It is insoluble in water. When used as a pesticide, kaolin is sprayed as a powdered suspension on crops, where it forms a barrier film that repels and prevents target pests from penetrating leaves or other parts of the plant. To be effective, the suspension must coat all parts of the plants. Kaolin is approved for use on a wide range of fruit and vegetable crops, including beans, beets, potatoes, eggplant, citrus fruits, apples, apricots, and berries. Kaolin has been extensively tested, and no evidence of toxicity to humans was detected.
Human exposure occurs primarily through numerous non-pesticidal uses of kaolin.
Toiletries such as toothpaste and antiperspirants contain kaolin, as do various cosmetics. In addition to being an active pesticide ingredient itself, kaolin is also an inert ingredient in other pesticide products. EPA finds that kaolin is not harmful to non-target organisms or to the environment. Aquatic organisms are not likely to be affected because kaolin does not dissolve in water.