B2

Question 1

Jan 20 See Jul 08 Jul 05

Animal studies can be used to assess 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)

(b) Outline the advantages and disadvantages of using animal studies to investigate whether a substance may be hazardous to humans. (6)

Answer 1

(a)
(i) NOAEL stands for No Observed Adverse Effect Level and is a level of exposure at which there is no evidence of harm.

(ii) LD50 is an abbreviation of “Lethal Dose 50%” - that is the single oral dose of a substance that is ingested and kills 50 per cent of a test population. LD50 is measured in milligrams (or grams) per kilogram body weight (mg / kg).

(b) Advantages
• Does not rely on exposing people to chemicals, thereby preventing human disease and suffering.
• Can be quicker and cheaper than epidemiological studies on human populations.
• Provides good-quality information about the effects of exposure to certain chemicals that could not be
determined by other types of study, such as in-vitro studies.
• Allows the long-term effects of exposure to low doses to be studied, replicating the actual types of
exposure that workers might experience at work.

Disadvantages
• Responses vary between species, so application to humans may be questionable
• Raises ethical questions about testing on animals
• Diseases like cancer may have a number contributing effects
• Can be expensive/time consuming

Question 2

Jul 19
(a) Explain how exposure to silica dust can cause silicosis. (4)

(b) The construction of a city’s underground rail line involves extensive tunnelling and concrete spraying activities.

Outline controls that reduce the risk of employees developing silicosis, while carrying out tunnelling and concrete spraying activities. (6)

Answer 2

(a) Once inhaled, the silica dust can be trapped in the alveoli and producing scarring or silicosis. The scarring, or hardening of lung tissue, affects the function of the lungs making breathing difficult. This is a chronic condition with sufferers often finding that symptoms of silicosis can worsen even if exposure ceases.
(b) Control measures: LEV; use of HEPA vacuum (workshop); use of power tools with integral extraction / water spray; wet working - water spray, damping down (workshop & on-site); PPE - eye protection, gloves, RPE (workshop & on-site); washing, changing, clothes / PPE / RPE storage facilities (workshop & on-site).

Question 3

Jan 19
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)

Answer 3

(i) a carcinogen is a substance or a mixture of substances which induce cancer or increase its incidence It attacks the mechanism which controls reproduction of normal cells and causes changes in the cell which divide uncontrollably. They grow, spread, invade and destroy the surrounding tissue.

(ii) Epidemiology Disadvantages
• Large study populations are needed and over a long period
• Often people are lost from the study as it progresses over time.
• Poor quality of health affects data and/or exposure data
• Such studies are costly.

Epidemiology Advantages
• Is based on actual experience in actual populations
• Can reveal links between a particular chemical and ill health in humans
Definitive method for identifying human carcinogens;

• (iii) Animal studies Disadvantages
• Responses vary between species, so application to humans may be questionable
• Raises ethical questions about testing on animals
• Cost and the amount of time it takes;
• Requires large populations in order to reduce sampling errors;
• Poor or inaccurate historical records;
• Affected by lifestyle factors;
• Not very useful for assessing completely new substances since latency periods may be extensive;
• The study might be affected by synergistic or additive effects.

Question 4

Jan 19
Human epidemiology and animal studies are methods that can be used to investigate whether a substance is carcinogenic.

(b) Outline the control measures that should be in place in a workplace where a carcinogenic substance is used. (8)

Answer 4

(b) Control measures include:

• Keeping quantities to a minimum
• Total enclosure,
• Use of Local Exhaust Ventilation
• Prohibition of eating and drinking in contaminated areas,
• Designation and cleaning of contaminated areas,
• The use of suitable warning signs
• Closed and labelled containers
• Reducing the number of people that are exposed
• Reducing the time that people are exposed
• Labelling and sealing of any contaminated waste

Question 5

Jan 17 Jan 14 Jan 11
A facilities manager of a multi-occupancy office block built in the 1970s is concerned about the risks associated with asbestos in the building.

(a) Outline the steps the facilities manager should take to minimise the risks associated with any asbestos that may be present in the building. (12)

Answer 5

(a) The facilities manager should:
accept responsibility as dutyholder in relation to CAR reg 4 “duty to manage asbestos”; assume asbestos present (age of building); carry out / arrange for an asbestos survey of the building by a competent person to identify suspected “asbestos-containing materials” (ACMs); carry out / arrange for (intrusive / destructive) sampling as necessary; survey / sampling to be conducted as per P402 or ABICS accredited); draw up an asbestos management plan; maintain records in an asbestos register; keep records of type, location and condition of ACMs; label asbestos / provide warning signs at appropriate locations; prioritise asbestos management – encapsulate / repair, remove; review and update register periodically and after any significant maintenance activity / disturbance; make register / information available to building occupants, contractors etc

Question 6

A facilities manager of a multi-occupancy office block built in the 1970s is concerned about the risks associated with asbestos in the building.

(b) An occupant of one of the offices engages a contractor to fit a hand dryer in a toilet which involves drilling through some asbestos insulating board.

