HAZARDOUS MATERIALS, CHEMICALS & ASSOCIATED HAZARDS

 

What is a hazardous material? A hazardous material is a material, including chemicals or biological agents, capable of producing harmful physical or health effects. Harmful physical effects include; fire, sudden release of pressure, explosion, and other violent reactions. Harmful health effects include; acute conditions or chronic conditions. Acute conditions develop soon after over-exposure to hazardous materials and include; burns, rashes, respiratory distress, convulsions, and possibly even death. Chronic conditions develop after long term exposure to hazardous materials and include; cancers, nervous system disorders, and damage to other organ systems.

 

In order to safely and properly handle and store hazardous materials, it is important to know the hazards of those materials.  Personnel working with hazardous materials must be aware of the hazards those materials present. Hazardous materials may generally be assigned to one or more of the following classifications.

 

Hazardous Materials Classifications

  • Biomedical – any laboratory and veterinary wastes which contain human disease-causing agents as well as sryinges, needles and sharps.
  • Combustible liquid - any liquid having a flash point > 1000F and < 2000F.
  • Compressed gas - a substance in gas or liquid form contained in a vessel under pressure. This includes cylinders and aerosol cans. These substances may be flammable, non-flammable, or poisonous.
  • Corrosive - a liquid that exhibits a pH < 2 or > 12.5.
  • Cryogenics - substances which are extremely cold such as liquid nitrogen, liquid helium and dry ice. These substances may also become asphyxiation hazards if spilled in non-ventilated areas.
  • Explosive - any chemical compound, mixture or device that reacts or decomposes with substantial instantaneous release of gas and heat when subjected to sudden shock, pressure or high temperature.
  • Flammable liquid - any liquid exhibiting a flash point < 1000F.
  • Flammable solid - a substance that can cause a fire through friction, absorption of moisture or spontaneous chemical changes and, when ignited, will burn so vigorously that it creates a hazard.
  • Organic peroxide - an organic compound containing the chemical bond -0-0- (oxygen joined to oxygen).
  • Oxidizer - a substance that readily yields oxygen or other electron acceptor to stimulate the combustion of organic matter (fuel).
  • Poison - a substance so toxic that it presents a risk to life or health.
  • Radioactive - any material having a specific activity greater than 0.002 microcuries per gram (uCi/g).
  • Sensitizer – a chemical that causes a substantial proportion of exposed people to develop an allergic reaction in normal tissue after repeated exposure to the chemical.
  • Water reactive – a chemical that reacts with water to release a gas that is either flammable or presents a health hazard.

Chemical Health Hazards

 

Chemicals are identified as hazardous if there exists statistically significant evidence, based on at least one study conducted according to established scientific principles, that acute or chronic health effects may occur in exposed employees, or if it is listed in any of the following:

  • 29 CFR §1910 Subpart Z, Toxic and Hazardous Substances;
  • "Threshold Limit Values for Chemical Substances and Physical Agents in the Work Environment", American Conference of Governmental Industrial Hygienists (latest edition;
  • "The Registry of Toxic Effects of Chemical Substances", National Institute of Occupational Safety and Health.

In most cases, the label will indicate if the chemical is hazardous. Look for key words such as caution, hazardous, toxic, dangerous, corrosive, irritant, or carcinogen. Old containers of hazardous chemicals (pre 1985) may not contain hazard warnings. If you are not sure a chemical you are using is hazardous review the Material Safety Data Sheet (MSDS) or contact your supervisor.

 

Types of Chemical Health Hazards

 

Irritants are materials that cause inflammation of the body surface with which they come in contact with (inflammatory) or changes in the mechanics of respiration and lung functions (respiratory). Long term exposures can result in increased mucous secretions and/or chronic bronchitis. Common laboratory inflammatory irritants include; ammonia, alkaline dusts, halogens, hydrogen chloride, and nitrogen dioxide. Common laboratory respiratory irritants include; acetic acid, formaldehyde, formic acid, halogens, and sulfuric acid.

Asphyxiants deprive the tissue of oxygen. Simple asphyxiants are inert gases that displace oxygen. Chemical asphyxiants render the body incapable of maintaining an adequate oxygen supply, and are active at very low concentrations in the ppm range. Common laboratory asphyxiants include; carbon dioxide, helium and nitrogen. Common chemical asphyxiants include include carbon monoxide and cyanides.

Primary anesthetics have a depressant effect upon the central nervous system, particularly the brain. Common laboratory anesthetics include halogenated hydrocarbons and alcohols.

Toxic chemical agents target and can damage a variety of human organs or systems. Neurotoxic agents (carbon disulfide, manganese, methyl mercury, tetraethyl lead) damage the nervous system. The nervous system is especially sensitive to organometallic and select sulfide compounds. Hematopoietic agents (aniline, benzenes, nitrites, toluidine) act on the blood system and can directly affect the bone marrow. Nephrotoxic (halogenated hydrocarbons, uranium) and Hepatotoxic (carbon tetrachloride, nitrosamines, tetrachloroethane) agents can act on the kidney and liver systems, respectively.

Carcinogens describe any agent that can initiate or speed the development of malignant or potentially malignant tumors, malignant neoplastic proliferation of cells, or cells that possess such material. Formaldehyde and formaldehyde mixtures, commonly used in quantities at SEFSC Laboratories, were identified as "Reasonably Anticipated to be Carcinogens" by the National Toxicology Program (a division of the National Institute of Health) as it causes statistically significant tumor incidence in experimental animals.

Mutagens and teratogens are chemicals that affect human reproductive capabilities. A mutagen (diethyl sulfate, ethylmethane sulfonate, formaldehyde, nitrous oxide)affects the chromosomal chains of exposed cells. The effect is hereditary and becomes part of the genetic pool passed on to future generation. A teratogen (dimethylphthalate, ionizing radiation) is an agent that interferes with normal embryonic development without damage to the mother or lethal effect on the fetus. Effects are not hereditary.

Highly toxic chemicals (isocyanates, mercaptans, methyl mercury) or gases (arsenic pentafluoride, chlorine, fluorine) are substances falling within any of the following categories:

  • A chemical that has a median lethal dose (LD50) of 50 milligrams or less per kilogram of body weight, when administered orally to albino rats weighing 200g to 300g each;
  • A chemical that has a median LD50 of 200 milligrams or less per kilogram of body weight, when administered by continuous contact for 24 hours, (or less if death occurs within 24 hours), to the bare skin of albino rabbits weighing 200g to 300g each;
  • A chemical that has a median lethal concentration (LC50) in air of 200 parts per million by volume, or less, of gas, or vapor, or 2 milligrams per liter or less, of mist, fume, or dust, when administered by continuous inhalation for one hour, (or less if death occurs within one hour), to albino rats weighing 200g to 300g each.