Have you ever wondered what makes anti-bacterial soap anti-bacterial? What really happens to all of those household products once they disappear down the drain and where do they end up? The answer might surprise you. Common household products like soaps, shampoos, prescription and non-prescription medicines get flushed down the drain in millions of homes and businesses every day. Our bodies metabolize some pharmaceuticals, but others are excreted, unchanged, in our urine. As consumers, we take for granted that the products we purchase for household use can be used and disposed of safely without any special considerations. For the most part, that’s true. We consume thousands of products every day which are successfully disposed of without impacting the environment, but some include ingredients that are not completely eliminated or decomposed during their trip down the drain.
"Unlike the current list of regulated contaminants, these compounds have little or no long-term health and environmental data on which to rely."
These new chemicals, not included in routine environmental monitoring, are now drawing increased attention from regulators and scientists alike. Labeled as emerging contaminants because of their relatively recent addition to the rolls of possible environmental pollutants, these compounds represent a different category of chemicals versus the industrial pollutant we’ve seen in the past. Their surprising prevalence in the environment has prompted researchers to give them their own class entitled “Pharmaceuticals and Personal Care Products” or PPCPs for short. What are the possible environmental and health risks of PPCPs? It is too soon to tell for sure, but what we do know is that some of these chemicals exhibit traits that allow them to successfully migrate through the ecosystem unaltered, an alarming characteristic when we consider a toilet-to-tap scenario. A logical question would be: if they’ve made it this far, how much farther might they go?
It is now necessary to have the ability to analyze for unique classes of chemical contaminates in addition to those historically identified, and at lower and lower levels
One of the inherent risks associated with PPCPs is their widespread use and unregulated discharge into the environment. We generally don’t take into consideration how much soap we’re using when we wash our hands or how much insect repellant we might be spraying around. It might be safe to say that, due to their use as personal care products, their acute risks have already been assessed and they have been deemed safe for their intended use. We know that the pharmaceuticals are safe for us at the prescribed dosages, but some of these compounds are exceptionally bioactive. We know that many of these compounds pass through sewage treatment plants unchanged, so they are discharged into lakes, rivers, and streams. What is not known is their ultimate transport and fate in the environment and their impact on organisms and ecosystems.
It should come as no surprise how little we know about PPCPs. The sheer number of compounds that we might have to consider is huge. Between 2005 and 2006 over 500 new products were introduced to the market in the antibacterial category alone. With their comparatively rapid emergence onto the stage, there has been little opportunity to develop comprehensive insight into their characteristics. Unlike the current list of regulated contaminants, these compounds have little or no long-term health and environmental data on which to rely. Researchers do not know for sure how they will act in the environment and whether or not they will be able to persist for long periods and, if so, whether they will bio-accumulate. The breadth of compounds in this group can be staggering, including such compounds asTriclosan (from anti-bacterial soaps), DEET (the active ingredient in insect repellants), or Bisphenol A (a plasticizer found in plastic bottles) just to name a few. It should be obvious from reading labels that our consumer products make use of a vast array of chemical compounds. While some may be innocuous or degrade rapidly on use, others don’t and it’s the latter that we will need to be able to identify and then develop meaningful long-term risk assessments. Figuring out how to accurately assess a compound’s potential for long-term harm will also require significant work given that, as in the case of other contaminants, it could be years before we have empirical proof. Another significant undertaking will be to establish background data for use in bio-accumulation evaluations in light of the typical use that these products see. If we are liberally applying these on almost a daily basis, will we be able to differentiate between that and ingestion?
"One of the inherent risks associated with PPCPs is their widespread use and unregulated discharge into the environment. "
There are many other examples where our use of chemicals for beneficial purposes has resulted in unintended consequences. One class of pollutants of particular concern are those that are able to persist in the environment. These compounds, commonly referred to as “Persistent Organic Pollutants” or POPs, have captured special attention from researchers and regulatory agencies due to their relative toxicities and their ability to persist for long periods in the environment (the "organic" reference in Persistent Organic Pollutants speaks more to their chemical composition as Carbon and Hydrogen containing compounds than to their origination as naturally occurring compounds). Organic compounds with the ability to survive unaltered in the environment present distinct problems from an environmental risk standpoint through the increased opportunity for prolonged exposure. If the chemical has the opportunity to persist within an ecosystem it might then accumulate into the top of that system’s food chain through bio-accumulation and potentially amplify its toxicity.
Bio-accumulation is not a new phenomenon. As early as 1964 Dr. Soren Jensen, a Swedish researcher, encountered a contaminant that would help bring the subject of POPs and bio-accumulation into the spotlight. During his research into the presence of DDT in blood samples, Dr. Jensen encountered an as yet unknown contaminant interfering with his analysis. He recognized he was seeing something new, without realizing that he was, in fact, encountering the emergence of one of the most significant chemical contaminants of the 20th century. He found the unknown constituent to be so pervasive that he was able to detect it, not only in the blood samples he had collected, but also in wildlife specimens collected almost thirty years earlier in 1935. In addition, he was even able to detect this unknown contaminant in hair samples taken from his wife and children. Ultimately, the unknown compound was characterized as belonging to a group of chemicals called Polychlorinated Biphenyls or PCBs. His research on PCBs in pike, published in 1966, detailed the bio-accumulative effect that PCBs had on the environment and showed how animals at the top of their food chain could accumulate and store high concentrations of these contaminants.
" Armed with a growing database of information, researchers may find they have adequate evidence to predict a possible crisis before it happens."
When DDT was sprayed in populated areas for mosquito control, and when PCBs were used in electric transformers, no one anticipated that they would become globally distributed. No one anticipated that they would be dispersed worldwide through the atmosphere. No one anticipated that they would appear in breast milk, contaminate the food source of Inuit tribes, or threaten the brown pelican with extinction; but all of these happened.
It’s clear that we will face long-term problems when it comes to environmental contaminants. What isn’t clear is how bad those problems might be and where they will come from, so it will be important to develop technologies and processes that enable early detection of contaminants and give researchers an opportunity to develop sound estimates for targeting those posing the most significant risk. Armed with a growing database of information, researchers may find they have adequate evidence to predict a possible crisis before it happens. Another challenge will be for the scientific community to keep pace with the evolving nature of these emergent classes of compounds specifically as new products are developed and find widespread use. New methods and techniques will most likely be needed to provide sufficient information on their identification and concentrations. It will be too easy to lose ground as their sheer numbers and diversity outstrip our ability to adequately respond using current methodologies. Lastly, education will become increasingly important once we identify contaminants and their sources and determine suitable mechanisms to control their introduction into the environment. Education and awareness may provide us with the insight to limit the potential impact to our environment by controlling or minimizing how we use these products.