Hydrogen chloride exposure

Bond GG, Flores GH, Stafford BA, et al Lung cancer and hydrogen chloride exposure results from a nested case control study of chemical workers. J Occup Med 33 958-961, 1991... 

Finally, the potential effects of hyperbaric atmospheres under the conditions found in a disabled submarine should be studied as they obtain in the case of hydrogen chloride exposures. 

Chemical vapor deposition (CVD) units normally operate as a closed system resulting in little or no chemical exposure to the operators. However, brief hydrogen chloride exposure above 5 ppm can occur when certain CVD prescmbbers are cleaned.F" ]... 

Most hafnium compounds requite no special safety precautions because hafnium is nontoxic under normal exposure. Acidic compounds such as hafnium tetrachloride hydroly2e easily to form strongly acidic solutions and to release hydrogen chloride fumes, and these compounds must be handled properly. Whereas laboratory tests in which soluble hafnium compounds were injected into animals did show toxicity, feeding test results indicated essentially no toxicity when hafnium compounds were taken orally (33,34). 

Hydrogen chloride in air can also be a phytotoxicant (88). Tomatoes, sugar beets, and fmit trees of the Pmnus family are sensitive to HCl in air. Exposure of concentrated hydrochloric acid to the skin can cause chemical bums or dermatitis. Whereas the irritation is noticed readily, the acid can be water flushed from the exposed area. Copious use of miming water is the only recommended safety procedure for any external exposure. Ingestion is seldom a problem because hydrochloric acid is a normal constituent of the stomach juices. If significant quantities are accidentally swallowed, it can be neutrali2ed by antacids. 

Health nd Safety Factors. Thionyl chloride is a reactive acid chloride which can cause severe bums to the skin and eyes and acute respiratory tract injury upon vapor inhalation. The hydrolysis products, ie, hydrogen chloride and sulfur dioxide, are beheved to be the primary irritants. Depending on the extent of inhalation exposure, symptoms can range from coughing to pulmonary edema (182). The LC q (rat, inhalation) is 500 ppm (1 h), the DOT label is Corrosive, Poison, and the OSHA PEL is 1 ppm (183). The safety aspects of lithium batteries (qv) containing thionyl chloride have been reviewed (184,185). 

Hydrogen chloride is produced when PVC bums. A series of tests for the Federal Aviation Administration studied this issue. In those studies, test animals were able to survive exposures to hydrogen chloride reaching 10,000 ppm (190). More recent studies indicate less of a potential for delayed effects on lung function than expected (191). In a typical fire, hydrogen chloride levels rarely exceed 300 ppm, a fact confirmed by the Boston Fire Department and Harvard University (192). In hundreds of autopsies conducted on fire victims in the United States, not one death has been linked to the presence of PVC. 

Chloroform slowly decomposes on prolonged exposure to sunlight in the presence or absence of air and in the dark in the presence of air. The products of oxidative breakdown include phosgene, hydrogen chloride, chlorine, carbon dioxide, and water. At 290°C, chloroform vapor is not attacked by oxygen. In contact with iron and water hydrogen peroxide is also produced, probably by the following reaction sequence (2) ... 

Acetic acid and 10, 15, or 20% acetyl chloride were fed as a mixture into a modified falling film micro reactor (also termed micro capillary reactor in [57]) at a massflow rate of 45 g min and a temperature of 180 or 190 °C [57]. Chlorine gas was fed at 5 or 6 bar in co-flow mode so that a residual content of only 0.1% resulted after reaction. The liquid product was separated from gaseous contents in a settler and collected. By exposure to water, acetyl chloride and acetic anhydride were converted to the acid. The hydrogen chloride released was removed. 

Figure 4.4 A series of STM images recorded during the exposure of a Cu(l 10) surface to hydrogen chloride at 295 K resulting in the formation of domains accompanied by step movement (1-8). With time this surface at 295K relaxes to give a well-ordered c(2 x 2)0 overlayer (9).

It explodes on exposure to mechanical or thermal shock. Care is necessary during preparation to eliminate hydrogen chloride from the precursory acid chloride, to prevent formation of hydrogen azide. 

A mixture of the three slowly reacted, creating a pressure of 122 bar ( of chlorine and possibly hydrogen chloride) in 41 days, and the residue reacted spontaneously on exposure to air. 

May cause severe and painful irritation of the eyes, nose, throat, and lungs. Severe exposure can cause accumulation of fluid in the lungs (pulmonary edema). Inhalation toxicity similar to hydrogen chloride and hydrogen fluoride. May cause second or third degree burns upon short contact with skin surfaces. Oral ingestion may result in tissue destruction of the gastrointestinal tract. Decreased blood cholinesterase levels have been reported in animals. 

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