Flea Dip

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Chemical Description

There are many different Chemicals List and combinations of chemicals in different brands of flea dip. For example, some brands contain rotenone, which is known to be toxic in high levels and has a dermal LD50 of 200 mg/kg (#PubChem Rotenone). Several different organophosphates and carbamates are also listed as active ingredients, and are known to cause cancer (#Harms, et al, 2008). The former can include any of the following organophosphates: chlorpyrifos, parathion, diazinon, famphur, phorate, terbufos, and Malathion (#Harms, et al, 2008). Like other organophosphate insecticides, tetrachlorvinphos, that is found in some flea dips, is a known cholinesterase inhibitor. (#PubChem Tetrachlorvos).

Mechanism of Action

Main Article: Cholinesterase Inhibitor
For those flea dips that contain rotenone, it is known that are able to work by inhibiting complex I in the electron transport chain. This can be determined by measuring the lower levels of NAD and the higher levels of NADH, relative to controls. Specifically, "the function of NADH dehydrogenase (which converts the electron carrier, NADH, to NAD) (can be) blocked by fleacide" (#Kumar, 2005).

For those formulations that contain high levels of organophosphates or carbamates, one must be aware that these insecticides are fat soluble, and therefore easily absorbed through the skin and then transported through out the body. As mentioned previously, these chemicals kill insects (and other organisms) via inhibition of the enzyme acetylcholinesterase (AChE). This enzyme is normally very important in the degradation of acetylcholine (ACh) neuromuscular junction (NMJ). Organophosphates and carbamates can lead to over-stimulation of muscles through prolonged activation of ACh receptors. This leads to muscular fasciculation and tremors initially followed by flaccid paralysis. Since the directions for use require multiple exposures, and because of the lipophilicity of these compounds, the effects of flea dip can be long lasting (#Harms, et al, 2008).

Uses and Benefits

Flea dip and related products are used to rid animals and homes of fleas, which can be hard to get rid. This is because, according to Dr. Denice Moffat, "An average flea's life span can be up to 2-3 years" This is further complicated by the fact that one female can lay up to a million eggs, and these eggs can remain dormant for up to a year until an environment conducive to hatching occurs. Taken together, these characteristics have allowed the flea, which is the second oldest insect (the cockroach the first), to flourish because of its excellent survival mechanisms (#Moffat, 2007).

Health Effects

High exposure to flea dip can lead to "massive cell death in the kidneys, lungs, thymus, and heart" (A. Kumar). Death from acute poisonings is frequently due to respiratory failure. This is because the active ingredients can lead to respiratory inhibition, excess bronchial secretions, and bronchospasms "coupled with depolarizing blockade at neuromuscular junctions (diaphragm and intercostals)" (#Harms, et al, 2008).

Case Studies

In one case study a woman was poisoned with the organophosphate phosmet (1), after "she complained of periodic headaches, nausea, dizziness, tiredness, and blurred vision and of sweating and feeling 'confused' and 'spaced out' ". Her symptoms had occurred for years and were getting more severe with each subsequent exposure. Although her cholinesterase activity was within normal range, upon being treated with atrophine, her symptoms diminished (#CDC, 1998).

Another case indicated that a 43-year-old female dog groomer had been treating as many as 8-12 dogs each day for 3 years with flea dip. She presented the doctor with a variety of symptoms, many of which had been present for at least a year, including periodic dizziness, fatigue, blackouts, blurred vision, chest pains, sweating, coldness, and chills. After three months of avoiding flea dip, her symptoms abated(#CDC, 1998).


Dips that kill "fleas and mites are all highly toxic and shouldn't be used more than three times a year. More than that leads to cancer due to over exposure of organophosphates" (#Moffat, 2007). In an effort to prevent over-exposure, the EPA requires that flea dips must have labels "cautioning users to wear long-sleeved shirts, long pants, elbow-length waterproof gloves, waterproof aprons, and unlined waterproof boots. Because animals that have been dipped or sprayed with pesticides have become ill or have died, EPA now requires that the product label state that a dog or cat may be poisoned if the product is not properly diluted" (#CDC, 1998).


A Kumar. "Teaching Systems Biology: An Active-learning Approach." CBE Life Sci Educ, December 1, 2005. 4(4): 323 - 329.

Centers for Disease Control (CDC). "Epidemiologic Notes and Reports Organophosphate Toxicity Associated With Flea-Dip Products- California". Morbidity and Mortality Weekly Report (MMWR, 03 June 1988. 37(21): 329-330, 335-6.

Harms, Jennifer; Wilson, Christina; Everson Robert; Hooser, Stephen. "Organophosphates and Carbamate Insecticide Poisoning". 1998. Purdue University. February 19, 2008.

Moffat Denice M. "Flea Control Strategies". Pets and Animals Community, October 18, 2007. : 1-7.

PubChem Compound. CID 5842000. Tetrachlovinphos.

PubChem Compound Summary. CID6758. Rotenone.

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