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  Discussion on Deet spray?
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Member:
dres

Posted on Wednesday, Mar 21, 2007 - 10:45 am:

Is there a horse product that we can buy with Deet in it ..?? OFF is very expensive for multi horse owners..

On the first day God created horses, on the second day he painted them with spots..
Member:
corinne

Posted on Wednesday, Mar 21, 2007 - 12:55 pm:

I am not sure Ann, but I just thought of something that might mitigate the cost, in the military the troops impregnate their uniforms and special mesh jackets in a Deet wash when they are entering high risk areas for Malaria. I have often wondered if such a product was available from Army surplus stores and if it could be used for fly sheets. I think once the fabric is impregnated and drys there is less of a chance for reactions than with Deet sprayed directly on the skin. I have to ask Herb about the product at his readiness shop as it's been years since I was in the field and we were never in high risk areas. It might be worth inquiring about, then I can ask Dr. O to see if it might be something we could use on flysheets. Of course it might only be available to the military but one never knows. I am sure outfitters in high risk areas in the world do the same thing and it just might be the ticket for helping our horses rid themselves of pests without constant application of an expensive product. I know it's good for seven washings and doesn't compromise the integrity of the fabric.
I will let you know what I found out ie concentrations, cost, etc and availability to civilians etc. If it's safe for humans perhaps it just might be the ticket for horse clothing. Then Dr O can comment.
Member:
dres

Posted on Wednesday, Mar 21, 2007 - 1:08 pm:

Great Corinne that would be helpful.. I have new neighbors that don't take care of their paddocks that are over loaded with cows/ goats/ and horses... I know Fly season is going to be terrible here this year.. I have two mares that are pretty sensitive to the bites... the boys seem to tolerate it better..

Now go rest..

On the first day God created horses, on the second day he painted them with spots..
Member:
erika

Posted on Wednesday, Mar 21, 2007 - 4:42 pm:

Corinne, are you sure that's not a pyrethrin product instead of deet? We used pyrethrin on clothes for the jungles of Chiapas.
Member:
corinne

Posted on Wednesday, Mar 21, 2007 - 7:12 pm:

Erika you would make such a cute Jungle Jane LOL. I am not too sure as I remember that we used DEET products in the field but I will ask Herb when he gets home tonight. They gave us some teaching on the products while in combat casualty care course with the Army but that was in 2001 and I could have them mixed up but I will get back to you all when I get more information. I don't like the humidity in the jungle. Okinawa had lots of them and we would hike. The sweat would be pouring and the insects were huge. Butterflies with a three foot wing span. LOL. The mosquitoes were awful! We got a bit of a break while in MT, but when we lived in Minot you could not go out after dusk unless fully covered with Deet. They had to bring in the C130's to spray the towns a few times a year. I like the bugs in OK much better! :-)
Member:
irvincd

Posted on Friday, Jun 13, 2008 - 2:44 pm:

I am retired Marine and have a couple cans of this stuff at the house. I still work with the Marines so I come up with it at times. What I have and have always used is spray wraped in the yellow paper with all the safety info. Almost Marine proof.

Any way you can probably get it at most (serious) Bow Huntin stores.

One store I know I have seen it at is Terry's Archery in NC. Google it and Im sure he will mail you some if you need it. He has mailed stuff all over.
New Member:
lwmilne

Posted on Thursday, Apr 16, 2009 - 11:07 pm:

you can also get this stuff to wash the clothes (or in this case the fly sheets) at outdoor sporting stores like REI or EMS. it is supposed to last through 7 washes.
Member:
mitch316

Posted on Friday, Apr 17, 2009 - 10:34 pm:

Hi all. I just retired from the Army in 2005, and the Army had replaced DEET with Pyrethrin due to a slight risk of cancer. As far as DEET for horses, or any animals for that matter, it is effective, yet can produce a burning sensation, and it IS absorbed through the skin and can be found in the bloodstream within 6 hours of application (I am reading this from my Survival Manual from US Special Ops). While medical science has shown no ill effects from this absorption, it should only be used when pyrethrin is not available. In Malarial areas, the benefits far outweigh the risks, as the disease can still be attained (man ya gotta love Army language) despite prophylactics you take before any deployment.

What this means for horses? My opinion is use DEET on the ground, stall, and barn and use pyrethrin on the animals...but that is my opinion.

A great product that can be used on ALL of your animals and works on fleas, sand fleas, ticks, mites, flies, HORSE FLIES, deer flies, did I mention flies. It comes in a spray or a shampoo. I use the spray. It kills on contact and also has a residual effect. It will last up to 6 weeks for animals with shelter (such as house kept or barns for rain) and 2-4 without. You have all prob. heard of it, as and it is called Ovitrol.

In our part of KY, we had an outbreak of fleas due to the DrOught which no flea medicine would get control of. Ovitrol did. It has a trace amount of deet I think, but it is very effective at any rate. Some may have had different results, but i have used it on kittens, my snakes, and my horses, and all have done well.
Moderator:
DrO

Posted on Saturday, Apr 18, 2009 - 8:35 am:

Jesse,
I cannot speak for the US Army Manual and its recommendations or why they make this suggestion. The studies on carcinogencity that I have seen have not been convincing, including the Swedish testicular cancer study. I am not the only one who feels this way as the EPA has listed it as a Class D carcinogen which essentially means it is not a human carcinogen. They also conclude it is not a mutagen.

