Biomedical Engineering Reference
In-Depth Information
changes that may or may not have been treatment related were noted
(body weight gain, liver, and spleen weights changes in rats exposed to
1000 ppm methanol). One rat died during the study and one was
scarified (level not indicated). The NOEAL appeared to be 100 ppm
with small body decrease rate of weight gain and possible organ weight
treatment-related effects seen at the LOAEL of 1000 ppm.
Methanol effects testicular production of testosterone and testes
morphology was also studied in folate-deficient rats exposed to
800 ppm methanol 6-20 hours per day, 5-7 days per week for up to
13 weeks. Exposure to 200 ppm methanol had no effect on testosterone
production in either normal rats or folate-deficient rats. Methanol had
no adverse effect on testes morphology at the end of 13 week exposure
to 800 ppm methanol in either normal rats or folate-deficient rats. An
increase incidence of testicular degeneration was noted in 18-month-old
folate-deficient rats exposed to 800 ppm methanol for 13 weeks
(20 hours per day 7 days per week) suggesting an age-related testes
degeneration in these folate-deficient rats (Lee et al., 1991).
In a limited study, Sprague Dawley rats were exposed to 200, 2000,
or 10,000 ppm for 6 hours per day for as long as 6 weeks. The rats were
sacrificed 16 hours after last exposure and the lungs were removed and
lavaged. The lavage fluid was analyzed for lactic dehydrogenase. No
significant treatment-related effects were noted. No histopathological
evaluation of the lung was conducted, but gross evaluation of the lung
showed no indication of inflammation or irritation (White et al., 1983).
Folate-deficient rats were used successfully as amodel to studymethanol
effects on the optic system in rats following inhalation exposure up to
3000 ppm methanol or orally at 3500 mg/kg. No changes in blood formic
acid were seen in normal rats exposed to methanol, but blood formic acid
was greatly increased at the same level of exposure in folate-deficient rats.
Eight of 11 folate-deficient rats died after exposure to 3000 ppm methanol,
but none of the normal rats exposed at the same concentration died. The
blood formic acid increase in folate-deficient rats is similar to what is seen
in humans followingmethanol exposure (Lee et al., 1994). The role of folate
and difference in metabolism are discussed in Chapter 7 on metabolism.
In two similar inhalation studies, Sprague Dawley rats were exposed
to methanol or a combination of methanol/toluene,
toluene or
