The concentration in air to which it is believed that most workers can
be exposed daily without an
adverse effect (
i.e., effectively, the
threshold between safe and dangerous concentrations). The values
were established (and are revised annually) by the
ACGIH and are
time-weighted concentrations (
TWA) for a 7- or 8-h workday and
40-h workweek, and thus are related to chronic effects. A short-term
exposure limit (
STEL) is defined as a 15-min
TWA exposure, which
should not be exceeded at any time during a workday even if the 8-h
TWA is within the
TLV-
TWA.
Source:
PAC, 2001, 73, 993
(Risk assessment for occupational exposure to chemicals. A review of current methodology
(IUPAC Technical Report))
on page 1024