OSHA Hazardous Chemicals List
Does OSHA have a list of hazardous chemicals?
OSHA has no single master list of "hazardous chemicals" under the Hazard Communication Standard. Chemical manufacturers and importers have to classify each chemical themselves. OSHA does publish several chemical lists, but each one is tied to a specific standard.
Hazard Communication Standard (29 CFR 1910.1200). The standard defines "hazardous chemical" by its properties, not by listing names: "any chemical which is classified as a physical hazard or a health hazard, a simple asphyxiant, combustible dust, or hazard not otherwise classified." Under paragraph (d)(1), "the chemical manufacturer or importer shall determine the hazard classes, and where appropriate, the category of each class that apply to the chemical being classified." The standard covers any chemical in the workplace that employees may be exposed to "under normal conditions of use or in a foreseeable emergency" ((b)(2)). (OSHA, 1910.1200)
Lists OSHA does publish:
- Air contaminant tables, 29 CFR 1910.1000 (Tables Z-1, Z-2, Z-3). These are substances that have legal exposure limits (PELs). For example, ethyl benzene (CAS 100-41-4) has a PEL of 100 ppm / 435 mg/m3 [1]. Some entries point to a separate standard for that one substance; the benzene entry says "see 1910.1028" [2].
- Process Safety Management, 29 CFR 1910.119, Appendix A, "List of Highly Hazardous Chemicals, Toxics and Reactives (Mandatory)." It lists toxic and reactive chemicals that "present a potential for a catastrophic event at or above the threshold quantity," each with a CAS number and a threshold in pounds. Examples are acetaldehyde at 2,500 lbs and acrolein at 150 lbs. (OSHA, 1910.119 App. A)
- OSHA Occupational Chemical Database. This is a reference resource, not a regulation. Each chemical's entry gives physical properties, OSHA sampling methods and exposure limits. The benzene entry, for example, shows an OSHA PEL-TWA of 1 ppm, a STEL of 5 ppm and NIOSH REL-TWA 0.1 ppm, and cross-references 29 CFR 1910.1028 [us_osha_chemical_exposure_data_hub:BENZENE].
In practice, being in a Z table or on the PSM list does not decide whether a chemical needs a label and safety data sheet under HazCom. That depends on the manufacturer's or importer's classification.
Approach: I searched OSHA's Table Z-1, the Annotated PEL Tables and the Occupational Chemical Database. I read the Hazard Communication Standard and PSM Appendix A on osha.gov, since those texts aren't in the datasets I can search.
Which chemicals does OSHA treat as carcinogens?
OSHA has no single list of carcinogens. It treats a chemical as a carcinogen in three ways: it names 13 in the "13 Carcinogens" standard (29 CFR 1910.1003); it lists about 30 general-industry standards on its carcinogens page, most for one substance; and under the Hazard Communication Standard, manufacturers and importers classify carcinogenicity themselves using the GHS criteria.
1. The "13 Carcinogens" standard, 29 CFR 1910.1003(a)(1) (osha.gov)
| Substance | CAS (as printed) | (a)(2) exemption for mixtures below |
|---|---|---|
| 4-Nitrobiphenyl | 92933 | 0.1% |
| Methyl chloromethyl ether | 107302 | 0.1% |
| bis-Chloromethyl ether | 542881 | 0.1% |
| beta-Naphthylamine | 91598 | 0.1% |
| Benzidine | 92875 | 0.1% |
| 4-Aminodiphenyl | 92671 | 0.1% |
| alpha-Naphthylamine | 134327 | 1.0% |
| 3,3'-Dichlorobenzidine (and its salts) | 91941 | 1.0% |
| Ethyleneimine | 151564 | 1.0% |
| beta-Propiolactone | 57578 | 1.0% |
| 2-Acetylaminofluorene | 53963 | 1.0% |
| 4-Dimethylaminoazobenzene | 60117 | 1.0% |
| N-Nitrosodimethylamine | 62759 | 1.0% |
The standard applies wherever these are "manufactured, processed, repackaged, released, handled, or stored." It does not apply to transshipment in sealed containers, except for the labeling requirements.
2. Other carcinogen standards on OSHA's carcinogens page (osha.gov/carcinogens/standards) In general industry (Part 1910), besides 1910.1003 and the separate sections 1910.1004 to 1910.1016 for each of the 13, OSHA lists:
- asbestos (1910.1001)
- vinyl chloride (1910.1017)
- inorganic arsenic (1910.1018)
- lead (1910.1025)
- chromium (VI) (1910.1026)
- cadmium (1910.1027)
- benzene (1910.1028)
- coke oven emissions (1910.1029)
- 1,2-dibromo-3-chloropropane (1910.1044)
- acrylonitrile (1910.1045)
- ethylene oxide (1910.1047)
- formaldehyde (1910.1048)
- methylenedianiline (1910.1050)
- 1,3-butadiene (1910.1051)
- methylene chloride (1910.1052)
- respirable crystalline silica (1910.1053)
- ionizing radiation (1910.1096)
The shipyard (Part 1915) and construction (Part 1926) lists are similar, and both add coal tar pitch volatiles (1915.1002, 1926.1102). The same page also points to OSHA's carcinogen policy in 29 CFR 1990.
