Magnesium oxalate is a skin and eye irritant. If inhaled, it will irritate the lungs and mucous membranes.  Magnesium oxalate has no known chronic effects nor any carcinogenic effects.  Magnesium oxalate is non-flammable and stable, but in fire conditions it will give off toxic fumes.  According to OSHA, magnesium oxalate is considered to be hazardous.