Cyanides exposure limits

Inhalation. The threshold limit value of HCN is 4.7 ppm. This is defined as the maximum average safe exposure limit for a 15-min period by the Occupational Safety and Health Administration. Exposure to 20 ppm of HCN in air causes slight warning symptoms after several hours 50 ppm causes disturbances within an hour 100 ppm is dangerous for exposures of 30 to 60 min and 300 ppm can be rapidly fatal unless prompt, effective first aid is adininistered. There is always a small concentration of cyanide (0.02 to 0.04 mg/L) in the blood, and the body has a mechanism for continuous removal of small amounts, such as from smoking, by converting it to thiocyanate, which is discharged in the urine. 

Process Applications TABLE 8.4.1 Exposure Limits for Hydrogen Cyanide 265... 

OSHA sets levels of cyanide that are allowable in workplace air. The permissible exposure limit (PEL) for cyanide salts is 5 milligrams of cyanide per cubic meter of air (mg/m3) averaged over an 8-hour workday and 40-hour workweek. NIOSH sets guidelines for chemicals in workplace air. Their recommended exposure limit (REL) for workers for 10 minutes is 5 mg/m3 for calcium cyanide, hydrogen cyanide, potassium cyanide, and sodium cyanide. 

Information regarding ocular effects in animals after inhalation exposure to cyanide is limited to a report of eye irritation in rats acutely exposed (7.5-120 minutes) to 250 ppm cyanogen (500 ppm cyanide) (McNemey and Schrenk 1960). 

Hematological Effects. Information regarding hematological effects in humans after oral exposure to cyanide is limited. No adverse hematologic effects were reported in a man who ingested 15 mg CNVkg as potassium cyanide (Liebowitz and Schwartz 1948). 

OSHA requires employers of workers who are occupationally exposed to cyanide to institute engineering controls and work practices to reduce and maintain employee exposure at or below permissible exposure limits (PEL). The employer must use engineering and work practice controls, if feasible, to reduce exposure to or below an 8-hour time-weighted average (TWA) of 5 mg/m3 as cyanide. Respirators must be provided and used during the time period necessary to install or implement feasible engineering and work practice controls (OSHA 1974). 

Although the 0SHA/NI0SH air sampling scheme has not been applied to acute hazards, it would be useful to illustrate the implications of doing so. Consider exposures to the acute toxin, hydrogen cyanide (HCN). Let us assume that the current exposure limit recommended by NIOSH of 5.0 mg/m3 (18) is used as the PEL and that the AL is one half of this value (2.5 mg/m3). The air concentration of HCN required to produce death in man in 10 min is V lOO mg/m3 (18 >19) or 20 times the PEL. 

Exposure limits The U.S. EPA has set a limit of 0.2 ppm for cyanide in drinking water. OSHA has set a limit of 10 ppm for hydrogen cyanide and most other cyanide salts in the workplace. ... 

National Institute of Occupational Safety and Health recommended exposure limit (cyanide) TWA CL 5mgm per lOmin. 

See also Cyanide Neurotoxicity Occupational Exposure Limits Respiratory Tract Sensory Organs. 

The Occupational Safety and Health Administration (OSHA) and (other reconunendations) the American Conference of Governmental Iiulustrial Hygienists (ACGIH) have set a permissible exposure limit of 5 milligrams of cyanide per cubic meter of air (S mg/m3) in the workplace during an 8-hour workday, 40-hour workweek. 

A. Exposure to hydrogen cyanide gas (HCN) even at low levels (150-200 ppm) can be fatal. The air level considered immediately dangerous to life or health (IDLH) is 50 ppm. The recommended workplace ceiling limit (ACGIH TLV-C) for HCN is 4.7 ppm (5 mg/m. The OSHA pennissible exposure limit (PEL) is 10 ppm. HCN is well absorbed across the skin. 

Cyanogen bromide is a volatile solid, which dissolves readily in water, diethyl ether, and alcohol. It is a highly toxic substance through inhalation, ingestion and skin contact. It is usitally considered about 2-3 times less toxic than hydrogen cyanide, but the exact lethal dose is imknown. In the developed coirrttries, the permissible workplace exposure limits in the air are 5 mg/m (as cyanide, time-averaged concentration in an 8-h shift), and 20 mg/m (as cyanide, peak concentration). 

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