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Calcium hydroxide (Respirable Fraction)

General Description

  • Synonyms: Calcium hydrate; Caustic lime; Hydrated lime; Slaked lime
  • OSHA IMIS Code Number: C330
  • Chemical Abstracts Service (CAS) Registry Number: 1305-62-0
  • NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: EW2800000
  • NIOSH Pocket Guide to Chemical Hazards, Calcium hydroxide: chemical description, physical properties, potentially hazardous incompatibilities, and more

Exposure Limits

  • OSHA Permissible Exposure Limit (PEL):
  • American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): 5 mg/m3 TWA
  • National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL):5 mg/m3 TWA

Health Factors

  • Potential Symptoms: Irritation of eyes, skin, upper respiratory system; eye, skin burns; skin vesiculation; cough, bronchitis, pneumonitis
  • Health Effects: Irritation-Eye, Nose, Throat, Skin---Marked (HE14)
  • Affected Organs: Eyes, skin, respiratory system
  • Notes:
    1. Calcium hydroxide is affirmed by the FDA as a generally recognized as safe (GRAS) direct food substance (21 CFR 184.1205).
    2. Prolonged contact with wet cement, which is alkaline due to the reaction of water with calcium oxide to form calcium hydroxide, can result in full-thickness skin burns that may require surgical treatment.
  • Literature Basis:
    • NIOSH Pocket Guide to Chemical Hazards: Calcium hydroxide.
    • International Chemical Safety Cards (WHO/IPCS/ILO): Calcium hydroxide.
    • Pohanish, R.P. (editor): Calcium Hydroxide. In, Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens, Fourth Ed., Vol. 1. Norwich, NY: Noyes Publications, William Andrew Publishing, 2002, pp. 464-465.
    • Sherman S.C. and Larkin, K.: Cement burns. J. Emerg. Med. 29(1): 97-99, 2005.
    • Spoo, J. and Elsner, P.: Cement burns: a review 1960-2000. Contact Dermatitis 45(2): 68-71, 2001.
    • Winder, C. and Carmody, M.: The dermal toxicity of cement. Toxicol. Ind. Health 18(7): 321-331, 2002.
  • Date Last Revised: 06/04/2007

Monitoring Methods used by OSHA

Primary Laboratory Sampling/Analytical Method (SLC1):
  • Tared 37-mm diameter low-ash polyvinyl chloride filter preceded by 10 mm Nylon Cyclone
  • maximum volume: 816 Liters
  • minimum volume: 408 Liters
  • maximum flow rate: 1.7 L/min
  • current analytical method: Gravimetric
  • method reference: OSHA Analytical Method (OSHA PV2121)
  • method classification: Partially Validated
  • note: OSHA personnel can obtain tared sampling media from the Salt Lake Technical Center (SLTC).
  • note: If the net weight of the sample yields a concentration below the standard for the substance, the Salt Lake Technical Center (SLTC) will perform no further work on that sample. If the net weight corresponds to an amount greater than the standard, the sample may be analyzed for the appropriate element and the result reported as the substance.
  • current elemental analysis method: Atomic Absorption Spectroscopy; AAS
  • method reference: OSHA Analytical Method (OSHA ID-121)
  • method classification: Fully Validated
  • note: Submit as a separate sample. When analysis of a compound is requested, an elemental analysis is performed and reported as the compound. The analytical method does not distinguish between dust and fume.

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