Cyanide exposure sources

Vitamin B12 is a chemical substance containing cyanide that is beneficial to your body because it prevents anemia (iron-poor blood). The cyanide is bound in Vitamin B12 so that it does not serve as a source of cyanide exposure and cannot harm you. You can find more information on the harmful effects of cyanide in Chapter 2. 

Cyanide in the body is biotransformed to thiocyanate quickly. People may also be exposed to thiocyanate from dietary, industrial, and medical sources. The plasma concentration of thiocyanate has also been used as an index of long-term exposure to cigarette smoke (Liu and Yun 1993). Some authors have determined thiocyanate in body fluids as a measure of cyanide exposure, while others measure cyanide concentrations in body fluids as a measure of cyanide exposure. 

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. 

Smoking cigarettes is probably one of the major sources of cyanide exposure for people who do not work in cyanide-related industries. 

Smoking cigarettes and breathing smoke filled air during fires are major sources of cyanide exposure. 

The greatest source of cyanide exposure to humans and range animals is cyanogenic food plants and forage crops, not mining operations. 

Cyanohydrins are highly toxic by inhalation or ingestion, and moderately toxic through skin absorption (21). AH a-hydroxy nitriles are potential sources of hydrogen cyanide or cyanides and must be handled with considerable caution. Contact with the skin and inhalation should be rigorously avoided. Special protective clothing should be worn and any exposure should be avoided (18,20). The area should be adequately ventilated. Immediate medical attention is essential in case of cyanohydrin poisoning. 

The Environmental Protection Agency (EPA) identifies the most serious hazardous waste sites in the nation. These sites make up the National Priorities List (NPL) and are the sites targeted for long-term federal cleanup. Cyanide has been found in at least 84 of the 1,430 current or former NPL sites. However, it s unknown how many NPL sites have been evaluated for this substance. As more sites are evaluated, the sites with cyanide may increase. This information is important because exposure to this substance may harm you and because these sites may be sources of exposure. 

Chronic-Duration Exposure and Cancer. Some reports of occupationally exposed workers indicated that low concentrations of hydrogen cyanide may have caused neurological, respiratory, and cardiovascular effects (Blanc et al. 1985 Chandra et al. 1980, 1988 El Ghawabi et al. 1975 Kumar et al. 1992). The route of exposure was predominantly inhalation, although dermal exposure can also occur in the work place. The studies, however, lacked either information about exposure levels or used small cohorts of workers. Studies in populations that used cassava roots as a main source of their diet described the neurological effects of cyanide consumption (Osuntokun 1972, 1980). However, these effects may be due to a recently identified substance, scopeletin, rather than due to cyanide (Obidoa and Obasi 1991). 

Reproductive Toxicity. No data were located regarding reproductive effects of cyanide in humans. One animal study reported increased resorptions in rats following oral exposure to a cassava diet (Singh 1981). Because some human populations use cassava roots as the main source of their diet, further... 

The primary route of exposure to thiocyanates for the general population appears to be from ingestion of foods in which thiocyanate occurs naturally (e.g., cabbage, kale, spinach, kohlrabi). Estimates of the thiocyanate concentration in the total diet of an adult in the United States were not located in the available literature however, these would be expected to be quite low. Exposure to cyanide also is a source of thiocyanate exposure because thiocyanate is a major metabolite of cyanide in the human body. 

A disadvantage to measuring toluene exposure by hippuric acid is the production of this metabolite from natural sources, and the determination of toluylmercapturic acid is now favored as a biomarker of toluene exposure.10 An interesting sidelight is that dietary habits can cause uncertainties in the measurement of xenobiotic metabolites. An example of this is the measurement of worker exposure to 3-chloropropene by the production of allylmercapturic acid.11 This metabolite is also produced by garlic, and garlic consumption by workers was found to be a confounding factor in the method. Thiocyanate monitored as evidence of exposure to cyanide is increased markedly by the consumption of cooked cassava. 

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