State the effects on the body of the following types of hazardous substances giving a relevant EXAMPLE of each: -I rritant. -Corrosion. -Toxic -Carcinogen Answer 1
• Irritant: is a substance that causes an inflammation of skin, eyes or respiratory tract. Examples: organic solvents, detergents & cement dust, ammonia, chlorine.
• Corrosive: is a substance the reacts with body proteins and has a penetrating and burning effects on the parts of the body with which they come into contact "skin, eyes, gastrointestinal tract".
Examples: phenol, ammonia, sulphuric acid, caustic soda, etc.
• Toxic: is a substance that has an adverse (poisonous) effect ona target organ or body system. The substance causes its adverse effect when taken in relatively small dose. The effect is either acute or chronic.
Example: lead, mercury, arsenic, etc.
• Carcinogens: are substances capable, often after long periods of exposure, causing disorders to cell growth and may lead to cancer.
Example: asbestos, vinyl chloride, chromium.
Exercise 2
In relation to substances used at work:
-Explain the meaning of the term toxic.
-Describe, using an example in EACH case, the difference between acute and chronic health effects.
Answer 2
• Toxic: is a substance that has an adverse (poisonous) effect on a target organ or body system. The substance causes its adverse effect when taken in relatively small dose. The effect is either acute or chronic.
• Acute health effect: an adverse effect resulting from a single or short-term exposure and producing an immediate or rapid effect.
Examples: corrosive action, narcosis and primary irritation.
• Chronic health effect: is an adverse health effect resulting from prolonged or repeated exposures with a gradual or latent and often irreversible effect that may often go unrecognized for a number of years.
Exercise 3
In relation to the spillage of a toxic substance from a ruptured drum stored in a warehouse: 1. Identify THREE ways in which persons working in close vicinity to the spillage might be
harmed.
2. Outline a procedure in the event of such a spillage. Answer 3
i) The ways in which persons might be harmed are: • Direct contact with the skin.
• Direct contact with eyes. • Inhalation of fumes or particles.
• Ingestion of the materials (direct which is rare and indirect through contaminated hands and ingestion while eating, drinking or smoking at work).
• Slipping hazards.
• Hazards: depending on the chemical nature of the substances (as flammability for example).
ii) The procedure in the event of a spillage: • Isolate or evacuate the area.
• Make an initial assessment to determine extent of spillage, type of spillage (liquid, powder, etc.).
• Summon help: from emergency services (if this is required).
• Deal with the spillage according to its type (for example, in liquid spillage, use absorbent material).
• Issue the appropriate PPE to those involved in dealing with the spillage. • Give appropriate first aid and medical treatment to any person who might
have been harmed by the initial spillage.
• Ongoing health surveillance for the persons exposed to the initial spillage. • Safe disposal of the spilled substance together with any contaminated
material. Exercise 4
A shoe repairer is required to trim soles by hand gluing them on to shoes with a solvent-based adhesive. Outline the measures to minimize the health risks from the tasks.
Answer 4
Solvent hazards and ergonomic hazards are the main health hazards. The following are the measures required to minimize the health risks: Measures for solvent hazards:
• The use of adhesive of a low toxicity solvent.
• The installation of local exhaust ventilation system and ensuring adequate general ventilation.
• Ensuring adhesive containers are closed when not in use. • The prohibition of eating or smoking in the work area. • The use of appropriate PPE (gloves, overalls, etc.).
• Health surveillance programme to identify the early signs of any ill health effects. Measures for Ergonomic Hazards:
• Proper work station design to reduce awkward postures e.g., stooping, twisting, overreaching, etc.
• Good standard of seating and lighting.
• Reduce constant pressure on the body by varying the task, job rotation or by providing breaks away from the work.
• Use proper ergonomically designed tool (with a proper handle & kept sharp to minimize the force required, etc.
