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【社会人文】大量化学药品存在水中，是否有害
Drugs Are in the Water. Does It Matter?
Residues of birth control pills, antidepressants, painkillers, shampoos and a host of other compounds are finding their way into the nation’s waterways, and they have public health and environmental officials in a regulatory quandary.
William Duke
On the one hand, there is no evidence the traces of the chemicals found so far are harmful to human beings. On the other hand, it would seem cavalier to ignore them.
The pharmaceutical and personal care products, or P.P.C.P.’s, are being flushed into the nation’s rivers from sewage treatment plants or leaching into groundwater from septic systems. According to the Environmental Protection Agency, researchers have found these substances, called “emerging contaminants,” almost everywhere they have looked for them.
Most experts say their discovery reflects better sensing technology as much as anything else. Still, as Hal Zenick of the agency’s office of research and development put it in an e-mail message, “there is uncertainty as to the risk to humans.”
In part, that is because the extent and consequences of human exposure to these compounds, especially in combination, are “unknown,” the Food and Drug Administration said in a review issued in 2005. And aging and increasingly medicated Americans are using more of these products than ever.
So officials who deal with these compounds have the complex task of balancing reassurance that they take the situation seriously with reassurance that there is probably nothing to worry about. As a result, scientists in several government and private agencies are devising new ways to measure and analyze the compounds, determine their prevalence in the environment, figure out where they come from, how they move, where they end up and if they have any effects.
In many cases, the compounds enter the water when people excrete them or wash them away in the shower. But some are flushed or washed down the drain when people discard outdated or unused drugs. So a number of states and localities around the country have started discouraging pharmacies, hospitals, nursing homes and residents from disposing of drugs this way. Some are setting up “pharmaceutical take-back locations” in drugstores or even police stations. Others are adding pharmaceuticals to the list of hazardous household waste, like leftover paint or insecticides, periodically collected for safe disposal, often by incineration.
For example, Clark County, Wash., has a program in which residents with unwanted or expired drugs can take so-called controlled substances, like prescription narcotics, to police stations or sheriffs’ offices for disposal. They can drop noncontrolled drugs at participating pharmacies, and 80 percent of the pharmacies in the county participate.
In guidelines issued in February, three federal agencies, including the E.P.A., advised people with leftover medicines to flush them down the drain “only if the accompanying patient information specifically instructs it is safe to do so.” Otherwise, the guidelines say, they should dispose of them in the trash (mixed with “an undesirable substance” like kitty litter to discourage drug-seeking Dumpster divers) or by taking them to designated take-back locations.
Worries about water-borne chemicals flared last summer when researchers at the United States Geological Survey said they had discovered “intersex fish” in the Potomac River and its tributaries. The fish, smallmouth and largemouth bass, were male but nevertheless carried immature eggs.
Scientists who worked on the project said they did not know what was causing the situation, or even if it was a new phenomenon. But the discovery renewed fears that hormone residues or chemicals that mimic them might be affecting creatures that live in the water.
In a survey begun in 1999, the agency surveyed 139 streams around the country and found that 80 percent of samples contained residues of drugs like painkillers, hormones, blood pressure medicines or antibiotics. The agency said the findings suggested that the compounds were more prevalent and more persistent than had been thought.
Meanwhile, the Food and Drug Administration started looking into the effects of residues of antibiotics and antiseptics in water, not just to see if they might affect people but also to assess their potential to encourage the development of drug-resistant bacteria.
Reports of contamination with pharmaceutical residues can be alarming, even when there is no evidence that anyone has been harmed. In 2004, for example, the British government reported that eight commonly used drugs had been detected in rivers receiving effluent from sewage treatment plants. A spokeswoman for the Department for Environment, Food and Rural Affairs said it was “extremely unlikely” that the residues threatened people, because they were present in very low concentrations. Nevertheless, news reports portrayed a nation of inadvertent drug users — “a case of hidden mass medication of the unsuspecting public,” as one member of Parliament was quoted as saying.
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作者:admin@医学,生命科学 2010-12-17 07:31
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