The no-effect level of sodium bromide in healthy volunteers.

1. A total of 0, 4 and 9 mg kg-1 body weight sodium bromide was administered orally to 45 healthy female volunteers. 2. The experiment lasted for six menstrual cycles: only during the first three cycles was bromide administered; 3. At the start, at the end of the administration period and at the end of the experiment a physical examination and haematological and routine clinical chemistry tests were performed. Except for nausea in relation to the intake of bromide, no adverse effects were observed. 4. The bromide concentration in plasma rose to 3.22 +/- 0.93 mmol kg-1 in the 4 mg kg-1 group and to 7.99 +/- 1.89 in the 9 mg kg-1 group by the end of the administration period. 5. Before and at the end of the experiment the thyroid hormones (T4, FT4, TBG, T3 and TSH) were analysed. No significant differences were observed between the groups. 6. Before, after three menstrual cycles and at the end of the experiment an EEG with a Visual Evoked Response was recorded. At the 4 and 9 mg kg-1 dose level in the alpha 1-band and the beta-bands significant changes were found (P < 0.1 and P < 0.05, respectively). The Visual Evoked Response showed no significant differences between the three groups. 7. From this experiment and previous experiments a no-effect level in humans for sodium bromide of 4 mg kg-1 body weight is proposed.