The news is that the watermelons in the country have high levels of nitrate, many times higher than they are. The excess of chemicals in this fruit turns into a toxic substance when it enters the body and causes poisoning. The most common symptoms of watermelon poisoning are dizziness, mood swings and stomach spasms. There are a few simple ways to distinguish high nitrate watermelons from others. First, carefully observe the white part of the crust after you wait. It should be white and not yellow. Also, in pulp, watermelon should not have white yarn.