Read the following text written in 2001 and answer the questions on pages 4 and 6.

The recently started North Pole route between New York and Hong Kong has caused concern among airline unions and scientists. According to international experts, the passengers and crew members are exposed to unusually high levels of cosmic and solar radiation.

Passengers taking five round trips on the nonstop route could exceed maximum recommended levels for annual radiation doses, according to scientists who have studied the issue individually. In fact, any air travel involves greater exposure to cosmic and solar radiation than staying on the ground. That is because the air is thinner at high altitudes and provides less protection against the radiation that constantly hits Earth from space.

The New York-Hong Kong flights involve more exposure, scientists say, in large part because of higher radiation levels resulting from the magnetic attraction that the North Pole exerts on charged radioactive particles from space. A pilot from one airline who requested anonymity said that captains had recently started insisting on flying at lower than optimal flight altitudes along this and other routes to avoid excess radiation exposure.

Robert Barish, a New York health physicist who specializes in studying in-flight radiation and has written a book on the subject, reckons that the dosage received during each flight along the transpolar route is equivalent to three chest X-rays and may be significantly increased by solar flare radiation. A standard one-way trans-Atlantic flight between New York and London exposes fliers to the equivalent of less than two chest X-rays, Mr. Barish said.

The dose of in-flight radiation for each one-way transpolar flight from New York to Hong Kong could reach 0.10 millisievert, a standard measure of radiation exposure, even without additional radiation from a solar flare, according to calculations made by Martha Waters, a research scientist for the US government. According to Ms. Waters' calculations, a passenger taking only one return trip on the route every other month could surpass the maximum dosage guideline of one millisievert per year set for the general public by the EU and the Radiological Protection agency. Calculating separately and independently, scientists have affirmed that radiation from five roundtrip flights could surpass the threshold of one millisievert.

Heavy doses of radiation can cause damage to a developing fetus, provoke cancer or produce genetic mutations in human egg and sperm cells. ( A ), the neutron-intensive radiation experience in flight is more damaging to cell structure than X-rays, Ms. Waters said.

Another scientist has said, "The radiation on one flight may not be an immediate health hazard but it is important that air captains, first officers and frequent travelers know about the risks." The airlines flying the North Pole route said they do not inform passengers of the increased cosmic radiation risks. But they said they take precautionary measures, such as monitoring for solar storms. (B)Research into the radiation risks of high-altitude flights remains in its infancy, but several cancer studies among pilots have found increases in certain cancers often associated with radiation. A paper published in 1996 found a higher incidence of myeloid leukemia*, astrocytoma**, prostate cancer and malignant melanoma*** among 2,740 Air Canada pilots than in the general population.

Scientists and airline employees unions, who have raised the issue in the past, have expressed concern, especially for (C)pregnant women and frequent travelers. Anecdotal reports of high rates of miscarriage and menstrual disorders among flight attendants have prompted the U.S. government's Centers for Disease Control to start a broad-based study on the impact of in-flight radiation.

Another large-scale study, on cancer rates among flight crews, will be completed this summer. Early reports of preliminary findings suggest that flight attendants have breast cancer rates twice those of the general population and that their skin cancer rates may be 15 times as high.

（註）
• *myeloid leukemia:骨髄性白血病
• **astrocytoma:星状細胞腫
• ***melanoma:メラノーマ、黒色腫

• 1. Choose the most appropriate title for the text from the choices below.
  • a. A New Discovery for a New World
  • b. Choosing a Safe Flight
  • c. Flying on Top of the World: A Radiation Risk
  • d. Radiation and Vacation
• 2. Why is exposure to radiation more serious at high altitude?
  • a. People are not used to that height in their daily lives.
  • b. People receive radiation in one dose.
  • c. The higher the plane is, the farther it is away from the earth.
  • d. The layer of protective air is thinner.
• 3. Which is NOT true about the flight route between New York and Hong Kong?
  • a. It is more subject to radiation exposure because it passes near the North Pole.
  • b. It is a safer route than the trans-Atlantic route between New York and London in terms of radiation exposure.
  • c. If you take this route round-trip, it is possible that the dose of in-flight radiation could reach 0.20 millisievert.
  • d. If a passenger takes this trans-polar route, he/she may receive the dosage equivalent to three chest X-rays.
• 4. Choose the most appropriate word or phrase for (A) in the text.
  • a. Because
  • b. Consequently
  • c. However
  • d. In addition
• 5. Which of these does NOT result from large doses of radiation?
  • a. damage to developing fetuses
  • b. malignant melanoma
  • c. mutations in reproductive cells
  • d. vision problems
• 6. Which word or phrase is the closest in meaning to (C)pregnant in the text?
  • a. affective
  • b. affluent
  • c. efficient
  • d. expectant
• 7. According to the passage, which of the following is NOT true?
  • a. Flight attendants are less likely to get breast cancer than the general public.
  • b. Flight attendants report high rates of miscarriages.
  • c. Flight crews have cancer rates 15 times as high as the general population.
  • d. Flight crews have a greater chance of suffering from leukemia.
• 8. According to the text, what do some scientists worry about?
  • a. Air Canada pilots are seriously worried about flying at low altitudes.
  • b. Air captains, first officers and frequent travelers should know about the risks of in-flight radiation.
  • c. Even one flight's radiation can cause immediate damage to flight crews.
  • d. Heavy doses of radiation can influence viruses associated with human diseases.

次の問題$\fbox{1}$、$\fbox{2}$の解答は記述式解答用紙に記入しなさい。

• $\fbox{1}$ Translate the underlined part (B) in the text into Japanese.
• $\fbox{2}$ Would you continue to fly on a New York-Hong Kong route if you were a pilot or a flight attendant? Why or why not?