Exercise 5
Identify the routes of entry of chemical agents into the body: Answer 5
By inhalation: if the chemicals agents is in the form of dust, vapour, fume, gas, etc. it is the most rapid route of entrance.
By contact with the skin: chemicals can either: o Irritate the skin causing dermatitis.
o Penetrate the skin causing systemic toxicity.
By ingestion: can occur directly (by mistake if chemicals are not properly labeled) or indirectly through hands contaminated with chemicals and reaching the mouth during eating, drinking or smoking.
Exercise 6
Outline the advantages and limitations of using a chemical indicator (stain detector) tube to monitor the atmospheric concentration of hazardous substances.
Answer 6
The advantages are: • Cheap.
• Simple and easy to use. The limitations are:
• It requires correct assembly with a properly sealed joint between the tube and bellows pump .
• It requires effective counter for the number of pump strokes.
• It requires the reagent to be homogeneously distributed in the tube. • Cross reactively of the reagent with other substances can occur. • Reaction in the tube is affected by temperature and pressure:
o Change of temperature of 10° C can cause a reaction rate to be doubled. o Change in altitude can cause problems.
• The tube has a shelf life so care is required to ensure the tube is currently operative. • Due to reagent complexity, adjustments cannot be made on one spot sample.
Exercise 7
Outline the factors to be considered when managing the risk of exposure to hazardous chemicals at work?
Answer 7
• Factors related to purchasing the hazardous chemicals as: o Purchasing the chemical with the least hazards. The Key Consultancy Ltd 2005: All Rights reserved
o Ensuring that material safety data sheet is supplied with the substance. • Factors related to transportation of the hazardous chemicals:
o To follow instructions including: proper stacking, exclusion of ignition sources, driver training, emergency equipment, etc.
o Safety signs including HAZCHEM and TREM cards. • Factors related to storage of the hazardous chemicals:
o To be stored in a separate external area, which is properly ventilated, adequately lit, of a suitable temperature.
o Proper stacking. o Good housekeeping.
o Keeping incompatible chemicals apart. o Exclusion of ignition sources.
o Stand by-emergency equipment as fire extinguisher, etc. • Factors related to use of the hazardous material:
o The amount required only to be used.
o To provide information to users about nature of substance, it hazards, which type of PPE in required to be used while dealing with it, etc. (this information is included in the substance safety data sheet)
• Factors related disposal of the substance:
o The safest way for disposal of the substance. o The precautions required for disposal workers.
Exercise 8
Identify FOUR forms that an airborne hazardous substances may take? Answer 8
The forms are:
o Dust: are solid particles suspended in the air. It is created by such operations as grinding.
o Vapour: is the gaseous form of a liquid. It results from heating a liquid. o Fume: fine particulate solids resulting from condensation of a vapuor. o Gas: is a formless chemical that occupies the area in which it is enclosed.
Ventilation
Exercise 1
Explain the meaning of the term "dilution ventilation".
Answer 1
• Dilution ventilation is designed to induce a flow of air through a room such that contaminants are sufficiently diluted by the coming air. This is achieved by the use of inlet fans to ensure a supply of clean air.
• Natural ventilation provided by opening windows or doors is also sometimes included as a form of dilution ventilation, although any flow of air is less certain and therefore it cannot be thought of as an "engineering" solution to an airborne contaminant problem.
Exercise 2
Outline the circumstances in which the use of dilution ventilation may be appropriate.
Answer 2
• Contaminants of low toxicity. • Contaminants of low concentrations. • Uniformly evolved contaminants. • Low density contaminants (not dust).
• Areas where there is a non specific point of release.
Exercise 3
List the main components of a local exhaust ventilation (LEV) system.
Exercise 3
• Exhaust inlet (hood). • Ducting.
• Purifying system (filter) . • Fan and motor.
• Exhaust outlet.
1 2 3
A Local Exhaust Ventilation System
Exercise 4
Outline the factors that may effect the efficiency of a local exhaust ventilation (LEV) system.
