Pyrethroid Ester & Insecticide Warnings

What They Are

• A pyrethroid, in its basic definition, is a man-made, synthetic form of pyrethrin. Pyrethrins are naturally occurring insecticides derived from a chemical known as pyrethrum found in chrysanthemums. Pyrethrins are liquid esters derived from the pyrethrum. Because the original insecticidal chemicals are found in flowers, many people may mistakenly believe they are safe. However, the synthetic pyrethroids found in most pyrethrin insecticides are engineered to be much more toxic to target organisms and have longer breakdown times.

How They Work

• Pyrethroids affect the contacted insects' nervous systems. Once an insect is affected, its nervous system begins releasing neurotransmitters that become confused with the messages between nerve cells. These messages are responsible for a wide range of the insect's body, including movement. The insecticide creates an overload of potential actions in the insects' nervous systems, resulting in paralysis and eventually death.

Effects on Humans and Lab Animals

• If a human accidentally inhales pyrethroid insecticide, he may experience a wide range of side effects including coughing, shortness of breath, chest pain, wheezing, difficulty of breath or a stuffy nose. Rats exposed to the insecticide exhibited similar symptoms with the addition of twitching, tremors, aggression, incoordination and sprawling of limbs. A human who accidentally gets the pyrethroid on her skin may experience rash, itching or even blisters.

Effects on the Environment

• Although pyrethroids are considered relatively low in toxicity in mammals due to the quickness in which they break down and leave the body, they are still highly toxic to other members of the ecosystem and environment. For example, aquatic life, including fish and tadpoles, are highly affected by the toxicity of pyrethroids, according to the National Pesticide Information Center, Extension Toxicology Network and the University of Florida IFAS Extension. These insecticides are also highly toxic to beneficial arthropods, including honeybees.