Your answers:
6. Source of systemic poisons
7. Method of entry into humans
8. One effect of poisoning

Question 9
Paragraph 2 of Reading Passage 1 describes two ways in which poisons are sbsorbed by plant tissues. According to the information in this paragraph, which two of the following describe these ways?
A. absorption through root system
B. contamination by vegetable matter
C. poisons land in soils
D. entry through leaves
E. gravity and rainfall
Your answer:

9.

PART 2: ASBESTOS

READING PASSAGE 2: ASBESTOS INHALATION

Asbestos is the generic name for a number of natural occurring fibrous mineral silicates of which the most common types are crocidolite, also known as blue asbestos, and chrysotile (white asbestos).

Employed for at least 2000 years, it is valued by industry because of its tensile strength and flexibility, and its resistance to acids, heat and friction. Asbestos has had a very wide variety of applications. It has been commonly employed in the building industry as a fireproofing agent and as a strengthener. The metal frames of buildings were sprayed with an asbestos solution to prevent the spread of fires, while asbestos was routinely mixed in with cement to provide greater resistance to weathering agents. It is also used in motor-vehicle brake linings, gas-mask filters, certain types of talcum powder, fire-resistant clothing, corrugated-iron roofing and in water and air pipes. As a result of such wide employment, it is likely that most people have been exposed to at least a small quantity of asbestos fibres.

During inhalation, all particles which enter the respiratory tract pass through a series of filter mechanisms. Particles are filtered out at different points of the respiratory tract depending on their size. The smaller the particle, the further into the respiratory it may penetrate before being arrested. The first set of filters consists of the hairs and mucous lining of the nose and mouth which prevent the entry of larger particles. When large particles are inhaled, they stimulate this mucous lining, which results in coughing and the consequent expulsion of the particles. The mucous lining extends downwards through hair-lined bronchial tubes of increasingly fine diameter which further filter the air before it reaches the respiratory bronchioles, a series of very fine tubes attached to air exchange chambers known as alveoli. The alveoli are composed of a thin layer of cells through which oxygen passes into blood vessels and is then distributed to the bloodstream.

Particles smaller than eight micrometres may reach the alveoli. This is the case with blue asbestos particles, which are very straight and slender and tend not to be arrested by mucous and expelled. As a result, they may reach the alveoli and penetrate the delicate cells lining the walls.

Some asbestos fibrils (particles) which reach the alveoli may be surrounded by scavenger cells known as macrophages, which serve to remove the fibrils from the body by expectoration or excretion. Other particles may remain in the alveoli with no adverse effects. In cases where the asbestos particles have penetrated the alveolar wall, scar tissue develops. This reduces the effectiveness of the alveoli and so less oxygen passes into the blood and less carbon dioxide is removed from it. This condition is known as asbestosis. The process of scarring may take place gradually and the disease may not be diagnosed until 20 or 30 years after the initial exposure.


You should spend about 15 minutes on Questions 10-25.

Questions 10-25

The passage below summarises the main points of Reading Passage 2. Decide which word or phrase should go in each gap and write the corresponding letter in the space provided. Write only one letter in each space.

Summary of 'Asbestos Inhalation'

Due to its Example , asbestos has been (10)____ since ancient times in a wide range of (11). When asbestos (12)__ are (13)___ they pass through a series of (14)___ which arrest their (15)___. The stimulation of (16)___ causes (17)___ which expels them from the respiratory tract. If particles are very (18)____, which is the case with (19)___ asbestos, they may (20)___ as far as the alveoli. Some of these particles may (21)___ the alveolar wall and cause (22)____ to develop. This reduces the (23)___ of the lung and causes the condition known as (24)___. Symptoms of the disease may take up to (25)___ to appear.

PART 3: ASBESTOS-RELATED DISEASES

READING PASSAGE 3: ASBESTOS-RELATED DISEASES

The inhalation of asbestos particles is associated with a number of lung diseases (example)

Asbestosis is caused by the entry of asbestos particles into the walls of the alveoli, (26)___. The lung loses its elasticity and may change shape. The initial symptoms of asbestosis are a tightness in the chest and breathlessness. In its later stages, sufferers (27)_____.

Lung cancer, the generic term for malignant tumours of the alveoli and bronchial tubes, has been shown to be directly related to the inhalation of asbestos particles. As in the case of asbestosis, there is generally a period of latency (28)___, despite the absence of further exposure. Research suggests that there is a direct correlation between the degree of exposure to asbestos and the incidence of lung cancers. Where exposure occurs, the level of risk is further increased by cigarette smoking. Asbestos workers who smoke cigarettes have a 90% greater risk of contracting lung cancer than worker who do not smoke.

Exposure to blue asbestos has been shown to produce mesothelioma, a rare cancer of the outer lining of the lung or pleura. In a normal population (29)__ . where epidemiological surveys have revealed a higher incidence of the disease, it is almost always related to asbestos exposure.

Other changes in lung tissue caused by exposure to asbestos are pleural plaques and effusions. The former refer to a thickening of the lining of the chest wall, (30)___. Pleural plaques commonly remain undiagnosed and generally have no detrimental effect on health.


You should spend about 15 minutes on Questions 26-30.

Questions 26-30

Five phrases have been left out of Reading Passage 3 'Asbestos-related Diseases' on page 170. Decide which phrase from the list A-H should go in each gap and write the letter in the space provided. The first one has been done for you as an example.

