May 19, 2014: How does one obliterate one’s insect enemies?

With the advent of good weather, our crawling “friends” come back in force, and our yearly battle begins again.   How do we deal with them?  Most commonly, in the home setting, we use three main categories of insecticides: pyrethrins, organophosphates and carbamates.  Used properly, these tend to work well and we go on normally with our lives; however, improperly used, these chemicals can present a health risk that we as health professionals have to potentially treat.

Pyrethrins tend to be the less toxic of the three, but can cause dermal irritation, allergic dermatitis, urt irritation, headache, dizziness paresthesia, GI symptoms, ocular irritation, rare seizures.

Organophosphates and carbamates have a similar clinical picture: one can possibly see muscarinic (cholinergic), nicotinic and central effects.

The muscarinic/cholinergic effects in mild to moderate poisonings can manifest as salivation, lacrimation, loss of bladder and bowel contol, diaphoresis, bradycardia, miosis; in more serious situations, one can see bronchorrhea, bronchospam.

The nicotinic effects in mild to moderate exposures can manifest as tachycardia, increased bp, muscle cramps, mydriasis; in more serious exposures, can see muscle fasciculations, weakness, respiratory failure.  Central effects are generally seen in more serious exposures and can show as cns depression, agitation, seizures, secondary problems.

The main exposure routes with which we deal are dermal, inhalation and ingestion. 

Dermally, decontamination is the most important step ---- at home, removal of clothing and a good shower are the things to do; in the er, this can be more difficult to do, of course, but dermal decontamination is still the thing to do as best can be done  (with protection of the staff being kept in mind).

Inhalation exposures generally tend to be milder in nature ---removal from the source and fresh air are the things to be done, with symptomatic treatment thereafter.

Ingestion exposures can range from the accidental swallow to the intentional unknown amount. Intentional ingestions tend to have greatest potential for significant symptoms.  Gi decontamination (ie, lavage, charcoal) has not proven to be efficacious unfortunately; so, symptomatic treatment is the approach.

With organophosphates and carbamates, atropine is used to treat significant muscarinic (cholinergic) symptoms.  Pralidoxime is used to treat the more serious symptoms of fasciculations, muscle weakness, respiratory depression, coma, seizures.  The caveat with pralidoxime is to make sure the patient is properly atropinized first; also, efficacy of pralidoxime use in carbamate poisonings is questionable.

This is a brief overview of insecticide poisoning, of course, so we invite any of our health care community to call us for particulars with the individual situations they might encounter.


This Question prepared by:  Scott Muir, RN, CSPI (Certified Specialist in Poison Information)  Tennessee Poison Center


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Donna Seger, MD

Medical Director

Tennessee Poison Center

Poison Help Hotline: 1-800-222-1222