Potential Effects
So what are the potential effects of these very low levels of EDC’s and PPCP’s? The effects can be of two sorts: environmental and human health.
Environmental
Environmental issues can arise when the compounds interact with organisms in the environment, especially aquatic organisms. These aquatic critters are particularly susceptible to problems because not only do they drink the water, they are submersed in it. They are in intimate contact with the water, and whatever is in it, 24/7, so any adverse effects from chemicals in the water can be amplified. Studies abound regarding fish and amphibians changing sex, or showing androgynous characteristics due to exposure to EDC’s in wastewater effluent. There are also many indications of effects on invertebrate aquatic species as well. These issues in and of themselves seem sufficient to require monitoring and treatment to remove these compounds from wastewater effluent, thus protecting these susceptible organisms from being exposed. But treatment can be problematic and should be approached with caution. More on that later.
Human Health
Human’s encounter these compounds through the water we drink. Drinking the recommended volume of 2 liters per day, the average persons exposure to these compounds is extremely slight, given that they are present at such very low concentrations (remember, parts per trillion). Although it may seem a little troubling to be drinking something that has elements of someone’s shampoo in it, is it really something that can adversely affect our health? Should we spend the millions of dollars it would cost to remove these compounds? And remember, no big anonymous corporation somewhere can be made to pay for all of this; the problem is a result of the actions of each and every one of us, and we all will pay for any “solution” in our water rates. The answer to these questions is a resounding, “No one knows!”. There is very little, if any, toxicological data regarding consuming any of these compounds, so no one knows what the effects might be, or even if there are any. When it comes to pharmaceuticals, there are large quantities of data on what happens to people when they consume them at vastly higher concentrations for short periods of time, but not on what happens when they are consumed in very low concentrations for long periods of time. And what are the consequences of consuming a mixture of these compounds? Are there synergistic effects, where a mixture can be more potent than the individual compounds separately? Sort of a “The whole is greater than the sum of the parts” scenario? Again, unfortunately, no one knows; even less, if any, data exists on this subject. So should we treat the water we drink for these compounds or not? There’s no easy answer, but maybe looking at what happens when we treat the water will help.
Treatment
The treatment techniques for dealing with EDC’s and PPCP’s in wastewater and drinking water are pretty much the same. They consist or reverse osmosis to remove them, or oxidation to break them apart. Oxidation can consist of the traditional technique of adding chlorine, or what’s known as advanced oxidation.
Reverse osmosis consists of using pressure to force the water through a membrane. In theory, the water passes thru and everything else remains behind and is filtered out. But in practice, only some or most of the impurities are filtered out; others pass through the membrane and remain in the water, so it’s only a partial solution at best. In addition, the impurities that are filtered out are still there in a very concentrated form that has to be disposed of by dumping it in the ocean or injecting it into a deep well. Since the EDC’s and PPCP’s still get dumped back into the environment, maybe this is really no solution at all.
Oxidation by chlorination is a common practice well established in the industry and used for many years both to treat for certain impurities and to disinfect the water. However, when it comes to EDC’s and PPCP’s, it does only a very limited job, leaving many of these compounds intact.
Advanced oxidation involves adding ozone or peroxide to the water, then subjecting it to high intensity UV light. This two step process is very effective at breaking chemicals of almost any sort into smaller pieces. But the key thing to remember is that it does not make them disappear; it does not reduce them all the way to their atomic constituents; it simply breaks large molecules into smaller ones. The resulting smaller pieces are still present in the wastewater effluent or drinking water that has been treated. What are those smaller pieces? Are they harmful, either to people or organisms in the environment? Are they more or less of a problem than the chemical compounds we started with? Once again, we have to say we just don’t know, because we don’t even know what smaller molecules we are producing in most cases, much less anything about how they react with humans or the environment.
One chemical that has been studied a bit is carbamazepine, and how it breaks down when subjected to advanced oxidation. The researchers had the following observation in regard to this process:
“The three (breakdown) products were determined to be 1-(2-benzaldehyde)-4-hydro-(1H,3H)-quinazoline-2-one (BQM), 1-(2-benzaldehyde)-(1H,3H)-quinazoline-2,4-dione (BQD), and 1-(2-benzoic acid)-(1H,3H)-quinazoline-2,4-dione (BaQD)…Currently, there are no data available on the biological effects of the formed oxidation products.” Ozonation of Carbamazepine in Drinking Water: Identification and Kinetic Study of Major Oxidation Products Derek C. McDowell,, Marc M. Huber,, Manfred Wagner,, Urs von Gunten, and, Thomas A. Ternes, Environmental Science & Technology 2005 39 (20), 8014-8022
So, the major issues can be broken down into two questions. First, should we treat for EDC’s and PPCP’s in wastewater to protect the environment? The effects of these compounds on the environment are known and demonstrated, so maybe we should. The risk does remain that we could be creating a bigger problem because we don’t know the effects of the new, smaller molecules we are creating in the treatment process. So in addition to treatment, we should implement extensive environmental monitoring. Second, should we treat for these compounds as a part of the drinking water treatment process? There are no known toxicological effects of these compounds on humans, and we have virtually no information on what the breakdown products from treatment even are, much less their toxicity, so maybe we shouldn’t treat drinking water this way. Of course, if we treat wastewater effluent and discharge the breakdown products into the environment, they will eventually find their way into our drinking water (remember the whole water cycle thing), but they could be attenuated by natural processes in the environment before becoming drinking water. That’s something else to carefully monitor.
There are definitely no easy answers to this complex issue. The worst thing that we could possibly do is rush toward regulations and treatment regimens that we have no idea are required, could possibly cause more harm than good, and would substantially increase everyone’s water bills. If you would like more information on this subject, a good place to start is the EPA website at http://www.epa.gov/ppcp/
