Arsenic (Inorganic) (7440-38-2)
Arsenic (Inorganic) is a metal fume with CAS Registry Number 7440-38-2. 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 0.01 mg/m3. The principal target organs are the Skin; lungs; nervous system, and workplace air is sampled and analyzed by NIOSH 7300.
Exposure Limits at a Glance
| Limit | Value | Basis |
|---|---|---|
| OSHA PEL (8-hr TWA) | 0.01 mg/m3 | 29 CFR 1910.1000 |
| NIOSH REL | See note below | NIOSH Pocket Guide |
| Hazard Class | Metal Fume | Metal Fume |
| Target Organs | Skin; lungs; nervous system | NIOSH / OSHA |
| Sampling Method | NIOSH 7300 | NIOSH Manual of Analytical Methods |
NIOSH REL note: NIOSH RELs target the respirable fraction and apply to the specific metal species. 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 Arsenic (Inorganic) is assessed against the Skin; lungs; nervous system — the organ systems most consistently affected in occupational studies. Employers must ensure no employee’s 8-hour TWA exceeds the 0.01 mg/m3 PEL, and must use engineering controls, work practices, and — where required — respiratory protection to keep exposures at or below that level.
- Hazard class: Metal Fume. Metal Fume-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 7300 for laboratory analysis.
- Medical surveillance: consult the OSHA substance-specific standards and the NIOSH Pocket Guide when the target organs are the Skin; lungs; nervous system.
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 Metal Fume-class agents regardless of the 8-hour average.
- Calibrate personal sampling pumps before and after each shift and record flow rates; method NIOSH 7300 specifies media, flow, and analysis.
- Compare analytical results to the OSHA PEL of 0.01 mg/m3 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 Arsenic (Inorganic)?
The OSHA Permissible Exposure Limit (8-hour TWA) for Arsenic (Inorganic) is 0.01 mg/m3.
What is the CAS number for Arsenic (Inorganic)?
The CAS Registry Number for Arsenic (Inorganic) is 7440-38-2.
What are the target organs for Arsenic (Inorganic)?
The primary target organs are the Skin; lungs; nervous system.
How do you measure Arsenic (Inorganic) in workplace air?
Use NIOSH analytical method NIOSH 7300 for air sampling and laboratory analysis.
What hazard class is Arsenic (Inorganic)?
It is classified here as a Metal Fume (Metal Fume).