Resins · CAS Database
Toluene-2,4-diisocyanate
Toluene-2,4-diisocyanate (CAS 584-84-9) — TDI isomer for foams. Get the SDS and OSHA HazCom guidance you need to store, label, and handle it safely on the job site.
Verified vs OSHA sources · October 5, 2026
CAS Registry Number CAS 584-84-9 · also known as 2,4-TDI
Overview
TDI isomer for foams
Toluene-2,4-diisocyanate on the job site
Toluene diisocyanate is used in urethane coatings, elastomers, and some foams, and it carries the same defining hazard as MDI — respiratory sensitization that can permanently end a worker's ability to be around it — with one difference that matters on site: TDI is more volatile than MDI, so it puts more vapor into the air at room temperature even without spraying.
That higher vapor pressure means the 0.02 ppm ceiling is easier to exceed, and it makes ventilation and respiratory protection central even for brush and roller work, with supplied-air respirators for spraying. Skin and eye protection (nitrile or butyl gloves, sealed goggles, coveralls) is required because TDI sensitizes through the skin as well. Keep uninvolved workers out of the area and follow the product's cure/re-entry guidance.
Key takeaways
- Like MDI, TDI is a potent respiratory sensitizer — sensitization can be career-ending.
- TDI is more volatile than MDI, so the 0.02 ppm ceiling is exceeded more easily — ventilate even for brush/roller work.
- Spraying needs supplied-air respiratory protection; protect skin/eyes and keep others out of the area.
Field guidance for planning and training — not a substitute for the manufacturer Safety Data Sheet, which controls the exposure limit, PPE, and handling for your specific product.
OSHA Exposure Limits
OSHA permissible exposure limit (PEL) and secondary limit for Toluene-2,4-diisocyanate on a US construction site. Where a substance-specific 1926 standard applies, its codified limit is shown; otherwise the figure comes from Table 1 to 29 CFR 1926.55, the construction air-contaminants table. Where 1926.55 does not list the substance, the Safety Data Sheet (Section 8) controls.
| Limit | Value | Basis / citation |
|---|---|---|
| OSHA PEL (ceiling) | (C) 0.02 ppm | 29 CFR 1910.1000 Table Z-1 |
| Action level | See SDS / standard | Not all substances define an action level |
| Averaging period | ceiling | A ceiling is never averaged: it must not be exceeded at any moment of the shift. Compare with ACGIH TLV / NIOSH REL — often more protective than the OSHA PEL |
This limit is a ceiling. Exposure must at no time exceed it. Where instantaneous monitoring is not feasible, 29 CFR 1926.55(a)(1) lets the employer assess the ceiling as a 15-minute time-weighted average — one that still may not be exceeded at any time during the working day.
This is the general-industry figure. Construction air contaminants are listed separately in Table 1 to 29 CFR 1926.55, and on 33 substances the two differ — sometimes by a wide margin. Where they differ, the construction value governs work on a jobsite.
Many OSHA PELs date to 1971 and may be less protective than current ACGIH/NIOSH values; always check the manufacturer SDS (Section 8) for the controlling limit and engineering-control guidance. Not legal advice.
GHS Classification
Physical Properties
Where Toluene-2,4-diisocyanate shows up on the job
Trades that commonly handle Toluene-2,4-diisocyanate, each with an OSHA HazCom guide built for the chemicals and tasks on that kind of site:
OSHA & HazCom Compliance Requirements
For construction work, Hazard Communication is governed by 29 CFR 1926.59 (adopts 29 CFR 1910.1200). Employers who use Toluene-2,4-diisocyanate must:
- •Maintain an accessible SDS for Toluene-2,4-diisocyanate (readily accessible during each work shift, 29 CFR 1910.1200(g)(8))
- •Label all containers with GHS-compliant labels (29 CFR 1910.1200(f)(1) shipped / 29 CFR 1910.1200(f)(6) workplace)
- •Include it in the workplace chemical inventory
- •Train employees on hazards before initial assignment
- •Retain employee exposure and medical records per 29 CFR 1910.1020 — 30-year retention applies to exposure/medical records, not to SDSs generically
HazCom (1910.1200 / construction 1926.59) covers labels, SDSs, and training only — it does not impose chemical storage segregation. Flammable & combustible liquid storage for construction is 29 CFR 1926.152; segregation of incompatibles is planned from SDS Sections 7 and 10. Not legal advice; state-plan states may have stricter rules.
Handling & Secondary-Container Labeling
When you transfer Toluene-2,4-diisocyanate into a workplace (secondary) container, OSHA gives two compliant options under 29 CFR 1910.1200(f)(6):
- •(f)(6)(i): full GHS label elements (as on the shipped container)
- •(f)(6)(ii): product identifier + words/pictures/symbols (or combination) that provide AT LEAST general information on the hazards
There is no volume/size cutoff for secondary containers — the ≤100 ml / ≤3 ml accommodations (29 CFR 1910.1200(f)(12) (added by the HCS 2024 final rule)) apply only to the manufacturer's shipped container. A portable container filled for the immediate use of the worker who fills it needs no label (29 CFR 1910.1200(f)(8)).
