Section A Questions Deck 3

Question 1

Human epidemiology and animal studies can be used to investigate whether a substance is carcinogenic.

(a) Outline the advantages of EACH of these methods. (3)
(b) Outline the disadvantages of EACH of these methods. (7)

Human epidemiology and animal studies are methods that can be used to investigate whether a substance is carcinogenic.

(a) (i) Explain what is meant by the term ‘carcinogen’. (2)
(ii) Outline the advantages and disadvantages of human epidemiology. (5)
(iii) Outline the advantages and disadvantages of animal studies. (5)
(b) Outline the control measures that should be in place in a workplace where a carcinogenic substance is used. (8)

Answer 1

(a) human epidemiology is a definitive method for identifying human carcinogens as it is based on experience in actual populations.

Animal testing studies are the best experimental method as animals are closest biochemically to humans. There is no direct human risk with animal studies and data can be gathered more rapidly than with epidemiology.

(b) Human epidemiology can be expensive and time-consuming and usually requires large populations to reduce sampling errors that may otherwise distort the real, underlying picture. It is not a method to be deployed for assessing the carcinogenic potential of new substances because of the timescales involved, it suffers from problems of sensitivity and specificity, human lifestyle factors could affect the study, and it may rely on poor and inaccurate historical records.

Animal studies can also be time-consuming and expensive depending on the type of animal needed. Apart from ethical considerations, there are difficulties in extrapolating animal data to humans and often very large doses are required to produce a response that may, in any case, vary with different animal species.

(i) a substance capable of causing cancer in living tissue as well as inducing a tumor, promoting genetic mutations, or increasing the rate of cell division.
(ii) the disadvantages are:

• sensitivity and specificity,
• lifestyle factors affecting the study,
• and the time-consuming nature associated with human studies.

Advantages included:

the retrospective nature and use of real experiences in populations.

(iii) animal studies in that it is a study set up in a laboratory where animals in the test group are exposed to carcinogens intentionally and the effects observed and recorded.

an advantage is that laboratory animals have very similar or identical biochemistry to humans; however, the ethical considerations are a disadvantage.

(b)

• procedures for time limitation,
• reduction in numbers of people exposed,
• prohibition of eating drinking and smoking in working areas
• and the need for segregation of contaminated clothing

engineering/process controls, such as:

• total enclosure,
• segregation or local exhaust ventilation (LEV).

Question 2

(a) Outline the four stages of occupational health and hygiene practice. (4)
(b) An organization is concerned about the level of absence arising from work-related injuries and ill-health.

Outline practical ways in which the organization’s occupational health department could assist in the management of this problem. (6)

Answer 2

(a)

• The first stage in occupational health and hygiene practice is identifying factors that can cause harm in the workplace.
• This would be followed by taking measurements to determine who might be affected and to what extent.
• Once the measurements have been completed, an evaluation of the level of risk posed by the identified hazards will have to be carried out.
• and this will point to the need to introduce control measures to eliminate or minimize the risk.

(b) There are several practical ways in which the organization’s occupational health department might assist in managing the problem described such as:

• using pre-employment screening to identify potential workers who would be at a greater risk of suffering ill-health resulting in absence;
• carrying out regular health surveillance of existing workers engaged in activities with known health hazards for example those exposed to lead;
• collecting data on sickness absence, analyzing it to identify trends or reasons for absence, and training managers in the importance of monitoring absence from work;
• liaising with medical practitioners, arranging vaccination or immunization programmes and providing rapid access to treatments such as physiotherapy and counseling which will aid return to work;
• assisting managers to arrange phased return to work in certain circumstances and providing practical advice on adaptations to work practice to minimize risk of repeat injury;
• and taking an active part in carrying out risk assessments at the workplace.

Question 3

According to current veterinary and medical opinion, the bacterium E. coli O157 should be assumed to be carried by all ruminants (cattle, sheep, goats and deer). In addition, this bacterium can exist for long periods of time outside the animal (in soil and faeces).

