Environmental Engineering Reference
In-Depth Information
100,000
LC
50
(rats) (46,000 mg/m
3
)
LC
50
(mice) (37,000 mg/m
3
)
10,000
NIOSH IDLH (1,800 mg/m
3
)
1,000
NOAEL (liver, kidney, blood)
(400 mg/m
3
)
OSHA PEL (360 mg/m
3
)
100
ACGIH TLV (70 mg/m
3
)
10
Cal EPA reference
exposure level
(3 mg/m
3
)
NIOSH ceiling
(3.6 mg/m
3
)
1
ACGIH TLV
American conference of governmental and industrial hygienists' threshold limit value
expressed as a time-weighted average; the concentration of a substance to which most
workers can be exposed without adverse effects.
Lethal concentration (50% mortality); a calculated concentration of a chemical in air to
which exposure for a specific length of time is expected to cause death in 50% of a defined
experimental animal population.
National Institute of Occupational Safety and Health's immediately-dangerous-to-life-or-health
limit; NIOSH recommended exposure limit to ensure that a worker can escape from an exposure
condition that is likely to cause death or immediate or delayed permanent adverse health
effects or prevent escape from a hazardous atmosphere.
NIOSH's recommended exposure limit ceiling; the concentration that should not be exceeded
at any time.
No observed adverse effect level.
LC
50
NIOSH IDLH
NIOSH
ceiling
NOAEL
OSHA PEL
Occupational safety and health administration's permissible exposure limit expressed as a
time-weighted average; the concentration of a substance to which most workers can be exposed
without adverse effect averaged over a normal 8-h workday or a 40-h workweek.
California Environmental Protection Agency; the reference exposure level is based on nasal
and eye irritation in healthy human volunteers where exposure averaging time is 1 h. The
chronic exposure REL is based on the liver, kidney, and hematological changes in rats and is
an 8-h exposure level. Both the acute and chronic RELs are 3 mg/m
3
.
Cal EPA
reference
exposure
level
FIGURE 6.1
Comparison of health guidance and regulatory levels of 1,4-dioxane in 1 m
3
of air at standard
temperature and pressure for inhalation of 1,4-dioxane. [After U.S. Environmental Protection Agency (USEPA),
2007 g, 1,4-Dioxane (1,4-diethyleneoxide) hazard summary. U.S. Environmental Protection Agency, Technology
Transfer Network, Ofi ce of Air and Radiation.
http://www.epa.gov/ttn/atw/hlthef/dioxane.html
(accessed
November 11, 2007)].
T
is the temperature (in Kelvin;
T
=
298.16 K [25°C]),
P
is the pressure (in atmospheres;
P
=
1 atm
=
101.325 kPa),
m
is the molecular weight (in g/mol),
R
=
8.205
×
10
−5
(m
3
atm)/(mol K), and
W
/
m
=
n
,
the number of moles.
For 1,4-dioxane at 25°C (molecular weight, 88.20), 1 μg/m
3
is equivalent to 0.278 ppb, and 1 ppb
is equivalent to 3.6 μg/m
3
.
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