Table
A1. U.S. guidelines and limits for occupational exposure to
crystalline silica
|
Reference
|
Substance
|
Guideline
or limit (mg/m3)
|
NIOSH
[1974] |
Crystalline
silica:* quartz, cristobalite, and tridymite as respirable
dust |
REL
= 0.05 (for up to a 10-hr workday during a 40-hr workweek) |
OSHA
[29 CFR
1910.1000Table Z-3] |
Respirable
crystalline silica, quartz
Respirable crystalline silica, cristobalite
Respirable
crystalline silica, tridymite |
PEL
= 10 ÷ % quartz + 2 (8-hr TWA)
PEL = half of the value calculated from the formula for quartz
PEL = half of the value calculated from the formula for quartz |
MSHA
[30 CFR 56, 57, 70, 71] |
Respirable
quartz in underground and surface metal and nonmetal mines
Respirable crystalline silica present in concentrations >5% in
surface and underground coal mines |
PEL
= 10 ÷ % quartz + 2 (8-hr TWA)
RDS
= 10 ÷ % quartz (8-hr TWA) |
ACGIH
[2001] |
Respirable
crystalline silica, quartz
Respirable crystalline silica, cristobalite
Respirable crystalline silica, tridymite |
TLV = 0.05 (8-hr TWA)
TLV = 0.05 (8-hr TWA)
TLV = 0.05 (8-hr TWA) |
Adapted
from Hearl [1996].
* Identified by NIOSH as a potential occupational carcinogen
[54 Fed Reg. 2521 (1989)].
Abbreviations: REL = recommended exposure limit;
PEL = permissible exposure limit;
RDS = respirable dust standard; TLV = threshold limit value; TWA =
time-weighted average. |