Frostbite

The hazards considered in this chapter are those associated with the exposure of humans to the cryogenic fluids and their vapors. Such exposure may result in the freezing of tissue and in various respiratory and other ailments. These are discussed here under three categories— frostbite, respiratory ailments, and miscellaneous effects. 

In general, frostbite occurs only after prolonged exposure of tissue to temperatures below 0°C. Because blood delivers heat to the affected part, the amount of heat actually removed from the tissue and the rate at which it is removed determine the extent of frostbite when it occurs. Both factors depend on the contact time and on the heat flux to the low-temperature vapor, fluid, or solid. As the body normally 

The internal organs are cooled by the blood from the outer parts of the body. However, a dangerous condition may result if the heart and brain are cooled to any great extent. For example, cardiac disturbances may occur when the rectal temperature drops to about IVC (80 F) death may result at lower temperatures.  

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Health and Safety Factors. VDE is a flammable gas its combustion products are toxic. Liquid VDE on contact with the skin can cause frostbite. Acute inhalation toxicity of VDE is low median lethal concentrations (LC q) for rats were 128,000 ppm after a single 4-h exposure (52) and 800,000 ppm after a 30-min exposure (53). Cumulative toxicity is low exposure of rats and mice at levels of up to 50,000 ppm for 90 days did not cause any... 

Inositols, ie, hexaliydrobenzenehexols, are sugars that have received increasing study and are useful in the treatment of a wide variety of human disorders, including vascular disease, cancer, cirrhosis of the Hver, frostbite, and muscular dystrophy (269). Myoinositol esters prepared by reaction with lower fatty acid anhydrides are useful as Hver medicines and nonionic surfactants the aluminum and ammonium salts of inositol hexasulfate are useful anticancer agents (270). Tetraarjloxybenzoquinones are intermediates in the preparation of dioxazine dyes (266,271). The synthesis of hexakis(aryloxy)benzenes has also beenpubUshed (272). 

Absorption of heat (auto-refrigeration) and eonsequent temperature reduetion on flashing may have a serious effeet on assoeiated heat transfer media, upon the strength of materials of eonstruetion, and result in frosting at the point of leakage. Exposure of personnel eandes a risk of frostbite. 

On contact with the skin, liquid ammonia produces severe burns compounded by frostbite due to the freezing effect from rapid evaporation from the skin. 

Health Hazards Information - Recommended Personal Protective Equipment Individual breathing devices with air supply neoprene gloves protective clothing eye protection Symptoms Following Exposure Inhalation of concentrated gas will cause suffocation. Contact will liquid can damage eyes because of low temperature. Frostbite may result from contact with liquid General Treatment for Exposure INHALATION remove to fresh air use artificial respiration if necessary. EYES get medical attention promptly if liquid has entered eyes. SKIN soak in lukewarm water (for frostbite) Toxicity by Inhalation (Threshold Limit Value) Data not available Short-Term Exposure Limits Data not available Toxicity by Ingestion Not pertinent (boils at -24.7°C) Late Toxicity Data not available Vtqtor (Gas) Irritant Characteristics Data not available Liquid or Solid Irritant Characteristics Data not available Odor Threshold Data not available. 

Health Hazards Information - Recommended Persoruil Protective Equipment Self-contained breathing apparatus for high vapor concentrations Symptoms Following Exposure In high vapor concentrations, can act as simple asphyxiant. Liquid causes severe frostbite General Treatment for Exposure Remove from Exposure, support respiration Toxicity by Inhalation (Threshold Umit Value) Not pertinent Short-Term Exposure Limits Not pertinent Toxicity by Ingestion Not pertinent Late Toxicity None Vapor (Gas) Irritant Characteristics Vapors are nonirritating to the eyes and throat Uquid or Solid Irritant Characteristics Not pertinent appreciable hazard. Practically harmless to the skin because is very volatile and evaporates quickly Odor Threshold 899 ppm. 

Limits Data not available Toxicity by Ingestion Not pertinent Late Toxicity None Vcpor (Gas) Irritant Characteristics None Liquid or Solid Irritant Characteristics No appreciable hazard. Practically harmless to skin because it is very volatile and evaporates quickly. Some frostbite possible Odor Threshold Data not available. 

For outdoor work there may be a risk of frostbite in the wintertime. The report uses the wind chill temperature, WCI, calculated as... 

Low-boiling-point materials can cause frostbite on contact with living tissue. While this is an obvious hazard with cryogenics, e.g. liquid nitrogen or oxygen, cylinders of other liquefied gases also become extremely cold and covered in frost as the contents are discharged. 

Clinicians should instruct patients to use crushed ice or ice chips because the area will cool more evenly than with large pieces of ice. Patients should not apply ice directly to the affected area or leave it on for longer than the recommended 20 minutes because frostbite may occur.12 A thin sheet or napkin will protect the skin and also allow for better cold transfer than thicker material such as a towel. Alternatively, soaking the area for 20 minutes in a cool bath (55°F or 13°C) provides effective cooling. 

Eye Contact In case of contact, immediately flush eyes with plenty of water for at least 15 min. Call a physician. Skin Contact Flush area with lukewarm water. Do not use hot water. If frostbite has occurred, call a physician. Ingestion Ingestion is not considered a potential route of exposure. 

Elder flower ointment (Ungentum sambuci) was commonly used topically to treat human conditions such as hemorrhoids, chilblains (a milder version of frostbite) as well as treating horses wounded in battle. During World War I, Ungentum sambuci was... 

No studies were located regarding respiratory, cardiovascular, gastrointestinal, hematological, musculoskeletal, hepatic, renal, dermal, or ocular effects in humans or animals after dermal exposure to hydrogen sulfide. However, several sources indicate that care must be taken with liquefied hydrogen sulfide in order to avoid frostbite (ATSDR 1994 NIOSH 1997). 

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