CHLORINE

Chlorine
CAS 7782-50-5

Cl₂

Greenish colored gas or amber liquid
bp -34.1 °C, mp -101 °C
Slightly soluble in water (0.7 g/100 mL)

Highly pungent, bleach-like odor detectable at 0.02 to 3.4 ppm (mean = 0.08 ppm)

2.4 (air = 1.0)

4800 mmHg at 20 °C

LC₅₀ inhal (rat) 293 ppm (879 mg/m³;1 h)

PEL (OSHA) 1.0 ppm (3 mg/m³)

TLV-TWA (ACGIH) 0.5 ppm (1.5 mg/m³)

STEL (ACGIH) 1 ppm (2.9 mg/m³)

Highly irritating and corrosive to the eyes, skin, and respiratory tract; reacts violently with readily oxidized substances.

Chlorine is a severe irritant of the eyes, skin, and mucous membranes. Inhalation may cause coughing, choking, nausea, vomiting, headache, dizziness, difficulty breathing, and delayed pulmonary edema, which can be fatal. Exposure to ~500 ppm for 30 min may be fatal, and 1000 ppm can be lethal after a few breaths. Chlorine is highly irritating to the eyes and skin; exposure to 3 to 8 ppm causes stinging and burning of the eyes, and contact with liquid chlorine or high concentrations of the vapor can cause severe burns. Chlorine can be detected by its odor below the permissible limit; however, because of olfactory fatigue, odor may not always provide adequate warning of the presence of harmful concentrations of this substance.

Chronic exposures in animals up to 2.5 ppm for 2 years caused effects only in the upper respiratory tract, primarily the nose. Higher concentrations or repeated exposure has caused corrosion of the teeth. There is no evidence for carcinogenicity or reproductive or developmental toxicity of chlorine in humans.

Chlorine is noncombustible but is a strong oxidizer and will support combustion of most flammable substances.

Chlorine reacts violently or explosively with a wide range of substances, including hydrogen, acetylene, many hydrocarbons in the presence of light, ammonia, reactive metals, and metal hydrides and related compounds, including diborane, silane, and phosphine.

Chlorine should be handled in the laboratory using the "basic prudent practices" described in Chapter 5.C, supplemented by the procedures for work with compressed gases discussed in Chapter 5.H. All work with chlorine should be conducted in a fume hood to prevent exposure by inhalation, and splash goggles and impermeable gloves should be worn at all times to prevent eye and skin contact. Cylinders of chlorine should be stored in locations appropriate for compressed gas storage and separated from incompatible compounds such as hydrogen, acetylene, ammonia, and flammable materials.

In the event of skin contact, immediately wash with soap and water and remove contaminated clothing. In case of eye contact, promptly wash with copious amounts of water for 15 min (lifting upper and lower lids occasionally) and obtain medical attention. If chlorine is inhaled, move the person to fresh air and seek medical attention at once.

In case of accidental release of chlorine gas, such as from a leaking cylinder or associated apparatus, evacuate the area and eliminate the source of the leak if this can be done safely. Full-face supplied-air respiratory protection and protective clothing may be required to deal with a chlorine release. Cylinders with slow leaks should be carefully removed to a fume hood or remote outdoor locations. Chlorine leaks may be detected by passing a rag dampened with aqueous ammonia over the suspected valve or fitting. White fumes indicate escaping chlorine gas.

Excess chlorine in cylinders should be returned to the manufacturer for disposal.

The information in this LCSS has been compiled by a committee of the National Research Council from literature sources and Material Safety Data Sheets and is believed to be accurate as of July 1994. This summary is intended for use by trained laboratory personnel in conjunction with the NRC report Prudent Practices in the Laboratory: Handling and Disposal of Chemicals. This LCSS presents a concise summary of safety information that should be adequate for most laboratory uses of the title substance, but in some cases it may be advisable to consult more comprehensive references. This information should not be used as a guide to the nonlaboratory use of this chemical.

Copyright 1995 National Academy of Sciences. All rights reserved.