1. Key Terms
1.1. CHEMICAL AGENTS - Hazards created by one or more chemicals
1.1.1. More than 70k chemicals in use in NA & about 800 new ones introduced every year
1.1.2. No toxicity data available for about 80% of commercially-used chemicals
1.1.3. Physiological reactions to low-level chemical exposures in the environment
1.1.3.1. Headaches, dry nasal passages, nausa
1.1.3.1.1. Labelled: multiple chemical sensitivity (MCS), 20th-century disease. total allergy syndrome, environmental illness
1.2. BIOLOGICAL AGENT or BIOHAZARD - Hazard created by exposure to biological material
1.3. TOXICITY - Ability to cause injury to human biological tissue
1.4. Agents are either
1.4.1. AMBIENT - All-encompassing condition associated w/ a given environment - Composite of inputs from sources all around us
1.4.2. Acute
1.5. AEROSOLS - Airborne respirable contaminants ex. liquid droplets or solid particulate, dispersed in air, that are of a fine enough particle size (0.01 to 100 micrometres) to remain suspended for a time
2. Biological Agents
2.1. BIOLOGICAL AGENTS - Natural organisms of products of organisms that present a risk to humans
2.1.1. Natural organisms or products of organisms that present a risk to humans
2.1.2. Diseases resulting from biological agents include
2.1.2.1. Legionnaires' disease
2.1.2.2. AIDS
2.1.3. Exposure to biohazards is not as common as exposure to chemical agents but can be just as deadly
2.1.3.1. Most occur through inhalation
2.1.3.2. Most workplace biohazards fall into BSL 1
3. Control of Exposures
3.1. Engineering controls
3.1.1. Substitution w/ less hazardous solvents
3.1.2. Process enclosure exhaust ventilation
3.1.3. Closed systems
3.1.4. Maintenance of engineering control systems
3.1.5. Vapour recovery system
3.1.6. Control of ignition systems
3.1.7. Do not store adjacent to highly reactive chemicals
3.2. Work practices & procedures
3.2.1. AGENTS - Any substances-chemical, biological, or physical-to which a human may be exposed at work or at home
3.2.2. Standard work procedures
3.2.3. Education & training for workers
3.2.4. Labels/MSDS
3.2.5. Safety cans
3.2.6. Good housekeeping
3.2.7. Preventative maintenance
3.2.8. Record keeping
3.2.9. Waste disposal
3.3. Administrative controls
3.3.1. Most important is education & training of all employees in safe work practices
3.3.2. Employees should receive training in
3.3.2.1. Safe operating & emergency procedures
3.3.2.2. Use & care of PPE
3.3.2.3. Handling & control of agents
3.3.3. Training must be conducted on an ongoing basis, given that new solvents & other agents are continually entering the workplace
3.3.4. Workers must be familiar w/ WHMIS legislation
4. Personal Protective Equipment (PPE)
4.1. Inhalation is the most common & hazardous route of entry
4.2. Most commonly used protection device is a respirator
4.3. Respiratory protection is more specialized for biohazards than it is for chemical agents
4.4. PPE for hands, face & other body parts must be provided where necessary
4.5. No single protective device ex. face mask will adequately address all conditions for all workers
4.6. Device must be properly fitted to individual
4.7. One size does not fit all
5. Personal Hygiene Practices
5.1. Ingestion of chemicals or biological particulate is often the result of poor hygiene
5.2. Individuals who handle agents w/o wearing proper protective gear ex. are at risk of food contamination
5.3. Chemicals that are not adequately removed at the workplace can be transferred to worker's home
5.4. Individuals who handle toxic substances must adhere to the following
5.4.1. Remove outer protective clothing, clean hands, arms, face nails before entering rest areas or lunchrooms
5.4.2. Avoid touching lips, nose, eyes w/ contaminated hands
5.4.3. Wash hands before eating, drinking, smokint
5.4.4. Eat, drink, smoke only in designated areas
5.4.5. Remove work clothes & wash or shower before leaving work
6. Medical Surveillance
6.1. Pre-employment & preplacement medical examinations should be conducted to establish a baseline of the employee's health & exposure to agents in previous workplace
6.2. Follow-up medical examinations should be conducted periodically
6.3. Record keeping is an important aspect
6.4. Types of exposures employees face & their health records before & after exposure should be included in this process
7. Characteristics & Properties of Solvents
7.1. Eight general characteristics/properties
7.1.1. 1. Low surface tension
7.1.1.1. Allows solvent to spread evenly & quickly, provide excellent wetting of contact surface
7.1.2. 2. High vapour pressure
7.1.2.1. Increases w/ temperature, increases volume or concentration of generated vapour or gas
7.1.3. 3. Low boiling point
7.1.3.1. BOILING POINT - Temperature at which the vapour pressure of a liquid equals atmospheric pressure
