Biomedical Engineering Reference
In-Depth Information
of mortality data, and the lack of measured air concentration of
methanol (values calculated based on amount of methanol vaporized
and air volume) make it difficult to assess what might be the LC
50
in
the monkey.
Narcotic effects were reported in mice exposed to 30,800-
1,528,000 ppm methanol from 89 to 153 minutes. Overall 45% of
the mice died (Mashbitz et al., 1936). In another study, mice were in
a state of narcosis but survived 48,000 ppm methanol for 3.5-4 hours
daily for 6 days, but mice exposed to 54,000 ppm methanol died after a
cumulative 54 hours of exposure (Wesse, 1928). Rats became drowsy,
but survived when exposed to 49,700 ppm methanol for 1 hour
(Lehmann and Flury, 1943).
The RD
50
(the concentration necessary to decrease respiratory
frequency by 50%) is considered a measure of pulmonary and sensory
irritation. The RD
50
values of methanol in mice are reported to be
25,300 to 41,524 ppm indicating that methanol is not a potent pulmo-
nary or sensory irritant (Lington and Bevan, 1994).
In an inhalation study in rats to evaluate the effect of methanol on
serum hormones lutenizing hormone (LH), follicle stimulating hormone
(FSH), prolactin, and testosterone were measured in male rats exposed to
0, 200, 5000, or 10,000 ppmmethanol for 6 hours Some were scarified at
the end of the 6-hour exposure period and others at 24 hours after
exposure. In addition both acclimated and nonacclimated rats were
evaluated to access the effect of prior handling on the hormone levels.
FSH and testosterone were not affected in rats sacrificed immediately
after 6-hour exposure tomethanol. LHwas affected by prior handling and
methanol exposure at different time periods. At the 24-hour sacrifice, the
results showed a prior handling affected the LH response more than the
methanol exposure. No effects on tissue or body weight were noted.
Exposure to 5000 ppm methanol and higher resulted in changes in
testosterone, prolactin, and LH levels. The NOAEL was 200 ppm
(Cooper et al., 1992). This lack of effects on methanol on these pituitary
and testicular hormones support the TLVof 200 ppm in contrast to earlier
studies that report adverse effects on testosterone and gonadotropins at
200 ppm immediately after 6 hour exposure (return to normal by 18 hours
after exposure) (Cameron et al., 1984, 1985).
