For mixtures or products, this chemical search includes the name of each chemical in the mixture, including active ingredients, inactive ingredients, and impurities. The specific chemical identity of all chemicals on your Chemical Inventory should be carefully and completely compiled. The specific chemical identity should include:. Correct identification of chemicals is critical for data retrieval. Use the precise chemical name and CAS number when searching for information.
Dry Cleaning, Some Chlorinated Solvents and Other Industrial Chemicals
A problem with the use of common names or abbreviations is that they may be used for more than one molecular entity. For example, TCE is sometimes used as an acronym for tetrachloroethylene, although it more frequently refers to trichloroethylene. To avoid confusion, literature is often indexed using the CAS number or the primary chemical name. Several databases exist that can be searched for the CAS number or chemical name if one only has a trade or common name s or abbreviation s. The percent composition should be available in-house for all chemicals and products manufactured or imported.
The chemical composition information should be based on an analysis of the final or technical product. A technical grade product is not usually a pure substance and often contains other chemicals such as stabilizers, solvents, carriers, "inert" ingredients, or impurities. For the hazard evaluation process, these other chemicals must also be listed if they are more than 1. Thus, the initial step is to collect as much data as possible pertaining to the physical and chemical properties and toxicity data for chemicals on your chemical inventory.
The physical properties of a substance can be directly related, in many cases, to the probability of the substance representing a physical hazard. However, the fact that a substance has a certain physical property cannot necessarily be used to predict a physical hazard. For example, all volatile substances are not necessarily explosive.
Some solids can also be explosive e. Nevertheless, knowing the physical properties has great value in predicting whether a substance may pose a physical hazard. The HCS includes a list of 14 potential health hazards, as well as the criteria for determining when a chemical represents a health hazard see Section 3. In many cases, a chemical may pose more than one type of health hazard. This data should be used to assist with hazard determination and the preparation of MSDSs and labels.
For chemicals that have not been studied in-house or via company-sponsored toxicology studies, the company should seek toxicity data from the literature, government, or private sources. Some recommended reference sources are listed below. The third step in the hazard determination process is data analysis. This step is the most demanding in terms of technical expertise. The HCS requires that chemical manufacturers and importers conduct a hazard determination to determine whether physical or health hazards exist.
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In some cases, especially for physical hazards, a definition in the HCS establishes the criteria to be followed. This type of procedure is a simple data analysis. You can look up the flashpoint in a standard reference and accept it at face value. In the event that your company is manufacturing or importing a chemical for which there is no information on the flashpoint, you may choose to determine the flashpoint by laboratory testing, but testing is not required by the HCS. As a rule, the HCS attempts to minimize the burden of literature search and review while satisfying the need to provide information required to protect employees who are exposed to hazardous chemicals.
For this reason, a suggested approach is to go to the most likely sources first to obtain the needed data, and then proceed to additional sources, if necessary.
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For health hazards, explicit criteria are provided in the HCS for some health hazards. For example, criteria are given for classifying a chemical as highly toxic or toxic based on acute effects, and for designating a chemical as a carcinogen. For other health hazards, a simple generic requirement is provided for the determination of a specific health hazard.
The HCS states that "evidence that is statistically significant and which is based on at least one positive study conducted in accordance with established scientific principles is considered to be sufficient to establish a hazardous effect if the results of the study meet the [HCS] definitions of health hazards. Let us examine this requirement further. There are three key criteria that must be met, namely "statistically significant", "positive study", and "established scientific principles". Thus, the evaluation of study results requires some knowledge of statistics, commonly accepted scientific test methodology, and the definitions of health hazards.
Statistical significance is a mathematical determination of the confidence in the outcome of a test. The usual criterion for establishing statistical significance is the p-value probability value.
Most reports of toxicity testing will include some information on the confidence in the data. Most toxicity and epidemiology reports will provide an analysis of the data and conclude whether the results were positive or negative, or will describe the adverse effects observed at specific dose levels. Positive results mean that the exposed humans or animals were more likely to develop toxic effects than the non-exposed population. Hazard evaluation relies on professional judgment, particularly in the area of chronic hazards.
The performance-orientation of the HCS does not diminish the duty of the chemical manufacturer, importer or employer to conduct a thorough evaluation, examining all relevant data and producing a scientifically defensible determination. In the remainder of this section, an overview is presented of the HCS designated hazards and their definitions. In addition, a brief discussion is presented to further explain the specific hazard as well as procedures that can be used to analyze the data.
Because this document can only present a limited discussion of the various hazards, you are encouraged to consult references that go into greater detail see Appendix B of this document. The ability of a chemical to either burn or support burning is a potentially disastrous physical hazard. The two primary measures of the ease with which a liquid will burn are the flashpoint and autoignition temperature. The flashpoint is the lowest temperature at which a liquid will emit sufficient vapors to form an ignitable mixture with air.
