INDUSTRIAL HYGIENE - GASES, VAPORS, AND SOLVENTS UNIVERSITY OF HOUSTON – DOWNTOWN FALL 2013

GAS/VAPOR For IH purposes, a substance is a GAS if this is normal physical state at room temperature (25 degrees C) and one- atmosphere pressure. Examples: CO, Cl, Oxygen, and Nitrogen. If substance is normally a liquid at normal temperature and pressure, then the gaseous component in equilibrium with liquid state is a VAPOR. Examples: CCl4, HCOH, and Benzene.

MORE TERMS Vapor Pressure – measure of the concentration of the chemical in the air at equilibrium. Solvents are liquids in which a solute can be dissolved. -Volatility -Volatility -Polarity (like dissolves like) -Polarity (like dissolves like) -Solubility -Solubility

ROUTES OF EXPOSURE Dermal absorption Dermal absorption Inhalation of vapors Inhalation of vapors Aerosolized mist of the solution can cause exposure to solutes Aerosolized mist of the solution can cause exposure to solutes

EXPOSURE FACTORS Temperature and Volatility Temperature and Volatility Concentration Concentration Reactivity (air, moisture, acids and bases) Reactivity (air, moisture, acids and bases)

ORGANIC COMPOUNDS Organic Solvents (Table 7-A) Organic Solvents (Table 7-A) -Hydrocarbons contain carbon and hydrogen atoms -Hydrocarbons contain carbon and hydrogen atoms -Halogenated hydrocarbons – chlorine, fluoride, iodine and/or bromine -Halogenated hydrocarbons – chlorine, fluoride, iodine and/or bromine

HAZARDS OF GASES, LIQUIDS, SOLVENTS and VAPORS Compressed gas – pressure build up Compressed gas – pressure build up Cryogenic Liquids – frostbite, oxygen deficiency Cryogenic Liquids – frostbite, oxygen deficiency Flammability Flammability Explosions Explosions Reactivity Reactivity

HAZARDS OF GASES, LIQUIDS, SOLVENTS, AND VAPORS Flash point - is when a liquid is the lowest temp at which it gives off enough vapor to form an ignitable mixture with the air near the surface of the liquid or in a vessel capable of flame propagation away from the source of ignition Flammable liquid - CC flashpoint below 100 F and vapor pressure not exceeding 40 psi absolute at 100 F (Class I liquid) Combustible Liquid - CC flashpoint at or greater than 100 F (Class II – III liquids)

HAZARDS OF GASES, LIQUIDS, SOLVENTS, AND VAPORS Lower and Upper Flammable Limit- mixture of vapor with air that, if ignited, just propagate flame. (% by volume of vapor in air) Flammable Range (Explosive Range) – includes all the concentrations of a vapor in air between the lower explosive limit (LEL) or lower flammable limit (LFL) and the upper explosive limit (UEL) or upper flammable limit (UFL).

HEALTH EFFECTS

IRRITANTS Solubility vs. Activity Considerations. Upper Respiratory Tract Examples: Ammonia, Acrolein, Formaldehyde, Sulfur Oxides. Lower Respiratory Tract Examples: Nitrogen Dioxide, Phosgene, Ozone. Both Upper and Lower Irritants Examples: Chlorine, Ozone.

ANESTHETICS Central Nervous System (CNS) depressants; cause narcosis. depressants; cause narcosis. Examples: Most Aliphatic Hydrocarbons or Organic Solvents; Alcohols, Esters, Aldehydes, Ketones.

HEMOLYTIC AGENTS Cause damage to the blood or hematopoietic system. Examples: Aniline, Arsine, Benzene, Nitrobenzene.

ASPHYXIANTS Ability to deprive tissue of oxygen. Two Types: –Simple – physiologically inert gases which act by accumulating in sufficient quantity to exclude adequate oxygen supply. Examples: CO 2, methane, ethane, He, H, N. –Chemical – act through direct chemical action to render the body incapable of utilizing oxygen. Examples: CO, HCN, and H 2 S.

HEPATOTOXIC AGENTS Adversely affect liver function. Examples: Carbon Tetrachloride, Chloroform, Nitrosamines, Tetrachloroethane.

NEPHROTOXIC AGENTS Adversely affect kidney function. Examples: Most Halogenated Hydrocarbons, Uranium, Mercury, Lead, Cadmium.

NEUROTOXIC AGENTS Interfere with proper function or cause damage to the nervous system. Interfere with proper function or cause damage to the nervous system. Examples: Examples: CNS - Organometallic Compounds, Methyl Mercury, Tetraethyl Lead. Peripheral - Arsenic, TOCP.

SENSITIZERS Agents that cause recurrent effects after the worker becomes sensitized (allergic) to the toxin. First few exposures may cause no reaction, but then reactions can occur from later contact with small quantities for very short periods of time.

CARCINOGENS Stimulate or speed the development of cancer. Examples: BCME, Vinyl Chloride, Benzidine, Chromium.

EVALUATION OF HAZARDS Toxicity of the substance Concentration in the breathing zone Manner of use Length of time of the exposure Control in place Employee susceptibilities

CONTROL OF HAZARDS Substitution (i.e. benzene for toluene, xylene) Engineering controls PPE (respirator, gloves, eye wear)