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 can you eat the day before a colonoscopy? The day before a colonoscopy, MD Anderson Cancer Center recommends eating a clear liquid diet. Patients are to avoid eating solid foods, but the diet allows them to have gelatin and broth.