Cashews are never sold in their shells because the shell contains caustic oil that causes severe chemical burns.The shell liquid is related to poison ivy and can cause permanent skin damage within minutes of contact. Processing cashews is one of the most dangerous jobs in the food industry.
Raw cashew shells contain urushiol, the same toxic compound found in poison ivy, but in much higher concentrations. Workers who process cashews must wear protective gear because direct contact with cashew shell oil causes immediate blistering and scarring.Even breathing the vapors can damage lungs and airways.
The "raw" cashews sold in stores aren't actually raw —they've all been steamed or roasted to neutralize the toxic oils. Truly raw cashews would be dangerous to eat because trace amounts of shell residue can cause mouth burns and digestive problems.
Cashew processing is so hazardous that most of it happens in developing countries where safety regulations are minimal. Workers often suffer permanent hand damage and respiratory problems from repeated exposure to cashew shell toxins. The beautiful, smooth cashews in your trail mix come at a significant human cost.
The toxic shell oil isn't wasted, though:it's used to make industrial lubricants, brake linings, and waterproof coatings.The same poison that makes cashew processing dangerous is valuable for manufacturing.
Every cashew you've ever eaten was extracted from its toxic shell by someone wearing protective equipment —making cashews the only nut that requires hazmat procedures to harvest safely.