Outline the steps that should be taken by the contractor to carry out this work in accordance with the Control of Asbestos Regulations 2012. (8)

Answer 6

(b) The contractor should: carry out this work, in accordance with the Control of Asbestos Regulations 2012.
• Ensure the area is appropriately signed and cordoned off;
• Remove furniture and fittings from the area or protect using 500-gauge polythene sheeting;
• Protect nearby surfaces from contamination by covering with 500-gauge polythene sheeting and fix with duct tape to non-asbestos surface;
• Cover the drill entry and, if accessible, exit points with a generous amount of paste or foam - us a hand drill rather than an electric drill;
• Drill through the paste or foam;
• Clean off the paste, foam and debris with damp rags;
• Seal the drilled edge with sealant;
• Clean the area and equipment with the Class H vacuum cleaner and damp rags;
• Double bag all debris, used rags, paint brushes, polythene sheeting and other waste as dispose of as asbestos waste;

Question 7

Jul 13 Jan 10 Jan 06

(a) Outline the principles of a prospective cohort study, as used in epidemiology. (4)
(b) Outline factors that may affect the reliability of such cohort studies. (6)

Answer 7

(a) A prospective cohort study is designed to verify or deny a hypothetical link between an occupational exposure and an ill-health condition. It involves following two similar groups (cohorts) forward in time to evaluate their future health outcomes. One of the groups / cohort has been (or is being) currently occupationally exposed to the agent under investigation while the other cohort has not. For example, workers in the micro-electronics industry who are exposed to toxic chemicals are followed forward in time (tracked) to see if there is an excess of cancers arising in future years; their health outcomes can be compared to those for a similar unexposed cohort (a control group).

(b) Reliability of epidemiological cohort studies is affected by:
• inadequacy of the data - health records / death certificates are not very reliable sources of information on occupation / illness / cause of death
• inaccurate recollection of past exposures / occupational history etc
• tendency to tell researchers what they “want to hear” (“now you come to mention it…” = recall bias)
• cohort size - need reasonably large numbers to ensure statistical validity
• difficulties in selecting comparable cohorts
• confounding factors - lifestyle (smoking / diet / exercise etc); social class / income
• long latency periods for certain conditions requires long term studies - delayed results
• difficulty in tracking people / people drop out / move away
• “healthy worker effect” - sick individuals tend to be “selected out” of workforce so cohort is not representative of general population (selection bias)

Question 8

Jan 13
(a) Outline the advantages and disadvantages of animal testing as a model to predict the effects of hazardous substances on humans. (6)

Answer 8

a) Advantages of animal testing:

• Avoids human exposure and hence possible human risk;
• Data can be collected more quickly than by using epidemiological methods;
• Environment of the animal can be better controlled;

Disadvantages of Animal testing

• The dose/response effect may vary in different animal species (converting data to humans may not always be reliable);
• Time-consuming and expensive dependent on the species used;
• Ethical considerations and public opinion that can make this approach more difficult to undertake;

Question 9

(b) A principle of REACH legislation is that animal testing should only be done as a last resort.

Outline how each of the following can provide data on the human health effects of hazardous substances without animal testing:

(i) in vitro testing (3)
(ii) read-across (3)
(iii) Quantitative Structure Activity Relationship (QSAR) (2)

Answer 9

(b)

(i) in vitro
• Ames test for mutagenicity;
• Involves experiments carried out in a test tube or petri dish;
• Tissue without histidine are exposed to a substance – the substance is a mutagen if it allows the tissue to grow;
• Involves exposing cells or tissues, grown outside a living organism, to a hazardous substance;
• As a result, an understanding of how that substance was metabolised or affected the cells was gained.

(ii)
• Read-across is based on the assumption that substances with similar chemical structures will have similar toxicological effects on humans, so this approach can be used to avoid or reduce the need for animal testing on new substances that are similar in structure to those already tested;
• Instead the data already recorded for similar substances can be read across to predict the toxicological properties of the new substances.

(iii)
• Uses computer based models to predict the likely effects of substances on humans;
• The predictions are based on chemical structure and can also provide an estimation of the risks in relation to the levels of exposure.

Question 10

(c) A UK company manufactures 3 tonnes / year of a new hazardous substance for sale in the EU.

Outline the steps a company must take in order to comply with the REACH legislation. (6)

Answer 10

c)
• Quantities of more than 1 tonne make the REACH legislation applicable;
• The substance must be registered with the European Chemicals Agency (ECHA);
• Part of this registration process is to provide technical information on the physiochemical, toxicological and the eco-toxicological properties of the substance;
• A safety data sheet would need to be provided to users;
• If changes were made to the substance or the quantities being manufactured were to increase, then this would need to be notified and further information may have to be provided;

[* only required if manufacturing >10 tonne / year]

Question 11

Jan 13
The Control of Lead at Work Regulations 2002 require that where the exposure to lead of any employee is, or is likely to be, significant, the employer must ensure that the employee is under medical surveillance by a relevant doctor.

(a) Outline the meaning of the term “significant” in relation to lead exposure. (2)
(b) In an organisation that manufactures lead-acid batteries, some of the employees handle lead oxide powder. These employees take part in biological monitoring to measure their lead-in-blood concentration. The results for two general male employees, X and Y, are shown in the table below.

(i) Explain the relevance of the results, with reference to CLAW. (4)
(ii) On the basis of these results outline the actions the employer should take in relation to employee Y in order to comply with CLAW. (4)

Answer 11

(a).
• where any employee is or is liable to be exposed to a concentration of lead in the atmosphere exceeding half the occupational exposure limit for lead;
• where there is a substantial risk of any employee ingesting lead;
• Where there is a risk of lead being absorbed through the skin.

(b)The employees undergo biological monitoring to measure blood-lead concentrations. The results for two general male employees are shown below:
Male employee Lead-in-blood concentration (μg / dl)
X
55
Y
65

(b)(i)
• X had a blood-lead concentration above the action level but below the suspension level;
• Y had a blood-lead concentration that exceeded the suspension level.

