cancer. The concern has recently broadened to include chemicals, such as alkylphenol ethoxylate, that have produced apparent estrogen effects in fish (see Chapter 2). Endocrine disrupters are specifically identified for evaluation of health impacts in the latest reauthorization of the Safe Drinking Water Act. A potentially important issue for potable use of reclaimed water is that chemicals producing endocrine disruption have been associated with municipal wastewater effluents (Sumpter, 1995).

Implications for Future Safety Testing

The Denver and Tampa studies found no signs of significant adverse effects of consumption of reclaimed water. However, two sets of data drawn from two discrete points in time and conducted at a pilot plant level of effort provide a very limited database from which to extrapolate to other locations and times.

If these data are inadequate, what more should be done? Clearly the approach taken in the Tampa and Denver studies does more to establish safety than other studies have. However, there are several reasons to believe that such testing will always be less than satisfactory.

One critical problem is with the preparation of the water sample to be tested. As long as the sample can be considered less than fully representative of the chemical constituents in the source water, the testing can be criticized as incomplete. As discussed in Chapter 4, organics are concentrated both to increase the effective dose for testing purposes and to separate inorganics that might dehydrate the test organisms. But the processes that concentrate the organics may create reactions that remove or add chemical compounds, thus changing the mixture of chemicals. So far we have no reliable way to verify how well a sample represents the water from which it is derived. As explained in Chapter 2, certain chemical characteristics can be used to describe the nature of the organic chemicals in water. It is possible that a confirmatory procedure could be developed that would (1) verify the consistency of the chemical characteristics of samples produced and (2) verify that the process of concentration did not cause chemical components of the mixture to react and change. Developing such a procedure would require a very significant research effort.

Another major issue is the expense of completing an adequate safety evaluation. Cost estimates should consider not only the investment for original testing at the pilot stage but also for ongoing measures to monitor and ensure the safety of the product water over time. Such ongoing efforts must address not only potential changes in the quality of the water but also changing priorities regarding what health risks should be addressed.



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