Ask A Scientist© Chemistry Archive

name        Rhea
status      educator
age         40s

Question -   I'm on the local school board here in Missouri and an
issue concerning mercury has been blown out of proportion by the DNR
having been told it was in our HS lab. Some students acquired it and took
it home-since has been located but now the teacher is in big trouble for
this happening. Which chemicals are not allowed in Mo. schools -I'm sure
all chemicals can be a safety hazard if not properly demonstrated in
experiments-but why is mercury disposed of when our scanned levels were
within the norm? If you could answer me by 6pm tomorrow I'd appreciate it!
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You raise several issues that are important.

1. Years ago it was thought that metallic mercury was harmless. Kids used to
spread it on dimes where it amalgamated to give a mirror-like shine. We had
similar disregard for many other substances found in high school and college
chemistry labs, where they accumulated, unattended and uninventoried for
years.

2. With regard to mercury specifically, we now know that mercury, like lead,
can have very subtle but serious toxicological effects. It is not a toy. It
is a hazardous chemical substance that should be handled only with proper
precautions. Once it "splatters" as it is prone to do because of its high
surface tension, it is extremely difficult to re-collect or de-toxlify.

3. The Federal government for setting exposure standards for chemical
substances, especially in the workplace. Various agencies have different
responsibilities.
NIOSH [National Institute of Occupational Safety and Health] is a division
of the Center for Disease Control and Prevention [CDC]. It is
a research agency responsible for conducting research and making
recommendations for the prevention of work-related illnesses and injuries.
One of its responsibilities is to investigate the acute toxicity chemicals
in the workplace and to sets concentrations they determine constitutes an
IDLH [Immediate Danger to Life and Health],
  OSHA, the Occupational Safety and Health Administration, is a division of
the Department of Labor. OSHA's function is to enforce the laws regarding
the safety of workers in the workplace. It also publishes several different
types of exposure limits: TWA, STEL, TLV, REL, PEL. This alphabet soup of
acronyms need not concern us here. They are different measures of the
toxicity of a material under different condtions, times of exposure, and
levels. They are complicated because that is how real world exposure occurs.
Interested readers can find more details at thewebsite:
http://www.epa.gov/swercepp/cameo/worklms.htm.

[2] A tabulation of IDHL concentrations of various chemical substances can
be found at the website: http://www.cdc.gov/niosh/idlh/idlh-1.html. and
http://www.cdc.gov/niosh/idlh/intridl4.html

These levels are really the alarm bell. In the judgment of NIOSH that
published level of the substance constitutes and Immediate Danger to Life
and Health.The maximum concentration of several metals are:       Hg
(mercury)   10mg/m^3
    Pb (lead dust)   200mg/m^3
    Cu (copper dust)   100mg/m^3
    Cr (metal dust)   250

Instead of pointing the finger at one another and seek BLAME. I would
suggest an approach that's had similar problems. O.K. there's lots of blame
to go around, when we stop finger pointing what will we have gained.

Set of a committee of two dependable students, and two Chemistry staff, or
at least one Chemistry and another Science Dept.

Conduct and inventory of what chemicals are present, where they are, and how
long have they been there.

Any chemical over two years old, or not dated, or not identified, or with no
staff member's name who ordered the chemical--all these go. You will
probablly need outside assistance to do this so that incompatible chemicals
aren't stored together. This should be a one-time expenditure.

Establish inventory rules: Do you need 1 Kg of XXXX, because its 10 cents
cheaper a pound and Oh! I forgot, we only need 10 gm.

Gaining control to access to and scrupulous record keeping can relolve the
problem.

Vince Calder
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