Radiation occurs from three natural sources: radioactive material

Question

Radiation occurs from three natural sources: radioactive material in the environment, such as in soil, rock, or building materials; cosmic rays; and substances in the human body, such as radioactive potassium in bone and radioactive carbon in tissues. These natural sources account for an exposure of about 100 millirems a year for the average American.

The largest single source of man-made radiation is medical X rays, yet most scientists agree that hazards from this source are not as great as those from weapons test fallout, since strontium 90 and carbon 14 become incorporated into the body, hence delivering radiation for an entire lifetime. The issue is, however, by no means uncontroversial. The last two decades have witnessed intensified examination and dispute about the effects of low-level radiation, beginning with the United Nations Scientific Committee on the Effects of Atomic Radiation, which reported in 1958 that “even the smallest amounts of radiation are likely to cause deleterious genetic and perhaps also somatic effects.”

A survey conducted in Britain confirmed that an abnormally high percentage of patients suffering from arthritis of the spine who had been treated with X rays contracted cancer. Another study revealed a high incidence of childhood cancer in cases where the mother had been given prenatal pelvic X rays. These studies have pointed to the need to reexamine the assumption that exposure to low-linear energy transfer presents only a minor risk.

Recently, examination of the death certificates of former employees of a West Coast plant that produces plutonium for nuclear weapons revealed markedly higher rates for cancers of the pancreas, lung, bone marrow, and lymphatic system than would have been expected in a normal population.

While the National Academy of Sciences committee attributes this difference to chemical or other environmental causes rather than radiation, other scientists maintain that any radiation exposure, no matter how small, leads to an increase in cancer risk. It is believed by some that a dose of one rem, if sustained over many generations, would lead to an increase of 1 percent in the number of serious genetic defects at birth, a possible increase of 1,000 disorders per million births.

In the meantime, regulatory efforts have been disorganized, fragmented, inconsistent, and characterized by internecine strife and bureaucratic delays. A Senate report concluded that coordination of regulation among involved departments and agencies was not possible because of jurisdictional disputes and confusion. One federal agency has been unsuccessful in its efforts to obtain sufficient funding and manpower for the enforcement of existing radiation laws, and the chairperson of a panel especially created to develop a coordinated federal program has resigned.   1 
 1. The primary purpose of the passage is to

A. Explain the difference between natural and man-made radiation
B. Arouse concern about the risks connected with exposure to radiation
C. Criticize the United Nations Scientific Committee on the Effects of Atomic Radiation
D. Advocate limiting the use of atomic weapons testing, since the fallout is extremely hazardous
E. Publicize the results of British medical survey

2 
 2. Which of the following, according to the passage, is a list of three natural sources of radiation?

A. Radioactive potassium in bone, strontium 90, uranium ore
B. Carbon 14 in tissues, cosmic rays, X rays
C. Cosmic rays, radioactive potassium in bones, radioactive carbon in tissues
D. Plutonium, radioactive material in rock, strontium 90
E. X rays, carbon 14, plutonium

3 
 3. The passage contains information that answers which of the following questions?

A. How many millirems of radiation from man-made sources is the average American exposed to each year?
B. Is exposure to radiation linked to any other diseases besides cancer?
C. How many types of radiation are there?
D. What is the maximum level of radiation to which humans can safely be exposed?
E. Why is exposure to the fallout from weapons testing considered by some to be more hazardous than exposure to X rays?

4 
 4. According to the passage, some scientists believe that a dose of one rem of radiation continued over a period of generations would

A. Raise the strontium 90 levels in the body but otherwise have little effect
B. Relieve the acute suffering of those afflicted with arthritis of the spine without side effects
C. Have the effect of increasing by 1 percent the cases of serious genetic defects
D. Have little impact on the regulatory efforts of federal agencies
E. Cause an additional 1,000 per million cases of cancer of the bone marrow or lymphatic system

5 
 5. It can be inferred from the last paragraph of the passage that the chairperson who resigned from the panel to develop a coordinated federal program for radiation regulation most likely did so because

A. He or she disagreed with the findings of the Senate committee
B. His or her agency could not obtain funding or manpower for implementation of existing laws
C. He or she supported the position of the National Academy of Sciences committee and opposed regulation of radiation exposure
D. He or she was disorganized and inconsistent in chairing the panel
E. Regulatory efforts have been balked by disputes, confusion, and bureaucratic delays

6 
 6. The passage contains evidence suggesting that it was most likely written

A. In 1958
B. By a British scientist
C. For the journal of the National Academy of Sciences
D. By a lobbyist for the defense industry
E. In the late 1970s

7 
 7. The passage implies that each of the following statements about radiation has been disputed EXCEPT?

A. Even small doses of radiation are likely to cause birth defects.
B. Exposure to low-linear energy transfer presents only a minor risk.
C. Many small doses of radiation are as harmful as a single large dose.
D. Humans can tolerate a certain amount of radiation.
E. Exposure to radiation causes cancer.

ballest127 · Answer

Hi experts,

Could you please post the OE for question 5.

Why B is incorrect?

Thank you.

navderm · Answer

You can clearly see that the reason that federal agency has not been able to get funding, has insufficient staff and people are leaving is because of the state of disputes and confusion.