(ii)
• suspend an employee because their blood-lead concentration requires this and a doctor has considered it necessary;
• record this in the employee’s health record;
• check that the doctor has communicated this to the employee;
• review the lead risk assessment and control measures;
• check the health of other employees with similar exposures to lead.

Question 12

Jul 12 Jan 10 Jul 08

Employees can be exposed to corrosive substances.

(a) Give the meaning of the term “corrosive”. (2)
(b) The data below, for three forms of the same product, is taken from a supplier’s catalogue.

Using the data outline the likely routes of entry AND the effects of exposure when handling EACH of these products.(8)

Prodcode Chemical name / form Conc Physical form

C1. Sodium hydroxide (NaOH). 99.9% Pellets

C2 Sodium hydroxide (NaOH). 97%. Powder

C3 Sodium hydroxide (NaOH) 50% in water Liquid

Answer 12

a) Corrosive = may rapidly destroy living tissue if inhaled, ingested or on contact / splashed onto the body.
(b) All corrosive / irritant:

• C1 is in pellet form, it may be ingested (accidentally) affecting the digestive tract and may contact or penetrate the skin. Additionally, dust from the pellets may be inhaled affecting the respiratory tract;
• C2 being a powder, the most likely route of entry would be via inhalation; therefore, the effects of exposure to C2 would be in the respiratory tract. The powder C2 when airborne could also affect the eyes and skin;
• C3 is in liquid form and though it has the lowest concentration of NaOH, will be likely to splash and affect the skin of the face and hands and the eyes;

Question 13

Jan 12 Jul 09 Jul 07

(a) Describe the structure of the skin and how hazardous substances may enter the body by this route. (6)
(b) Outline how hazardous substances can enter the body through the skin. (4)
(c) Construction company employees regularly lay floors and use a cement-based levelling compound which contains Chromium VI. Several of the long term employees and one of the new recruits have complained about red and sore skin on their hands.
(i) Explain the possible reasons for the symptoms they are now experiencing. (6)
(ii) Outline control measures that could be used to minimise these symptoms in this situation. (4)

Answer 13

(a) & (b) Skin consists of:
• The skin consists of an outer layer, the epidermis which consists of dead cells that are continually shed. It provides some protection against physical and chemical damage but some hazardous substances, particularly biological agents can enter through cuts, abrasions or puncture wounds;
• Beneath this lies the dermis (living cells) containing blood vessels nerve endings and sweat glands. It is partially permeable to water-soluble and fat-soluble substances such as organic solvents which could then enter the bloodstream.
• Below this layer is the hypodermis layer. It is made up of fat and connective tissue and insulates the body against heat/cold and protects our organs/bones from outside forces, such as pathogens.

(b)• beneath this lies the dermis (living cells) containing blood capillaries, nerve endings, sweat glands; partially permeable to water-soluble and fat-soluble substances eg organic solvents / oils which may permeate the skin and then enter the bloodstream.
• Subcutaneous layer - arteries, veins, fatty tissue

(c)
(i) Reasons for symptoms associated with contact dermatitis include prolonged / frequent contact with irritant(s) - eg cement dust / wet cement containing chromium (VI) salts which are recognised skin sensitisers; sensitising agents initiate an allergic / immune response on exposure; sensitisation can occur rapidly (acute) or arise after prolonged exposure (chronic) by degreasing the skin and progressively undermining the skin’s natural defence and repair mechanisms; exposure to abrasive materials is likely to exacerbate the condition.

(ii) Control measures include:
elimination - use alternative compound not cement-based or substitute with a compound containing less cement / lower concentrations of Cr(VI) salts; provide protective neoprene gloves / gauntlets; provide moisturising hand creams / barrier creams; provide washing / drying facilities; provide training and information on health risks / dermatitis; introduce a skin inspection programme (health surveillance) - self inspection / supervision by appointed person

Question 14

Jan 12 Jul 08 Jan 07

Human epidemiology and animal studies are methods that 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)

Answer 14

(a)
Human epidemiology
• Definitive method for identifying human carcinogens;
• Based on experience in actual populations;
• Can be done retrospectively.

Animal studies
• Avoids human exposure and hence possible human risk;
• Data can be collected more quickly than by using epidemiological methods;
• Environment of the animal can be better controlled

(b) The disadvantages of using animal studies to investigate the possible carcinogenic effects to humans are:

Human epidemiology
• Cost and the amount of time it takes;
• Requires large populations in order to reduce sampling errors;
• Poor or inaccurate historical records;
• Affected by lifestyle factors;
• Not very useful for assessing completely new substances since latency periods may be extensive;
• The study might be affected by synergistic or additive effects.

Animal Studies
• The dose/response effect may vary in different animal species (converting data to humans may not always be reliable);
• Time-consuming and expensive dependent on the species used;
• Ethical considerations and public opinion that can make this approach more difficult to undertake;
• Difficulties in converting animal data to humans;

Question 15

Jul 11 Jan 09

(a) Describe the ways the body may defend itself against inhaled dusts. (12)
(b) A company uses a substance in the form of a powder, which is added directly to a mixing vessel from sacks during the manufacture of paints.

