Scientists have recently discovered that, in doses massive enough to

Question

Scientists have recently discovered that, in doses massive enough to kill cells, almost any chemical is carcinogenic because cell death causes rapid division among surviving cells, promoting cancer-causing mutations. A few chemicals are also carcinogenic without causing cell death. Until now studies of the carcinogenicity of food additives have always involved administering to test animals doses of additives larger than the largest possible human exposure levels and massive enough to kill large numbers of cells in the animals, and then observing the animals' cancer rates.

If the statements above are true, which one of the following conclusions is most strongly supported by them?

(A) In the doses heretofore used in carcinogenicity studies of food additives, cell death often does not occur in test animals.

(B) Until now results of carcinogenicity studies encouraged overestimation of the degree to which some food additives are carcinogenic.

(C) Truly carcinogenic chemicals usually cause some immediate cell death, even in small doses.

(D) Carcinogenic chemicals are usually absorbed in small doses in the natural environment.

(E) Most of the food additives that are now banned because of carcinogenicity could safely be used in human foods.

VibhuAnurag · Answer

The answer is B.

The argument says that almost any chemical can appear carcinogenic if it is given in doses massive enough to kill cells. This is because cell death causes rapid division among surviving cells, and that rapid division can promote cancer-causing mutations. But, previous studies of food additives used doses that were far higher than possible human exposure levels and massive enough to kill many cells in test animals. So, these studies may have made some additives look more carcinogenic than they would be at realistic human exposure levels.

Option (A): 
 This says that in the doses used in studies, cell death often does not occur. 
 This directly contradicts the passage. The passage says the doses used were massive enough to kill large numbers of cells. 
 So this is not supported.

Option (B):
This says that previous carcinogenicity studies encouraged overestimation of how carcinogenic some food additives are.
This is strongly supported.
The studies used unrealistically large doses, and those doses caused cell death. Since cell death itself can create conditions that promote cancer-causing mutations, some additives may have appeared more dangerous than they would be under normal human exposure levels.
This does not say all studies were wrong. It only says the results encouraged overestimation in some cases, which is appropriately cautious.
So this is the correct answer.

Option (C): 
 This says truly carcinogenic chemicals usually cause immediate cell death even in small doses. 
 The passage does not support this. In fact, it says a few chemicals are carcinogenic without causing cell death. 
 The passage gives no basis for saying what carcinogenic chemicals usually do in small doses.

Option (D): 
 This says carcinogenic chemicals are usually absorbed in small doses in the natural environment. 
 The passage is about food-additive studies and test doses. It does not discuss natural environmental absorption. 
 So this is outside the scope.

Option (E): 
 This says most food additives banned for carcinogenicity could safely be used in human foods.   This goes too far. 
 The passage suggests that some additives may have been judged too harshly because of unrealistic test doses. But it does not tell us that most banned additives are safe. 
 Also, some chemicals can be carcinogenic even without causing cell death, so we cannot conclude that banned additives are generally safe.

guddo · Answer

Scientists have recently discovered that, in doses massive enough to kill cells, almost any chemical is carcinogenic because cell death causes rapid division among surviving cells, promoting cancer-causing mutations. A few chemicals are also carcinogenic without causing cell death. Until now studies of the carcinogenicity of food additives have always involved administering to test animals doses of additives larger than the largest possible human exposure levels and massive enough to kill large numbers of cells in the animals, and then observing the animals' cancer rates. 
 
If the statements above are true, which one of the following conclusions is most strongly supported by them?

The passage says past tests used extremely large doses that killed many cells, and cell death itself can make almost any chemical appear carcinogenic.  So past studies may have made some additives look more dangerous than they would be at realistic human exposure levels.

(A) In the doses heretofore used in carcinogenicity studies of food additives, cell death often does not occur in test animals.

Wrong. The passage says those doses were massive enough to kill large numbers of cells.

(B) Until now results of carcinogenicity studies encouraged overestimation of the degree to which some food additives are carcinogenic.

Correct. Since the test doses caused cell death, and cell death can itself promote cancer-causing mutations, some additives may have appeared carcinogenic because of the unrealistically massive dose, not because they would be carcinogenic under  normal human exposure .

(C) Truly carcinogenic chemicals usually cause some immediate cell death, even in small doses.

Wrong. The passage says a few chemicals are carcinogenic without causing cell death, but it does not say truly carcinogenic chemicals usually cause cell death in small doses.

(D) Carcinogenic chemicals are usually absorbed in small doses in the natural environment.

Wrong. The passage says nothing about absorption in the natural environment.

(E) Most of the food additives that are now banned because of carcinogenicity could safely be used in human foods.

Wrong. Too strong. The passage supports possible overestimation in some cases, not that most banned additives are safe.

Answer: (B)

yc168 · Answer

OE for reference:

Overview:  This passage consists of a number of statements about carcinogenic chemicals and about studies of the carcinogenicity of food additives. The task is to decide which of the five answer choices gets the most support from the statements in the passage.

The Correct Answer:

B  The passage tells us that almost any chemical is carcinogenic if taken in doses that are large enough to kill cells. It also tells us that until now studies to determine whether food additives are carcinogenic involved giving the test animals doses of additives that are "massive enough to kill large numbers of cells in the animals." So we can conclude that in most cases such studies would find that the additive being tested causes cancer in the test animal. But the first two sentences of the passage strongly imply that many chemicals are not carcinogenic if taken in small doses. So we can also conclude that in many cases the additive might not have caused cancer in test animals if it had been given in smaller doses.

The passage indicates that doses as large as those used in studies until now are larger than anything humans might be exposed to. Studies that used smaller doses, therefore, would better represent the levels of human exposure to food additives. And we have already seen that such studies would conclude less often that food additives are carcinogenic. Hence the passage supports (B).

The Incorrect Answer Choices:

A  The passage tells us that until now studies of the carcinogenicity of food additives have always involved administering to the test animals doses of the additive that are "massive enough to kill large numbers of cells in the animals." So the passage provides no support for (A).

C  The passage does not tell us about the effects of small doses of chemicals. It does, however, tell us that although almost any chemical is carcinogenic in doses massive enough to kill cells, a few chemicals are carcinogenic even without causing cell death. The passage does not use the term "truly carcinogenic chemicals," but if there are any chemicals that deserve to be called "truly carcinogenic chemicals," it would probably be the ones that are carcinogenic without causing cell death. Perhaps these chemicals are carcinogenic in small doses, but they cause cancer without causing cell death. So the passage provides no support for (C).

D  The passage tells us that studies of the carcinogenicity of food additives have until now "involved administering to test animals doses of additives larger than the largest possible human exposure levels." But this tells us nothing about amounts of carcinogenic chemicals usually absorbed in the natural environment. As far as the passage is concerned, those amounts may be small, large, or somewhere in between. So the passage provides no support for (D).

E  The passage provides some support for the view that in many cases, the cancer rate observed in carcinogenicity studies is higher than it would be if the test animals had been given a dose of the additive that was more in line with typical human exposure levels. But it provides no support for thinking that any of the additives that are now banned because of carcinogenicity could be safely used in smaller doses. In part, this is because the passage does give us details about why any of these additives have been banned. So the passage provides no support for (E).

Scientists have recently discovered that, in doses massive enough to

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Critical Reasoning (CR) Questions

Scientists have recently discovered that, in doses massive enough to

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards