OSHA chemical database search and exposure limits explained
Use the OSHA chemical database to find chemical identities, exposure limits and sampling references, then distinguish OSHA PELs from recommended limits.
The OSHA chemical database is the agency's public Occupational Chemical Database for chemical identification, physical properties, exposure limits and sampling information. Open the official database, then use its chemical-name index or Advanced Search to find a substance.
For an EHS manager or industrial hygienist, the main task is choosing the right record and reading its limits correctly. An OSHA permissible exposure limit (PEL), a NIOSH recommended exposure limit (REL) and an ACGIH threshold limit value (TLV) have different roles. They are not interchangeable workplace requirements. OSHA's annotated PEL tables explain these distinctions.
How to search the OSHA chemical database
Use the Chemical Name A-Z Index when you know the substance name. Select a letter, browse the listings and open the chemical's record. The index has multiple pages, so don't treat the first page as the full list.
For a more targeted lookup, open Advanced Search. The panel labelled “Search Occupational Chemical Database” provides fields for:
- Chemical name or a name fragment.
- CAS number, including a number fragment.
- Analyte Code, labelled “IMIS #”.
The form also offers filters for “Carcinogenic classifications” and “IDLH ppm”. Search results display chemical names, CAS numbers, analyte codes and synonyms. These controls help narrow the lookup, but don't assume every substance has every field populated. Search fields and result columns
Check the identity before copying a limit. Compare the name and CAS number with the substance you intend to assess. Then use synonyms as a further identity check. A familiar name alone is a poor basis for choosing between records.
For example, select A, then ACETONE in the A-Z index. The acetone record, reached through that index, identifies it as CAS 67-64-1. It lists dimethyl ketone and 2-propanone as synonyms. Compare these identifiers before using the record's exposure or sampling information.
What a chemical record contains
OSHA groups the database's content into four categories: chemical identification and physical properties, exposure limits, sampling information, and additional resources. It compiles this information from several agencies and organizations. Treat it as a reference, not an exhaustive list of all chemicals or regulated substances. Database overview
The acetone record shows how those categories work in practice:
| Record section | What to look for |
|---|---|
| Identification | Chemical name, CAS number, formula and synonyms |
| Physical properties | Fields such as boiling point, vapor pressure, flash point and specific gravity |
| Exposure limits | The source of each value, its units and averaging period |
| OSHA monitoring information | Analyte code and sampling-method references |
These are examples from the acetone record, not a promise that every substance has the same coverage. Open acetone through the chemical-name index to inspect the fields. If an abbreviation is unclear, consult OSHA's Label Abbreviations & Descriptions.
Blank fields are an unresolved lookup, not proof that a chemical has no hazard or applicable limit. Check the relevant standard and the organization responsible for the value before drawing that conclusion.
How to read the exposure-limit columns
Keep the source, units and averaging period attached to every exposure value you record. Copying only a number strips away the information needed to interpret it.
OSHA's annotated tables compare federal OSHA, Cal/OSHA, NIOSH and ACGIH values. Federal OSHA's mandatory PELs in the Z-Tables remain in effect. NIOSH RELs are recommendations from a federal agency. ACGIH describes its TLVs as health-based values, not legal standards. Cal/OSHA PELs are enforceable within that agency's jurisdiction, not everywhere.
Acetone makes the difference visible. The CDC/NIOSH Pocket Guide entry lists:
| Source and limit | Listed TWA value |
|---|---|
| OSHA PEL | 1,000 ppm (2,400 mg/m³) |
| NIOSH REL | 250 ppm (590 mg/m³) |
Both values belong to the same chemical. Their different numbers do not make them competing versions of one federal OSHA requirement. Retain each source label and check the applicable standard for the workplace decision.
OSHA also warns that many PELs are outdated and potentially insufficiently protective. Meeting a PEL is not proof that an exposure poses no health risk. Its annotated tables omit skin-absorption and sensitization notations, so consult the originating organizations for current values and explanations. OSHA's cautions about exposure limits
ACGIH references may appear without a numerical TLV. The acetone record, reached through the A-Z index, refers readers to ACGIH's site and annual publication for current information. Follow that reference if the numeric entries are blank. A blank cell does not mean “no limit”.
Use sampling references, not just the summary
Acetone's OSHA monitoring section lists analyte code 0040 and OSHA 5004 as a fully validated method. The record warns that sampling instructions are recommended guidelines for OSHA Compliance Safety and Health Officers and directs readers to the full method. Acetone via the A-Z index
Read that method before planning sampling. OSHA's Sampling and Analytical Methods hub provides a methods index, validation guidance and withdrawn methods. It directs users to substance records for current sampling media and flow rates. A short database entry is not a complete sampling protocol.
The database does not replace your chemical list or SDSs
The Hazard Communication Standard has separate chemical-list and SDS duties, subject to its scope and exceptions. Under paragraph (e)(1)(i), the written program must list hazardous chemicals using product identifiers referenced on the appropriate safety data sheets. Paragraphs (g)(1) and (g)(8) require an SDS for each hazardous chemical used and ready access during each work shift. Electronic access must create no barrier to immediate access. A public substance lookup cannot establish which products are present or replace these duties.
For a question-led explanation, read RegAffairs AI's answer on using the OSHA chemical database. Keep the official record's update date with your lookup notes, but don't assume every field was revised on that date. OSHA database