A. the incidence of mesothelioma is extremely low
B. which may extend from 25 to 30 years after initial exposure
C. whereas the latter consist of a collection of fluid in the chest region outside the lungs
D. on the other hand, is exclusively associated with exposure to the less harmful white asbestos
E. such as asbestosis and lung cancer
F. causing scarring which limits the functioning of the lungs
G. resulting from inadequate ventilation.
H. Develop the barrel-shaped chests associated with emphysema, cyanosis, (where the skin assumes a bluish colour) and club fingers.

Your answers:
Example: E
26. 27. 28.
29. 30.

PART 4: SAFETY RECOMMENDATIONS

READING PASSAGE 4: SAFETY RECOMMENDATIONS

In 1967, in response to widespread public concern aroused by medical reports of asbestos-related deaths, the National Medical Research Council instituted a commission of enquiry to investigate the health hazards associate with the use of asbestos in the building industry.

After examining evidence submitted by medical researchers and representatives of building workers and management, the NMRC published a report which included guidelines for handling asbestos. The report confirmed the findings of similar research in the United States and Canada. Exposure to relatively small quantities of asbestos fibres, they concluded, was directly responsible for the development of cancers, asbestosis and related diseases. Taking into account evidence presented by economists and building industry management, however, the report assumed that, despite the availability of other materials, asbestos would continue to play a major role in the British building industry for many years to come because of its versatility and coat effectiveness.

As a result, the council issued a series of recommendations which were intended to reduce the risks to those who might be exposed to asbestos in working enviroments. They recommended that, where possible, asbestos-free materials should be employed. In case where asbestos was employed, it was recommended that it should be used in a bonded form with materials such as cement, so that loose fibres were less likely to enter the air. The report recommended that special care should be baken during work in environments which contain asbestos. Workers should wear protective respiratory equipment and take special care to remove dust from the environment and clothing with the use of vacuum cleaners.

The report isolated five factors which determine the level of risk involved. The state and type of asbestos is critical to determining the risk factor. In addition to the use of bonded forms of asbestos in preference to loose forms, dust formation was found to be limited where the asbestos was worked when wet rather than dry.

The choice of tools was also found to affect the quantities of asbestos particles that enter the air. Machine tools produce greater quantities of dust than hand tools and, where possible, the use of the latter was recommended.

A critical factor in risk reduction is the adequate ventilation of the working enviroment. Where work takes place in an enclosed space, more asbestos particles circulate and it was therefore recommended that natural or machine ventilation should be used. By rigorously following these guidelines, it was claimed that exposure can be reduced to a reasonably practicable minimum.

The report stated that research carried out by the NMRC showed that the maximum safe level of exposure to blue asbestos was 0.1 fibres per millilitre of amosite and chrysotile (white asbestos) could be inhaled. If these levels are strictly adhered to, the report claimed that the onset of asbestosis in a normal working life should not develop.

Critics of the report pointed out that insufficient longitudinal studies had been carried out to determine that the report's recommended maximum safety levels were acceptable. If, as some as yet unconfirmed data suggest, even minimal exposure to asbestos may result in disease, then clearly the report should have stated that the employment of asbestos was unacceptable in any form.

The claim that 'the onset of asbestosis in a normal working life should not develop if exposure is maintained within maximum limits' was cited by critics as evidence of insufficient assurance. Given the time lag which exists between esposure and the diagnosis of asbestos-related diseases, it was unlikely that disease would be diagnosed 'in a normal working lifetime' irrespective of levels of exposure.

Despite these criticisms, the recommended guidelines were incorporated into the working practice of the British Builder's Federation. As a result, it is possible that workers who have been exposed to asbestos may continue to die of asbestos-induced tumours well into the 21st century.



You should spend about 20 minutes on Questions 31-36.

Questions 31-36

Answer the following questions by referring to Reading Passage 4. For each question choose one answer and write the corresponding letter in the space provided. The first one has been done for you as an example.

Example:
According to paragraph 1, the commission of enquiry was instituted as a result of:

A. medical reports of asbestos-related deaths.
B. pressure from the building industry.
C. public apprehension concerning the effects of asbestos.
D. the health hazards associated with the use of asbestos in the building industry.

31. According to paragraph 2:
A. exposure to even minimal levels of asbestos is unacceptable.
B. asbestos should not be used in the building industry.
C. The findings of US and Canadian reports differed from the NMRC report.
D. The characteristics of asbestos would probably assure its future use.
32. The report assumed that asbestos would continue to be employed in the gbuilding industry on the basis of evidence procided by:
A. its versatility and cost effectiveness.
B. Building workers.
C. Building management and economists.
D. US and Canadian reports.
E. None of the above.

33. In bonded form:
A. no asbestos fibres are released.
B. asbestos fibres may enter the air.
C. there is an increased likelihood that asbestos fibres enter the air.
D. asbestos can be bonded with cement.

34. Dust formation can be reduced by:
A. the use of wetted, bonded forms of asbestos.
B. inadequate ventilation.
C. the use of protective respiratory equipment.
D. the vacuuming of clothing.

35. The report claimed that:
A. higher levels of amosite and chrysotile can be safely inhaled.
B. lower levels of amosite and chrysotile are dangerous.
C. White asbestos can be safely inhaled only in smaller quantities than blue asbestos.
D. There are no safe maximum levels of asbestos inhalation.

36. The statement that 'If maximum exposure levels are strictly adhered to, the onset of asbestosis in a normal working life should not develop' is:
A. the opinion of the writer of the reading passage.
B. a claim made by the authors of the NMRC report.
C. the assurance given by critics of the report.
D. a claim rejected by building workers.

Your answers:
Example: C
31. 32. 33.
34. 35. 36.