Chris, That's a good short list. But I'm such an idealist, I hope that on occasion a student asks: "If the TLVs are based only on health factors, what other factors are being used by OSHA to set PELs?"
And if those other factors are economic and feasibility factors, are US workers really told that, as a condition of employment, they can be exposed to levels determined by ACGIH, NIOSH and other agencies to be unhealthy? And is that hazard information provided in enough depth to enable workers to provide informed consent?
The same type of problem occurs in universities when faculty doesn't fully inform and train their students.
I recently visited a school that will remain nameless. The EH&S people are planning to finally start hazard communication training program in the art department after an incident--the usual reason they call me. The EH&S people, as usual, were not very familiar with conditions in art and suitably shocked when they saw them. But it was the comments of the art faculty that that email is about. They told the EH&S people that they must not train the students about the hazards or they might lose enrollment.
So in schools, I guess we can add "keeping your enrollment high so your job is secure" as yet another factor that should be considered in setting exposure levels and providing training.
In a message dated 12/4/2010 4:44:08 AM Eastern Standard Time, cekohler**At_Symbol_Here**INDIANA.EDU writes:
Here is a nice little summary I use in class. For worker safety it always better to use the lower thresholds but the OSHA thresholds are the legally enforceable ones.
OSHA (or state established) exposure limits are law:
PEL =3D Permissible Exposure Limits (29 CFR 1910.1000)
=E2=80=A2Based on health factors, economic and technical feasibility.
=E2=80=A2TWA =3D 8 hour time weighted average
=E2=80=A2STEL =3D 15 minute Short Term Exposure Limit
=E2=80=A2C =3D Ceiling Concentration must never be exceeded.
Other exposure limits are guidelines or BMPs:
NIOSH - National Institute for Occupational Safety and Health
=E2=80=A2Based on chemical, medical, biological, engineering, trade and other information.
=E2=80=A2REL =3D Recommended Exposure Limits (10 hr TWA, used for recommending new exposure limits to OSHA)
=E2=80=A2IDLH =3D Immediately Dangerous to Life and Health (based on 30 min. exposure but must exit)
ACGIH =3D American Conference of Governmental Industrial Hygienists
=E2=80=A2Based on health factors only.
=E2=80=A2TLV =3D Threshold Limit Value (8 hour TLV-TWA, TLV-STEL, TLV-C, they also establish =E2=80=9CExcursion Limits=E2=80=9D commonly used in emergency response activities =3D 3 to 5 x TLV for 30 min.)
=E2=80=A2BEI =3D Biological Exposure Indices (mg/l of body fluid to be used in biological monitoring)
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