Drinking Water (17 page)
D
ANGEROUS CHEMICALS IN OUR WATER ARE NOT MERELY CONFINED
to poisons such as arsenic and cyanide. Recently, evidence has mounted that some chemical contaminants may disrupt the development of humans and animals by fooling our endocrine system. The endocrine system controls the production and release of hormones, the chemical signals that regulate critical aspects of our development and behavior. Crucial to the development of the fetus and the young child, hormones are, in certain respects, as important as genes in determining physical and psychological characteristics. Endocrine disruptors, a class of synthetic compounds, are able to mimic hormones and potentially interfere with the endocrine system and sexual development.
About fifty chemicals have thus far been shown to have the capacity to act as endocrine disruptors. Research has linked
endocrine-disrupting chemicals to adverse effects on sexual behavior, structural deformities in the reproductive tract, lowered sperm counts, and atypical sex ratios in populations of wildlife. These studies suggest such chemicals can also harm the immune systems and perhaps even change the behavior of certain wildlife species. Chemically stable and difficult to remove with conventional drinking water treatment methods, endocrine disruptors’ presence in our drinking water and likely impact on human populations are highly disputed.
What makes endocrine disruptors particularly worrisome is that they behave contrary to basic assumptions about toxicology. The working premise of toxicology is that “the dose determines the poison.” A drop of chlorine in a tank of water can make it safe to drink by killing microbes. Drinking a cup of chlorine will kill you. The more exposure to a pollutant, the greater the impact. The very mechanism of hormones, however, relies on minute exposure at particularly sensitive times—tiny amounts at precise periods can lead to gross developmental changes. In contrast to traditional assumptions, this is a nonlinear relationship—a small amount may be enough to cause major developmental change—and it suggests that we should be concerned about trace amounts of endocrine disruptors, particularly when ingested by pregnant women (because of the fetuses they carry) and growing children. The development of both a fetus and a young child is critically regulated by hormonal levels. The concern is that synthetic hormones will disrupt this process.
In the Great Lakes, for example, certain species of fish as well as eagles, gulls, and cormorants are all showing increased birth defects and other harm that some scientists have linked with the high level of PCBs (polychlorinated biphenyls, used for electrical transformers and coolants), dioxins, and other persistent organic pollutants in the ecosystem. Researchers have suggested the decline in beluga whales in the St. Lawrence Seaway is likely related to the high levels of such compounds found in their bloodstream. One beluga whale had levels of PCBs in its body ten times higher than the level necessary to qualify as a hazardous waste under Canadian law. Albatross living on remote Midway Island in the center of the North Pacific also carry
heavy loads of persistent organic pollutants and display symptoms consistent with exposure, including eggshell thinning, deformed embryos, and a drop in nest productivity. These birds are believed to be contaminated by DDT coming from the coast of Southeast Asia, where it is still widely used for controlling mosquitoes and crop pests.
Troubling data have demonstrated the presence of so-called intersex fish—fish that show both male and female characteristics —in rivers and bays in many parts of the country. Alligators exposed to a pesticide (dicofol) in Florida’s Lake Apopka—a freshwater lake about 125 square kilometers in size—have suffered severe damage to both male and female reproductive organs. In many cases the linkage to specific endocrine disruptors is still debated, but the body of circumstantial evidence is growing. Trace amounts of endocrine disruptors have been detected in drinking water sources, but does that make the water unsafe to drink?
Others are concerned about levels of pharmaceuticals and personal care products in our drinking water. Millions and millions of people ingest pharmaceutical products every day of the year, drugs treating a dizzying range of conditions from cancer, arthritis, bacterial infections, and hair loss to blood pressure, depression, and high cholesterol. These drugs are specifically designed to change our bodies’ chemistry, so their presence in the water we drink has caused alarm in some quarters. And these drugs are surely present in our water. A 1999 study by the U.S. Geological Survey identified eighty-two contaminants, many of them pharmaceuticals and personal care products, in 80 percent of the streams they sampled in thirty states. A 2006 Geological Survey study of private wells was similarly eye-opening. In a widely publicized study, the Associated Press documented the presence of fifty-six pharmaceuticals or their by-products in treated drinking water, including in the water of metropolitan areas supplying more than forty million people across the nation. But how do the drugs get in the water?
