Tap Water Linked to Miscarriages
Drinking five or more glasses of cold tap water per day could increase the risk of miscarriage to women in their first trimester, according to a large-scale study of chlorinated drinking water by California state researchers.
That finding already is stirring political and scientific debate as officials weigh the risks of overreaction against the actual threat to public health.
Local officials, noting that they had not yet read the study, expressed concern.
S. David Freeman, the general manager of the Los Angeles Department of Water and Power, America’s largest municipal utility, said women in their first trimester would be prudent to boil water before drinking it.
“You do run a risk [if drinking unboiled water],” he said. “Nobody knows how high. . . . The most practical thing that we’ve come up with is to tell women in that category to boil some water and put it in the refrigerator.”
Despite the provocative findings, state and federal officials said the study is not definitive. It is just one part of a large-scale effort by the U.S. Environmental Protection Agency to balance the need for protection against microbes--such as those that cause dysentery and cholera--with the need to keep the dangers of disinfection itself to a minimum. The EPA, which partly paid for the current study, is planning to fund another comparable study in another part of the country to see if the California results are replicated.
Nevertheless, Mayor Richard Riordan, who learned of the study late Monday, echoed Freeman’s concerns and said through his press secretary that he was seeking more information on the seriousness of the threat.
State heath officials said they were not making any recommendations at this point, but that boiling water would be one option.
At the Metropolitan Water District, which supplies most of Southern California outside of the city of Los Angeles with water, officials said their average levels of the contaminant in question are well below those that triggered concern in the study.
The heightened risk is linked to exposure to total trihalomethanes (TTHMs)--a common contaminant found in chlorinated drinking water in a large majority of municipal water systems nationwide. The chemical forms when chlorine, added to disinfect the water, reacts with acids from plant material.
Chlorine helps purify water and prevents an array of bacterial infections. But it creates problems of its own. TTHMs have long been associated with increased cancer risk, at least in animals, and the EPA has for many years regulated the amount of the contaminant that is allowed in drinking water.
According to the study, led by investigators Kirsten Waller and Shanna H. Swann and scheduled for publication in the Feb. 18 issue of the medical journal Epidemiology, the amount of risk to pregnant women depends on the concentration of TTHMs in the water.
The researchers emphasized that only about 2% of the 5,144 women in their study were found to have been exposed to the highest risk levels--that is, they consumed five or more glasses of water per day and the water contained at least 75 micrograms per liter of TTHMs. Nonetheless, a spokesman for the California Department of Health Services, which performed the study, described the findings as particularly disturbing because pregnant women are often advised by physicians to drink a lot of fluids.
The study has not been publicly released but state officials agreed to discuss it with The Times after it became a subject of concern among Los Angeles city officials. Some of those officials were doubly worried by their inability to get copies of the study despite its potential implications for public health.
State health officials advised that women continue to heed their doctors’ recommendations on fluid intake. Pregnant women who are concerned about the risk can take several steps to protect themselves. Using carbon-activated water filters, letting tap water stand in the refrigerator in an open container for several hours and boiling the water for one minute before cooling it all are considered common-sense ways to reduce risk, although the study was not large enough to allow researchers to calculate precise effects. Using bottled water is an option, although the quality of such water may vary.
The study examined records of 5,144 pregnant Kaiser patients from the Fontana, Santa Clara and Walnut Creek areas. All the women in the study drank water that met all state and federal drinking standards.
The study found that women who drank five or more glasses of tap water per day with at least 75 micrograms per liter of trihalomethanes had an increased risk of miscarriage. Their risk was calculated at 15.7%, compared with 9.5% among women who received low exposure.
EPA allows up to 100 micrograms per liter in water. The agency plans to reduce that standard to 80 micrograms in November.
Even before details of the report became known, water agencies were bracing for its impact. The American Water Works Assn. notified its members that a study was forthcoming and distributed suggested response points emphasizing the association’s commitment to providing clean, safe drinking water.
“We feel strongly that additional research needs to be completed and that more accurate means of exposure assessment should be developed,” the association said in a public affairs advisory to utilities.
Although Los Angeles was not specifically studied, the average concentration of TTHM in Los Angeles city tap water exceeds the level that triggered concern in the study, leading local officials to debate whether city leaders should be warning pregnant women about possible risks in drinking water supplied by the DWP.
“We’re making every effort to make sure that people are candidly informed,” Freeman said.
Particularly difficult, Freeman noted, was the fact that the normal response to a pollution hazard--eliminating the pollutant--is not feasible in this case.
“You can’t just take the bad stuff out,” he said. “The bad stuff is what makes the water safe.”
Because of the importance of protecting the public against disease, the EPA has no plans to lower its standards below 80 micrograms per liter based on one study, an official there said.
State officials agreed that would be premature.
“We are in that awkward in-between stage between when something starts showing up [as a possible problem] and when we have definitive proof,” said Jim Stratton, the state health officer.
DWP and other agencies are busy trying to figure out how to reduce TTHMs in drinking water, but some of the methods for reducing it are politically challenging. Locally, covering city reservoirs would help by keeping plant material out of the water supply. But it would surely run into opposition from homeowners whose views of local lakes would lose their allure.
The long-term solution may be elimination of chlorine treatment, but the chief alternative, ozone treatment, is expensive. The MWD is considering installation of ozone treatment facilities, but they are estimated to cost about $600 million.
Times staff writer Daniel Yi contributed to this story.
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Purifying Tap Water
Some methods pregnant women can use to remove TTHM contaminants from their water:
* Boil water for one minute
* Let tap water sit in an open container in the refrigerator for several hours before drinking
* Use an activated-charcoal water filter
Source: State and federal health officials
Para Purificar el Agua
Algunos metodos que las mujeres embarazadas pueden usar para depurar el agua de contaminantes conocidos como TTHM son:
* Hervir el agua por un minuto
* Dejar el agua da la llave por varias horas en el refrigerator en un recipiente destapado antes de tomaria
* Usar un filtro de carbon activado
Fuente: Funcionarios estatales y federales de salubridad