As a fumigant, Methyl Bromide is highly toxic via inhalation, if swallowed, or if it comes into contact with skin. When inhaled, the bromine ion and methanol are detectable in blood and tissues along with organic bromides in stomach fluid and mucous. The half-life of Methyl Bromide in the blood is approximately 12 days, resulting in delayed or prolonged effects of Methyl Bromide toxicity.
Methyl Bromide is extremely irritating to skin, eyes, and airways. Symptoms of Methyl Bromide toxicity include an acute toxicity phase followed by a chronic toxicity phase, which can last years depending on the initial dose. In humans, acute exposure can result in:
Irritation of the skin, eyes, and mucous membranes of the upper respiratory tract
Kidney damage, paralysis, convulsions, tremors, and death
Dizziness
Speech impairment
Visual effects
Decreased respiratory function
Forelimb twitching
Tremors and paralysis
Abnormal electroencephalograms
Peripheral neuropathy, and reduced Wechsler Memory Scale scores
Irritation of the skin, eyes, and mucous membranes of the upper respiratory tract
Kidney damage, paralysis, convulsions, tremors, and death
Dizziness
Speech impairment
Visual effects
Decreased respiratory function
Forelimb twitching
Tremors and paralysis
Abnormal electroencephalograms
Peripheral neuropathy, and reduced Wechsler Memory Scale scores
Additionally, Methyl Bromide inactivates enzyme systems in cells, therefore, prolonged exposure to small doses can cause severe toxicity.
While safety measures have been in place, poisoning due to Methyl Bromide still occurs with more than 950 fatalities described in the literature. Studies have found that exposure to Methyl Bromide can lead to neuropathological, neurophysiological, and biochemical changes in exposed workers. In New Zealand, the use of Methyl Bromide has been linked to a cluster of port employees suffering from motor neurone disease.