Hazard statements vs. precautionary statements: what each one does

The HazCom standard defines both (29 CFR 1910.1200(c)). A hazard statement is assigned to a hazard class and category and describes the nature of the chemical's hazards, including, where appropriate, the degree of hazard. A precautionary statement describes recommended measures to minimize or prevent adverse effects from exposure, or from improper storage or handling.

Together with the pictogram and the signal word, they are the four "label elements" (§1910.1200(c)). None of them is free text. Appendix C assigns each one to a specific hazard class and category (§1910.1200(f)(2); Appendix C.2), and the same elements appear in Section 2 of the SDS.

A hazard statement is fixed text tied to a classification. A flammable liquid in Category 1 is "Extremely flammable liquid and vapor"; in Category 2, "Highly flammable liquid and vapor"; in Category 3, "Flammable liquid and vapor" (Appendix C.4.19). Here the wording carries the degree of hazard, so the category is readable from the sentence. That isn't true of every class: acute oral toxicity Categories 1 and 2 share "Fatal if swallowed."

The rules are short (Appendix C.2.2). The text of every applicable hazard statement must appear on the label. Where the prescribed text includes italic instructions, such as stating the organs affected, that information has to be filled in. Hazard statements may be combined to reduce text and improve readability, as long as every hazard is still conveyed. A statement may be omitted only where the manufacturer, importer, or responsible party can demonstrate it is inappropriate for that specific product.

Signal words and pictograms have their own precedence rules (Appendix C.2.1). If "Danger" applies, "Warning" doesn't appear. If the skull and crossbones appears, the exclamation mark isn't also used for acute toxicity. If the corrosion symbol appears, the exclamation mark isn't used for skin or eye irritation. And if the health hazard symbol appears for respiratory sensitization, the exclamation mark isn't used for skin sensitization or skin or eye irritation. A pictogram appears only once on a label, however many hazards call for it (C.2.3.4).

Precautionary statements come in four types: prevention, response, storage, and disposal (Appendix C.2.4.1). In Appendix C, the core text that must appear on the label is printed in bold. The rest of the notation tells the preparer what to decide:

Beyond that, the preparer has some room. Statements may be combined or consolidated to save space and improve readability (C.2.4.6). Minor wording variations, such as spelling variants or synonyms, are allowed if they help communicate the safety information, don't dilute it, and are used consistently on the label and the SDS (C.2.4.7). Where a product's hazards trigger similar statements, the most stringent one goes on the label (C.2.4.8). And a statement can be omitted if the preparer can demonstrate it's inappropriate for that product (C.2.4.9).

The codes you see on most SDSs, such as H225 or P210, are not in OSHA's standard. Appendix C prints the statements' text, with no numbers. The codes come from the UN's Globally Harmonized System (GHS), whose numbering groups statements by type:

Combined statements join their codes with a plus sign: P303+P361+P353 is the skin-contact response "If on skin (or hair): Take off immediately all contaminated clothing. Rinse skin with water [or shower]." The codes are a convenient shorthand. Under HazCom, it's the text that has to be on the label and the sheet.

Two code families are worth recognizing on a U.S. sheet. OSHA's definitions of physical and health hazards don't include the GHS environmental classes (§1910.1200(c)), and Section 12, where ecological information sits, isn't enforced by OSHA (Note 2 to §1910.1200(g)(2)). So H400-series statements aren't an OSHA requirement, though many sheets carry them because the same document is used in other countries. Likewise, OSHA didn't adopt acute toxicity Category 5 or a few other GHS categories, such as mild skin irritation (H316) and aspiration hazard Category 2 (H305) (see the definition of a hazard not otherwise classified, §1910.1200(c)). Statements such as H303, H316, and H305 aren't OSHA requirements and don't make a product a hazardous chemical. For Category 5, OSHA has said it doesn't preclude the information on a label or SDS, for example on one label used for both workplace and consumer sale (77 FR 17715). Our H-code reference flags the Category 5 codes.

Here is how the flammability elements line up for a flammable liquid in Category 2, such as acetone, using the statements Appendix C.4.19 assigns:

This table shows a subset. The condition that brings in P233 and P403+P235 for a volatile liquid also brings in grounding and bonding, explosion-proof equipment, and static-discharge precautions; non-sparking tools apply only when the minimum ignition energy is very low. The product's other hazards, such as eye irritation, add their own elements. The shipped label carries the full set that applies; a workplace label inside your facility can be simpler, as long as it carries the product identifier and at least general information about the hazards, with the rest available through the SDS and training (§1910.1200(f)(6)(ii)). The labeling guide covers when that's enough.

The H-code and P-code references cover the statements for the hazard classes our engine classifies (H224 to H413), each with its class, category, and the precautionary statements that go with it. If you write sheets yourself, the SDS creation guide covers the classification that decides which statements apply, and SDS HQ's authoring assigns them from the classification it computes, so Section 2 and the classification can't drift apart.