Carbon Tetrachloride (56-23-5)
Carbon Tetrachloride is a halogenated hydrocarbon with CAS Registry Number 56-23-5. Under the OSHA air contaminants standard (29 CFR 1910.1000), its Permissible Exposure Limit (PEL) — the legal 8-hour time-weighted average (TWA) for general industry — is 10 ppm. The principal target organs are the Liver; kidneys; CNS, and workplace air is sampled and analyzed by NIOSH 1003.
Exposure Limits at a Glance
| Limit | Value | Basis |
|---|---|---|
| OSHA PEL (8-hr TWA) | 10 ppm | 29 CFR 1910.1000 |
| NIOSH REL | See note below | NIOSH Pocket Guide |
| Hazard Class | Halogenated Hydrocarbon | Halogenated |
| Target Organs | Liver; kidneys; CNS | NIOSH / OSHA |
| Sampling Method | NIOSH 1003 | NIOSH Manual of Analytical Methods |
NIOSH REL note: NIOSH recommends the lowest feasible concentration (LOQ-based) for many chlorinated solvents. The REL is a non-regulatory recommendation; where a NIOSH REL exists it is typically more protective than the OSHA PEL.
How It Enters the Body & Health Effects
Exposure to Carbon Tetrachloride is assessed against the Liver; kidneys; CNS — the organ systems most consistently affected in occupational studies. Employers must ensure no employee’s 8-hour TWA exceeds the 10 ppm PEL, and must use engineering controls, work practices, and — where required — respiratory protection to keep exposures at or below that level.
- Hazard class: Halogenated Hydrocarbon. Halogenated-class agents are managed with the hierarchy of controls (elimination, substitution, engineering controls, administrative controls, then PPE).
- Monitoring: collect personal air samples in the breathing zone and submit them under NIOSH 1003 for laboratory analysis.
- Medical surveillance: consult the OSHA substance-specific standards and the NIOSH Pocket Guide when the target organs are the Liver; kidneys; CNS.
Sampling & Compliance Notes
- Determine whether the exposure is a full-period 8-hour TWA or a short-term / ceiling scenario. Ceiling and STEL excursions apply to several Halogenated-class agents regardless of the 8-hour average.
- Calibrate personal sampling pumps before and after each shift and record flow rates; method NIOSH 1003 specifies media, flow, and analysis.
- Compare analytical results to the OSHA PEL of 10 ppm and the NIOSH REL. Document the higher of the two for internal exposure-control targets.
- Where the PEL includes a “skin” notation, dermal absorption can contribute to the dose — glove selection and hygiene facilities are part of compliance.
Frequently Asked Questions
What is the OSHA PEL for Carbon Tetrachloride?
The OSHA Permissible Exposure Limit (8-hour TWA) for Carbon Tetrachloride is 10 ppm.
What is the CAS number for Carbon Tetrachloride?
The CAS Registry Number for Carbon Tetrachloride is 56-23-5.
What are the target organs for Carbon Tetrachloride?
The primary target organs are the Liver; kidneys; CNS.
How do you measure Carbon Tetrachloride in workplace air?
Use NIOSH analytical method NIOSH 1003 for air sampling and laboratory analysis.
What hazard class is Carbon Tetrachloride?
It is classified here as a Halogenated Hydrocarbon (Halogenated).