Answer 4
• Lack of maintenance and testing. • Unauthorized alternation.
• Inadequate design.
• Overwhelming by increased contaminant levels. • Wear or corrosion of fan blades.
• Blocked filters.
• Hood being placed too far from the source of the contaminant.
Exercise 5
LEV is to be maintained by law every 14 months, outline the maintenance requirements between the statutory dates.
Answer 5
• To check if the filters are blocked.
• To check if there is any obvious damage.
• To check if there is overwhelming by increased contaminant level. • To check if there are obvious unauthorized alternations.
• To adjust the hood in the correct angle. • To lubricate moving parts.
• To check effectiveness of the motor. • To check blades.
Health Hazards
Exercise 1
List THREE Respiratory diseases that could be caused by exposure to dust at work. Answer 1
• Asbestosis. Silicosis. Byssinosis. Farmer's lung. • Asthma, Bronchitis, Emphysema & Lung cancer.
Exercise 2
Describe the body's respiratory defence mechanisms against atmospheric dust. Answer 2
• Anatomical structure: Nose and nasopharynx are perpendicular to Trachea and this help reduce velocity of inhaled air by collision with nasopharynx.
• Respiratory ciliary's escalator: Particles impinge on the mucous lining of respiratory tract and are moved upwards by small hairs or cilia).
• Reflex actions: as sneezing & coughing to remove any foreign irritating material. • Phagocytosis: Is a mechanism by which particles in the alveoli are engulfed and
digested (by the aid of phagocytes).
Exercise 3
Outline the control measure that may be used to eliminate or reduce dust in a work environment using practical examples where appropriate.
Answer 3
• Elimination of dust (by process change).
• Substitution (e.g. use of pellets instead of powders).
• Quality Control (as to reduce the amount of grinding required). • Isolation (enclosure of the process e.g. in a glove box).
• Local exhaust ventilation (LEV): To extract dust close to source. • Vacuuming instead of sweeping.
• Dust Suppression by wet methods. • Damping down.
Exercise 4
Explain the meaning of the term "respirable dust"
Answer 4
-Respirable dust: Is an airborne dust of such a size that it is able to enter the lungs during normal respiration. Dust of 5 microns size or less is respirable.
Exercise 5
Outline the ways in which the levels of dust in a workplace can be assessed.
Answer 5
• Visual signs of dust accumulation. • Dust lamps.
• Direct reading instruments.
• Sampling using pumps and filters followed by analysis. Exercise 6
Give TWO occupational examples of diseases from a biological hazard and outline the control measures necessary to reduce the risk of infection from one of theses hazards.
Answer 6
Example of occupational diseases from a biological hazards: • Hepatitis
• Weil's diseases (Leptospirosis) • Legionnaire's disease.
• Anthrax. • Tetanus.
Control measures to reduce the risk of infection from Anthrax: • Disinfection of materials infected with Anthrax spores (as wool).
• Procedures for disposal of potentially infected materials (as meat, milk, etc.).
• Protection of personnel dealing with infected animals (by using the appropriate PPE). • Proper ventilation.
Control measures to reduce the risk of infection from Hepatitis: • Immunization of groups at risk.
• Use of disposable syringes.
• Strict care in blood transfusion procedures.
• Procedures for proper disposal of hospital refuse (including syringes & needles). • Boiling of water or water super chlorination.
• Medical personnel wear suitable PPE at work. • Health surveillance.
Exercise 7
Identify the possible routes of entry of biological organisms into the body. Answer 7
• Inhalation. • Ingestion. • Injection.
• Entry through open wounds.
• Through eyes.
• Entry through body orifices as: nose, ear, anus, vagina, etc. • Through placenta (from mother to baby).
Exercise 8
Outline control measures that could be used to reduce the risk of infection from biological organisms.
Answer 8
• Disinfection for materials or equipment contaminated with the agent. • Good personal hygiene.
• Immunization: vaccination or seroprophylaxis. • Chemoprophylaxis.
