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Unformatted text preview: ic form called “paraformaldehyde.” Paraformaldehyde decomposes into the monomer on heating. Inhalation of formaldehyde
vapors from formalin or paraformaldehyde can result in severe irritation of the upper
respiratory tract and lead to edema.
Do not breathe formaldehyde vapors; they are suspected to be carcinogenic and are
23 students short index 1/15/03 12:45 PM Page 24 a severe eye irritant, causing delayed effects that are not appreciably eased by eye
washing. Skin sensitization can result from repeated exposure to liquid solutions.
Because repeated exposure to formaldehyde solutions can lead to a formaldehyde
allergy, avoid skin contact with solutions by wearing neoprene, butyl rubber, or
polyvinyl chloride gloves. Note that these gloves can resist permeation of formaldehyde for only a limited time. Formaldehyde should be used and handled only in a
designated laboratory hood.
Cyanides and nitriles. Cyanides and nitriles are rapidly acting toxic substances.
Overexposures can be fatal. Symptoms of toxicity occur if these materials are swallowed, inhaled, or absorbed through the skin. A few inhalations of hydrogen cyanide
can cause mental deterioration; a few more can be fatal. Some metal cyanides are
hydrolyzed in aqueous solution and form hydrogen cyanide; all are converted to hydrogen cyanide in the presence of acid. Before you work with cyanides, make sure that
amyl nitrite pearls are on hand as a first aid antidote. Also be sure that your instructor
knows the name of a physician who can treat overexposures to cyanide and can
administer sodium nitrite and sodium thiosulfate solutions, as appropriate. Organic Peroxides and Peroxide Formers
Organic peroxides are a special class of compounds that pose unusual stability problems. These peroxides are among the most dangerous chemicals normally handled in
chemical laboratories and manufacturing. As a class, organic peroxides are lowpower explosives. They are hazardous because of their extreme sensitivity to shock,
sparks, heat, or other forms of accidental explosive initiation. Many peroxides that
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