Pistachio nuts can spontaneously combust when shipped in large batches. The nut's high oil content and low water content mean that large batches can self-heat to the point where they catch on fire. Pistachios also absorb oxygen and put out carbon dioxide, so they can be a health hazard when they are in large amounts in enclosed areas, such as in cargo ships or delivery trucks. This is why pistachio nuts have to be shipped under very careful conditions and must be regularly monitored for temperature during the shipping process.
More facts about pistachios and spontaneous combustion:
- Pistachios aren't the only food that can spontaneously combust. Walnuts, sunflower seeds, apricot kernels, flaxseed and cashews can also self-heat and spontaneously combust under the right circumstances.
- Iran produces the most pistachios of any country in the world: more than 423 million pounds (about 192 million kg) of pistachios a year. The United States produces the next most, followed by Turkey, Syria and China.
- Other things that can spontaneously combust in large amounts include haystacks, coal, cotton and even piles of manure.