Hazardous Chemicals
Brainstorming
Globally Harmonized System of Classification
While the existing laws and regulations are similar, they are different enough to require multiple labels for the same product both within the U.S. and in international trade and to require multiple safety data sheets for the same product in international trade. Several U.S. regulatory agencies and various countries have different requirements for hazard definitions as well as for information to be included on labels or material safety data sheets. Pasted from <http://www.osha.gov/dsg/hazcom/ghs.html>
The Hazard Communication Standard (HCS) also requires training for employees exposed or potentially exposed to hazardous chemicals. The Hazard Communication Standard does not, however, cover hazardous wastes as defined and regulated by the EPA. For other hazardous chemicals known to be present at the workplace, the standard states that health hazard information is required to be transmitted from the chemical manufacturer or importer and flow "downstream" with the substance as it is used by industry. Pasted from <http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=20295>
6. Health Effects of Toxic Chemicals
There are many materials used in the workplace that can be hazardous. However, in order for them to affect your health, they must contact the body or be absorbed into the body. When assessing the potential health effects from working with a particular material it is necessary to understand difference between "toxicity" and "hazard".
1. TOXICITY is the ability of a substance to produce an unwanted effect when the chemical has reached a sufficient concentration at a certain site in the body.
The more toxic a material is, the smaller the amount of it necessary to be absorbed before harmful effects are caused. The lower the toxicity, the greater the quantity of it necessary to be absorbed. The toxicity of a chemical is generally measured by experiments on animals (quite often rats). If it is measured in terms of the amounts of material necessary to cause death in 50% of the test animals. These values are called LD50 (lethal dose) or LC50 (lethal concentration), and are usually given in weight of material per kg of body weight or airborne concentration of material per set time period respectively.
2. HAZARD is the probability that this concentration in the body will occur.
Toxicity is an inherent property of the material. A material may be very toxic, but not hazardous, if it is handled properly and is not absorbed into the body. On the other hand, a material may have a very low toxicity, but be very hazardous.
Example:
1. An open container of an acid is much more hazardous than a closed container of the same material.
2. Two liquids may possess the same degree of toxicity but present different degrees of hazard:-
One material may be non-irritating to the eyes and nose and odourless. The other may be irritating to the eyes or respiratory system and possess a pungent odour.
The latter material, because of its warning properties presents a lesser degree of hazard.
In order for toxicants to affect the human system either they must cause damage to external tissues, such as the skin or eyes, or they must be able to enter the body by some mechanism.
Pasted from <http://www.ehs.utoronto.ca/resources/whmis/whmis6.htm>
Physiological Classification of Materials
This classification identifies toxic materials on the basis of biologic action.
Irritants - refers to some sort of aggravation of whatever tissue the material comes in contact with.
e.g. ammonia, nitrogen dioxide.
Asphyxiants - exert their effects through a depletion of oxygen to the tissues
e.g. - simple asphyxiants - carbon dioxide, nitrogen, methane, hydrogen
chemical asphyxiants - carbon monoxide, hydrogen cyanide, hydrogen sulphide.
Narcotics or Anaesthetics - the main toxic action is the depressant effect upon the Central Nervous System.
e.g. - many organics, chloroform, xylene.
Systemic Poisons - the main toxic action includes the production of internal damage
e.g. Hepatotoxic agents - toxic effects produce liver damage. eg. carbon tetrachloride.
e.g. Nephrotoxic agents - toxic effects produce kidney damage eg. some halogenated hydrocarbons
Carcinogens - agents/compounds that will induce cancer in humans.
e.g. benzene, arsenic, inorganic salts of chromium, nickel, beryllium.
Mutagens - agents that affect the cells of the exposed people in such a way that it may cause cancer in the exposed individiual or an undesirable mutation to occur in some later generation.
e.g. radiation, variety of chemical agents that alter the genetic message.
Teratogens - Agents or compounds that a pregnant woman takes into her body that generate defects in the fetus
e.g. Thalidomide, possibly steroids
Sensitizers-Agents that may cause allergic or allergic-like responses to occur. After an initial exposure to a substance an individual may become sensitized to that substance. Subsequent exposures to the same substance, often at a much lower concentration than before, produce an allergic response. This response may be a skin rash (dermatitis) or an asthmatic-like attack, depending on the route of exposure.
e.g. cutting oils, isocyanates in polyurethane foam operations and paint spraying operations, some laboratory solvents.
Pasted from <http://www.ehs.utoronto.ca/resources/whmis/whmis6.htm>
TOXICOLOGY AND EXPOSURE GUIDELINES
http://ehs.unl.edu/chemicalinfo/tox_exposure_guidelines.pdf
Dose-Response Terms. The National Institute for Occupati onal Safety and Health (NIOSH) defines a number of general dos e-response terms in the "Registr y of Toxic Substances" (1983, p.xxxii). A summary of these terms is contained in Table 1.
• Toxic dose low (TDLO) : The lowest dose of a substance introduced by any route, other than inhalation, over any given period of time, and reported to produce any toxic effect in humans or to produce tumorigenic or reproductive effects in animals.
• Toxic concentration low (TCLO) : The lowest concentration of a substance in air to which humans or animals have been exposed for any given period of time that has produced any toxic effect in humans or produced tumorigenic or reproductive effects in animals.
• Lethal dose low (LDLO) : The lowest dose, other than LD50 of a substance introduced by any route, other than inhalation, which has b een reported to have caused death in humans or animals.
• Lethal dose fifty (LD 50): A calculated dose of a substance which is expected to cause the death of 50 percent of an entire defined expe rimental animal populati on. It is determined from the exposure to the substance by any route other than inhalation.
• Lethal concentration low (LCLO) : The lowest concentration of a substance in air, other than LC50, which has been report ed to cause death in humans or animals.
• Lethal concentration fifty (LC 50): A calculated concentration of a substance in air, exposure to which for a specified length of time is expected to cause the death of 50 percent of an entire defined experimental animal population.
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Note to Self: Continue review at page 7 of this PDF.