(a) Identify ways in which schoolchildren visiting a farm might be exposed to E. coli O157 bacterium. (4)
(b) Explain a range of practical control measures that should be put in place to reduce this risk of exposure. (6)

Answer 3

(a) The bacterium was transmissible through hand-to-mouth contact. The children’s hands could be contaminated by:

• touching animals, for example in petting areas or in bottle feeding.
• touching surfaces contaminated by feces such as gates and fences and coming into contact with contaminated footwear during its removal.
• The transfer of the bacteria to the mouth could take place during eating or drinking before hands had been thoroughly washed or from putting fingers near or in the mouth for any other purpose - as young children often do.

(b) There are a range of control measures that could be put in place.

• It would be important before the visit took place to brief schools of the precautions to be observed so that the children could be advised of what they should and should not do once they arrived at the farm.
• On the farm, contact with animals should be restricted to specified areas and arrangements put in place to clean, disinfect and remove feces from these areas on a regular basis.
• Visitor contact with animals in other areas should be prevented.
• Handwashing facilities should be provided, ideally placed at the exits from contact areas and before the entrance to areas set aside for taking refreshment and it would be sensible for children to be advised on thorough hand washing techniques at the start of the visit.
• The animal areas should be segregated from areas set aside for eating and signs warning of the risks of contamination and the precautions to be taken placed in strategic positions.
• Finally, the farm management should ensure that there is an adequate number of staff on duty to supervise and advise visitors in the contact areas.

Question 4

(a) Explain what is meant by “threshold shift‟. (2)
(b) Outline the significance of the shape of the audiogram. (2)
(c) Outline the benefits AND limitations of audiometry as part of a hearing conservation program. (6)

Answer 4

(a) A threshold shift is an increase in the hearing threshold for a particular sound frequency. It means that the hearing sensitivity decreases and that it becomes harder for the listener to detect soft sounds.

Temporary Threshold Shift (TTS)

Exposure to a high noise level; hearing acuity returns with time. (Caused by the fatigue of the hair cells in the cochlea.) A dip in hearing acuity occurs at 4,000 Hz.

Permanent Threshold Shift (PTS)

A non-reversible condition; usually follows from continual TTS exposure.

(b) 4 KHz notch is typical of noise-induced hearing loss.
(c) the benefits of audiometry (Measuring sensitivity of hearing) are:

• it can identify those with existing problems (screening) or at least early signs of hearing loss. Identification of early signs of noise-induced hearing loss to be able to remove affected workers from high noise areas.
• Monitoring the effectiveness of any hearing conservation program on the basis that if the program is working, then audiometry will show no significant NIHL (noise-induced hearing loss) cases.
• From an employer’s point of view, it may also help defend against civil claims

The limitations of audiometry are:

• If not Making sure operators for example are not exposed to high noise levels prior to the test this can cause a Temporary Threshold Shift which skews the results.
• audiometry requires some expertise and does not itself prevent hearing damage.
• The findings might well encourage employees to pursue civil claims if their hearing is shown to be damaged.
• Unscrupulous employees may well abuse this fact by pursuing false claims

Question 5

Hand-Arm Vibration Syndrome (HAVS) can be caused by the frequent and prolonged use of hand-held power tools.

(a) Identify the signs and symptoms of HAVS. (2)
(b) Outline a range of control measures that could be used to minimize the risks to workers of developing HAVS when using such power tools. (8)

Answer 5

(a) Symptoms of Hand-Arm Vibration Syndrome include:

• Loss of feeling, Numbness, Tingling and loss of dexterity in the tips of the fingers.
• Blanching (white finger);
• An increase in the severity of the symptoms during cold weather and the progressive nature of the condition, affecting more fingers or parts of fingers and leading possibly to gangrene.

(b) Organisational and technical control measures relevant to the use of hand-held power tools and presented them in an appropriate hierarchy.

Technical control measures would start with

• The consideration of alternative work methods to eliminate the task, but if this is not practicable, to automating or mechanizing the work;
• Avoiding tools that are too small and not powerful enough since these prolong the task and of course the exposure;
• Replacing the equipment with a lower vibration model and introducing a system of regular maintenance to ensure vibration was kept to its designed level.