Outline the practical control measures that could be used to minimise exposure during the addition. (8)

Answer 15

(a) Dust larger aerodynamic diameter than 10 microns will lodge in nasal hair and mucous in upper respiratory tract - removed by sneezing, coughing, spitting mucous, sneezing, swallowing; dust particles of 5-10 microns will deposit in the “thoracic” area - trachea, bronchi, bronchioles - removable via ciliary escalator, mucous, ejection etc; the respirable dust - less than 5 microns - will penetrate to the gas-exchange regions of the lung (alveoli) where it may pass across cell membrane into blood stream or deposit initiating an auto-immune response whereby the dust particles are engulfed by phagocytes (white blood cells) which may cause scarring / fibrosis / pneumoconiosis (dependent on physico-chemical properties of the dust); respirable dust may also be transported back to ciliary escalator or lymphatic system.
(b) Apply hierarchy of control (eliminate process not acceptable since colour required) but: change physical form of dye from powder to pellets / granules or liquid to reduce or eliminate dust generation; alternative to sacks = automated / enclosed feed system for dispensing powder into mixing vessel; LEV; spill control measures - HEPA vacuums/ spill containment kits etc; PPE - gloves, overalls, goggles; RPE - FFP / respirator; hygiene arrangements - washing / changing facilities

Question 16

Jan 11

A company is considering substituting a solvent it currently uses for one that is thought to be more effective.

Outline the factors affecting health that should be considered before a decision is taken to make the change. (10)

Answer 16

Factors that should be considered include:

• information provided in the Safety Data Sheet / label - eg hazard classification (toxic / corrosive carcinogenic etc); risk phrases / safety phrases eg R45 May cause cancer; physical properties - volatility / vapour pressure / boiling point etc
• the physical form of the substance (liquid / spray)
• relevant occupational exposure standards - WELs / OELVs
• routes of entry - inhalation; ingestion; skin contact / pervasion
• health effects - acute / chronic: narcotic / nausea / dizziness; dermatitis; respiratory / occ asthma; neuro-toxicity; cancer
• volume / quantity used
• duration of use / exposure
• frequency of use / exposure
• number of persons (users) exposed; others / inadvertent exposure
• individual susceptibility eg YPs / N&EMs; those with existing health conditions - asthma / dermatitis etc that may be aggravated
• availability and / or effectiveness of existing control measures - LEV / PPE / RPE etc
• any additional control measures required
• storage arrangements - security / signage / spill control etc
• emergency arrangements - spill kits / containment

Question 17

Jul 10 Jul 07

(a) Describe the physiological effects of carbon monoxide on the body and identify the symptoms that may be experienced by exposed persons. (4)
(b) Outline the control measures that could be used to reduce exposure to carbon monoxide in a motor vehicle repair premises. (6)

Answer 17

(a) Carbon Monoxide is inhaled into the lungs where it passes into the bloodstream, displaces oxygen and combines with haemoglobin to form carboxy-haemoglobin; as this is a relatively stable chemical combination which is only slowly displaced from the blood stream it reduces the capacity of the blood to carry oxygen to the brain, vital organs and body tissues. Resulting symptoms include fatigue, loss of concentration, disorientation, headaches, nausea, dizziness, breathlessness, collapse and ultimately death.
(b) Exposure to CO in a MVR workshop can be reduced by providing suitable LEV (connected to exhaust system); reducing the duration of engine running tests etc; carrying out work outside; providing natural ventilation of work area / vehicle pits; monitoring airborne CO levels; health surveillance - biological monitoring (exhaled breath); installing CO monitors / alarms; providing relevant training and information; segregating test areas from customer facilities.

Question 18

Jan 10 Jul 08 Jul 06

(a) Identify published sources of information an employer could use to determine if carcinogens are being used in their workplace. (4)

Answer 18

(a)
Carcinogen = substance that may cause cancer (R45 & R49);

Carcinogens initiate uncontrolled cell proliferation to form a tumour; Mutagen = substance that may give rise to alterations in genetic material that can then be transmitted to a subsequent generation. Sources of information: Product label and MSDS - risk phrases R45 May cause cancer; COSHH Schedule 1 List of carcinogens & EH40 entry; CHIP - criteria for self- classification; Annex VI of CLP Regulation for classification as a carcinogen; European Chemicals Agency lists / Substances of very high concern (SVHC); Trade Association reports - Chemical Industry Association; HSE / WHO / ILO / HPA reports; scientific papers; epidemiological studies / reports / data

Question 19

(b) Outline the control measures that should be used when, because of the nature of the work, it is not possible to eliminate a carcinogen or substitute it with an alternative substance. (16)

Answer 19

b)
• Reduce exposure to a level as low as reasonably practicable - minimising quantities used and/or changing the physical form;
• Totally enclosed system or automation of the process to physically separate workers from the process and, where this is not possible, the use of a partial enclosure in the workplace or appropriate local exhaust ventilation;
• Provide appropriate storage including the use of closed/sealed containers and recognition that it may be better to store one large quantity in a controlled manner than to deal with frequent supplies of smaller amounts.
• Label materials correctly and restrict areas of use - signs to indicate their boundaries;
• Waste carcinogenic products should be labelled and stored in a secure area pending removal by a specialist contractor;
• Restrict the number of worker and exclude non-essential personnel;
• Prohibit eating, drinking and smoking to reduce contamination;
• Warning signs to demark these areas;
• Adequate washing facilities;
• Monitoring of levels of exposure should be carried out on a regular basis to ensure the adequacy of the control measures in place with the recognition that the use of personal protective equipment can only be used as a secondary control in combination with other controls.

Question 20

Jul 09 Jan 07
Stonemasons cutting and finishing limestone are exposed to limestone dust. Limestone dust has been assigned a Workplace Exposure Limit (WEL) under the COSHH Regulations 2002.

