It's difficult to draw lines of cause and effect between exposure to endocrine disruptors and human disease or disorder because people are exposed to so many chemicals from so many sources over many years, and because some effects may take years or decades to manifest themselves. But an increasing number of researchers are finding strong correlations between the massive increase in synthetic environmental contaminants produced since World War II and such health problems as cancer, declining sperm counts in male humans of all ages, increases in birth defects and diabetes, and flawed fetal development.

 Of course, humans aren't exposed to the chemicals in effluent in the same way that Boulder Creek's white suckers are; we aren't swimming in the water 24/7. And by the time a creek, or the Colorado River, enters our faucets, the loads of trace organics poured into it from treatment plants upstream have been significantly reduced. Natural processes, such as degradation by ultraviolet light and the action of microbes, do remove some chemicals from stream water, while others chemically bind to sediment particles. But the intensity of water use in the West means that, in many river systems, water is taken in for further municipal use before natural cleansing mechanisms can do their full work.

 "Our rivers and lakes do clean water, especially if they have long stretches between communities using it," says Colborn. "But we've exceeded their carrying and assimilation capacity."

 That's especially true, Colborn says, because so many sources contribute to the loads of trace organic compounds carried by streams and rivers. While wastewater treatment plants are perhaps the largest single sources, leaching from septic systems, runoff from car washes and feedlots, leakage from sewage pipes, and overflows from water-intensive natural gas drilling all contribute doses.

 When surface water is taken in for municipal use, it is treated with filtration and disinfection treatments that significantly reduce contaminant concentrations. But low concentrations of some compounds - often in the parts-per-trillion range - do remain to make their way into drinking water.

 Some water experts argue that the amounts of endocrine disruptors people ingest in water are insignificant compared to those we get from other sources - plastic containers, foods, soaps, cosmetics, and many other products.

"In terms of relative risk, the risk from drinking water is minuscule," says Kim Linton, senior account manager at the Denver-based American Water Works Association Research Foundation. "For example, DEET is one of the most persistent of these trace compounds. Are people more likely to get sick from West Nile virus or from trace levels in the water? Are they going to stop spraying themselves?"

No, most probably won't. But some biologists argue that the cumulative effects of endocrine disruptors make it imperative to reduce their concentrations anywhere possible.

"You would have to drink incredible amounts of the water to amount to an effect that these chemicals naturally have," says David Norris. "But adult humans are getting estrogenic compounds from an incredible number of sources. So any amount we get from water will add to that, since these chemicals have additive effects.

"If wastewater is my only source of estrogenic compounds, I'm not going to worry about it. But if I'm also getting them from my water bottles, from my personal-care products, etc., then maybe that's just enough to push me over the edge into prostate cancer or breast cancer. There's a lot of circumstantial evidence in humans that is supported by experimental work in mice and rats that suggests that this may be a much bigger problem than a few intersex fish below a wastewater treatment plant."

The water-processing system has to balance needs and costs. People may choose to lower the quantities of trace organic compounds they ingest with their water, but they're going to have to pay to do so. And that means they'll have to consider how the risk represented by these chemicals stacks up against others.

"What's more risky, bridges falling or the water you drink?" asks Linton. "The utility folks are out there prioritizing what to spend money on. They may need to focus resources on putting a new pipe in rather than on removing a minuscule level of contaminants. There's a cost associated with all these things."

If consumers do decide they want to lower their exposure to trace organics, though, then water-reuse projects of the sort San Diegans have rejected, for now, may be a good way to go. Such projects are expensive, but they have the virtue of providing dual benefits: concentrations of contaminants that will probably be as low as feasible, and a reliable flow.

Still, there are going to be cases where no amount of investment and public outreach will suffice to assuage public concerns, where the arguments about what's healthy and appropriate touch on realms even more abstract than parts per trillion, and less quantifiable than the yuck factor. One of the flashpoints in proposed reuse projects, for example, is the San Francisco Peaks, a small mountain range in northern Arizona. The owners of the Arizona Snowbowl want to make artificial snow using treated municipal wastewater purchased from the city of Flagstaff. The Snowbowl's skiing seasons have been abbreviated in recent dry winters, and artificial snow would instill an element of predictability in what has been a highly unpredictable business.

But the idea provoked outrage from environmentalists and from members of Southwestern tribes, many of which consider the San Francisco Peaks sacred. The Hopi, for example, see the Peaks as the home of the Kachinas, deities who bring water; to traditional Hopis, making artificial precipitation there is profoundly sacrilegious.

 It is offensive to many Navajos, too. Klee Benally, the son of a traditional healer, has become a leading activist in the Flagstaff-based Save the Peaks Coalition. Benally argues that the source of the water - its history, in other words - renders it incompatible with traditional spiritual uses of the San Francisco Peaks, from the gathering of medicinal plants to a holistic view of the entire mountain range as a sacred site.

 "We have standards that the EPA could never match," he says. "To have the water coming from hospitals, from morgues, from industry - no matter the process of reclamation, it could never be clean enough to meet those standards from the Navajo perspective. Wastewater would contaminate the entire ecosystem, the entire spiritual purity of the mountain. It's like getting a shot of something: The needle affects only a tiny, tiny area, but the medicine affects your whole system. We couldn't restore it back to its natural state after that contamination occurred."

 The Forest Service, which leases use of the ski area to the Snowbowl, approved the artificial snow proposal; a coalition of tribes and environmental groups sued and lost in U.S. District Court. But in March, a three-judge panel of the 9th Circuit Court of Appeals agreed with the coalition and denied the snowmaking request, writing that the Forest Service had inadequately assessed how the use of reclaimed wastewater might affect both tribal religious practice and the health of skiers exposed to artificial snow. The U.S. Department of Justice, on behalf of the Forest Service, and the owners of the Snowbowl have asked the Court of Appeals to reconsider that ruling.

 There may not be many places where the potential use of reclaimed water arouses quite as much passion as on the San Francisco Peaks. But the yuck factor will surely continue to be an issue water managers have to contend with. It seems to have deep roots in human history and perception, after all, and perhaps will be overcome on a wide scale only when it collides head-on with another deep-rooted but not always accurate Western perception - namely, that the water will always be there.

Already, as the West's drought continues, California is looking for new means of conserving water. This summer, the San Diego County Water Authority, citing concerns about the reliability of future deliveries from the State Water Project, began a campaign that urges each of its customers to use 20 fewer gallons of water a day.

The campaign is voluntary, but it may help drive home the message that external water supplies aren't assured - and that recycling may be a reliable way of ensuring that at least some water remains available. After all, people do keep showering, and flushing, and drinking their coffee, no matter how little runoff the Rockies or Sierra Nevada produce in a given year.

"Now that we're going into a dry-year cycle, we're seeing the acceptance of water recycling go up," says the water authority's Maria Mariscal. "Nothing gets the public's attention like a drought."

Peter Friederici teaches journalism at Northern Arizona University in Flagstaff. His latest book is Nature's Restoration (Island Press, 2006).

This article was made possible with support from the William C. Kenney Watershed Protection Foundation and the Jay Kenney Foundation.

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