Exposure to low concentrations causes eye and lung irritation. Metal fluorides are very toxic. Organic fluorides are generally much less toxic and are often quite harmless. Chlorine Chlorine gas is very toxic because of its strong oxidising nature. Even low concentrations of chlorine gas attack eyes, throats, and lungs with painful effects.
Chloride is relatively harmless.
Bromine Bromine is a very corrosive oxidising liquid whose vapour attacks the eyes and lungs with painful effects. Bromides salts should be treated as toxic. Excessive bromide intake leads to depression and of weight loss. Iodine Elemental iodine, I2, is toxic, and its vapour irritates the eyes and lungs. The maximum allowable concentration in air when working with iodine is just 1 mg m-3.