The dominant contributor seems to be us. Despite warnings against the practice, many people flush unused drugs down the toilet. We contribute unintentionally, as well. When we take a pill, our bodies metabolize some of the active ingredients but not all.
The remainder are excreted and flushed down our toilets, making their way through sewers and treatment plants into the environment and, eventually, drinking water sources. Most treatment plants are not designed to remove drug residues, and few actually test for their presence. Nor is this only a concern in highly populated areas. Drugs given to cattle make their way into water tables in agricultural areas, as well. Studies have shown high levels of steroids and antibiotics near cattle feedlots.
There are no regulations requiring testing for the presence of pharmaceuticals in drinking water or limiting their concentration. The Associated Press study contacted sixty-two major drinking water providers. Twenty-eight of those, just under half, tested for drugs in water. Those not testing included facilities serving some of our nation’s largest cities—New York, Houston, Chicago, and Phoenix.
Should we be concerned? Dr. David Carpenter, director of the Institute for Health and the Environment of the State University of New York at Albany, states the fear factor in plain terms: “We know we are being exposed to other people’s drugs through our drinking water, and that can’t be good.” A review of the literature in a peer-review scientific journal hedged its bets: “Water scarcity, climate change, aging and increasing population density, increasing use of pharmaceutical products, and rising dependence on water reuse may lead to an increase in the presence of pharmaceuticals in groundwater, surface water, and drinking water in the near future that might pose a risk to water safety or an exacerbation of perceived risk.”
As with arsenic, however, the question is whether the levels present are high enough to cause harm or simply perceptions of harm. Scientists tell us that the concentrations are extremely low—sometimes in parts per billion or even parts per trillion. This is far, far below the level of a prescribed medical dose. Nor are there any documented cases of pharmaceutical traces in drinking water leading to harm in people drinking that water.
The EPA refers to these chemicals and others as “emergent contaminants.” The risk may be real, but it is largely unknown. Christian Daughton, one of the EPA’s leading authorities on the topic, explains the safety dilemma well: “Scientists have only recently become able
to detect contaminants at the extremely low levels at which drugs appear in water supplies—typically, around one part per trillion. You’re at the outer envelope of toxicology. Historically we’ve worried about substances like pesticides that are present in much higher concentrations. It’s also very hard to study effects at that level because the doses are so small, and the effects are subtle and delayed.”
Our scientific progress has created two sorts of problems. The first, seen with endocrine disruptors and pharmaceuticals, is that we are introducing compounds into our environment and drinking water sources that quite literally did not exist decades ago. We are creating risks that have never existed before. So how can we assess the unknown? The second problem, ironically, is that our detection capability has dramatically improved. We can now identify traces of pollutants at excruciatingly tiny levels, at parts per billion and some even at parts per quadrillion. It’s worth pausing to consider this awesome power of detection. One part per trillion is the equivalent to one drop of water diluted into twenty Olympic-size swimming pools. It seems hard to believe that such trace amounts could harm us.
But we can’t say for sure. Our progress in detection of harmful compounds has not been matched by equal progress in our ability to link the presence of these compounds at very low levels with the actual risks they pose to us. Toxicology and epidemiology studies often rely on data from animals that have been exposed to or ingested massive amounts of the compound being studied. Making these results meaningful in the everyday human context requires three significant extrapolations: (1) from mice or other test animals to humans, (2) from mega-doses the control animals were exposed to the trace levels that we ingest, and (3) accounting for differences among humans exposed to the compound (e.g., adults versus children). These all require significant assumptions and modeling. If you read somewhere that a level of fifty parts per billion of some compound in our drinking water will lead to ten, twenty, or any specific number of cancers or deaths, then you are not getting the whole story. Any responsible risk assessment will result in a range of impacts depending on the specific assumptions within the model. Moreover, it may well be that some of the contaminants we are detecting at smaller and smaller levels
are not new problems. They may have been in our water for decades.
