Skip directly to site content Skip directly to search


Español  Other Languages


Centers for Disease Control and Prevention. CDC twenty four seven. Saving Lives, Protecting People
 Search
		×
			NIOSH
			NIOSH
				All CDC
				Submit
			For a full list of topics:A-Z Index
			Advanced Search
		Advanced Search


The National Institute for Occupational Safety and Health (NIOSH)








CALCIUM OXIDE										Related Pages
										*OSHA comments from the January 19, 1989 Final Rule on Air Contaminants Project extracted from 54FR2332 et. seq. This rule was remanded by the U.S. Circuit Court of Appeals and the limits are not currently in force.*
**CAS:** 1305-78-8; **Chemical Formula:** CaO
OSHA’s former 8-hour TWA permissible exposure limit for calcium oxide was 5 mg/m3, and the proposal contained a revised 8-hour TWA PEL of 2 mg/m3 for this substance. NIOSH (Ex. 8-47, Table N1) concurred with this proprosal. This revised limit was consistent with the ACGIH TLV for calcium oxide, which was set on the basis of analogy with sodium hydroxide, a widely recognized sensory irritant. The final rule retains OSHA’s former 5-mg/m3 8-hour TWA PEL for calcium oxide, for the reasons discussed below.
Calcium oxide (lime) is produced when limestone is calcined to drive off carbon dioxide. Calcium oxide is used as a refractory material; as a flux in steelmaking; as a binding agent in building, pulp and paper manufacture, sugar refining, and leather tanning; as the raw material for chlorinated lime bleaching powder, and as a soil treatment in agriculture (Encyclopedia of Occupational Health and Safety, Vol. 2, p. 1234, International Labour Office 1983).
The amount of information that has been published specifically about calcium oxide’s toxicological effects in animals or humans is limited, which accounts for the ACGIH’s reliance on the similarity in action between calcium oxide and sodium hydroxide in establishing a TLV of 2 mg/m3 for calcium oxide. The National Lime Association (NLA)(Ex. 3-890) and the American Iron and Steel Institute (Tr. p. 11-130 to 11-131; Ex. 188) objected to the comparison of calcium oxide’s properties with those of sodium hydroxide; according to the NLA, “no qualitative or quantitative analysis is offered [in the proposal] to support the use of this analogy.” OSHA’s analysis of this issue is discussed below.
In direct contact with tissues, calcium oxide can result in burns and severe irritation because of its high reactivity and alkalinity. The major complaints of workers exposed to lime consist of irritation of the skin and eyes, although inflammation of the respiratory passages, ulceration and perforation of the nasal septum, and even pneumonia have been attributed to inhalation of the dust (ACGIH 1986/Ex. 1-3, p. 92). The Pennsylvania Department of Health reported that strong nasal irritation occurred as a consequence of exposure to a mixture of calcium-oxide-containing dusts at a concentration of approximately 25 mg/m3, but that exposure to concentrations of 9 to 10 mg/m3 produced no observable irritation (Wands 1981a, in Patty’s Industrial Hygiene and Toxicology, 3rd rev. ed., Vol. 2B, p. 3054). By comparison, exposure to airborne sodium hydroxide at a concentration of between 0.005 and 0.7 mg/m3 produced burning/redness of the nose, throat, or eyes in workers engaged in cleaning operations (Hervin and Cohen 1973/Ex. 1-945, as cited in NIOSH 1976k/Ex. 1-965). Thus, the demonstrated effect level for sensory irritation caused by exposure to sodium hydroxide is below 1 mg/m3, while that for calcium oxide is above 9 mg/m3.
OSHA finds that analogy with sodium hydroxide is not an appropriate basis for establishing a PEL for calcium oxide, because there is nearly a tenfold difference in the no-effect levels for these two substances. Based on evidence that exposure to calcium oxide at levels above 9 mg/m3 may cause eye-tearing and mucous membrane irritation, OSHA concludes that the Agency’s former limit of 5 mg/m3 as an 8-hour TWA continues to be appropriate for this substance. The Agency concludes that this limit protects exposed workers from the significant risk of sensory irritation known to occur at concentrations somewhat above 9 to 10 mg/m3.
							
					
							Last Reviewed:  September 28, 2011						Source: 	National Institute for Occupational Safety and Health
					Facebook
        Twitter
        LinkedIn
        Syndicate NIOSH
1988 OSHA PEL Project Documentation
Index of Chemical Names
Index of CAS Numbers Follow NIOSH Facebook
Pinterest
Twitter
YouTube
 NIOSH Homepage NIOSH A-Z
Workplace Safety & Health Topics
Publications and Products
Programs
Contact NIOSH


About CDC
					Contact Us
					800-232-4636
 Facebook Twitter Instagram LinkedIn Youtube Pinterest Snapchat
 CONTACT CDC
				Contact Us
							Call 800-232-4636
							Email Us
			ABOUT CDC
				About CDC
							Jobs
							Funding
			POLICIES
				Accessibility
							External Links
							Privacy
							Policies
							No Fear Act
							FOIA
							OIG
							Nondiscrimination
							Vulnerability Disclosure Policy
			CONNECT WITH US
				Facebook
								Twitter
								Instagram
								LinkedIn
							Youtube
								Pinterest
								Snapchat
								Email
			LANGUAGES
				Español
							繁體中文
							Tiếng Việt
							한국어
							Tagalog
							Русский
							العربية
							Kreyòl Ayisyen
							Français
							Polski
							Português
							Italiano
							Deutsch
							日本語
							فارسی
							English


U.S. Department of Health & Human Services
			Accessibility
			External Links
			Privacy
			Policies
			No Fear Act
			FOIA
			Nondiscrimination
			OIG
			Vulnerability Disclosure Policy
			USA.gov


Exit Notification / Disclaimer Policy Close
 Links with this icon  indicate that you are leaving the CDC website. The Centers for Disease Control and Prevention (CDC) cannot attest to the accuracy of a non-federal website.
				Linking to a non-federal website does not constitute an endorsement by CDC or any of its employees of the sponsors or the information and products presented on the website.
				You will be subject to the destination website's privacy policy when you follow the link.
				CDC is not responsible for Section 508 compliance (accessibility) on other federal or private website. Website Disclaimers
 Cancel Continue