In June, 1930, the Committee on Poisonous Gases of the American Medical Association issued a report on "Household Mechanical Refrigeration," emphasizing particularly the hazard arising from the use of methyl chloride in such devices. While methyl chloride, when released in the atmosphere, is less poisonous at the moment than either ammonia or sulphur dioxide, its action, unlike that of these substances, may be far more serious over a longer period. Its initial action is that of a narcotic akin to the chloroform type of anesthetic. Its secondary action is probably due to decomposition products in which the primary harmful factor is methyl alcohol or some decomposition substances of methyl alcohol formed in the body, such as formaldehyde or formates.
At the time of its report the committee properly pointed out that it disapproved of the use of warning agents added to such substances as methyl chloride, because warning agents are