CYANAMIDE

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: 420-04-2; Chemical Formula: H₂NC=N

Previously, OSHA had no limit for cyanamide. The ACGIH has a TLV-TWA of 2 mg/m³. The proposed PEL for cyanamide was 2 mg/m 3 as an 8-hour TWA; NIOSH (Ex. 8-47, Table N1) concurs that this limit is appropriate. An 8-hour PEL of 2 mg/m³ is established in the final rule. Undiluted cyanamide is a deliquescent, crystalline solid.

The average oral LD(50) for cyanamide in rats is 125 (85 to 180) mg/kg, and cyanamide has been observed to be very irritating and caustic to the skin (American Cyanamide Company Product Information Bulletin, as cited in ACGIH 1986/Ex. 1-3, p. 152). The dermal LD(50) in rabbits is 590 mg/kg (Dangerous Properties of Industrial Materials, 7th ed., Sax and Lewis 1989, p. 891). Irritation occurred in the form of primary skin irritation and, following instillation into the eye, slight irritation of the conjunctival sac (American Cyanamide Company Product Information Bulletin, as cited in ACGIH 1986/Ex. 1-3, p. 152).

When cyanamide is ingested or inhaled by a person who has also consumed an alcoholic beverage, the person experiences vasodilation of the face and neck, tachycardia, tachypnea, nausea, vomiting, and hypotension. This syndrome is referred to as the Antabuse effect. Studies of cyanamide’s Antabuse-like effects indicate that the effect is about one-half that of an equivalent dose of tetraethylthiuram disulfide (Antabuse) and one-sixth that of tetramethyl thiuram disulfide (Hald, Jacobsen, and Larsen 1952/Ex. 1-905).

OSHA received comments on cyanamide from the American Cyanamid Company (Exs. 8-76, 3-961, and 94). Linda Dulak, Toxicology Program Manager for American Cyanamid, argued that the final rule should not promulgate limits for substances for which there are no analytical methods (Ex. 3-961, p. 13). According to Dr. Dulak:

Without an analytical limit, the employer cannot determine whether employee exposures are being maintained below those limits…(Ex. 3-961, p. 13).

OSHA notes, however, that Dr. Dulak later stated (Tr. XI, p. 75) that American Cyanamid measures the airborne cyanamide level in their plants by sampling for calcium cyanamide. However, Dr. Dulak was unsure whether this method is applicable to hydrogen cyanamide. OSHA notes that a method for the sampling and analysis of cyanamide has been submitted to the docket.

According to Dr. Dulak (Ex. 3-961), OSHA also has not evaluated the technological and economic feasibility of the 2 mg/m³ limit for cyanamide. However, OSHA notes that American Cyanamid’s representatives testified at the hearing (Tr. XI, p. 76) that, although the company has no internal standard for cyanamide, it controls airborne cyanamide exposures by measuring and controlling airborne levels of calcium cyanamide. According to Dr. Dulak, her company has had “no problems” controlling cyanamide exposures (Tr. XI, p. 76).

Dr. Dulak’s third point is that there is no health basis for setting an inhalation limit for cyanamide (Ex. 3-961, p. 13). OSHA does not agree with this view and finds the evidence of cyanamide’s irritant properties sufficient to warrant the establishment of an 8-hour TWA limit. Sax and Lewis (Dangerous Properties of Industrial Materials, 7th ed., 1989, p. 981) note that this substance is a severe eye irritant, a moderately toxic substance by skin contact, and a poison by ingestion, inhalation, and intraperitoneal injection. The ACGIH (1986/Ex. 1-3, p. 152) set its limit, which is the same as the final rule’s PEL, on the basis of cyanamide’s relative potential to cause irritation when compared with other irritants (ACGIH 1986/Ex. 1-3, p. 152). Thus, OSHA finds the final rule’s PEL both appropriate and protective.

In the final rule, OSHA is establishing an 8-hour TWA limit of 2 mg/m³ TWA for cyanamide. The Agency concludes that this limit will protect against the significant risks of irritation and of the Antabuse syndrome in individuals who have ingested alcohol. The Agency has determined that this limit will substantially reduce these significant risks, which constitute material health impairments.