GHS Hazard Classification under OSHA HCS
OSHA's Hazard Communication Standard adopts the GHS (primarily GHS Revision 7 (HCS 2024)). It requires 8 hazard pictograms (Appendix C, Figure C.1). The Environment pictogram (GHS09) is not required by OSHA — Not in App C; outside OSHA jurisdiction; voluntary.
The 8 OSHA-required pictograms:
For flammable liquids, OSHA classifies by flash point and boiling point (App B.6.1 / 1910.106(a)):
- •Category 1: FP < 73.4°F AND BP <= 95°F
- •Category 2: FP < 73.4°F AND BP > 95°F
- •Category 3: FP >= 73.4°F AND <= 140°F
- •Category 4: FP > 140°F AND <= 199.4°F
The specific GHS classification of Toluene-2,4-diisocyanate comes from its Safety Data Sheet (Section 2). Use the live classification panel above and the manufacturer SDS to confirm pictograms and categories.
HCS 2024 Update Deadlines
Under the Hazard Communication Standard 2024 update (aligned primarily GHS Revision 7):
- •May 19, 2026 — manufacturers, importers, and distributors update substance labels & SDSs (1910.1200(j)(2)(i))
- •November 20, 2026 — employers update workplace labeling, the written program & training (1910.1200(j)(2)(ii))
During the interim, parts may comply with the 2012 HCS, the 2024 HCS, or both.
Quick Actions
Put Toluene-2,4-diisocyanate on your written inventory, print the workplace label your containers need, and keep your supplier’s sheet reachable on the jobsite.
The safety data sheet for your product comes from the supplier who sold it to you — no public registry can provide it. For the underlying chemistry, the public record is on PubChem.
Where this fits in your HazCom program
- SDS management — collecting the sheet, keeping it current, and making it readable during each work shift.
- GHS labels & workplace labeling — what has to appear on the shipped container, and what a secondary container needs instead.
Free Compliance Tools for Toluene-2,4-diisocyanate
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Frequently Asked Questions
What is Toluene-2,4-diisocyanate (CAS 584-84-9)?
TDI isomer for foams
What are the OSHA HazCom requirements for Toluene-2,4-diisocyanate on a construction site?
For construction work, Hazard Communication is governed by 29 CFR 1926.59 (adopts 29 CFR 1910.1200). Employers who use Toluene-2,4-diisocyanate must maintain an accessible Safety Data Sheet (SDS), label containers with GHS-compliant labels, include the chemical in the workplace chemical inventory, and train workers on its hazards before initial assignment.
What is the OSHA permissible exposure limit (PEL) for Toluene-2,4-diisocyanate?
OSHA's permissible exposure limit for Toluene-2,4-diisocyanate is (C) 0.02 ppm (ceiling), per 29 CFR 1910.1000 Table Z-1. That figure is the GENERAL-INDUSTRY limit; construction air contaminants are listed separately at 29 CFR 1926.55 Table 1, and where the two differ the construction value governs work on a jobsite. TDI. Where the ACGIH TLV or NIOSH REL is more protective, follow the lower value, and confirm the limit for your specific task against Section 8 of the manufacturer Safety Data Sheet.
When does the updated HCS 2024 labeling apply to Toluene-2,4-diisocyanate?
Under the Hazard Communication Standard 2024 update (aligned primarily GHS Revision 7), chemical manufacturers, importers, and distributors must update substance labels and SDSs by May 19, 2026, and employers must update workplace labeling, the written program, and training for substances by November 20, 2026. During the interim, parties may comply with the 2012 HCS, the 2024 HCS, or both.
How do I label a secondary (workplace) container of Toluene-2,4-diisocyanate?
Under 29 CFR 1910.1200(f)(6) you have two options: (i) the full GHS label elements as on the shipped container, or (ii) the product identifier plus words, pictures, symbols, or a combination that provide at least general hazard information. There is no volume/size cutoff for secondary containers. A portable container filled for the immediate use of the worker who fills it does not require a label (29 CFR 1910.1200(f)(8)).
How long must SDS and exposure records for Toluene-2,4-diisocyanate be kept?
Under 29 CFR 1910.1020, 30-year retention applies to employee exposure and medical records (medical records: duration of employment plus 30 years) — not to SDSs generically. Where an SDS is not retained, a record of the chemical's identity, where it was used, and when must be kept for at least 30 years.
Where can I find the SDS for Toluene-2,4-diisocyanate?
Under 29 CFR 1910.1200(g)(6) and (g)(7), the manufacturer, importer or distributor that sold you Toluene-2,4-diisocyanate must send its Safety Data Sheet with the first shipment, and again with the first shipment after the sheet is updated. HazComFast keeps the sheets you collect in one inventory per jobsite, searchable by product, manufacturer or CAS number, and your jobsite's SDS load onto the phone on their own.
Sources & Primary References
Regulatory data on this page is sourced from HazComFast's verified regulatory module (29 CFR 1926.59 / 1910.1200 and substance-specific 1926 standards), last verified October 5, 2026 against eCFR, OSHA.gov, and the Federal Register. Physical-property data comes from PubChem. Confirm it against the manufacturer Safety Data Sheet. This page is informational and is not legal advice.
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