Methyl bromide is an odorless, colorless gas that is usually used as a fumigant for insect and rodent infected structures. It is as poisonous to humans as it is to other life forms. However, methyl bromide requires a much higher concentration in air and time of exposure to be toxic. A typical toxic dose of methyl bromide is about 10 times greater than a toxic dose of carbon monoxide and takes much longer to work.
However, methyl bromide's delayed effect often means that victims can be far removed from the source of the poison before they develop symptoms. It also means that the progression of the symptoms will often get worse over time, even in a hospital setting. Methyl bromide's primary toxic effect is to interfere with the function of nerves, although it will also irritate the lungs, skin and eyes.
There is no antidote or direct treatment for methyl bromide poisoning. In most cases, the patient will recover over time given supportive care, such as fluids and oxygen as required. First aid is to remove the patient's clothing and wash their skin as the toxin will persist on both the skin and clothing and will continue to be absorbed. Patients may also be given painkillers to deal with the resulting pain. Patients who survive a very high dose may require a lengthy period of convalescence.
Luckily, deaths from methlyl bromide are getting rarer. It used to be used widely as a pesticide and soil sterilizer, but this type of use has been discontinued in most countries. Most illnesses now are from accidental exposure to fumigated areas, such as wooden shipping containers which require very high concentrations of the gas to kill any foreign insects.