1 In general, the total dissolved solids concentration is the sum of the cations (positively charged) and anions (negatively charged) ions in the water.  Parts per Million (ppm) is the weight-to-weight ratio of any ion to water.
If you refrigerate the rice, and you want to eat it cold, its perfectly fine. People eat cold rice salads all the time. Cold rice pudding is fine. Its just sitting around at room temperature that is the problem.
What foods can you eat the day before a colonoscopy? The day before a colonscopy, one's diet is extremely limited, allowing only clear liquids and clear liquid foods, such as clear juices, broths and bouillons, and popsicles or Jell-O. The day of the colonoscopy, one should follow the same restrictions until 2 hours before the procedure, notes Harvard Medical School.