Lecture 6: Physical, Chemical,& Biological Hazards

PEMEP

People, Equipment, Materials, Environment, Process.

Hazard statement

Identifies the job position, task being performed, and maximum reasonable consequence.

LEV (Local Exhaust Ventilation)

Captures contaminants at or near their source before they spread.

Ionizing radiation

Radiation with enough energy to remove electrons from atoms and create ions.

Examples of ionizing radiation

X-rays and gamma rays.

Effects of ionizing radiation

Cell and DNA damage, mutations, burns, and radiation sickness.

Factors affecting radiation risk

Exposure amount, duration, and whether exposure is localized or whole-body.

Non-ionizing radiation

Radiation without enough energy to ionize matter, but which can still damage tissue.

Examples of non-ionizing radiation

Radiofrequency, microwaves, infrared, visible light, and ultraviolet.

Radiation-specific controls

Shielding, monitoring, limiting exposure, and radiation-specific protective equipment.

Frequency (Hz)

Number of sound-wave cycles per second; determines pitch.

Decibels (dB)

Measure sound intensity.

dB(A)

Decibel measurement adjusted to reflect human hearing sensitivity.

Human hearing range

Approximately 20–20,000 Hz.

Decibel scale

Logarithmic.

Conductive hearing loss

Problem transmitting sound through the outer or middle ear.

Sensorineural hearing loss

Damage to the inner ear or auditory nerve; commonly associated with noise exposure.

Tinnitus

Ringing or buzzing in the ears.

TTS (Temporary Threshold Shift)

Temporary hearing loss following noise exposure.

PTS (Permanent Threshold Shift)

Irreversible hearing loss.

Other effects of noise

Stress, communication difficulties, and reduced concentration.

Doubling distance from a point noise source

Reduces sound level by approximately 6 dB in a free field.

NRR (Noise Reduction Rating)

Indicates the potential noise reduction of hearing protection.

Actual hearing protection effectiveness

Depends on proper fit and consistent use.

Segmental/hand-arm vibration

Vibration transmitted through the hands and arms, such as from power tools.

Whole-body vibration

Vibration transmitted through the entire body, such as in vehicle operators.

HAVS (Hand-Arm Vibration Syndrome)

Can involve numbness, tingling, circulation problems, and reduced dexterity.

Raynaud's phenomenon / vibration white finger

Reduced circulation causing fingers to become pale or white.

Resonance

Occurs when vibration frequency matches a body part's natural frequency, increasing vibration effects.

Vibration-specific controls

Reduce vibration at the source, maintain equipment, limit exposure, and use suitable tools.

Homeostasis

The body's ability to maintain a stable internal environment.

Conduction

Heat transfer through direct contact.

Convection

Heat transfer through movement of air or liquid.

Radiation (heat transfer)

Transfer of heat through electromagnetic waves.

Evaporation

Heat loss when sweat evaporates from the skin.

WBGT (Wet Bulb Globe Temperature)

Measures environmental heat stress using temperature, humidity, radiant heat, and air movement.

Humidex

Combines temperature and humidity to describe how hot conditions feel.

Heat edema

Swelling, especially in the hands and feet.

Heat rash

Skin irritation caused by blocked sweat ducts.

Heat cramps

Painful muscle cramps associated with fluid and electrolyte loss.

Heat syncope

Fainting caused by reduced blood flow to the brain.

Heat exhaustion

Heavy sweating, weakness, dizziness, and nausea due to heat stress.

Heat stroke

A medical emergency involving severe overheating and possible confusion or unconsciousness.

Heat exhaustion vs. heat stroke

Exhaustion involves weakness, dizziness, and heavy sweating; heat stroke is a life-threatening emergency.

Heat-specific precautions

Water, rest breaks, shade, ventilation, acclimatization, and appropriate clothing.

Non-freezing cold injuries

Chilblains and immersion/trench foot.

Freezing cold injuries

Frostnip and frostbite.