• Water control (by boiling or chlorination). • Proper disposal of wastes.
• Use of the appropriate PPE. Exercise 9
In relation to occupational dermatitis: -Describe typical symptoms.
-Identify T\NO substances that may cause the condition.
-Outline the specific control measures designed to prevent its occurrence. Answer 9
Typical symptoms of occupational dermatitis: • Skin inflammation.
• Dryness of skin. • Cracking of skin. • Rash.
Dermatitis Substances:
• Solvents as xylene, turpentine. • Cement dust.
• Chrome.
• Nickel compounds. • Formalin.
• Wood dust.
Specific control measures designed to prevent occurrence of dermatitis • Elimination of the dermatitis substances (by process change). • Substitution (e.g. use of pellets instead of powders).
• Engineering methods as:
• Splash guards to minimize contact with the substance. • Segregation of workers.
• Ventilation.
• Wet methods for dust. • Good personal hygiene.
• Use of barrier and after work creams. • Use of specific PPE.
Exercise 10
Define the term "target organ" within the context of occupational health. Answer 10
Target organ: is the part of the body that sustains an adverse effect when exposed to or contaminated by a particular harmful substances or agent.
Examples: -Skin is the target organ of Dermatitis. -Liver is the target organ of Hepatitis. Exercise 11
Outline the personal hygienic practices that should be followed to reduce the risk of ingestion of a hazardous substance.
Answer 11
• Regular hand washing.
• Restriction of smoking and eating in the workplace. • Removing and cleaning contaminated clothes. • The use of suitable PPE (as gloves).
Exercise 12
State TWO diseases that may be caused by exposure to asbestos: Answer 12
• Asbestosis. • Lung cancer. • Mesathelioma. Exercise 13
Identify where asbestos is likely to be encountered in a building during innovation work. • Wall and roof panels.
• Pipe lagging.
• Coating as fire resistant encapsulation of metal girders. • Insulation materials.
• Gaskets. Exercise 14
Outline the factors that may increase risks to pregnant women. Answer 14
• Excessive movement and physical activities.
• Manual handling activities: as lifting, carrying, pushing, pulling, etc. • Dietary Factors: -Lack of essential nutrients in the diet as Proteins,
Calcium, and Iron.
-Intake of excess fats or carbohydrates. • Smoking: whether active or passive.
• Alcohol and drug abuse.
• Indiscriminate use of legal drugs: without medical advice (Panadol is an example. • Exposure of radiation: as Medical X-Ray.
• Infection by biological agents as German measles virus. • Stresses & psychological disturbances.
Exercise 15
Identify the possible indications of a dust problem in a workplace:
Answer 15
• The process carried out may suggest that dust will be generated e.g.: Grinding.
• Dust in the atmosphere: may be visible particularly in a beam of sunlight or by the beam from a tyndalllamp.
• Visual signs of dust accumulation: Deposits of dust might be evident on benches, articles, equipment, etc.
• Air monitoring: by drawing air through a filter, then analyzing the filter, this will help to detect low dust concentrations.
• Dust effect on health: as coughing, sneezing, asthmatic symptoms, etc.
• Impaired respiratory function due to dust inhalation (as detected by health surveillance tests as X-Ray or Pulmonary function tests.).
Exercise 16
For each of the following agents, outline the principal health effects and identify a typical work place situation in which a person might be exposed:
i. Carbon Monoxide iii. Asbestos
ii. Legionella iv. Hepatitis Virus
Answer 16
Health Effects Situation of exposure
i) Carbon Monoxide *Headache *vehicle repair premesis
*Drowsiness *underground car park
*Possible Asphvxia & death *boiler with a defective flue.
ii) Asbestos *Asbestosis *Maintenance work for a
*Lung Cancer building where asbestos is
*Mesothelioma contained.
