Miss those chemistry experiments in high school? Well then it’s time to wax nostalgic because you're participating in one right now: chemical compounds found in everyday products like pharmaceuticals, shampoos, sunscreens and plastics are working their way into our air, water and land, and we have little idea what the implications might be. What we do know about these “emerging contaminants” – pollutants that pose a real or perceived threat to human health or lack a published health standard – is that some are endocrine disruptors or can cause cancer. For humans and wildlife, the effects of long-term, cumulative exposure to even low levels of these chemicals remains unknown.
Even more distressing is that new chemical compounds are constantly entering the marketplace. Here’s the scorecard: there are over 80,000 known chemicals on the market, the EPA has required full toxicity testing for only 200 of them, and just five are regulated by the agency. At least when it comes to the nation’s water resources, some scientists are beginning to take a chemical inventory.
Under the Clean Water Act, the EPA creates water quality criteria based on uses like swimming, fishing or drinking. If the levels of a particular pollutant are too high for you or me to go into a river that’s been designated as “swimmable,” then the sources of those pollutants have to be found and addressed so that we can safely enjoy a refreshing dip. These levels, often based on individual contaminants, comprise what the EPA calls the “ambient water quality criteria.” There are particular sets of criteria to protect fish and other aquatic life called, appropriately enough, “aquatic life criteria.” These criteria exist for better-known contaminants like MTBE, lead and arsenic, but with the chemical and pharmaceutical industries furiously cranking out new compounds for the market, it’s hard for regulators to keep up.
Several recent studies have shed a little light on the new chemicals that are washing off farms, out of industrial plants, down our toilets and into our waters, and the results are troubling.
Rainer Lohman, a chemical oceanographer at the University of Rhode Island, tested for three different emerging contaminants at sites throughout Narragansett Bay and found them…everywhere. So now we know that a major American estuary is being injected with triclosan, alkylphenols and PDBEs (found in flame retardants) – all of which pose risks to humans and wildlife, and all of which are poorly regulated.
As Lohman explains, those three contaminants are just the beginning: “We know there are hundreds more out there. The totality of all those compounds together is what may be worrisome.”
Each of the three contaminants were detected at low levels, certainly not enough to raise alarms about swimming in or eating fish from Narragansett Bay. But as Lohman indicates, the cumulative effect of hundreds of different synthetic compounds entering water bodies is alarming.
The concern is shared for the Great Lakes, the drinking water source for 40 million people. Unlike coastal waters that are “flushed” by tides and currents, some of the Great Lakes can take a century or more to flush away persistent contaminants. That makes a recent Alliance for the Great Lakes review of emerging contaminant data particularly troubling. Just as in Narragansett Bay, studies have found numerous poorly-understood contaminants including flame retardants, pesticides, triclosan, DEET and BPA throughout the Great Lakes. Again, many of these contaminants have documented impacts on aquatic life, and few are regulated.
The danger of emerging contaminants in our waters isn’t from inadvertently wading into a hypothetical glob of chemical compounds, but rather it’s the unknown impacts of persistent, low level and multiple exposures. As most fish lovers are aware by now, toxins work their way up the food chain - like mercury in top-level predators such as tuna. The big unknown here is how low levels of exposure to emerging contaminants might impact base-level fish species, and whether these contaminants will bioaccumulate and reach us apex-level predators as we dig into our favorite freshwater or saltwater fish.
In fact there are few studies that have looked into the potential relationship between emerging contaminants, human health issues and impacts on fish and other aquatic organisms. We might understand how some individual chemicals impact aquatic life in controlled lab experiments, but we don’t fully understand how these different chemical compounds might interact with each other in the environment, how they might break down over time or even how they might affect humans or wildlife over the long term.
The good news is that the USGS is sponsoring research into emerging contaminants, and the EPA and the states are beefing up their monitoring programs. The bad news is that, perhaps predictably, some members of the current Congress have labeled additional research into chemical toxicity a “job killer.” And, to be honest, we still struggle to properly regulate the exposure to humans of well-understood toxins like mercury and PCBs in fish.
But even a rapidly growing list of potentially harmful chemical pollutants is not an unsolvable problem. For example, the Alliance for the Great Lakes has a clear three-point call-to-arms: more chemical research, new technology to remove more contaminants via wastewater treatment and marketplace behavioral changes and policy reforms. Some of these ideas are already being implemented, like pharmaceutical take back programs and water and wastewater treatment plants that are able to remove several different emerging contaminants. By combining a better understanding of what’s entering our waters with green chemistry efforts to keep the toxicity of new chemical compounds in check, maybe we can stop treating our waters as part of a grand chemistry experiment gone awry.