MERCURY

Mercury
(Quicksilver, hydrargyrum)
CAS 7439-97-6

Hg

Silvery, mobile liquid
bp 357 °C, mp -39 °C
Very slightly soluble in water (0.002 g/100 mL at 20 °C)

Odorless

6.9 (air = 1.0)

0.0012 mmHg at 20 °C

Noncombustible

LC_LO inhal (rabbit) 29 mg/m³(30 h)

PEL (OSHA) 0.1 mg/m³(ceiling)

TLV-TWA (ACGIH) 0.025 mg/m³--skin

Repeated or prolonged exposure to mercury vapor is highly toxic to the central nervous system.

The acute toxicity of mercury varies significantly with the route of exposure. Ingestion is largely without effects. Inhalation of high concentrations of mercury causes severe respiratory irritation, digestive disturbances, and marked kidney damage. There are no warning properties for exposure to mercury vapor, which is colorless, odorless, and tasteless.

Toxicity caused by repeated or prolonged exposure to mercury vapor or liquid is characterized by emotional disturbances, inflammation of the mouth and gums, general fatigue, memory loss, headaches, tremors, anorexia, and weight loss. Skin absorption of mercury and mercury vapor adds to the toxic effects of vapor inhalation. At low levels the onset of symptoms is insidious; fine tremors of the hand, eyelids, lips, and tongue are often the presenting complaints. Mercury has been reported to be capable of causing sensitization dermatitis. Mercury has not been shown to be a human carcinogen or reproductive toxin.

Mercury is not combustible.

Mercury is a fairly unreactive metal that is highly resistant to corrosion. It can dissolve a number of metals, such as silver, gold, and tin, forming amalgams. Mercury can react violently with acetylene and ammonia.

Mercury should be handled in the laboratory using the "basic prudent practices" described in Chapter 5.C. In particular, precautions should be taken to prevent spills of mercury because drops of the liquid metal can easily become lodged in floor cracks, behind cabinets, and equipment, etc., with the result that the mercury vapor concentration in the laboratory may then exceed the safe and allowable limits. Containers of mercury should be kept tightly sealed and stored in secondary containers (such as a plastic pan or tray) in a well-ventilated area. When breakage of instruments or apparatus containing significant quantities of Hg is possible, the equipment should be placed in a plastic tray or pan that is large enough to contain the mercury in the event of an accident. Transfers of mercury between containers should be carried out in a fume hood over a tray or pan to confine any spills.

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

In the event of a spill, collect the mercury using the procedures described in Chapter 5.C, place in an appropriate container, and dispose of properly. Respiratory protection will be necessary in the event of a large spill, release in a confined area, or spill under conditions of higher than normal temperatures.

Excess mercury should be collected for recycling, and waste material containing mercury 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.