(a) Give the meaning of ‘Workplace Exposure Limit’ (WEL). (3)

Answer 20

(a) WEL = the maximum concentration of limestone dust averaged over an 8 hour reference period (8 hour Time-Weighted Average), to which employees may be exposed by inhalation

The WEL for limestone dust is measured in mg/m3. (EH40 Total inhalable=10mg/m3; respirable=4 mg/m3)

For control of exposure to be adequate under the COSHH regulations, the principles of good practice set out in Schedule 2A should be applied and the WEL should not be exceeded.

Question 21

Jul 09 Jan 07
Stonemasons cutting and finishing limestone are exposed to limestone dust. Limestone dust has been assigned a Workplace Exposure Limit (WEL) under the COSHH Regulations 2002.

(b) Explain the factors to be considered when undertaking a suitable and sufficient assessment of the risks from their exposure to limestone dust. (11)

Answer 21

(b) Factors to consider
• the health effects of the dust such as irritation to the skin, eyes and respiratory tract;
• the particle size of the dust which will determine how far into the body the dust will pass;
• the way in which the work is carried out whether by hand or power tool;
• Frequency of exposure;
• Individual suceptabilities;
• Number of people exposed;
• Effectiveness of existing controls;
• Thresholds of exposure - the amount needed to cause harm;
• Hazardous properties of the substance;
• Routes of exposure;
• EH40 exposure limits;
• Synergistic qualities;
• Health surveillance and exposure monitoring results;
• Operating conditions and processes - nature of the task, methods used, high temperature;
• Likelihood of failure of existing control measures;
• Duration of exposure;
• Review regularly;

o Suspect no longer valid;
o Significant change occurs;

Question 22

Jul 09 Jan 07
Stonemasons cutting and finishing limestone are exposed to limestone dust. Limestone dust has been assigned a Workplace Exposure Limit (WEL) under the COSHH Regulations 2002.

c) Outline a suitable range of control measures that could reduce the risk to stonemasons from exposure to limestone dust. (6)

Answer 22

(c) Control measures:

Workshop
• the use of local exhaust ventilation would be required;

Out on site
• Damping down;

Both
• the use of cutting tools with built-in extraction or a damping spray;
• the provision and use of respiratory protective equipment, which should;
o be comfortable to wear for extended periods of use; o be compatible with other PPE;
o be suitable for use during work at height;
• the provision of eye and hearing protection, gloves and overalls;

Question 23

Jul 09
According to the Control of Substances Hazardous to Health Regulations 2002 (COSHH), one of the circumstances in which health surveillance is considered appropriate “is where the exposure of the employee to a substance hazardous to health is such that an identifiable disease or adverse health effect can be related to the exposure”.

(a) Identify an example of an exposure to hazardous substance which could meet this requirement AND state the nature of the health surveillance to be undertaken in this case. (2)
b) Outline the procedures and facilities that an organisation should put in place if they are to carry out health surveillance in accordance with the COSHH regulations. (8)

Answer 23

a) Example = any toxic substance / other chemical that could enter system via inhalation / ingestion / skin absorption (organic solvents; mercury compounds; carbon monoxide etc):
HS = biological monitoring by means of analysis of samples of blood / urine / exhaled breath. Or dust / fume / vapour eg isocyanates / flour dust etc:
HS = lung function testing (spirometry) ; Or dyes, detergents, bleaches, solvents, cement, chromium compounds etc which can cause dermatitis:
HS = questionnaire, skin inspection
Comment: Not asbestos or lead (not included in COSHH Regs - see Q)

(b)
Procedures
• carrying out of medical surveillance for Schedule 6 substances by an appointed doctor on an annual basis;
• the completion of other health surveillance by a suitably qualified person such as an occupational health nurse or other responsible person under the supervision of a registered medical practitioner;
• procedures for assuring the integrity of any samples taken and their submission to an accredited laboratory;
• informing an employee if an adverse health effect or disease is identified during the surveillance;
• the maintenance of up to date health records and their retention for a period of forty years;
• arrangements for employees to view their own health records.

Facilities
• the allocation of a suitable room which would ensure privacy, provided with toilet and hand washing facilities;
• sufficient space to store records.

Question 24

Jul 08 Jul 05

(a) Outline the following toxicological terms:
(i) LD50 (2)
(ii) LC50 (2)

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

Answer 24

(a) (i) LD50 is an abbreviation of “Lethal Dose 50%” - that is the single oral dose of a substance that is INGESTED and kills 50 per cent of a test population. LD50 is measured in milligrams (or grams) per kilogram body weight (mg / kg).
(ii) LC50 is an abbreviation of “Lethal Concentration 50%” - that is the INHALED concentration sufficient to kill 50 per cent of a test population in a fixed period of time. LC50 is measured in milligrams (or grams) per cubic metre of air (mg / m3) or parts per million (ppm).

(b)
Advantages
• these methods avoid human exposure and therefore possible human deaths;
• the data can be collected more quickly than using epidemiological methods;
• Animals provide the best available models as they relate more closely to humans;
• More likely to detect carcinogenic potential than in vitro testing such as Ames tests.

Disadvantages
• The dose/response effect may vary in different animal species and so extrapolating data to humans may not always be reliable;
• Conducting animal studies can be time-consuming and expensive;
• ethical considerations and public opinion that can make this approach more difficult to undertake;
• 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;
• There are also difficulties with the “no observed effect level” for carcinogens.

