Scientific
Studies: Spray That Mosquito?
MCS
Researchers at the Neurotoxicology Division of the National Health and
Environmental Effects Research Laboratory performed a critical analysis of
research literature on pyrethroid-induced neurobehavioral toxicity and other
adverse effects in adult animals.
Pyrethroids are a class of synthetic chemical insecticides similar to the
natural pesticide pyrethrum. They are commonly used for mosquito
control.
All pyrethroids in the examined literature produced a decrease in motor
activity. Motor activity is described as the physical activity of an
organism that is associated with behavior.
Some pyrethroid exposure reduced grip strength and impaired coordination.
Pyrethroids have been shown to impair operant responding in animals. An
operant response is a learned response to operant conditioning, a type of
learning in which a behavior is strengthened (occurs more frequently) when it's
followed by reinforcement and weakened (happens less frequently) when followed
by punishment.
Certain pyrethroids cause an increase in startle response, while others cause a
decrease in startle response. Thresholds for motor activity decline were
found in pyrethroid doses well below those that would produce signs of
poisoning. Therefore, health effects are present long before signs of
poisoning occur, if they occur.
If these low dose effects have been shown, it is plausible that any exposure at
all is too much. If pyrethroids bioaccumulate, several low dose exposures
could eventually lead to poisoning.
Pyrethroid poisoning may disrupt the endocrine system by mimicking
estrogen. In males, this can lead to lowered sperm count. These
insecticides have also been shown to damage the thyroid gland. In toxic
doses, tremors, lack of coordination, and behavioral changes occur.
Children are at much greater risk than adults.
Fortunately, many alternatives are available, including some simple measures. Protective clothing and screening windows and
porches is very effective at eliminating mosquito bites. Removing
all sources of standing water limits breeding. Adding soap to any
standing water, if the water cannot be removed, also limits breeding.
These simple methods can go a long way towards personal protection and mosquito
reduction.
Reference
Wolansky MJ, Harrill JA. Neurobehavioral toxicology of pyrethroid
insecticides in adult animals: A critical
review. Neurotoxicol Teratol. 2007 Nov 17.
Copyrighted © 2008 MCS