Chronic inhalation exposure of male animals has resulted in effects on the testes at high concentrations. EPA has classified methyl bromide as a Group D, not classifiable as to human carcinogenicity , based on inadequate human and animal data. Exceedance of the RfC does not imply that an adverse health effect would necessarily occur. As the amount and frequency of exposures exceeding the RfC increase, the probability of adverse health effects also increases. Other secondary sources include The Merck Index and EPA's Health Effects Assessment for Bromomethane .
Some methyl bromide is formed naturally by algae or kelp in the ocean.
Inhaling large amounts of methyl bromide may cause pulmonary edema, impairing respiratory function. Acute exposure by inhalation of methyl bromide frequently leads to neurological effects in humans. Acute exposure may produce delayed effects. Symptoms may improve without treatment in less serious cases. Methyl bromide is irritating to the eyes, skin, and mucous membranes of the upper respiratory tract.