Abstract Ethidium bromide in water, TBE buffer, Mops buffer, and cesium chloride solution may be completely degraded by reaction with sodium nitrite and hypophosphorous acid. Only nonmutagenic reaction mixtures were produced. Destruction was >99.8% in all cases; the limit of detection was 0.5 μg ethidium bromide per milliliter of solution. Ethidium bromide also may be removed completely from the above solutions by using Amberlite XAD-16 resin. The limit of detection was 0.05 μg ethidium bromide per milliliter of solution (0.27 μg/ml when cesium chloride solution was used).