edmonton, Alberta, Canada
Infrastructure managers are under pressure from state regulators to deal with an issue that is getting press and popping up in mail from concerned citizens: How will the latest generation of wastewater contaminants affect water sources, and what can we do about it?
The issue is how “micro constituents”—emerging contaminants such as endocrine disrupting chemicals (EDCs)—impact environmental and human health.
EDCs, which have been detected at trace concentrations in waters around the world, interfere with hormonal processes and alter the way organisms reproduce and develop. They also affect the function of the thyroid and immune and nervous systems. Many are pharmaceutical products, such as contraceptives and hormone-replacement drugs, which are non-degradable, persistent, and effective even in small quantities. When these compounds flow from the sewage-treatment system into the effluent outlets of city systems, they have unwelcome effects.Estrogen Effect
EDCs first came to public attention in the 1990s when it was discovered that downstream of some municipal effluent discharges, the fish population exhibited an abnormally high percentage—more than 90% in some cases—of females. Further investigation found that estrogens in the wastewater from a variety of sources were a major cause of the phenomenon.
Under directives from the 1996 Food Quality Protection Act and 1996 amendments to the Safe Drinking Water Act, the EPA established the Endocrine Disruptor Screening Program (EDSP) in 1998. This program aims to use assay methods to identify chemicals that have the potential to interact with the endocrine system and to determine the endocrine-related effects caused by each chemical.
In turn, regulators are asking wastewater treatment plant managers to monitor for substances such as EDCs in their effluent. Estrogenic compounds are among the first EDCs in many jurisdictions to move toward regulation. One reliable, accessible testing tool uses genetically modified yeast that can bond to estrogens, producing an enzyme that can be measured. Even tiny amounts of estrogens cause the yeast to react reliably, forming a robust test system.
But the challenge lies beyond estrogens. Some 4000 substances, many of which will ultimately be flushed into our environment, are registered daily with the Chemical Abstract Service of the American Chemical Society. Scientists lack the technology and resources to measure the effects of all these potential contaminants, particularly from exposures to substances below analytical detection limits (quantities that exert an effect but are too low to measure).
Other compounds, such as those found in many plastics and naturally occurring substances, can mimic estrogens. Therefore, new formulations of such common household products as laundry detergent could likewise have unintended effects upon release into the aquatic environment.
Uncertain what to measure, plant managers usually consult a testing laboratory. The lab comes back with a long list of compounds to test for, a costly and ineffective way to predict the future effects of these substances. And some may have little environmental impact. Consider the range of EDC compounds for which one city recently asked a laboratory to test:
- Pharmaceuticals (48 drugs)
- Steroid hormones (12 analytes)
- Alkyphenol, ethoxylates, and carboxylates
- Phthalate esters
- Brominated flame retardants
- Chlorinated dioxins/furans
- Brominated dioxins/furans
- Congener specific PCBs
- Organochlorine pesticides
- Bisphenol A.