3. The "OSHA-Ca" tag in OSHA's Occupational Chemical Database. 33 entries, covering 25 substances or groups, are tagged OSHA-Ca. They match the regulated substances above, for example:
- benzene [5]
- the asbestos entries, e.g. chrysotile [6]
- cadmium [7]
- ethylene oxide [8]
- formaldehyde [9]
- methylene chloride [10]
- coke oven emissions [11]
- vinyl chloride [12]
Most of the 13 have no numeric PEL; their PEL field reads only "Ca," e.g. bis(chloromethyl) ether [13].
The tag does not cover everything that has a carcinogen standard. These entries carry IARC, NIOSH-Ca and NTP tags but not OSHA-Ca:
Inorganic lead is listed as IARC-2A with no OSHA-Ca tag [17]. I found no benzidine entry in the database. Since the tag misses some regulated substances, don't use it alone as the list.
4. Hazard Communication (29 CFR 1910.1200, Appendix A, A.6). Here carcinogenicity is a hazard class with Categories 1A, 1B and 2, decided by the classifier from the evidence. A mixture is classified once a carcinogenic ingredient is at or above 0.1% (Category 1A/1B) or 1.0% (Category 2) (osha.gov). So for labels and safety data sheets, the chemicals OSHA treats as carcinogens go well beyond the substances that have their own standards.
Approach: I searched OSHA's Occupational Chemical Database and read 1910.1003, OSHA's carcinogen standards page and HazCom Appendix A on osha.gov. I couldn't open HazCom Appendix F (the carcinogenicity guidance), so it isn't covered here.
How is that different from a hazardous chemical under HazCom?
Every carcinogen is a hazardous chemical under HazCom, but most hazardous chemicals are not carcinogens. "Hazardous chemical" is the whole category: anything classified as a physical hazard, a health hazard, a simple asphyxiant, combustible dust or a hazard not otherwise classified. Carcinogenicity is one of the health hazard classes inside it. The two concepts also come from different places. The carcinogens OSHA names come from substance-specific standards in Subpart Z. HazCom status comes from the manufacturer's or importer's own classification.
1. Scope
- OSHA's HazCom inspection directive, CPL 02-02-079 (HCS 2024, effective 05/19/2026), gives the definition: "Hazardous chemical means any chemical that is classified as a physical hazard or a health hazard, a simple asphyxiant, combustible dust, or hazard not otherwise classified." [18]
- "Hazard class" is defined with "carcinogen" as one of the examples, next to flammable solid and oral acute toxicity [18].
- So a flammable solvent, a skin irritant or wood dust can be a hazardous chemical without being a carcinogen. The directive notes that sawmills are manufacturers because they turn timber into wood dust, "which is a hazardous chemical under the HCS" [19].
2. Who decides
- Hazardous chemical status: it comes from classification, meaning reviewing the hazard data and deciding "whether the chemical will be classified as hazardous according to the definition of hazardous chemical in the standard" [20]. OSHA has no list for it.
- Carcinogens: the classifier has less freedom here.
- A chemical "must be classified as a carcinogen if the chemical is regulated as a carcinogen by 29 CFR part 1910, Subpart Z" [21]. Those are the 13 Carcinogens and the single-substance standards from my last answer.
- For everything else, the manufacturer or importer either runs its own weight-of-evidence evaluation under Appendix A, chapter A.6, or relies on IARC or the NTP Report on Carcinogens [21].
- Approximate equivalents: Category 1A = IARC Group 1 / NTP "known"; Category 1B = IARC 2A / NTP "reasonably anticipated"; Category 2 = IARC 2B [22].
3. Extra HazCom duties that apply only to carcinogens
- IARC/NTP findings on the SDS: these must appear in SDS Section 11 whatever classification route was used [23].
- Section 11 must mention any chemical in the NTP Report on Carcinogens or in IARC Group 1, 2A or 2B. If it doesn't, OSHA may issue a citation [24].
- If the label and SDS Section 2 don't call the chemical a carcinogen but Section 11 shows a positive IARC/NTP finding, inspectors refer the classification to OSHA's Health Response Team for review [24].
- One positive study: if the evidence falls short of the A.6 criteria, any properly conducted study with statistically significant carcinogenic findings must still be noted on the SDS [23].
- Category 2 ingredients in mixtures:
| Concentration | Where it must be disclosed |
|---|---|
| 0.1% to 1% | SDS only |
| ≥ 1% | SDS and label |
- Mixture classification rules: the general order of precedence for classifying mixtures does not apply to carcinogenicity, which follows A.0.4.2 and A.6 instead [25].
Practical upshot: a chemical with a substance-specific OSHA carcinogen standard is a hazardous chemical and must carry carcinogen labeling and SDS information [24]. A chemical that is a hazardous chemical for any other reason needs a label, an SDS and worker training, but carcinogen statements only if the classification puts it in Category 1A, 1B or 2.
Approach: I used OSHA's HazCom inspection directive CPL 02-02-079 and the 1910.1200 text on osha.gov for the definitions. I couldn't open HazCom Appendix F itself, so the IARC/NTP equivalents above come from the directive's version of it.