*Demolition work.
iii) Legionella * Legionnaires disease *Air conditioning system and manifested by flu-like symptoms, cooling towers where water pneumonia and 15% of cases droplets are released into
death can occur. atmosphere.
iv) Hepatitis *Jaundice, fever, abdominal pain. *Medical and paramedical *Iiver cell failure is the serious personnel exposed to needle
result. stick iniuries.
Exercise 17
Identify the possible effects on health that may be caused by working in a hot environment such a foundry.
Answer 17
-Dehydration: due to loss of fluids. -Heat stress in the form of:
• Heat syncope. • Heat cramps. • Heat exhaustion. • Heat stroke. -Heat rash.
-Radiant heat burns. -Eye infection or cataracts. Exercise 18
In relation to the ill-health from the use of vibrating hand-held tools:
a) Identify the typical symptoms that might be shown by affected individuals.
b) Outline the control measures that may be used to minimize the risk of such effects. Answer 18
i) The typical symptoms are: • Numbness of fingers. • Blanching of fingers. • Swollen painful joints.
• Reduction in manual dexterity (things may fall form hands and fine adjustment by hand cannot be achieved).
ii) The control measures are:
• Eliminate the risk: by process change to eliminate the need for using vibrating hand- held tools.
• Reduce the risk: To modify operating procedure so that the pressure upon the tool required by operator is reduced.
• Proper selection of equipment (with less vibration). • Good standards of equipment maintenance.
• Reducing time of exposure of operators to vibration (this may necessitate recruitment of new staff).
• Health surveillance to detect the early sings and symptoms of vibration illness. • Use of appropriate PPE (as gloves to keep hands warm).
Exercise 19
A fitter is employed to lay carpet tiles using a solvent-based adhesive in such circumstances. i) Identify the possible effects on health.
ii) Outline the control measures that should be considered. Answer 19
The possible health effects are: • Affecting the skin causing dermatitis.
• If it reaches the eye can cause eye inflammation. • If fumes are inhaled it will lead to:
o Effects on Central Nervous System. o Dizziness
o Narcosis
o Respiratory sensitization leading to asthma. The Key Consultancy Ltd 2005: All Rights reserved
The control measures that should be considered are:
• Elimination: Suggest the use of other alternatives for this process to eliminate the need for using solvent.
• Substitution: Use materials which are less hazardous.
• Provision of adequate instructions and training of workers about: o Hazards of adhesive materials.
o How to use it safely (safe system of work) o The importance of wearing the suitable PPE. • Provision of adequate ventilation in the area.
• Health surveillance to detect the early signs of exposure to the adhesive.
• Provision and use of the required PPE (as gloves, goggles, respirators, overall, etc.).
Exercise 20
Outline the possible routes of entry of biological organisms into the body.
Answer 20
• Inhalation: inhaling air contaminated by disease agents as bacteria, viruses, etc. is a common and rapid way of entrance of biological organisms into the body.
• Ingestion: which is either:
• Direct: through drinking and / or eating contaminated drink or food. • Indirect: through contaminated hand from soiled materials.
• Injection: through:
• Syringes and needles transmitting diseases as hepatitis. • Insects as anopheles causing malaria.
• Through cuts & wounds: leading to: • Local infection of the wound. • Systematic illness as tetanus.
• Through the eye: as due to housefly leading to infective conjunctivitis. • Through body orifices: as nose, ear, anus, vagina, etc.
Exercise 21
Outline measures that may be taken to help prevent possible effects on health due to working in hot environment as foundry.
Answer 21
The measures required are:
• Gradual exposure of workers to heat (to achieve physiological adaptation to heat. • Reducing the time of exposure to heat.
• Rest breaks in shady areas.
• Barriers or shields between hot source & workers. • Taking workers away from the hot source.
• Use of suitable clothes by the workers according to the type of heat: • Minimal clothes if heat is by conduction.
• Clothes to reflect heat if heat is by radiation. • Proper ventilation in the area.
• Sufficient supply of water and salts to the replace fluids lost.