But people are concerned, and they may have good cause. The number of synthetic compounds in the environment is steadily increasing. If public demand and scientific data grow strong enough, then government action may follow and some of the compounds will be regulated, but this is by no means a given. Keep in mind, as well, that removing truly trace amounts of compounds from drinking water will not come cheap. The combination of treatments used in the hightech treatment works of Orange County, California—ultraviolet light, reverse osmosis, and peroxide—appear to effectively remove emerging contaminants. But this is a cutting-edge and costly approach. Traditional treatment methods will not be nearly as effective, so more than a general unease may be needed to justify such expenditures to a public unwilling to spend much on water treatment in the first place.
Nor is there reason to think that our laws will address this situation any time soon. The Safe Drinking Water Act is the primary law safeguarding the water we drink. The law works in three steps. The first is to decide “what’s in and what’s out,” which contaminants the law will regulate and which will remain outside legal control. The EPA is supposed to assess the risk posed by contaminants and their likelihood to occur in public drinking water systems. For those posing the greatest risks, the agency sets maximum contaminant level goals (MCLGs)—the highest concentration of the contaminant in water that allows an adequate margin of safety. For many contaminants, such as microbes and carcinogens, this number is zero. It may not be practical to eliminate these contaminants, though, so in the second step, the EPA then sets a maximum contaminant level (MCL). This is the practical standard, and it is as close to the MCLG as feasible, given technology and cost limitations. In the third step, the agency carries out a risk assessment and considers the costs to achieve the mandated reduction. The final level can then be modified to a level that “maximizes health risk reduction benefits at a cost that is justified by the benefits.”
Put simply, if the presence of a regulated contaminant in a drinking water sample does not exceed the MCLs, then drinking water from our tap is legally determined to be safe. The EPA is supposed
to periodically reevaluate the stringency of the standards, revising them in light of new data and considering new contaminant candidates to add. The EPA’s obligations do not extend to private well water, which supplies more than forty-five million Americans.
Since its passage in 1974, the Safe Drinking Water Act has regulated ninety-one contaminants. That sounds impressive until one realizes that more than sixty thousand chemicals are used within the United States, and the number is growing. Moreover, since the year 2000,
not a single chemical
has been added to the list. Indeed many of the standards for chemicals that are listed have not been revised since the 1980s or 1970s, when the law was first passed. As a result, the director of water quality for the city of Los Angeles, Dr. Pankaj Parekh, has explained, “People don’t understand that just because water is technically legal, it can still present health risks.” Given this track record, it seems unlikely that the new generation of water pollutants—endocrine disruptors and pharmaceuticals— will be addressed by the law anytime soon.
And even if these compounds are regulated, the law still needs to be enforced and this is by no means a given. A major investigative study by the
New York Times
in 2009 reported that more than 20 percent of the water treatment systems across the country had violated key provisions of the Safe Drinking Water Act over the past few years. Yet only a handful of these systems, a mere 6 percent, had been fined or punished by state or federal officials. Part of this meager enforcement record is due to inadequate funding, but part of it is institutional. Most water treatment systems are operated by local government, and the lion’s share of violations occur in the smaller systems, those serving fewer than twenty thousand residents. This should not be surprising, since it is at these smallest systems where resources for testing and maintenance are smallest, as well. As Professor David Uhlmann, former chief of the Environmental Crimes Section at the Department of Justice, explained, it is difficult for one arm of government to sue the other: “There is significant reluctance within the EPA and Justice Department to bring actions against municipalities, because there’s a view that
they are often cash-strapped, and fines would ultimately be paid by local taxpayers.”
