Piperonyl butoxide CAS# 51-03-6

Part 2: In-depth development

Insecticide synergist: A U.S. EPA restricted Use Pesticide (RUP). Not listed for use in EU countries. Piperonyl butoxide is a synergist, i.e., not a pesticide itself, but enhances the properties of other chemicals. It is used with other pesticides such as pyrethrins, pyrethroids, rotenone, and carbamates in food and non-food agricultural products, home and garden products, termite and mosquito products, and veterinary pesticide products. It inhibits the insect’s ability to break down an insecticide before it takes effect, thereby prolonging the action, and reduces the necessity for using a stronger formulation.

Piperonyl butoxide is used primarily in admixture with pyrethrins and some of the pyrethroids to enhance and prolong their insecticidal action. Much of this use is in domestic and industrial situations. Metabolism studies were conducted soon after their discovery and first use in the 1950s and 1960s. The main impetus initially was to understand the mode of action as a synergist. When this was shown to be due to the inhibition of oxidative metabolism, further studies were conducted to address possible toxic interactions with other pesticides and drugs in man.

Piperonyl butoxide undergoes rapid photodegradation and microbial degradation in soil. It is also rapidly metabolized in insects and mammals by an oxidative attack at the methylenedioxy carbon atom and in the side chain. A comprehensive review by Casida (1970) describes the chemistry, mode of action, and metabolism of piperonyl butoxide and several related methylenedioxyphenyl compounds. Though published nearly 30 years ago, the review remains a very useful compilation of a large amount of information, supported by more than 300 references.