Biomedical Engineering Reference
In-Depth Information
estimated to be 7.5-8.5mg/kg per day (for a 70 kg adult that equates to a
total methanol intake of 52.5-59.5mg/day). The upper 99th
%
has been
estimated to be 34mg/kg (238mg methanol for a 70 kg adult). At doses
higher in a control human experiment (100, 150, and 200mg/kg)
aspartame blood methanol concentrations was elevated, reaching its
highest-level 2-3 hours after ingestion. Levels return to normal by 8
hours (Stegink et al., 1981).
Methanol in the diet also comes fromdimethyl dicarbonate. It is a FDA
approved direct food additive, that is, added to wines and fruit juices as a
microbial control agent. Hydrolysis yields 48mg of methanol from each
100mg of dimethyl dicarbonate added. According to the FDA, an adult
human can metabolize 1500mg of methanol per hour with no adverse
effects (FDA, 1988). The FDA has concluded that a tolerable (safe) level
of exposure to methanol is 7.1-8.4mg/kg bw per day (FDA, 1994, 1996).
Formate, the toxic metabolite of methanol in humans, does not
accumulate if dietary exposure is below 20mg methanol per kilogram
(Anonymous, 1997).
3.2.2 Environmental
Methanol is used in the industrial production of many important
chemicals (formaldehyde, acetic acid, MTBE, glycol methyl ethers,
methylamine, and methyl methacrylate). It is also used in many
commercial products (paints, varnishes, antifreeze solutions, wind-
shield washer fluids, deicers, and fuels). These different uses may
result in low-level environmental or occupational exposure to methanol
(Anonymous, 1997).
High concentration of methanol in the air may be slightly irritating to
the eyes and mucous membrane (Delbrick et al., 1982; Rowe and
McCollister, 1982). Liquid methanol may cause burning or tearing of
the eyes. Long-term contact with the skin may result in dry, rough, or
chapped skin likely due to the defatting effect ofmethanol (Delbrick et al.,
1982). Other than dry rough skin following repeat exposure, there is little
or no information on the effect of chronic low-level dermal exposure to
methanol. High level of dermal methanol exposure can result in acute
methanol toxicity as discussed in the early occupational cases.