B and the question both are result of the disputes (There is correlation not causation)

OhMy · Answer

Thanks for this passage!

Can someone elaborate on Question 6? Why we can choose D over B or C?

Because i for my part can not eliminate B or C fully. 
And for E the only time reference i see, is in the second paragraph, talking about examinations in 1958 and the last two decades.

Am i missing something?

Posted from my mobile device

DhrumilP · Answer

I am not sure whether I understood Question 7 properly. Please help. 
"The passage implies that each of the following statements about radiation has been disputed EXCEPT?"
I understood that "which of the following has not been disputed?" Is that correct? And if yes, then I do not understand the answer choice. Option A has not been disputed in the passage. What am I missing?

Sajjad1994 · Answer

Always differentiate between  "Must be true"  and  "Could be true"  in these cases, Answer  choices B and C  both are dubious, answer  choice A  is definite wrong. When you struck in this situation just try to differentiate. E here is a best and doubtless answer and you are right we can detect this from the information in the  second paragraph  as you mentioned above.

Sajjad1994 · Answer

You have understood the question well but probably took it to the wrong direction. Read the passage again and you will realize that all others except option E are disputed or doubtful and only we can infer D with 100% confidence. Read the  last three lines  of the  second last paragraph  they are saying something else than what is said in A.

KumarMohan · Answer

Can someone pls explain Q3. Why B is not correct..?

As per paragraph 3 - "A survey conducted in Britain confirmed that an abnormally high percentage of patients suffering from arthritis of the spine who had been treated with X rays contracted cancer"

Based on the above lines we can say x-rays/radiation is linked to something (Arthritis) other than cancer.

Thanks!

sharmashruti2896 · Answer

why is option A incorrect in Q3?

bM22 · Answer

Hi  KumarMohan ,

Option B says: Is exposure to radiation linked to any other diseases besides cancer?

The lines that you have mentioned imply that people suffering from arthritis, who were treated X-rays  contracted  cancer and not the other way round.

Hope This Helps.

bM22 · Answer

Hi  sharmashruti2896 ,

Let me know if this helps or if you still have doubts.

Option A is question 3 is: How many millirems of radiation from man-made sources is the average American exposed to each year? - What's mentioned the passage is the millirems of radiation from natural sources, we can't infer how many millirems of radiation from man-made sources is an average American exposed to each year.

Thanks.

gullyboy09 · Answer

In the below Q, I choose C.

Now in the para, although it is discussed that small doses can also affect severly, but it was not discussed with respect to single large dose (Correct me if I am wrong!).

Now on D, although it's not explicitly mentioned, but case has been made to reexamine - "These studies have pointed to the need to reexamine the assumption that exposure to low-linear energy transfer presents only a minor risk." But National Science committee denied it by saying some other factors were the reason. Now it's not exactly the dispute here, but still I would pick C over D as C is clearly not disputed.

AND if C is disputed, i.e. "many small doses of radiations are as harmful" is disputed - then it means D is also disputed! D is more generalise version of C.

7. The passage implies that each of the following statements about radiation has been disputed EXCEPT?

A. Even small doses of radiation are likely to cause birth defects.
B. Exposure to low-linear energy transfer presents only a minor risk.
C. Many small doses of radiation are as harmful as a single large dose.
D. Humans can tolerate a certain amount of radiation.
E. Exposure to radiation causes cancer.

guddo · Answer

7. The passage implies that each of the following statements about radiation has been disputed EXCEPT:

The passage is mainly about a controversy over  the harmful effects of low-level radiation : whether small amounts can cause cancer, genetic damage, or other serious harm. So the right answer is the choice that is not really framed as part of that controversy.

(A) Even small doses of radiation are likely to cause birth defects.

This has been disputed. The passage says some scientists believe that even a dose of one rem, over many generations, could increase serious genetic defects at birth. So small-dose genetic harm is clearly part of the debate.

(B) Exposure to low-linear energy transfer presents only a minor risk.

This has been disputed directly. The passage says certain studies “pointed to the need to reexamine” that very assumption.

(C) Many small doses of radiation are as harmful as a single large dose.

This is not stated word for word, but it is still closer to the disputed issue than D is. The passage repeatedly discusses  small, prolonged, cumulative exposure : radioactive substances staying in the body for life, low-level radiation, and doses sustained over many generations. So the general question whether repeated small exposure can be seriously harmful is within the area of dispute.

(D) Humans can tolerate a certain amount of radiation.

This is the correct answer. The passage does not frame the controversy in terms of “tolerance.” That word suggests a threshold below which radiation is harmless or bearable. But the passage is not asking that question. It is asking whether even very small amounts raise cancer or genetic risk. Those are not the same issue. A person may “tolerate” some radiation in an everyday sense and yet still face a small increased risk. So D is the one not really presented as a disputed claim in the passage.

(E) Exposure to radiation causes cancer.

This has been disputed. The passage gives studies linking radiation to cancer, but also says the National Academy committee attributed one set of higher cancer rates to chemical or environmental causes instead of radiation.

Answer: (D)

The key distinction is: the passage debates  risk from low doses , not whether humans can “tolerate” radiation at all.

Radiation occurs from three natural sources: radioactive material

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Radiation occurs from three natural sources: radioactive material

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