Health Risk on Tap

Anew study showing that pregnant women who drink five or more glasses of chlorine-treated tap water a day could face an increased risk of miscarriage has been received with urgency by California officials. S. David Freeman, general manager of the Los Angeles Department of Water and Power, said women in their first trimester should boil drinking water, use carbon-activated filters or let tap water stand in the refrigerator in an open container for several hours to let chlorine byproducts evaporate. And the same advice should pertain to infants, people with autoimmune disorders like AIDS and cancer and other individuals with compromised immune systems.

The American Water Assn. was wrongly dismissive of the study, calling for “more accurate means of exposure assessment.” Yes, the federal Environmental Protection Agency, which helped pay for the study, is properly funding a comparable study to see whether the California results are replicated. But in the meantime, better safe than sorry.

The apparent culprit is trihalomethanes, or TTHMs, a common contaminant in chlorinated drinking water in municipal water systems nationwide. The contaminant forms when chlorine, added to disinfect the water, reacts with acids from plant material, such as leaves that fall into reservoirs, so concentrations are highly variable. The solution might seem simple--add less chlorine. But as Freeman puts it, “You can’t just take the bad stuff out. The bad stuff is what makes the water safe.”

Instead, water officials should:

* Upgrade protections for “source water,” so less chlorine is needed. Cover reservoirs so less plant material gets into them, even if that makes them less scenic. Other dangerous contaminants, lead for instance, make their way into regional water supplies when cities fail to treat runoff water. The federal government funds programs to upgrade regional water purification systems so long as the state matches 20% of the federal monies. California’s governor and Legislature should make sure that matching funds are budgeted.

* Develop alternatives to chlorine. In addition to allowing TTHMs to form, chlorine spoils the good taste of natural water, fails to kill some harmful microbes and is a slight cancer risk. The leading alternative is a combination of carbon filtration and ozonation. The Metropolitan Water District, which supplies water to most of Southern California outside the city of Los Angeles, says that ozonation/carbon filtration treatment could cost about $600 million to install. But in areas that already use the ozonation-carbon system--Cincinnati, for instance--the additional costs, about $25 per family per year, are not prohibitive.

* Regulate tap-water alternatives. While the federal Safe Drinking Water Act requires the Food and Drug Administration to develop bottled water labeling laws, almost nothing has been done yet. California water companies send consumers leaflets each year detailing the contaminants, including TTHMs, in their tap water, but the FDA has imposed no such requirement on bottled water companies.

Since 1995, the Centers for Disease Control and the Environmental Protection Agency have warned that TTHMs and other contaminants are increasingly making tap water unsafe to those without hardy immune systems. That’s unacceptable; solutions exist and it is time for our water agencies to embrace them.