Question 25

Jan 08 Jan 06

(a) Outline, using an example, why and how a retrospective case-control study is carried out.
(5)

(b) Outline the factors that affect the reliability of this type of study. (5)

Answer 25

(a)
Why
• Type of epidemiological study looking for a link between cause (exposure) and effect (ill- health);
• Studying two groups (cohorts), one exposed (case) and one not exposed (control) to see if there is a significant difference in the incidence of the ill-health effects between the two groups;
• Determining if there is a dose/response relationship;

How
• Involves a ‘look back’ often at statistical data, health records, death certificates and interviews to establish ‘occupational exposure history’;
• By studying and comparing health outcomes in both exposed and unexposed cohorts it may be possible to identify any differences that may be attributed to their exposure history;

Example
• Comparing illness in ex-miners with illness in ex-hospital porters of a similar age and socio- economic background, it may be possible to attribute specific types of lung disease to occupational agents (coal dust)

Question 26

Jul 07
Safety Data Sheets (SDS) provide important information to employers who are required to assess exposure to hazardous substances in their workplace.

(a) Identify FIVE types of information on a typical SDS. (5)
(b) In EACH case outline how the information could contribute to the assessment of exposure. (5)

Answer 26

a) Information included on a typical SDS will include:
• Regulatory information;
• Other information.
• Transport information;
• Toxicological information;
• Ecological information;
• Disposal information;
• First-aid measures;
• Fire-fighting measures;
• Ingredients;
• Storage;
• Hazards identification;
• Accidental release measures;
• PPE;
• Stability and reactivity;
• Identification of the substance/mixture and of the company/undertaking;

(b)• First-aid measures – know if special first aid considerations and equipment/ personnel needed;
• Fire-fighting measures – Information to tell the fire department;
• Ingredients – check against other chemicals to ensure if both spilt a chemical reaction
wouldn’t occur;
• Storage – if storage needs to be outside or away from anything;
• Hazards identification – what the chemical could do if people are exposed to it;

Question 27

Jul 07
(a) Describe the structure of skin and how hazardous substances may enter the body by this route. (6)

(b) Explain how contact (primary) dermatitis can occur. (4)
(c) A number of employees working in a busy city centre hair salon have reported problems of skin irritation on their hands, which for at least one employee has been diagnosed as contact dermatitis. Advise the salon manager on the likely causes and the steps that could be taken to overcome these instances of contact dermatitis. (10)

Answer 27

(a)
• The skin consists of an outer layer, the epidermis which consists of dead cells that are continually shed. It provides some protection against physical and chemical damage but some hazardous substances, particularly biological agents can enter through cuts, abrasions or puncture wounds;
• Beneath this lies the dermis (living cells) containing blood vessels nerve endings and sweat glands. It is partially permeable to water-soluble and fat-soluble substances such as organic solvents which could then enter the bloodstream.
• Below this layer is the hypodermis layer. It is made up of fat and connective tissue and insulates the body against heat/cold and protects our organs/bones from outside forces, such as pathogens.

(b)
• Following prolonged or repeated exposure to certain substances which de-fat or degrease the skin, destroying the natural oils and leaving it dry, cracked and inflamed;
• Corrosive or irritant substances may cause redness, itchiness and localised inflammation;
• The dermatitis occurs at the point of contact and skin normally recovers following cessation of exposure.

(c)
Causes
• exposure to irritant substances such as bleaches and dyes;
• prolonged contact with water and detergents, the removal of natural oils from the skin;
• the possibility of sensitisation to one or more of the materials used;
• individual susceptibility;
• the concentration and potency of the substances in use;
• the frequency and duration of exposure to the substances;
• damaged skin;
• poor personal standards of hygiene;
• a failure to protect hands by using barrier creams and gloves.

Steps to reduce
• a clear skin care policy;
• the identification of susceptible persons during recruitment procedures;
• ensuring safety data sheets are available for all products used;
• the elimination or substitution of allergic products;
• job rotation to reduce individual involvement in wet work, perms and the application of dyes;
• the provision and use of disposable gloves;
• the provision of training and information with particular reference to standards of personal
hygiene and the use of skin care creams;
• Health surveillance to ensure early recognition of skin problems.

Question 28

Jul 07 Jul 05
Contractors have been engaged to carry out re-cabling work in an office. During this work a small area of ceiling board is removed. At this point the office manager raises a concern that the ceiling material may contain asbestos and that office staff and contractors working in the area may be exposed to asbestos.

(a) Outline the steps that should be taken to deal with the immediate problem. (8)
(b) Suggest steps that could be taken to prevent a similar situation arising during future work of this nature. (2)

Answer 28

(a) Steps that should be taken include:
Stop the re-cabling work and any other activities that could give rise to airborne asbestos fibres
Cordon off the area - restrict access and place warning signs
Reduce air movements in the area - shut down air conditioning and ventilation systems, desk fans etc.; close doors and windows to reduce draughts
Do not allow contaminated tools, equipment or personnel to leave the area as this could help spread the contamination
Seal up anything potentially contaminated with ACMs (including tools, equipment or clothing belonging to the contractors) in double plastic bags appropriately labelled
Follow hygiene procedures - washing / showering where appropriate
Take a sample of the potential ACM for analysis if safe to do so - sealed as above
It may be necessary to seal off the area until a survey has been conducted by a competent person so that the condition of any ACM can be assessed (see below)
If the laboratory analysis identifies asbestos as being present its condition will have to be assessed by a competent person - an asbestos survey will be required
If the results of the survey indicate that remedial action is required this may entail sealing the asbestos in situ or its removal - the latter involving the services of a licensed asbestos removal contractor
Removal should be carried out under strictly controlled conditions - polythene enclosure at negative pressure; HEPA filters; wet stripping; suitable PPE / RPE; double bagging of waste in UN type-approved bags; segregated eating / drinking areas; use of decontamination unit with appropriate compartmentalisation: “dirty – shower – clean”; disposal via licensed waste carrier / licensed waste reception centre

(b)
• Carry out an asbestos survey to identify any further presence of asbestos;
• label the areas where any was found and to keep a record of its location;
• A duty holder would also have to be appointed;
• an asbestos management plan prepared;
• steps taken to ensure that any future maintenance work was carried out in accordance with the plan.

