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Chemical Sampling Information (CSI)
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General Description

Synonyms: Caustic soda; Sodium hydrate; Soda; Lye; Soda lye

OSHA IMIS Code Number: 2260

Chemical Abstracts Service (CAS) Registry Number: 1310-73-2

NIOSH Registry of Toxic Effects (RTECS) Identification Number: WB4900000

Department of Transportation Regulation Number (49 CFR 172.101) and 2012 Emergency Response Guidebook [4 MB PDF, 392 pages]: 1823 154 (dry, solid); 1824 154 (solution)

NIOSH Pocket Guide to Chemical Hazards - Sodium Hydroxide: Physical description, chemical properties, potentially hazardous incompatibilities, and more

Exposure Limits and Health Effects

Exposure Limit

Limit Values

HE Codes

Health Factors and Target Organs

OSHA Permissible Exposure Limit (PEL) - General Industry
See 29 CFR 1910.1000 Table Z-1

2 mg/m3 TWA

HE4

Ulceration of nasal passages

HE14

Eye, skin, and respiratory irritation

OSHA PEL - Construction Industry
See 29 CFR 1926.55 Appendix A

2 mg/m3 TWA

HE4

Ulceration of nasal passages

HE14

Eye, skin, and respiratory irritation

OSHA PEL - Shipyard Employment
See 29 CFR 1915.1000 Table Z-Shipyards

2 mg/m3 TWA

HE4

Ulceration of nasal passages

HE14

Eye, skin, and respiratory irritation

National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL)

2 mg/m3 Ceiling

HE4

Blindness; severe eye and skin burns

HE11

Pneumonitis

HE14

Severe eye, skin, and respiratory irritation

American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) (2001)

2 mg/m3 Ceiling

HE4

Ulceration of nasal passages; severe eye and skin injury

HE14

Severe eye, skin, and respiratory irritation

CAL/OSHA PEL

2 mg/m3 Ceiling

HE4

Ulceration of nasal passages; severe eye and skin injury

HE14

Severe eye, skin, and respiratory irritation

National Toxicology Program (NTP) carcinogenic classification: Not listed

International Agency for Research on Cancer (IARC) carcinogenic classification: Not listed

U.S. Environmental Protection Agency (EPA) carcinogenic classification: Not listed

EPA Inhalation Reference Concentration (RfC): Not established

Agency for Toxic Substances and Disease Registry (ATSDR) Inhalation Minimal Risk Level (MRL): Not established

NIOSH Immediately Dangerous to Life or Health (IDLH) concentration: 10 mg/m3

Notes on Other Potential Health Effects and Hazards

  1. When used as a solution in water, sodium hydroxide is a strong base and will react violently with acids (NIOSH/IPCS 2010).
  2. Sodium hydroxide is corrosive to metals and can react with them to form explosive hydrogen gas (NIOSH/IPCS 2010).
  3. Sodium hydroxide reacts with ammonium salts to form ammonia, which is a fire hazard (NIOSH/IPCS 2010).
  4. While sodium hydroxide has not been found to be carcinogenic in and of itself, an increased number of esophageal cancer cases have been documented as a result of a scarred esophagus after swallowing sodium hydroxide (NIOSH 1978).

Date Last Revised: 9/6/2012

Literature Basis

  • ACGIH: Documentation of the Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) - Sodium Hydroxide. 2001.
  • NIOSH: Occupational Health Guideline for Sodium Hydroxide. 1978.
  • NIOSH/IPCS: International Chemical Safety Cards - Sodium Hydroxide. 2010.
Monitoring Methods used by OSHA

Laboratory Sampling/Analytical Method:

  • sampling media: Mixed Cellulose Ester Filter (MCEF) 0.8 microns
    analytical solvent: Water extraction
    maximum volume: 960 Liters   
    maximum flow rate: 2.0 L/min (TWA)
    maximum volume: 30 Liters   
    minimum time: 15 Minutes  
    maximum flow rate: 2.0 L/min (Ceiling)
    current analytical method: Atomic Absorption Spectroscopy; AAS
    method reference: OSHA Analytical Method (OSHA ID-121)
    method classification: Fully Validated
    note: Submit as a separate sample. If the filter is not overloaded, samples may be collected up to an 8-hour period. When analysis of a compound is requested, an elemental analysis is performed and reported as the compound.

Wipe Sampling Method:

  • sampling media: Whatman smear tab
    analytical solvent: Deionized water

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