Skip directly to site content Skip directly to page options Skip directly to A-Z link


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)


Facebook
        Twitter
        LinkedIn
        Syndicate





METHYL IODIDE								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:** 74-88-4; **Chemical Formula:** CH3I
OSHA formerly had a limit of 5 ppm TWA, with a skin notation, for methyl iodide. The ACGIH has a TLV-TWA limit of 2 ppm, with a skin notation, for methyl iodide, and classifies it as a suspected human carcinogen (A2). NIOSH recommends reducing exposure to the lowest feasible limit, and also considers this chemical a carcinogen. The proposed PEL was an 8-hour TWA PEL of 2 ppm, with a skin notation; the final rule establishes these limits. Methyl iodide is a colorless, sweet-smelling liquid that turns yellow, red, or brown when exposed to light and moisture.
Methyl iodide has been reported to have an LD(50) in rats of 150 to 200 mg/kg; liver damage was evident after these lethal exposures (Kutob and Plaa 1962/Ex. 1-61). Fifteen-minute exposures to 3800 ppm were fatal in rats (Chambers et al. 1950, as cited in ACGIH 1986/Ex. 1-3, p. 399), and Bachem (1927/Ex. 1-1013) has reported that methyl iodide is six times as toxic in mice as methyl bromide. Inhalation studies have shown eye irritation and depressed body weight in rats as a result of 14-week exposures to 30 and 60 ppm (Blank, Nair, Roloff, and Ribelin 1984/Ex. 1-619). The same authors observed fatalities in rats within four weeks of exposure to 143 ppm; 10 ppm was reported to be a no-effect level.
In industry, fatalities have occurred from methyl iodide poisoning in chemical workers (Garland and Camps 1945/Ex. 1-1190; Appel, Galen, O’Brien, and Schoenfeldt 1975/Ex. 1-1076). However, the exposure levels associated with these fatal overexposures are not known (ACGIH 1986/Ex. 1-3, p. 399).
In tests of carcinogenicity, methyl iodide produced local sarcomas in rats injected subcutaneously and lung tumors in mice given intraperitoneal injections (Druckrey, Kruse, Preussman et al. 1970/Ex. 1-246; Poirier, Stoner, and Shimkin 1975/Ex. 1-686). These carcinogenic effects occurred at a dosage approximately equivalent to a daily 8-hour exposure to 20 or 25 ppm for an adult human (ACGIH 1986/Ex. 1-3, p. 399). OSHA received comments on methyl iodide’s health effects from the American Industrial Hygiene Association (AIHA) (Ex. 8-16; Tr. 3-309) and from NIOSH (Ex. 8-47, Table N6A). The AIHA stated that “[a] number of potentially carcinogenic substances for which PEL revisions are proposed appear to have been misclassified concerning their toxic effect” (Ex. 8-16, p. 6). The AIHA includes methyl iodide in this group of substances. As discussed in the introduction to Section VI.C, OSHA did not intend the proposal’s classifications to have regulatory implications; rather, both this classification and that of the final rule are intended only to reflect the health endpoint used by the ACGIH or NIOSH as the basis for selecting a particular PEL for a given substance, and to facilitate generic rulemaking. NIOSH (Ex. 8-47, Table N6A) agreed that the methyl iodide limit established by OSHA is appropriate, but pointed out that this substance could be classified as an occupational carcinogen.
In the final rule, OSHA establishes an 8-hour TWA limit of 2 ppm, with a skin notation, for methyl iodide. The Agency concludes that these limits will protect workers from the significant risk of irritation and liver and kidney damage, which are material impairments of health that are associated with exposure to methyl iodide in the workplace. The skin notation is needed to prevent dermal absorption of toxic amounts of methyl iodide.
										
							
								Page last reviewed:  September 28, 2011						Content source:  	National Institute for Occupational Safety and Health 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