In contrast, autoignition is the characteristic of a material in which it will spontaneously burn without the aid of an ignition source, such as a spark or flame. Many agents will burn when ignited whereas there are only a few that will spontaneously erupt into flames. While no single measure of flammability is sufficient for all purposes, the most commonly found measure in the literature is the flashpoint. For this reason, HCS uses flashpoint in classifying the fire hazard of a chemical. Flammable liquids and combustible liquids are discussed together since flashpoint is the criterion for classification of both.
The only difference between a "flammable" and "combustible" liquid is the relative ease temperature with which the substance burns or supports burning. The data analysis and hazard categorization are clear. For a pure chemical compound, the assignment to combustible or flammable liquid categories is quite simple:.
You see that the HCS has made exceptions for chemical mixtures.
Where data indicating the flashpoint of a chemical are not available, you may choose to test the chemical to determine the flashpoint. If data are available that were derived from another testing method, a description of the method should be provided along with the results of the testing.
When a substance flashes, the resulting flame will spread through the vapor from the ignition source to the nearby surface of the liquid. From a practical viewpoint, a flammable liquid is potentially more hazardous than a combustible liquid. A flammable liquid presents a fire hazard if present in an open container near an ignition source in an environment in which the temperature is near or below normal room temperature. For a combustible liquid to present a fire hazard it must be above normal room temperature.
The lower flammability limit LFL is the minimal concentration of vapor below which combustion will not occur even in the presence of an external ignition source, whereas the upper flammability limit UFL is the maximum vapor concentration above which combustion cannot take place. To understand the concept, that at a certain concentration combustion will occur whereas it will not if the concentration is too low or too high, consider the carburetor of an automobile.
Gasoline has an LFL of 1.
The analysis as to whether the chemical is a flammable aerosol is more difficult and usually must be based upon laboratory testing of the aerosol as emitted from a pressurized container. Their flammability is highly dependent on the nature of the propellant formulation. Therefore, data obtained from a literature search that does not pertain to the exact mixture of ingredients in the product may not be relevant when determining the flammability of the product. In the event that you choose to test a chemical product to determine if it is a flammable aerosol, the method described in 16 CFR A positive test is obtained if a flame is projected at least 18 inches at full valve opening, or if there is a flashback i.
Acetone is an example of a flammable liquid that volatilizes but does not represent a flammable gas. The analysis as to whether a solid chemical will burn with such intensity to be classified as a flammable solid usually must be based upon the results of laboratory testing. If you choose to test a chemical to determine if it is a flammable solid, such testing should be conducted by the method described in 16 CFR A flammable solid can be ignited readily and then will burn so vigorously as to create a serious fire hazard. Blasting agents or explosives may be solids that burn but with an intensity so great that they are classified as explosives.
An example of a flammable solid that can be ignited by friction is the chemical formulation on the head of matches. Some metal powders such as magnesium can react with moisture and burn and are thus classified as flammable solids. The HCS classifies a chemical as an oxidizer if it is a "chemical other than a blasting agent or explosive as defined in [29 CFR] An oxidizing agent is a chemical or substance that brings about an oxidation reaction.
The agent may provide the oxygen to the substance being oxidized in which case the agent has to be oxygen or contain oxygen , or it may receive electrons being transferred from the substance undergoing oxidation e.
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Oxidation materials can initiate or greatly accelerate the burning of fuels. The most common oxidizer is atmospheric oxygen. Oxygen-containing chemicals e. Some chemicals may be oxidizers with such an extremely fast burning potential that they are classified as explosives or blasting agents rather than oxidizers.
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Often the fact that a chemical possesses oxidizing potential can be determined by an examination of its chemical structure. For example, oxidizing substances usually include recognizable functional chemical groups, e. While the potential for oxidizing can often be inferred by chemical structure, absolute certainty can only be properly established in the laboratory since oxidation involves not only the oxidizing potential of the oxidizer, but also the chemical formulation of the fuel with which it comes in contact.
Oxidizers are classified by comparison with the oxidizing properties of a standard test chemical, ammonium persulfate, applied to dry, conditioned sawdust. A solid that promotes combustion of the conditioned sawdust at a greater rate than ammonium persulfate is classified as an oxidizer. Many of these are elements e. Moisture in the air often increases the probability of spontaneous ignition of pyrophoric materials.
All compressed gases are potentially hazardous since they are under great pressure in a container. Accidental rupture of the container and the rapid release of the pressurized gas can result in injury to persons and damage to objects in the vicinity.
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