Chemical Hazards and Safety Management

Chemical Hazards

• Chemical hazards are a significant concern in occupational safety and health.
• Different types of chemical hazards exist:
  • Toxic
  • Flammable
  • Explosive
  • Corrosive
  • Combustible
  • Reactive
• Chemicals are categorized by their physical state:
  • Liquid
  • Solid
  • Gas

Managing Chemicals Efficiently

• Essential to understand the characteristics and nature of chemicals being stored and the associated risks.
• Safety procedures during the manufacture, transportation, storage, handling, and use of chemicals are crucial.
• Safety Data Sheets (SDS) or labels provide information about hazardous chemicals.
• SDSs are documents with details of potential hazards (health, fire, reactivity, and environmental) and safe handling procedures.

Significant Chemical Disasters

• Flixborough, England (1974): Rupture caused by inadequately supported pipe; Vapor cloud of 30 tonnes cyclohexane; Explosion and fire; 28 deaths and 89 injuries.
• Seveso, Italy (1976): Reactor malfunction; Vapor cloud of 2 kg dioxin; 700 affected, 730 evacuated.
• Bhopal, India (1984): Scrubber and flare systems malfunction; Vapor cloud of 25 tonnes toxic carbides; 2000 deaths and 20,000 injuries.
• Bright Sparklers Fireworks fire, Sungai Buluh, Selangor (1991): Factory fire and explosion; 22 deaths and 103 injuries.

Classification of Chemicals

• Gases: Volatile with no definite shape or volume. Hazards depend on confinement methods. - Compressed gases - hazardous due to stored energy. - Liquified gases - hazards due to extremely low temperatures; toxic, flammable, corrosive, or oxidizing properties.
• Flammable liquids: Liquids becoming flammable at ambient temperatures; potential fire sources, toxicity and corrosiveness.
• Explosive substances: Solid, liquid, or mixtures reacting chemically; contain fuel and oxidant.
• Corrosive substances: Attack skin and materials like wood or metal; examples are sulfuric acid and caustic soda.
• Oxidizing agents: Supply oxygen to support combustion; increase fire development; example is sodium chlorate.
• Flammable solids: Readily ignite and cause quick fire propagation; examples include magnesium and plastics.
• Toxic substances: Very harmful to health when inhaled, ingested, or contacted with skin; examples are aniline, arsenic, benzene, beryllium, and cyanide. Toxicity can be immediate or long-term.

Identification of Chemicals

• United Nations' classification and a numbering scheme categorizes chemicals to facilitate global trade and transportation.

Classes of Dangerous Goods

• Explosives: classes 1.1 to 1.6. Examples include TNT and bombs.
• Gases: classes 2.1 to 2.3. Examples include acetylene, propane and butane.
• Flammable liquids: classes 3.1 to 3.4. Examples include paints and petrol.
• Flammable solids: classes 4.1 to 4.3. For example phosphorus.
• Oxidizing agents and organic peroxides: class 5.1 and 5.2. Examples include ammonium nitrate.
• Poisonous and infectious substances: classes 6.1(a) to 6.2. Examples include cyanides and lead compounds.
• Radioactive substances: Examples include uranium and radioisotopes.
• Corrosives: Examples include hydrochloric acid and caustic solutions.
• Miscellaneous dangerous substances: Includes aerosols and polyester beads.

UN Numbering and HAZCHEM Scale

• UN committee created a numbering system for hazardous chemicals (e.g., sodium hydroxide=caustic soda 1823, sulphuric acid 1830, acetone 1090, acetylene 1001).
• HAZCHEM scale developed by UK's Health and Safety Executive; used by emergency and fire crews for controlling spills and fires involving hazardous chemicals.

Material Safety Data Sheets (MSDS)

• MSDS are required for all hazardous chemicals and must be readily available during work hours, emergencies, and initial shipments.
• Failure to provide MSDS may be investigated.
• They may be kept centrally or in hard copy or soft copy format.

Biological Hazards

• Biological agent: Living organisms (viruses, bacteria) release toxins causing disease.
• Infection: Attack by a pathogenic organism (whether or not disease occurs).
• Host: The habitat of the agent.
• Environment: Living and non-living components - biosphere, atmosphere, lithosphere, hydrosphere.
• Bio-safety: Science field disconnecting elements in the infection chain.

Forms of Biological Agents

• Fungi: Microscopic organisms; reproduce through spores, causing allergies (athlete's foot, ringworm).
• Molds: Fungi growing in damp environments; beneficial (penicillin), or cause allergies (asthma).
• Bacteria: Single-celled organisms causing diseases (tuberculosis, legionella, tetanus); controlled by antibiotics.
• Viruses: Non-cellular organisms; reproduce in host cells and are often resistant to antibiotics. (examples include Hepatitis, AIDS, influenza).

Characteristics of Biological Agents

• No threshold exposure limit.
• Can exist in any environment
• Affected and influenced by biological competition.

Interaction of Agent, Host and Environment

• Agent: Vector, pathogens, antibiotic resistance, virulence factors, infection factors, and death factors.
• Host: Health status, management system, training, health monitoring, use of PPE, perception, and retention.
• Environment: Population density, medical support services, weather, politics, ethics, and design of facilities.

###Factors for Onset of Diseases

1. Pathogenic agent
2. Existence of reservoir
3. Agent capable of retention
4. Agent mobility
5. Entry in new host
6. Susceptible host

Infection Chain

• Pathogen* -> Retention -> Release from retention -> Transmission through environment -> Route of entry -> Susceptible host

GHS Pictogram

• Visual symbols for different types of chemical and biological hazards.
• Used to warn and instruct about handling procedures including precautions.

Do's and Don'ts for Handling Chemicals

• Do's: Read labels and MSDS, keep work areas clean, use appropriate protective equipment, follow safety procedures, and store chemicals properly.
• Don'ts: Leave containers open, depend on smell to detect hazards, mix chemicals without instructions, breathe fumes, eat or drink around hazardous materials, wear improper PPE.

Specific Disaster Example (Bhopal)

• Dec. 2nd and 3rd 1984 - Union Carbide pesticide plant leak released methyl isocyanate and other gases.
• The plant's safety systems were NOT functioning.
• 500,000 exposed; over 20,000 had died as of today with the rest suffering from serious health issues.
• Toxic waste continues to poison people 30 years later.