CHE 10 Chapter 1: Chemical Safety

Chemical Safety Overview

• Essential for environments involving chemical use to prevent health issues and environmental damage.
• Chemical safety encompasses the entire lifecycle of chemicals: manufacture, transport, use, and disposal.
• Distinction between hazard (potential to cause harm) and risk (likelihood of harm).

Routes of Entry

• Inhalation: Most common entry; can lead to effects from irritation to severe lung damage.
• Ingestion: Occurs when contaminated food or hands transfer chemicals into the bloodstream, potentially harming organs.
• Absorption: Chemicals can irritate or destroy skin and eyes upon contact.
• Injection: Occurs via sharp objects contaminated with toxic chemicals, leading to potential internal damage.

Acute and Chronic Effects

• Acute Effects: Immediate health impacts from high-level short-term exposure (e.g., chemical burns), often at high concentrations.
• Chronic Effects: Long-term damage from low-level exposure over time (e.g., lung cancer from asbestos); may be irreversible.

Classification of Chemicals

• Hazards are inherent properties of materials; risk is the potential for harm based on exposure.
• Example: Gasoline is hazardous but can be handled safely with proper precautions.
• Fire Triangle: Essential components for fire are heat source, oxygen, and fuel.

Flash Points and Ignition Temperature

• Flash Point: Lowest temperature at which a liquid emits flammable vapor (e.g., Benzene: -11°C, Diethyl ether: -45°C).
• Ignition Temperature: Minimum temperature for self-sustained combustion independent of external heat (e.g., Carbon disulfide: 90°C).

Causes of Ignition

• Spontaneous Combustion: Occurs when a substance reaches ignition temperature without heat application (e.g., oily rags).
• Ignition Sources: Common in laboratories include Bunsen burners and electrical equipment.

Personal Protective Equipment (PPE)

• Mandatory safety gear includes eye protection, gloves, laboratory coats, and closed-toe shoes.
• Ventilation systems, like chemical fume hoods, crucial for reducing exposure to airborne chemicals.

Hazard Control

• Effective management of spills minimizes risks of injury and environmental harm.
• Hierarchy of Control:
  • Eliminate Hazards: Most effective method.
  • Reduce Risk: Through substitution, isolation, or engineering controls.
  • Administrative Controls: Less reliable methods to reduce exposure.
  • PPE: Last line of defense against hazards.

NFPA Hazard Diamond

• System for identifying specific hazards and severity of materials for emergency responses.
• Focuses on health, flammability, instability, and special hazards related to short-term exposure.

Chemical Spill Management

• Immediate removal of contaminated clothing and washing skin with soap and water.
• Specific cleanup methods:
  • Acids: Use calcined absorbents (e.g., Oil-Dri).
  • Mercury: Requires immediate vacuum cleanup to avoid toxic vapor exposure.
  • Alkali Metals: Smother with graphite and handle with care.
  • Phosphorus: Use wet sand or absorbent for safe disposal.

Disposal of Chemicals

• Waste: Unwanted materials that need disposal.
• Hazardous Waste: Materials posing threats to health and environment, often generated in industrial or healthcare settings.
• Types of Hazardous Wastes:
  • Industrial Wastes: From industrial processes.
  • Infectious Wastes: Containing pathogens that could cause disease.