Note. Only chemical manufacturers and importers are required to perform hazard classifications on the chemicals they produce or import. Employers may also choose to conduct hazard classifications if they are concerned about the adequacy of the hazard information received for the chemicals used in their business or distributed to others.
A new OSHA guidance outlines the four main steps involved in conducting a hazard classification.
Step 1: Selecting Chemicals to Evaluate
The first step in documenting the hazards of chemicals is to select the chemicals that need to be evaluated. OSHA suggests that you begin by preparing an inventory of all the chemicals you manufacture or import, as well as a list of the ingredients in the mixtures produced. To create the list of ingredients from the mixtures produced, consider information found in such documents as the chemical formula, order receipts, and batch sheets. While a single safety data sheet (SDS) must be created for the mixtures produced, you may rely upon the information provided on the SDSs and labels for ingredients obtained from the chemical manufacturer or importer, unless you have reason to believe the information is incorrect.
However, you may choose to conduct a hazard classification for those ingredients if there is concern about the adequacy of the hazard information received.
Under OSHA’s Hazard Communication Standard (HCS), all employers are required to have a list of hazardous chemicals known to be present in the workplace. If a chemical inventory is not already in place, a good start would be to review purchase orders and receipts to create an initial inventory. Next, take time to inspect the workplace to identify any additional chemicals present. It would be ideal to note the location and quantity of each chemical found. Chemical inventories are often maintained as computer files for ease and efficiency in keeping them current. With knowledge of the chemicals in your possession, you can use this information to perform hazard classifications for chemicals that your organization manufactures or imports.
The chemical inventory or survey can also be used to decide which chemicals to dispose of, as well as to identify potentially unsafe storage areas and techniques. Some chemicals should not be stored near each other due to incompatibilities and potential reactions.
Step 2: Collecting the Data
The second step in the hazard classification process is data collection. There are two main questions to be answered:
- What type of data should be searched for and collected?
- How do I go about finding sources that might contain the desired data?
The hazard classification process involves the identification of all of the hazards associated with a chemical, not just some of them. OSHA expects classifiers to use reasonable efforts in their search for available data for all hazard classes. To complete the hazard identification, information is needed in three categories: chemical identity, physical and chemical properties, and health effects.
Information for the chemical identity includes the chemical name along with common name and synonyms, the Chemical Abstracts Services Registry Number (if available), and any other information that reveals the precise chemical designation and composition of the substance, such as impurities and stabilizers. Key sources of information related to chemical identification include:
- Company records;
- SDSs and product safety bulletins from manufacturers or suppliers;
- OSHA Chemical Sampling Information pages;
- The Merck Index;
- ChemID; and
- Trade associations.
Data for physical and chemical properties are gathered from observation or by tests performed on the chemical. For many hazardous chemicals, this data has been compiled and is readily available. According to OSHA, key sources of information related to physical and chemical properties include:
- Fire Protection Guide to Hazardous Materials;
- Department of Transportation Emergency Response Guidebook, most recent version;
- OSHA’s Occupational Chemical Database;
- Hazardous Substances Data Bank;
- Product safety bulletins from manufacturers or suppliers;
- National Institute for Occupational Safety and Health (NIOSH) chemical documents;
- NIOSH Pocket Guide to Chemical Hazards;
- International Chemical Safety Cards;
- Organization for Economic Cooperation and Development eChemPortal;
- The Merck Index;
- CRC Handbook of Chemistry and Physics;
- Sax’s Dangerous Properties of Industrial Materials, latest edition;
- Bretherick’s Handbook of Reactive Chemicals Hazards, latest edition; and
- Trade associations
There are numerous sources for information about the health effects of a chemical. The HCS includes the classification criteria for 11 health hazard classes. In many cases, a chemical may pose more than one type of health hazard. If your company is manufacturing a new chemical, you may be required to submit premanufacturing health effects data to the U.S. Environmental Protection Agency (EPA) to comply with the Toxic Substances Control Act. Data submitted to the EPA by other companies may be available to you by contacting the EPA. This data may be used to assist with hazard classification and the preparation of chemical SDSs and labels.
According to OSHA, in addition to the some of the data sources for chemical identity and physical and chemical properties, recommended reference sources for health effects data include:
- Center for Disease Control’s Agency for Toxic Substances and Disease Registry, found at www.atsdr.cdc.gov/toxprofiles/index.asp;
- NIOSH Registry of Toxic Effects of Chemical Substances®;
- OSHA Chemical Sampling Information pages;
- IARC Monographs on the Evaluation of Carcinogenic Risks to Humans (monographs.iarc.fr);
- The National Toxicology Program’s Annual Report on Carcinogens (ntp.niehs.nih.gov/pubhealth/roc);
- Threshold limit values and biological exposure indexes from the American Council of Governmental Industrial Hygienists; and
- Hawley’s Condensed Chemical Dictionary, latest edition.
Step 3: Analyzing the Data Using HCS Criteria
The third step in the hazard classification process is data analysis. According to OSHA, this step is the most demanding in terms of technical expertise. For both health and physical hazards, explicit classification criteria are provided in the HCS. For example, criteria are given for classifying a chemical as a flammable liquid, as an organic peroxide, and for designating a chemical as acutely toxic or a carcinogen.
In the HCS, the term “hazard classification” is used to indicate that only the intrinsic hazardous properties of chemicals are considered. Hazard classification incorporates three steps:
- Identification of relevant data regarding the hazards of a chemical;
- Subsequent review of those data to ascertain the hazards associated with the chemical; and
- Determination of whether the chemical should be classified as hazardous and the degree of hazard, where applicable.
According to OSHA, for many hazard classes, the criteria are semiquantitative or qualitative, and expert judgment is required to interpret the data for classification purposes.
Step 4: Documenting the Hazard Classification Process and Results
OSHA cautions that you do not neglect the fourth and final step in the hazard classification. All the other steps will be wasted if findings are not recorded carefully. If a chemical is found to be hazardous, OSHA recommends that the findings and the rationale used to arrive at these findings be documented.
The HCS no longer requires documentation of the procedures used to determine the hazards of a chemical since this is now provided through the classification procedures specified in Appendices A and B of the HCS, and all those performing hazard classification must follow the same process. However, OSHA still recommends the data, the rationale used, and other results gathered during the classification process be maintained for future reference and use.
OSHA recommends that a structured approach to data retrieval and compilation be adopted. This structured approach also applies to the preparation of SDSs and labels. Compilations of three types of data are considered essential:
- Initial chemical inventory;
- Specific data retrieved for each chemical; and
- The list of hazardous chemicals present in the workplace.
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