Organisational control measures would include

• Ensuring the organization’s purchasing policy takes account of vibration emissions (as well as other requirements);
• Changing workstation design to minimize loads on hands, wrists, and arms, for instance by the use of jigs or suspension systems to grip heavy tools;
• Planning work schedules to limit the time of exposure to vibration;
• Providing warm clothing and a warm environment to encourage good blood circulation;
• Referring those experiencing early symptoms to the occupational health department and having a health surveillance programme in place and
• Finally ensuring that workers receive adequate information and training on the risks associated with the process, the symptoms of the syndrome and the control measures that should be followed.

Question 6

Outline the occupational factors that can contribute to stress-related problems amongst call centre workers. (10)

Answer 6

Occupational factors that can contribute to stress-related problems in the scenario described include:

• work overload or underload with unacceptable work patterns;
• An adverse working environment with overcrowding and unacceptable levels of lighting, temperature, and noise; a lack of consultation and participation in how the work is carried out;
• A lack of encouragement from management and colleagues with little opportunity given to raise any problems that might arise;
• A lack of support given by the organization for further training or education;
• Cultural differences such as language, religion and ethnicity;
• Being required to cope with unacceptable behaviour such as bullying, harassment and violence leading to a lack of trust in colleagues;
• A lack of understanding of their role in the organisation since this has never been made clear by management with the result that several workers have conflicting roles; and
• Excessive organisational change with the resulting fear of job security and redundancy fuelled by a lack of communication by management of the nature of the changes that are to or have been made.

Question 7

Outline the factors that should be considered in relation to the job, the individual, and the work environment when carrying out an assessment of ergonomic risks in a workplace. (10)

Answer 7

Job factors relating to ergonomics include consideration:

• of the demands of the task, such as the duration, repetition, the work rate, and the opportunity to take breaks.
• The equipment that a person uses as part of the job can affect the ergonomic risks in a number of ways such as the amount of force or effort required to operate the equipment as well as the design and layout of the controls.
• The postures that are adopted when carrying out the job, whether or not equipment is involved, can increase the risks, especially if these postures are awkward or involve frequent twisting, stretching or prolonged stooping.

When considering factors relating to the individual,

• the stature, shape, strength, and general fitness and mobility of the individual are important
• as are factors such as gender, age, and sensory abilities such as hearing and vision.
• An individual’s mental capabilities, level of experience, knowledge, and level of training should also be taken into account.
• Finally, the physical aspects of the working environment, such as lighting, temperature, noise, humidity, space and floor conditions also need to be considered as part of any ergonomic assessment.

Question 8

a) Outline the following toxicological terms:
(i) LD 50; (2)
(ii) LC 50. (2)
(b) (i) Outline the toxicity test known as the fixed-dose procedure. (4)
(ii) Outline the possible reasons why the fixed-dose procedure has replaced previous methods that estimated LD 50. (2)

Outline the advantages and disadvantages of using animal studies to investigate whether a substance used at work may be carcinogenic to humans. (6)

Animal studies can be used to assess the acute and chronic effects of hazardous substances.

(a) Outline the meaning of the following terms used in animal studies:
(i) NOAEL; (2)
(ii) LD50. (2)

Answer 8

a) i) LD50 is the dose of a test substance that is lethal for 50% of the animals in a dose group (administered orally or dermally). It is usually expressed as the amount of chemical administered (e.g., milligrams) per 100 grams (for smaller animals) or per kilogram (for bigger test subjects) of the bodyweight of the test animal.
ii) LC50 is the concentration in air of airborne substance that is lethal for 50% of the animals in a dose group. Specified in mg of substance per liter of air and typically an exposure period of 4 hours.
(b) (i) The toxicity test is known as the fixed-dose procedure, used to determine acute oral toxicity with a rat normally being used as the test animal. An initial study is carried out to determine the starting dose for the main study and this uses single animals and a successively increased dose to determine the range of toxic effects. The initial test dose for the main study is chosen as the dose which can identify toxicity without mortality. In the main study, an animal is tested at one of four fixed doses namely 5, 50, 300, and 2000 mg/kg, with observation being carried out over fourteen days. The discriminating dose (i.e., That causes evident toxicity but not mortality) is determined and is used as the basis for classification such as very toxic, toxic or harmful or equivalent GHS classification.
(ii) Possible reasons for substituting the fixed-dose procedure for previous methods that estimated LD50 include the fact that a smaller number of animals is used; it uses morbidity rather than mortality as the endpoint, and it is considered more humane by many.
c) the advantages of using animal studies include:

