Naphthalene. Hexachlorobutadiene. Deisopropylatrazine. These are just a few intimidating chemical names that don’t exactly trickle tastefully off the tongue. Born out of natural geophysical processes, the Industrial Era and subsequent technological advances, these chemicals have made American commerce possible, but at the expense of our health, our environment, and our water.
Federal organizations like the U.S. Environmental Protection Agency and the U.S. Geological Survey are doing their best to monitor the contaminants in our water, but some experts say their methods may be too presumptuous and the list of chemicals too vast. Chemical Abstracts Service, which provides the largest collection of chemical substance information available, has just added the 50 millionth unique chemical to its inventory.
According to Simon Litten of New York’s Department of Environmental Conservation (NYDEC), the cost of managing every chemical permutation in the environment would be financially prohibitive. “There’s just this huge number of chemicals out there and the number we’re looking at is very small relative to the number of potential substances that we would want to measure,” he says. The only recourse is to whittle the list down and focus on curtailing the chemicals that seem the most threatening.
As a part of an initiative to monitor a few of the contaminants in our water, the USGS recently sampled untreated water from 932 public wells across the nation, from which over 1/3 of the U.S. population receives its drinking water. Of the 337 contaminants analyzed in this study, 278 are currently unregulated, which means that water utilities are not required to eradicate them in the disinfection process that produces the water we drink.
The chief scientist of this study, Patricia Toccalino, says that of all the untreated water samples drawn, over 20% had at least one contaminant at levels above human health benchmarks. Even after treatment, the contaminant levels in 94 wells remained similar. “The occurrence of organic contaminants in both source and finished water at similar concentrations indicates that commonly used disinfection practices (treatment) do not reduce concentrations of many organic contaminants. Because disinfection is not designed to treat organic contaminants…the frequent occurrence of these organic contaminants in finished water is likely, although usually at concentrations less than benchmarks [sic],” according to the USGS.
How can the EPA and the USGS know where to draw the line, or develop a “benchmark,” between safe and unsafe chemical concentrations?
Take, for example, the insecticide dieldrin, which the EPA categorizes as a probable human carcinogen. Dieldrin, which is an unregulated contaminant, has been implicated in liver and central nervous system problems, and has been found in the brain tissue of post-mortem Parkinson’s disease patients.
According to Toccalino, dieldrin was one of those chemical miscreants that jumped to the top of the list in her study, having exceeded its benchmark in at least 1% of untreated water samples. “It’s unregulated, but it’s been banned since 1987 and we’re still finding it because it’s a persistent contaminant in the environment, which just means it doesn’t break down very quickly,” says Toccalino.
Dieldrin’s benchmark is .002 micrograms per liter. So, if you have some groundwater in a bucket and it happens to contain .003 micrograms per liter of dieldrin, this concentration would be considered toxic to human health. Dieldrin’s benchmark is determined by an equation that factors in the contaminant’s toxicological data from the lab and assumes that a 154 lb person consumes an average of 2 liters of water per day. If the chemical is carcinogenic, the equation also factors in a risk value pertaining to the degree to which people should be protected against a lifetime chance of developing cancer.
Simon Litten says that the creation of benchmarks is in some sense an arbitrary process, but that benchmarks have proven a viable starting point in the race against contaminants. “It became a really useful compromise in that you can make lab methods and investigate these substances, where they’re coming from, and their fate in the environment,” says Litten.
However, he says, “We are better at measuring chemicals than knowing what they mean.”
Litten says part of the problem with developing these benchmarks is that the inherent priority is protecting people against the risk of contracting cancer to the degree that we would like to be protected. A poll conducted by NYDEC found that people generally want to be protected against the one in a million chance of developing cancer. “It’s like asking a rabbi how much pork he wants to eat,” jabs Litten, quick-wittedly. “You know! None!”
Even so, there’s a notion that a single molecule of a carcinogenic chemical in the right place at the right time under the right conditions, is enough to trigger a biological sequence of events that inevitably results in cancer, says Litten. “There is no minimum level below which the substance is totally safe, so even extremely low concentrations have a possibility of having a harmful effect,” says Litten.
Litten thinks that we may be approaching the problem from a futile angle, and he’s been pondering a seemingly more viable alternative. Essentially, his idea is that instead of measuring the individual concentrations of x number of contaminants in this bucket of water, why not find a way to determine the toxicity of the sample as a whole? “It’s not necessarily a slam-dunk because there are a lot of different types of toxicological responses,” he says, but simply changing our thinking might lead to a more productive means for monitoring water quality.
Or, maybe the more fitting place for chemical regulation would be in commercial industries, before contaminants even have the porous opportunity to make their way into our source water. The REACH program (Registration, Evaluation, Authorization, and Restriction of chemical substances), which has been in effect in the European Union since June 2007, requires that all chemicals used in any manufactured item for sale in the E.U. have to be registered and demonstrated to be safe. “This imposes the regulatory burden of evaluating all [these chemicals] on the supply chain,” says Litten.
Image: Locations of the 932 public wells (blue dots) sampled in this USGS study.