IODINE

Iodine
CAS 7553-56-2

I₂

Blue-violet to black crystalline solid
bp 185 °C, mp 114 °C
Slightly soluble in water (0.03 g/100 mL at 20 °C)

Sharp, characteristic odor

8.8 (air = 1.0)

0.3 mmHg at 20 °C

Noncombustible

LD₅₀ oral (rat) 14,000 mg/kg

LC_LO inhal (rat) 80 ppm (800 mg/m³; 1 h)

PEL (OSHA) 0.1 ppm (ceiling, 1 mg/m³)

TLV-TWA (ACGIH) 0.1 ppm (ceiling, 1 mg/m³)

Iodine vapor is highly toxic and is a severe irritant to the eyes and respiratory tract.

The acute toxicity of iodine by inhalation is high. Exposure may cause severe breathing difficulties, which may be delayed in onset; headache, tightness of the chest, and congestion of the lungs may also result. In an experimental investigation, four human subjects tolerated 0.57 ppm iodine vapor for 5 min without eye irritation, but all experienced eye irritation in 2 min at 1.63 ppm. Iodine in crystalline form or in concentrated solutions is a severe skin irritant; it is not easily removed from the skin, and the lesions resemble thermal burns. Iodine is more toxic by the oral route in humans than in experimental animals; ingestion of 2 to 3 g of the solid may be fatal in humans.

Iodine has not been found to be carcinogenic or to show reproductive or developmental toxicity in humans. Chronic absorption of iodine may cause insomnia, inflammation of the eyes and nose, bronchitis, tremor, rapid heartbeat, diarrhea, and weight loss.

Iodine is noncombustible and in itself represents a negligible fire hazard when exposed to heat or flame. However, when heated, it will increase the burning rate of combustible materials.

Iodine is stable under normal temperatures and pressures.

Iodine may react violently with acetylene, ammonia, acetaldehyde, formaldehyde, acrylonitrile, powdered antimony, tetraamine copper(II) sulfate, and liquid chlorine. Iodine can form sensitive, explosive mixtures with potassium, sodium, and oxygen difluoride; ammonium hydroxide reacts with iodine to produce nitrogen triiodide, which detonates on drying.

Iodine should be handled in the laboratory using the "basic prudent practices" described in Chapter 5.C. In particular, safety goggles and rubber gloves should be worn when handling iodine, and operations involving large quantities should be conducted in a fume hood to prevent exposure to iodine vapor or dusts by inhalation.

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 iodine is ingested, obtain medical attention immediately. If large amounts of this compound are inhaled, move the person to fresh air and seek medical attention at once.

In the event of a spill, sweep up solid iodine, soak up liquid spills with absorbent material, place in an appropriate container, and dispose of properly. Respiratory protection may be necessary in the event of a large spill or release in a confined area.

Excess iodine and waste material containing this substance should be placed in an appropriate container, clearly labeled, and handled according to your institution's waste disposal guidelines.

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.