Chilblains

Painful inflammation caused by cold exposure.

Immersion/trench foot

A non-freezing injury from prolonged exposure to cold, wet conditions.

Frostnip

An early, reversible freezing-related cold injury.

Frostbite

Actual freezing of body tissue, potentially causing permanent damage.

Hypothermia

Dangerously low core body temperature.

Cold-specific precautions

Insulated clothing, dry layers, warm breaks, limited exposure, and worker monitoring.

Biohazards

Biological agents that can cause infection, disease, or allergic reactions.

Four types of biological agents

Bacteria, viruses, fungi, and prions.

Bacterial hazards

Salmonella, Staphylococcus, and Anthrax.

Viral hazards

Hepatitis A and Hepatitis B.

Fungal hazards

Trichophyton and Histoplasma.

Prions

Infectious proteins capable of causing disease.

Carrier

An infected person who can transmit an infectious agent without showing symptoms.

Six links in the chain of infection

Infectious agent, reservoir, portal of exit, mode of transmission, portal of entry, susceptible host.

Infectious agent

The microorganism that causes infection.

Reservoir

The place where an infectious agent lives and multiplies.

Portal of exit

The route through which an infectious agent leaves its host.

Mode of transmission

The way an infectious agent spreads to another host.

Portal of entry

The route through which an infectious agent enters another host.

Susceptible host

A person capable of becoming infected.

Breaking the chain of infection

Breaking any one of the six links can prevent infection.

Transmission routes

Direct contact, droplets, contaminated food or water, and vectors such as insects.

Toxicity

A substance's ability to cause injury to biological tissue.

Toxicity vs. hazard

Toxicity is the ability to cause harm; hazard is the potential for harm in a particular situation.

Four factors affecting chemical risk

Toxicity, concentration, duration of exposure, and route of entry.

Synergistic toxicity

Two exposures together produce a greater effect than the sum of their individual effects.

Dust

Mechanically generated solid particles, such as from sanding.

Fume

Particles formed when heated vapour condenses, such as during welding.

Smoke

Particles produced by combustion.

Mist

Suspended liquid droplets, such as from sprays.

Vapour

Gaseous form of a substance normally existing as a liquid or solid.

Gas

A substance that naturally exists in the gaseous state, such as oxygen or carbon dioxide.

Aerosols

Fine airborne particles or droplets that can remain suspended in air.

Baker's asthma

Occupational asthma caused by repeated inhalation of flour dust.

Occupational asthma symptoms

Coughing, wheezing, shortness of breath, and chest tightness.

Occupational asthma during a shift

Symptoms may worsen throughout the work shift.

Workers at risk of occupational asthma

Bakers, salon workers, farmers, and automotive manufacturing workers.

Toxicology

The scientific study of poisons.

Four routes of chemical entry

Inhalation, skin absorption, ingestion, and penetration.

Inhalation

Breathing airborne contaminants; a major workplace exposure route.

Skin absorption

Chemicals pass through the skin and enter the bloodstream.

Ingestion

Swallowing chemicals, often due to poor hygiene.

Penetration

Chemicals or infectious agents enter through cuts, punctures, or needlesticks.

Defatting

Chemicals remove natural skin oils, causing dryness, cracking, and increased skin permeability.

Ototoxicity

Chemical damage to structures or nerves involved in hearing and balance; can cause hearing loss or tinnitus.

Dose

The amount of exposure and its possible reaction over time.

Acute toxicity

Toxic effects occurring immediately or shortly after exposure.

Chronic toxicity

Toxic effects appearing months or years after exposure.

Local toxicity

Damage occurring at the point of contact.

Systemic toxicity

Damage occurring elsewhere in the body after a substance is absorbed or distributed.

TLV (Threshold Limit Value)

A workplace exposure guideline.

Irritants

Substances that cause inflammation, such as acids and solvents.

Asphyxiants

Substances that interfere with the body's oxygen supply.