The general range of normal levels is 0.3 - 1.2 mg/dL with an average of approximately 0.5 mg/dL. Background concentrations are diet dependent. Workers exposed to methyl bromide with blood bromide concentrations greater than 1.2 mg/dL have shown 3.5 times higher risk of electroencephalogram disturbances than compared to those with normal levels. The bromide concentration may be elevated beyond normal levels if the individual is using bromides therapeutically. The antiepileptic effects of bromides are generally associated with plasma levels ranging from 75 - 150 mg/dL. The ratio of blood to plasma concentrations is 0.7 – 0.8.