7.1.3.1.1. The lower, the greater evaporation or genration of vapours from a liquid
7.1.4. 4. Low heat of vaporization
7.1.4.1. Relates to amount of heat or energy required to change a liquid into a gas or vapour
7.1.5. 5. High volatility
7.1.5.1. Main test of a solvent's effectiveness is the speed at which it will evaporate
7.1.5.1.1. Greater volatility = faster evaporation
7.1.6. 6. Ability to dissolve fats
7.1.6.1. DERMATITIS - The inflammation of the skin from any cause
7.1.6.2. More effectively a solvent dissolves fats or oils, the more useful it is
7.1.7. 7. Flammability
7.1.7.1. All organic solvents are flammable
7.1.7.2. One of main hazards associated w/ solvent use
7.1.7.3. a. Flash point
7.1.7.3.1. Lowest temperature at which liquid gives off enough vapour to form an ignitable mixture w/ air & produce a flame w/ a source of ignition
7.1.7.4. b. Lower explosion limit
7.1.7.4.1. Smallest fuel-air mixture that is ignitable, expressed as a percentage
7.1.7.5. c. Upper explosion limit
7.1.7.5.1. Highest fuel-air mixture that is ignitable, expressed as a percentage
7.1.7.6. d. Auto-ignition temperature
7.1.7.6.1. Lowest temperature at which a flammable fuel-air mixture will ignite from its own heat source
7.1.8. 8. Vaporization
7.1.8.1. Most solvents will form very large volumes of vapour from a small amount of liquid
7.2. Inorganic solvents - PH = degree of acidity, 1 = extreme acidity, 7 = neutral, 17 = extreme alkalinity
7.2.1. 1. Acids
7.2.1.1. Most common: hydrochloric acid (HCl), sulphuric acid (H2SO4), chromic acid (H2CrO4)
7.2.1.2. Highly corrosive
7.2.1.3. Used for refining & processing metals
7.2.1.4. Health effects: burns resulting from inhalation & skin contact
7.2.1.5. Eyes are most susceptible, splashing
7.2.1.6. HIghly corrosive
7.2.2. 2. Bases
7.2.2.1. Potassium hydroxide (KOH), sodium hydroxide (NaOH), sodium chloride (NaCl, table salt)
7.2.2.2. Sodium chloride in its refined state is a requirement of a normal diet; less refined form is road salt
7.2.2.3. Other two alkalines are used to etch or dissolve a variety of materials
7.2.2.4. All are toxic under certain circumstances
7.3. Organic solvents
7.3.1. Petrochemically based
7.3.2. Manufactured by combining carbon atom w/ other elements
7.3.3. Identified by molecular structure & can be grouped under 10 classifications
7.4. Classification of toxic substances
7.4.1. 1. Irritants
7.4.1.1. a. Inhaled irritants
7.4.1.2. b. Contact irritant
7.4.2. 2. Asphyxiants
7.4.2.1. a. Simple asphyxiants
7.4.2.2. b. Chemical asphyxiants
7.4.3. 3. Anesthetics & narcotics
7.4.4. 4. Systemic poisons
7.4.5. 5. Liver toxicants
7.4.6. 6. Kidney toxicants
8. Toxicology: An Overview
8.1. Toxicology - Scientific study of poisons - Study of chemical-related occupational illnesses
8.2. ROUTES OF ENTRY - Respiration (inhalation), skin absorption, ingestion & skin penetration
8.2.1. Four routes
8.2.1.1. Respiration (Inhalation)
8.2.1.1.1. Most human exposure to chemicals comes from breathing airborne contaminants
8.2.1.1.2. Five basic levels of protection
8.2.1.2. Skin absorption
8.2.1.2.1. Chemical contact w/ the skin is a common occurence
8.2.1.2.2. Chemicals not rapidly absorbed through skin may produce localized irritation (dermatitis)
8.2.1.2.3. Burns or blisters can result form contact w/ acids or alkalis (chemical action)
8.2.1.2.4. Skin disorders can result from contact w/ certain plants (biological action)
8.2.1.2.5. Skin damage can result from contact w/ radiation or heat (physical action)
8.2.1.3. Ingestion
8.2.1.3.1. Ingested solvents absorbed into bloodstream can be carried to TARGET ORGANS - Tissues or organs that are most affected by exposure to a particular substance
8.2.1.3.2. Ingested solvent may be aspirated into lungs & destroy SURFACTANT LAYER - Layer of liquids in the digestive tract & elsewhere ex. the cardiovascular system that modify or reduce the surface tension within the conductors - intestine, blood vessels. to allow material-blood, food, stools, etc.-to move easily
8.2.1.3.3. Poor personal hygiene, eating, drinking, or smoking in an area where solvents are used
8.2.1.3.4. Ingestion of most solvents causes damage to lining of digestive system
8.2.1.3.5. Ingested solvent may be absorbed into bloodstream & carried to organs where it will produce toxic effects
8.2.1.3.6. Infested solvent may be aspirated into the lungs where it can destroy the surfactant layer, causing a chemical pneumontis & collapse the alveoli
8.2.1.4. Penetration
8.2.1.4.1. Occurs when skin is cut or punctured by any sharp objet
8.2.1.4.2. Type of contamination on the source, such as a knife or needle, will determine possible trauma or illness
8.2.1.4.3. Workers such as doctors, nurses & vets can be punctured by a hypodermic needle
8.2.1.4.4. Disorders range in seriousness from low-grade infections to HIV