It looks a little like overkill, doesn't it? Some of us used to play with it as kids. But Mercury (Hg) is not a good toy. Here's what JT Baker Chemical company says about it in their MSDS:
"DANGER! CORROSIVE. CAUSES BURNS TO SKIN, EYES, AND RESPIRATORY TRACT. MAY BE FATAL IF SWALLOWED OR INHALED. HARMFUL IF ABSORBED THROUGH SKIN. AFFECTS THE KIDNEYS AND CENTRAL NERVOUS SYSTEM. MAY CAUSE ALLERGIC SKIN REACTION."
What many don't understand is that Mercury is most dangerous in its gaseous state because concentrations of it can then be inhaled. Or as JT Baker's MSDS says:
"Mercury vapor is highly toxic via this route. Causes severe respiratory tract damage. Symptoms include sore throat, coughing, pain, tightness in chest, breathing difficulties, shortness of breath, headache, muscle weakness, anorexia, gastrointestinal disturbance, ringing in the ear, liver changes, fever, bronchitis and pneumonitis. Can be absorbed through inhalation with symptoms similar to ingestion."
But it is still a underappreciated danger.
As far back as 1926, Alfred Stock of the Kaiser-Wilhem Chemistry Institute wrote:
"The insidious horror of mercury is not nearly sufficiently well known and is being taken note of too little in those places where one is particularly threatened by it, in chemical and physical laboratories."
And this is still true today.
Many emergency responders understand the dangers of contact with liquid mercury, but do not yet understand that 1) mercury readily vaporizes, and that 2) it is a terrible danger in the gas state. Many teams do not have readily available vaporized mercury detectors.
Three companies that I know of make fine mercury vapor detectors: Arizona Instruments, Lumex of Ohio, and Ion Sciences.
An article from MedicalNewsToday back in 2004 reported:
"All mercury spills, regardless of quantity, should be treated seriously. Metallic mercury slowly evaporates when exposed to the air. The air in a room can reach contamination levels just from the mercury in a broken thermometer - just a few drops.
When liquid mercury is spilled, it forms droplets that can accumulate in the tiniest of spaces and then emit vapors. Health problems caused by mercury depend on how much has entered your body, how it entered your body, how long you have been exposed to it, and how your body responds to it."
Mercury may be the densest liquid known, but it still has a vapor pressure of .2729 mmHg, which is still sufficient for it to vaporize into the air to the level that it can harm you. Like all liquids with a vapor head, the quantity of gaesous fumes that enter the air is temperature dependent. So the hotter the day, the faster the gasification occurs.
More on this next week.