OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

August 3, 2017


Mr. Kirk Nelson
Systems Administrator, Authoring Services
MSDSonline – A VelocityEHS Solution
222 Merchandise Mart Plaza, Suite 1750
Chicago, Illinois 60654

Dear Mr. Nelson:

Thank you for your letter to the Occupational Safety and Health Administration’s (OSHA) Directorate of Enforcement Programs (DEP). You requested clarification on the use of “trade secret” in lieu of known ingredient percentages (both exact and ranges) on safety data sheets (SDS) under OSHA’s Hazard Communication Standard (HCS), 29 CFR 1910.1200, and other questions about hazard classification. This letter constitutes OSHA’s interpretation only of the requirements herein, and may not be applicable to any questions not delineated within your original correspondence. Your paraphrased questions, followed by our responses are below.

Question 1: Is it allowable to claim and list an ingredient as trade secret in section 3 of the SDS if it is an actual range (e.g., 10-15%) due to substantially similar mixtures, or batch to batch variability? Can an actual range (10-15%) be masked with a wider range (e.g., 10-30%) and be claimed as trade secret? Can an ingredient concentration such as ≤5% be masked and replaced with trade secret instead of the value?

Response: The HCS allows a manufacturer or importer to indicate on the SDS that the specific chemical identity and/or the exact percentage of composition of a hazardous ingredient is being withheld as a trade secret.  A manufacturer or importer may not claim trade secret status for a concentration range and is prohibited from masking the true range by use of a wider range. If a concentration range is used on the SDS it must be limited in terms of the percentage concentration variation (i.e., the narrowest range possible), and the variation in concentration must have no effect on the hazard of the mixture. The HCS does not prohibit the use of symbols, such as ≥ or <, to identify a range of values in place of the exact percentage, as long as the range does not include zero percentage (0%) and represents the narrowest range possible; however, the symbol “~” (i.e., approximate or about) is not allowed to be used.

Question 2: Is it acceptable, in place of an actual percentage value (exact value or range, 5% or 1-5% respectively, as examples) for an ingredient in the composition table in section 3 of the SDS, to leave blank for trade secret purposes?

Response: See response to question 1. It is not appropriate to leave the concentration percentage (or identity of the ingredient(s)) blank in Section 3 of the SDS. Where a trade secret is claimed in accordance with § 1910.1200(i), a statement that the specific chemical identity and/or exact percentage (concentration) of composition has been withheld as a trade secret is required in Section 3 of the SDS. See 1910.1200(i)(1)(iii).

If the exact percentage of a hazardous ingredient in a mixture is considered a trade secret, a concentration range may be used in its place. The use of a concentration range in this situation would assist downstream users in providing appropriate protections and, at the same time, potentially eliminate requests from users for disclosure of the trade secret in accordance with § 1910.1200(i). As another option, the manufacturer or importer may use symbols (e.g., < or >) in lieu of the exact percentage in order to protect a trade secret concentration.

To help illustrate when a trade secret must be indicated in Section 3 of the SDS, below are examples when “trade secret” is required to be used and when it is not allowed.

Example Trade Secret Indications in Section 3 of the SDS for mixtures

Does the Mfg/Imp consider the specific chemical identity

a trade secret?

Is the Mfg/Imp using an exact percentage or percentage range to identify the ingredient?

Can the percentage be claimed as a trade secret?

Trade secret indication


Exact percentage


SDS indicates the ingredient name and/or exact percentage is being withheld as a trade secret.


Exact percentage


SDS indicates the exact percentage is being withheld as a trade secret but not the ingredient name.


Percentage range


SDS indicates the ingredient name is being withheld as a trade secret but not the percentage range.


Percentage range


SDS may not indicate either the ingredient name or percentage range as a trade secret.

Question 3: If using a range for an ingredient in Section 3 of the SDS, is it acceptable to use “0%” in that range (e.g., 0-5%)? Is it acceptable to use 0%? Is it acceptable to use <5% in place of a range that includes 0%?

Response: OSHA does not allow the use of zero percent (0%) as an ingredient’s exact percentage or as part of a concentration range on a SDS. The use of zero percent on the SDS may be misinterpreted to mean that a particular ingredient in a mixture is not present when in actuality it is. Therefore, the SDS would contain inaccurate or misleading information. An ingredient whose true concentration is 0% would not be expected to be listed in Section 3 of the SDS, as it would not be an actual ingredient in the mixture. 

Question 4: When OSHA mentions exact percentage in 29 CFR 1910.1200, Appendix D, Section 3, for mixtures, does exact percentage mean a discrete number (e.g., 5%) or can exact percentage mean a concentration range (e.g., 5-10%)?

Response: The use of the term “exact percentage” means a discrete number. Concentration ranges are allowed, however, in certain circumstances. As you alluded to in your letter, examples of appropriate use of concentration ranges include when there is batch-to-batch variability in the production of a mixture, or for a group of substantially similar mixtures with similar chemical composition.

Question 5: For a Chemical Substances of Unknown or Variable Composition, Complex Reaction Products and Biological Materials (UVCB) product, if you have an ingredient for which you do not know the exact concentration, is it acceptable to take the most conservative value for that ingredient and take this into account for the calculations for classification purposes?