Question 29

Jan 07
(a) Explain why it is difficult to determine whether cancers in the working population are caused by exposure to substances at work. (6)

Answer 29

(a) Difficult to determine whether cancers in the working population are caused by exposure to substances at work because of:
• long latency periods before cancers appear - exposed individuals may have changed jobs and / or moved away meaning that the connection between exposure and cancer is more difficult to establish
• multi-causality - few cancers can be attributed unambiguously to a specific agents (mesothelioma, angiosarcoma) - therefore difficult to make link with certainty (instead a statistical probability is applied)
• many cancers are common in the general population (eg lung cancer) so there is often no obvious link / clear pattern relating to occupational exposure
• cancer can be caused by a combination of social, environmental and occupational exposures interaction / synergism / potentiation (eg asbestos + smoking)
• poor historical records - death certificates, morbidity / mortality data; occupational history
• individual susceptibility / genetic vulnerability

Question 30

(b) Review the merits and limitations of each of the following methods for Identifying the carcinogenic potential of a substance.
(i) Human epidemiology (5)
(ii) Animal studies (5)
(iii) In vitro mutagenicity testing (4)

Answer 30

(i) Human epidemiology
MERITS
Involves the application of established methodologies
Techniques are validated, statistically-based & directly applicable to human exposures
Identify patterns of ill-health and potential causal relationships

LIMITATIONS
requires large populations / cohorts for analysis - need to track cohorts over long periods
resource intensive / time-consuming (delayed results) and requires high levels of expertise
results can be inconclusive - difficulty in screening out confounding factors - social / environmental / lifestyle / age / gender etc
reliability of data is questionable (medical records, death certificates, recall etc)

(ii) Animal studies
MERITS
avoids human exposures
results produced more quickly than above
certain species provide a good analogy for human exposures (but…)
no complications of tracking cohort etc
LIMITATIONS
results may not reflect human response to similar exposures (2-napthylamine = bladder cancer in humans not in rats)
animal studies tend to focus on acute effects - human cancers often involve chronic effects
animal studies are “artificial” and do not reflect the complexity of human exposures - diet / smoking etc
ethical objections to animal testing

(iii) In vitro mutagenicity testing
MERITS
Ames test = widely used / validated / recognised methodology
Quick and inexpensive
No ethical issues
Can form preliminary basis for further in vivo testing
Can help identify mutagenic / carcinogenic mechanisms
LIMITATIONS
Results not always relevant to human exposures
Not all mutagens are carcinogens(= false positives)
Results from Ames test may be unreliable - false positives / false negatives

Question 31

Jul 06

(a) State the purpose of, and Identify the duty holders under, the Chemicals (Hazard Information and Packaging for Supply) Regulations 2002 (CHIP) (3)
(b) Outline the specific measures that a duty holder under CHIP must take to comply with these regulations. (7)

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Answer 31

(a) The purpose of the CHIP regulations is to protect people and the environment by ensuring that hazardous substances are:
• properly classified (identified) in terms of their hazardous properties
• accompanied by appropriate hazard information (labels and safety data sheets)
• suitably packaged to reduce the likelihood of loss of containment, tampering etcThe CHIP regs place duties on suppliers of hazardous substances. ‘Supply’ means making a chemical available to another person. Manufacturers, importers, distributors, wholesalers and retailers are all examples of suppliers.

(b) Suppliers must classify hazardous substances / preparations in accordance with the requirements of the Approved Methods for the Classification of Hazardous Substances and the corresponding entries in the Approved Supply List. This involves identifying the substances in terms of their physico-chemical properties and allocating them to one of the relevant hazard categories – toxic, corrosive, irritant, harmful, carcinogenic, mutagenic, teratogenic etc.
Hazard information must include suitable labelling / SDS to include:
• the name, address, phone number of the supplier / manufacturer
• the appropriate hazard warning symbol
• details of the physical and chemical properties of the substance / preparation
• emergency information - first-aid, spill control
• risk phrases - R45 - may cause cancer
• safety phrases - S24 - avoid contact with skin
• disposal information
Hazardous substances / preparations must be packaged in accordance with to UN type-approved packaging standards which include features such as impact resistance for receptacles, child-proof openings, tactile warnings / information for products which are supplied to the public.

Question 32

Jul 06
The table below shows data provided in a supplier’s catalogue for three different grades of the same industrial chemical.

(a) Use the data to identify the likely distribution in the respiratory tract of each of these powders following inhalation.(3)
(b) In each case describe the mechanisms the body may use to defend itself. (7)

Answer 32

Prod code /Desc /Av part size (microns/)Particle size dist
AS1/01 Fine white powder. 15 12-20

AS1/02. Fine white powder 8 7-10

AS1/03 Fine white powder 2 1-5

(a) + (b)
AS1/01 - Particle size indicates that the dust will lodge in nasal hair and upper respiratory tract - removed by sneezing, coughing, mucous, swallowing

AS1/02 - Particle size indicates that the dust will deposit in the “thoracic” area - trachea, bronchi, bronchioles - removable via ciliary escalator, mucous etc

AS1/03 - Particle size indicates that the respirable dust will penetrate to the gas-exchange regions of the lung (alveoli) where it may pass across cell membrane into blood stream or deposit initiating an auto-immune response whereby the dust particles are engulfed by phagocytes which may cause scarring / fibrosis / pneumoconiosis (dependent on physico-chemical properties of the dust).

