Cyanide occupational exposure

Several studies of occupational exposures and one study with a human subject were located. In the occupational exposures (summarized in Table 5- 3), neurological symptoms consistent with cyanide intoxication were demonstrated, but the likelihood of concomitant exposure to other chemicals could not be ruled out. For example, cleaners and cutting oils, as well as sodium and copper cyanide, may be present in electroplating operations (ATSDR 1997). The experimental human study involved the exposure of a single subject and a dog to a high concentration for a short exposure period. 

The odor threshold, 0.58 ppm to 5.0 ppm (Amoore and Hautala 1983 Ruth 1986) is low compared with irritant or toxic concentrations. No acute exposures were located resulting in mild effects in humans. Three monitoring studies, involving no symptoms to mild symptoms during chronic occupational exposures of adult males, are relevant to development of AEGL-1 values. The symptoms and blood concentrations of cyanide in the monitoring study of Chandra et al. (1980) indicate that the workers may have been exposed at higher atmospheric concentrations than those reported. 

Several studies provided data on blood and urine concentrations of cyanide and thiocyanate following occupational exposures at low concentrations. These values are generally similar to those of smokers who have not been occupationally exposed to HCN. Whole-blood cyanide concentrations during... 

NIOSH (National Institute for Occupational Safety and Health). 1976. Criteria for a Recommended Standard. Occupational Exposure to Hydrogen Cyanide and Cyanide Salts (NaCN, KCN, and Ca(CN)2). PB 266 230, DHEW (NIOSH) Pub. No. 77-108, U.S. Department of Health, Education, and Welfare U.S. Government Printing Office, Washington, DC. 

Chronic dermal exposure of humans to cyanide can occur in occupational settings. However, the main route of exposure is considered to be inhalation and, therefore, the occupational exposure studies are discussed in Section 2.2.1. 

Reports of ingestion of cyanides by humans and reports of occupational exposure (see Section 2.5.1) indicate that cyanide is transformed into thiocyanate. A plasma half-life of 20 minutes to 1 hour has been estimated for cyanides in humans after nonlethal exposures (Hartung 1982). 

Following chronic occupational exposure to 0.19-0.75 ppm hydrogen cyanide, 24-hour urinary levels of thiocyanate were 6.23 (smokers) and 5.4 pg/mL (nonsmokers) in exposed workers as compared with 3.2 (smokers) and 2.15 pg/mL (nonsmokers) in the controls (Chandra et al. 1980). This study demonstrates that tobacco smoking contributes to higher thiocyanate levels excreted in the urine. No studies were located regarding excretion of cyanide in animals after inhalation exposure to cyanide. 

No acute-, intermediate-, or chronic-duration inhalation MRLs were derived for cyanide because of the limitations associated with the available studies. Many of the animal and human studies used lethality, or serious effects, such as coma, as the end point. Two epidemiological studies are available however, one study lacked good exposure data, and the other study involved occupational exposure in the electroplating industry where exposure to other chemicals may have occurred. 

Occupational exposures to cyanide occur primarily through inhalation and, less frequently, through dermal absorption. Estimates from the National Occupational Exposure Survey (NOES) conducted by the National Institute for Occupational Safety and Health (NIOSH) indicate that over 250,000 workers are... 

Levels of cyanide and its metabolite thiocyanate in blood serum and plasma, urine, and saliva have been used as indicators of cyanide exposure in humans, particularly in workers at risk of occupational exposures, in smokers or nonsmokers exposed to sidestream or environmental tobacco smoke, in populations exposed to high dietary levels of cyanide, and in other populations with potentially high exposures (see Section 5.6). The correlation between increased cyanide exposure and urinary thiocyanate levels was demonstrated in workers exposed to 6.4-10.3 ppm cyanide in air (El Ghawabi et al. 1975). In another study, blood cyanide concentrations were found to vary from 0.54 to 28.4 pg/100 mL in workers exposed to approximately 0.2-0.8 ppm cyanide in air, and from 0.0 to 14.0 pg/100 mL in control workers... 

Guidelines a. Air ACGIH Threshold Limit Values for Occupational Exposure (TLV-TWA) Cyanogen TLV - Ceiling Hydrogen cyanide, sodium cyanide, calcium cyanide, potassium cyanide, acetone cyanohydrin Cyanogen chloride 21 mg/m3 5 mg/m3 0.75 mg/m3 ACGIH 1996... 

Criteria for a Recommended Standard... Occupational Exposure to Hydrogen Cyanide and Cyanide Salts," USDHEW (NIOSH) Pub. 

United States Department of Labor (1978) Occupational exposure to acrylonitrile (vinyl cyanide). Proposed standard and notice of hearing. Fed. Regist., 43, 2586-2621... 

Occupational exposures to cyanide resulting from unsafe work practices and inadequate worker protection procedures typically involve longer term exposure to lower concentrations than those that are identified in association with industrial accidents. El Ghawabi et al. (1975) reported on the effects of hydrogen... 

NIOSH (1975). National Institute of Occupational Safety and Health. Criteria for a recommended standard occupational exposure to hydrogen cyanide salts (NaCN, KCN and Ca (CN2)). US Department of Health, Education, and Welfare Report No. NIOSH 77-108, pp. 1-204. 

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

The World War I chemical arsenal included cyanide. Other potential cyanide exposures in the twentieth century came from medicinal and industrial sources. Thiocyanate, a medicine in the early twentieth century prescribed for hypertension, caused severe psychosis (Barnett et al. 1951). Hamilton and Hardy (1974) reviewed two cases of chronic occupational exposure to cyanide that caused intellectual impairment in one case and nervousness in the other. 

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