Chapter 94 - Boric Acid and Inorganic Borate Pesticides

Abstract

This chapter focuses on boric acid and inorganic borates, primarily borax, disodium octaborate tetrahydrate, and their derivatives, since the major pesticide uses involve these materials. Most of the simple inorganic borates exist predominantly as undissociated boric acid in dilute aqueous solution at physiological pH, leading to the conclusion that the main species in the plasma of mammals is undissociated boric acid. Boric acid and borates are water-soluble white powder substances with low acute oral and dermal toxicity that are widely used for a variety of industrial purposes including manufacture of glass, insulation fiberglass (IFG), porcelain enamel, ceramic glazes, and metal alloys. They are also used as fire retardants, laundry additives, fertilizers, herbicides, and insecticides. The primary source of exposure for human populations is ingestion of boron from food. This is largely due to the essentiality of boron as a micronutrient in plants. Thus, plant-derived foods such as fruits, vegetables, and nuts contain significant amounts of boron. Boric acid and sodium borates given orally are readily and completely absorbed in humans and animals. Inhaled sodium borate dust is readily absorbed as demonstrated by the blood and urine levels among groups of workers occupationally exposed to various levels of boron. Absorbed boron rapidly distributes throughout the body water in humans and animals. In both humans and animals, boron levels in soft tissue are comparable to plasma levels, while a greater concentration of boron in bone is observed relative to other tissues. Boric acid and sodium borate salt compounds prevent pest infestation by inhibiting pest metabolism on a cellular basis.