• the fact that these methods avoid human exposure and hence possible human deaths,
• and that the data can be collected more quickly and arguably more ethically than using epidemiological methods.
• Animals provide the best available models as they relate more closely to humans and the studies are more likely to detect carcinogenic potential than in vitro testing such as Ames tests.

When considering the disadvantages:

• the dose/response effect may vary in different animal species and so extrapolating data to humans may not always be reliable.
• Additionally, conducting animal studies can be time-consuming and expensive and there are often ethical considerations and public opinion that can make this approach more difficult to undertake
• There is also the consideration that animals being treated for exposure to a particular substance may not help to identify synergistic effects that could arise in humans exposed to other substances at the same time and that the tests are carried out in laboratory conditions rather than in a workplace.
• There could also be difficulties with the “no observed adverse effect level” for carcinogens.

a) i) No Observed Adverse Effect Level (NOAEL) is the highest exposure level at which there are no biologically significant increases in the frequency or severity of adverse effect between the exposed population and its appropriate control; some effects may be produced at this level, but they are not considered adverse effects.

The units of NOAEL are mg/kg bw/day or ppm for dermal and oral routes.

Question 9

(a) Give the meaning of the term ‘occupational health’. (2)

A large organisation is outsourcing its occupational health service to a contractor. It has been advised to choose a contractor that carries the SEQOHS logo.

(b) (i) Identify what SEQOHS stands for. (1)
(ii) Outline how SEQOHS operates. (5)
(c) Outline TWO benefits to a worker of having access to an occupational health service at work. (2)

Answer 9

(a) Occupational Health is the promotion and maintenance of the highest degree of physical, mental and social well-being of workers in all occupations by preventing departures from health, controlling risks and the adaptation of work to people, and people to their jobs.
(b) (i) SEQOHS stands for Safe, Effective, Quality Occupational Health Service and is a set of standards and a voluntary accreditation scheme for occupational health services established by the faculty of occupational medicine.
(ii) SEQOHS aims to: enable services to identify the standards of practice to which they should aspire. They credit good work being done by high quality occupational health services and provide independent validation through audits that they satisfy standards of quality. And raise standards where they need to be raised.
(c) Having a workplace occupational health (OH) service gives your employer access on site to competent professional specialist advice which will help protect the health of workers.

OH services can provide direct help for workers who suffer an injury or ill health related to work. It gives you an opportunity to discuss worries about your medical problems and difficulties you may be facing at work.

Question 10

(a) Outline what is meant by the term ‘biological monitoring’ AND give examples where this type of monitoring may be appropriate. (6)
(b) Outline practical difficulties that an employer must overcome when introducing a programme of biological monitoring. (4)

Answer 10

(a) Biological monitoring is the measurement of a substance or its metabolite (substance formed when the body converts the chemical) in a biological fluid (breath, urine, or blood). An example of this is monitoring urine for the presence of isocyanates.

In principle, biological monitoring can be appropriate(useful) when:

• Absorption is likely to be through skin and ingestion rather than inhalation, therefore air monitoring is not a complete indicator of uptake.
• There are valid laboratory methods available for the detection of the chemical or its metabolites in the body.
• There are reference values available for the interpretation of the results obtained.
• PPE is used as a significant control; failure to wear PPE correctly would not be shown up by air monitoring, but it would be indicated by biological monitoring.

(b)

• Biological monitoring would normally require informed consent and maintaining confidentiality.
• Depending on the techniques used, suitable facilities would be needed (and perhaps specialist personnel), with the associated costs.
• Sample contamination also needs to be avoided.
• There is also little point in carrying out biological monitoring if no agreed technique exists or the result cannot be interpreted against any recognised standard.