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Researchers in City X recently discovered low levels of several pharmaceutical drugs in public drinking water supplies. However, the researchers argued that the drugs in the water were not a significant public health hazard. They pointed out that the drug levels were so low that they could only be detected with the most recent technology, which suggested that the drugs may have already been present in the drinking water for decades, even though they have never had any discernible health effects.
Which of the following, if true, would most strengthen the researchers' reasoning?
| Text from Passage | Analysis |
| Researchers in City X recently discovered low levels of several pharmaceutical drugs in public drinking water supplies. |
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| However, the researchers argued that the drugs in the water were not a significant public health hazard. |
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| They pointed out that the drug levels were so low that they could only be detected with the most recent technology, which suggested that the drugs may have already been present in the drinking water for decades, even though they have never had any discernible health effects. |
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The passage starts with a discovery that could seem alarming (drugs in water), but then the researchers flip this into a reassuring argument. They use two connected pieces of evidence: the levels are extremely low (so low only new tech can detect them) and this suggests a long history without problems (decades of presence with no health effects).
The pharmaceutical drugs found in City X's drinking water are not a significant public health hazard.
The researchers link detection difficulty to safety history. Their logic is: if the drugs are so hard to detect that we needed the newest technology to find them, they were probably there all along undetected. And if they were there for decades without causing noticeable health problems, then these low levels must be safe.
Strengthen - We need to find information that would make the researchers' conclusion (that low drug levels aren't a health hazard) more believable and well-supported.
The researchers make quality claims about safety (not a significant hazard) and temporal claims about duration (drugs may have been present for decades). Their reasoning relies on the connection between detection levels, duration, and absence of health effects.
The researchers argue: tiny drug levels + possibly decades of exposure + no observable health problems = not a health hazard. To strengthen this, we need information that either:
We should look for scientific evidence, historical data, or comparative studies that support their safety conclusion.
This choice presents a logical relationship that works backwards from the researchers' reasoning. The researchers are trying to prove that the drugs aren't a hazard partly because there are no discernible health effects. But this choice says 'if not a hazard, then no health effects' - which doesn't help prove the original point. We need evidence to support their conclusion, not a restatement of what that conclusion would imply. This is circular reasoning that doesn't strengthen their argument.
This choice discusses policy about removing drugs from water, but the researchers aren't arguing about what should be removed - they're arguing about whether these specific drugs pose a hazard. This choice assumes their conclusion is true (that low levels aren't hazardous) rather than providing evidence to support that conclusion. It doesn't strengthen their reasoning about safety.
This choice actually works against the researchers' argument. It suggests that even if something is hazardous, scientists might not be able to detect the health effects. This undermines the researchers' key reasoning that 'no discernible health effects' means 'not hazardous.' If we can't always detect health effects even when substances are harmful, then the absence of detected effects doesn't prove safety.
This choice provides exactly the kind of evidence that strengthens the researchers' argument. It shows that these same drugs were detected decades ago in a neighboring town using older, less sensitive technology (meaning higher concentrations) and still caused no discernible health effects. This directly supports both parts of the researchers' reasoning: it confirms that these drugs can exist in water for long periods without health problems, and it provides evidence from actual historical data rather than speculation. The fact that even higher detectable levels caused no problems strongly supports the safety of the current lower levels.
This choice directly contradicts the researchers' reasoning. If samples from decades ago show no pharmaceutical drugs when tested with today's technology, then the drugs haven't been present for decades as the researchers suggested. This would undermine their argument that long-term exposure without health effects proves safety, since it would show there was no long-term exposure.