Question 33

Jul 06

(a) Outline the routes of entry and possible effects on the body when someone is exposed to high levels of lead. (6)
(b) Outline the risk control measures that a lead-acid battery manufacturer should have in place to adequately control the risks of exposure of their employees to lead, and to comply with relevant statutory provisions. (14)

Answer 33

(a) Routes of entry:
• breathe in lead dust, fume or vapour;
• swallow any lead, eg if you eat, drink, smoke, or bite your nails without washing your hands and face;
• Lead alkyls (an additive to petrol) can be absorbed through the skin - circulate in your blood.
• If the level of lead in your body gets too high, it can cause:
o Headaches;
o Tiredness;
o Irritability;
o Constipation; o Nausea;
o Stomach pains; o Loss of weight.
• Continued uncontrolled exposure could cause more serious symptoms such as:
o Kidney damage;
o Nerve and brain damage;
o Infertility.

(b) Risk control measures -
• the control measures must comply with the specific statutory requirements of the CLAW Regs 2002;
• the design of work systems and processes to minimise exposure;
• the use of engineering controls;
• prohibition of young persons and women of child bearing age from working in certain parts of
the manufacturing process;
• the provision of washing/changing facilities and eating/rest facilities free from lead
contamination;
• employers must measure the concentration of lead in air if exposure is liable to be significant,
ie a concentration in air exceeding half the occupational exposure limit (=0.15mg/m3 8hr
TWA);
• take steps to ensure that this limit is not exceeded;
• The employer should arrange to undertake medical surveillance to measure blood-lead levels;
• if lead in blood levels reach or exceed action levels the employer must determine why and
take steps to reduce the level below the action level;
• If blood-lead levels reach or exceed suspension levels the employer should remove the
employee from lead work until a doctor confirms the blood-lead level has dropped below suspension level;
• Action and suspension lead in blood levels vary for different groups of workers (eg women child bearing age, young persons and other employees).

Question 34

Jul 05
A multi-storey office block built in the early 1960s has been disused for the last three years. The owner plans to refurbish the building before leasing it to tenants.

(a) With reference to the Control of Asbestos at Work Regulations 2002,

Outline the practical steps to be taken by the owner before, during and after the refurbishment work. (14)

Answer 34

(a) The practical steps that the owner should take are as follows:

Before
• arrange to have a survey undertaken to identify if asbestos is present (competent person)
• For major refurbishment, a Type 3 intrusive survey would be appropriate (in accordance with
HSE’s MDHS 100 “Surveying, sampling and assessment of asbestos-containing materials”);
• for more minor work, then a Type 2 survey might suffice;
• An asbestos management plan should be made (identified areas where, because of the condition and/or the level of disturbance of the asbestos, removal would be necessary,
sealing of some areas of asbestos);
• Removal should only be done by a licensed contractor and with HSE being notified of the work;

During
• ensure that all contractors are informed of the location and condition of ACMs in the building;
• contractors not involved in asbestos removal should be segregated;
• where asbestos is being removed, clearance air sampling should take place before subsequent refurbishment work is started;

After
• clearly labelling all remaining ACMs;
• updating the asbestos register for the building and informing all tenants of the asbestos management arrangements in the building;
• ensure that the condition of the remaining asbestos is re-assessed at regular intervals.

Question 35

Jul 05

A multi-storey office block built in the early 1960s has been disused for the last three years. The owner plans to refurbish the building before leasing it to tenants.

(b) Describe the features and principles of operation of the equipment that should be used to determine the airborne concentration of asbestos fibres. (6)

Answer 35

(b) The equipment that should be used to determine the airborne concentration of asbestos fibres includes:
a sampling pump that draws air at a controlled flow rate (2.2l/min) through an acetate membrane filter which collects the fibres; the filter is housed in a sampling head (IOM) with a cowl to prevent ingress of dust particles; the sampling head should be non-conductive to avoid static charge attracting dust/ fibres to the filter. Following the sampling process the filter is mounted on a microscope slide marking with a grating (graticule) and the filter is dissolved leaving the fibres on the slide; the fibres are then counted using phase contrast microscopy - only certain fibres are counted (aspect ratio 3:1 and > 5 microns)
the number of fibres and the volume of air drawn through the filter can be used to calculate the fibre concentration (fibres / millilitre of air)

Question 36

Jul 05

Outline the factors to be considered when assessing the health risks from exposure to solvents in a factory producing flat-pack furniture with a range of painted and varnished finishes. (10)

Answer 36

The factors to consider when assessing the health risks include:
• the potential route(s) of entry - how the substances can enter the body (eg. inhalation, skin
absorption)
• the effects that they might cause (eg. dermatitis, toxic effects)
• the physical properties of the materials (volatility in particular)• the quantities used
• the ways in which the solvent is applied - (by hand? by brush? spraying?)
• the frequency and duration of exposure
• the work methods employed
• who is being affected - the number of individuals exposed, their health status, pregnancy etc.
• whether solvent is listed in EH40 – WEL
• information available eg manufacturers’ material safety data sheets, HSE guidance etc.
• potential additive / synergistic effects from other substances
• existing control measures in terms of their nature and adequacy

Comment: Candidates wasted time outlining the control measures that should be in place, exploring issues other than solvents (eg noise, dust) or issues other than health risks (eg. flammability