Biomedical Engineering Reference
In-Depth Information
were not affected. The methanol elimination half-life was 3.2
2.3
hours (Osterloh et al., 1996).
In a controlled inhalation study six individuals (aged 29-55) were
exposed to 200 ppm for 6 hours. Blood and urinary levels of methanol
and formate were measured before and after exposure and with and
without exercise. Blood levels of methanol increased from 1.8mg/l
before exposure to 7-8mg/l after exposure, but formate levels
(
9.6mg/l) were not affected by methanol exposure at 200 ppm
with or without exercise (Lee et al., 1992).
In a study of human volunteers exposed to methanol by inhalation, a
time-weighted average of 176 ppm for 7 hours per day for 5 days,
urinary methanol and formic acid levels were measured before and after
each exposure. Urinary methanol levels were elevated at the end of
exposure but had return to baseline before the next exposure. No
changes were seen in urinary formic acid levels supporting the lack
of accumulation of urinary formic acid at levels close to the maximum
allowed workplace exposure levels (200 ppm) (Franzblau et al., 1993).
3.6
IN UTERO EXPOSURE
There is very little information about methanol poisoning and preg-
nancy. One case reported a 26-year-old woman ingested 250-500ml of
methanol during the 38th week of pregnancy. Maternal serum methanol
(230mg/l) and formate (33.6mg/l) were elevated initially and mild
acidosis was reported. Fetal monitoring showed no signs of fetal
distress. The patient was treated with ethanol infusion, bicarbonate,
and three treatments of hemodialysis. Delivery took place 6 days after
the methanol poisoning, and blood methanol levels were normal. There
were no complications or long-term problems in 10 years of follow up in
the mother or child (Hantson et al., 1997).
A case of transplacental poisoning was reported in a 28-year-old
mother about 30 weeks pregnant. The woman had a HIV infection and
asthma and was admitted to an emergency room with respiratory
distress and acidosis. Her son was delivered by C-section. Acidosis
in the son persisted in spite of
fluid, bicarbonate, and blood