Response: OSHA has previously provided guidance on classification and concentration usage for UVCBs in a letter to Mr. Erik C. Baptist, American Petroleum Institute, March 4, 2014 (enclosed). In brief, the API letter (using petroleum streams as an example of a UVCB) stated that it may be more relevant to know the total concentration of a class of constituents such as polycyclic aromatic hydrocarbons (PAH) to understand the health hazards of the stream, rather than knowing the concentration of each particular PAH. Where the classifier can show that it is toxicologically appropriate to treat a particular set of constituents as a group, and all of the toxicologically useful information about the constituents in that group is conveyed by treating them as a group, the SDS need only include the name and concentration of that group in Section 3 if present above the cut-off/concentration limit (or if the group presents a health risk below the cut-off/concentration limit).

The API letter further states that where the classifier does not know the exact concentration of a constituent or group of constituents included in Section 3 of the SDS, it may use a range of concentrations instead. Concentration ranges, if used, must be based on the information available to the classifier, such as analysis results, product specifications, or nature of the process, and the high end of the range reported may not affect the reported hazard classification.

Question 6: If multiple products are grouped together because they are substantially similar mixtures, is this based on hazard, or is this based on the actual ingredients that are present within a mixture (i.e., CAS number).  For example, if three paint products have the same exact ingredients at the same weight percent, except there are three different pigments at the same weight percentage (one different pigment per paint), would these be allowed to be grouped together?

Response: When grouping multiple products on a single SDS, it is appropriate to consider the hazard(s) being communicated. For a mixture of hazardous chemicals that has not been tested as a whole, the manufacturer must list all of the ingredients that are determined to be health hazards and that meet the Hazard Class cut-offs found in Appendix A of the HCS. If the mixture ingredients are determined to be health hazards and comprise less than the cut-off limits, but there is evidence that the ingredient(s) could present a health risk to employees under normal conditions of use or foreseeable emergency, then these chemicals must also be listed.

If all the ingredients have similar hazards that fall within the same cut-off values/concentration limits as that of the base material and do not react, one SDS listing the different possible combinations of hazardous ingredients may be used for the entire line even though the quantities and number of pigments may vary from product to product. However, if the ingredients being added have different hazards (e.g., one pigment is a carcinogen and the rest are not), the manufacturer or importer must use separate SDSs for the products with these additional hazards. 

Question 7: Are the hazards associated with metal alloy massive (grade) products (e.g., a manufactured iron/steel alloyed beam), such as from shavings, dust, fines, and other forms of processing, to be considered for classification in Section 2(a) and subsequently used for the labeling elements in Section 2(b) of the SDS if the manufacturer is not processing their material on-site and these by-products will not be developed as shipped? Does the manufacturer need to include the hazards in Sections 2(a) and 2(b) of the SDS if they or a downstream user are either processing or not processing the material? For example if these hazards could occur in a foreseeable emergency? Does this type of logic apply to metal massives (grade) that contain ingredients in OSHA substance-specific standards (e.g., Lead-29 CFR 1910.1025)?

Response: Yes, manufacturers or importers must consider, as a part of their hazard classification, downstream conditions of use and foreseeable emergencies for the product. As general guidance, manufacturers or importers of solid materials, such as iron/steel beams, may separate the classification under Section 2 of the SDS based on the solid material’s normal conditions of use or foreseeable emergency. For example, information on a solid material may be presented based on how a chemical or product is physically altered resulting in dust, fines, chips, or how it is heated above its melting point to cause fumes. The following provides example classifications addressing the hazard class and hazard statements only. In addition to the hazard class and hazard statements, the appropriate signal word, symbol(s), and accompanying precautionary statements are to be included in Section 2 of the SDS. 

The following is an example of separated classification:

Classification Intended Use: Physical alteration resulting in dust, fines, and chips

Hazard name

Combustible Dust
Flammable Solid 1
Eye Irritant 2A
Carcinogenicity 2

May form combustible dust concentrations in air
Flammable solid
Causes serious eye irritation
Suspected of causing cancer <…>
(state route of exposure if not other routes of exposure cause the hazard)


Classification Intended Use: Heating above melting point resulting in fumes

Hazard name

Acute Toxicity 4 (Oral)
Respiratory Sensitization 1
Specific Target Organ Toxicity – Repeated Exposure 1 (STOT-RE 1)

Harmful if swallowed
May cause allergy or asthma symptoms or breathing difficulties if inhaled
Causes damage to organs <…> through prolonged or repeated exposure <<…>>
<…> (state all organs affected, if known)
<<…>> (state route of exposure if no other routes of exposure cause the hazard)

For additional information, you may find useful a Frequently Asked Question developed by OSHA regarding the use of concentration ranges, and the applicability to trade secrets. The FAQ can be found on OSHA’s web site at https://www.osha.gov/dsg/hazcom/hazcom-faq.html#collapse33.

Thank you for your interest in occupational safety and health. We hope you find this information helpful. OSHA’s requirements are set by statute, standards, and regulations. Our letters of interpretation do not create new or additional requirements but rather explain these requirements and how they apply to particular circumstances. This letter constitutes OSHA’s interpretation of the requirements discussed. From time to time, letters are affected when the Agency updates a standard, a legal decision impacts a standard, or changes in technology affect the interpretation. To ensure that you are using the correct information and guidance, please consult OSHA’s website at https://www.osha.gov; If you have further questions, please feel free to contact the Office of Health Enforcement at (202) 693-2190.



Amanda Edens, Acting Director
Directorate of Enforcement Programs