If repelling biting insects is important pyrethrins make a very poor substitute for DEET when you compare efficacy. As to safety all I can really say is that current research, and I have spent hours on this often questioned recommendation, I have done on this and the FDA and EPA, not known for their lax standards, still feel this safe to use when used as labelled.

While any product placed on the skin can cause reactions, I have never seen a horse react to its use, nor have I nor my family, nor any friends we have gone ridding with using the product experienced trouble. I have seen several pyrethin product reactions however though I suspect it was a carrier chemical. If your measurement sensitivity is fine enough you will find anything you put on your skin is absorbed to some degree but again extensive testing on this product continues to find it safe to use. I will continue to watch for evidence to the contrary. The following are two easy to find references on the Internet.

We should note there is not a product approved for horse use so this is done at your own risk. Human's should carefully follow label directions.
DrO

I took this off the EPA site today:

The Insect Repellent DEET
Current as of: March 23, 2007

Safety review of DEET completed in 1998
After completing a comprehensive re-assessment of DEET, EPA concluded that, as long as consumers follow label directions and take proper precautions, insect repellents containing DEET do not present a health concern. Human exposure is expected to be brief, and long-term exposure is not expected. Based on extensive toxicity testing, the Agency believes that the normal use of DEET does not present a health concern to the general population. EPA completed this review and issued its reregistration decision (called a RED) in 1998. (More about REDs)

Here is a very good study that revied the literature in 2002 and concluded that the product is safe, as long as not ingested, to use in infants as young as 6 months but with caveats. This appeared in the Canadian Medical Jounal with the sponsorship by Canadian Society for Clinical Pharmacology.

DEET-based insect repellents: safety implications for children and pregnant and lactating women

Gideon Koren, Doreen Matsui and Benoit Bailey
From the Division of Clinical Pharmacology and Toxicology, Hospital for Sick Children and University of Toronto, Toronto, Ont. (Koren); the Division of Clinical Pharmacology, Children's Hospital of Western Ontario and University of Western Ontario, London, Ont. (Matsui); and the Divisions of Emergency Medicine and of Clinical Pharmacology and Toxicology, Hôpital Ste-Justine and Université de Montréal, Montréal, Que. (Bailey)

Correspondence to: Dr. Gideon Koren, Division of Clinical Pharmacology, Hospital for Sick Children, 555 University Ave., Toronto ON M5G 1X8; fax 416 813-7562; gkoren@sickkids.ca

Abstract

REDUCING THE RISK OF MOSQUITO BITES is currently the only way to reduce the risk of West Nile virus infection. Methods for avoiding mosquito bites include limiting the time spent outdoors at dawn and dusk, wearing protective clothing and using an insect repellent. Repellents containing DEET (N,N-diethyl-m-toluamide, also known as N,N-diethyl-3-methylbenzamide) are the most effective and most widely used. However, concerns have been raised over the risk of adverse toxic effects, especially in young children and pregnant and lactating women. In this article, we review the available evidence on the effectiveness and safety of DEET-based products. The evidence does not support increased risk in young children.

The emergence of West Nile virus (WNV) infection in Canada has led to high levels of anxiety and vigilance. As there is no vaccine currently available, illness is prevented by avoiding bites of infected mosquitoes.

DEET (N,N-diethyl-m-toluamide, also known as N,N-diethyl-3-methylbenzamide) is the most effective and most widely used insect repellent. It was first used by the US military in 1946 and has been sold commercially for almost half a century. Products are available with concentrations of 5% to 100% of DEET and come in a variety of forms: aerosols, pump sprays, lotions, creams, liquids, sticks, roll-ons, towelettes and wristbands. The US Centers for Disease Control and Prevention (CDC) has estimated that 30% of Americans are using DEET-based insect repellents to avoid mosquito bites, as well as bites of other insects, such as the ticks responsible for transmitting Lyme disease.1 An estimated 23%–29% of American children are exposed to DEET.2

Although DEET is very effective, its use in young children has been limited because of case reports associating it with seizures.1,3,4,5,6,7,8 Yet, young children may be outdoors for extended periods, and suboptimal use of mosquito repellents may increase their risk of WNV infection. There is also apprehension about DEET's potential effects on the developing fetus and child when used by pregnant and lactating women. In this review we attempt to address this complex issue by critically analyzing existing evidence.

Pharmacology
Although the mechanism of action of DEET is unknown, the main theory is that the chemical disturbs the function of receptors in the mosquito's antennae that allow it to locate humans. The effectiveness of DEET in repelling mosquitoes is directly related to the concentration of the chemical applied (Table 1).9 However, the duration of action reaches a plateau at a concentration of 50%.10 This is in part why Health Canada is phasing out insect repellents containing DEET at concentrations higher than 30% by December 2004.10

Although DEET's effectiveness is related to its topical use, its systemic adverse effects are related to the amount that is absorbed into the blood. After 6 hours, 9%–56% of the dose appears in the circulation (systemic bioavailability). However, if DEET is ingested, intentionally or unintentionally, peak plasma levels are much higher and are achieved within 1 hour.11 For example, 10–12 g of a 75% DEET solution applied to the skin can lead to a blood concentration of about 0.0005 mmol/L; ingestion of a similar amount of DEET can result in a blood concentration that is hundreds of times higher (1 mmol/L). The latter concentration has been associated with seizures and death.11 The elimination half-life of DEET is 2.5 hours, and most of the body load is metabolized by hepatic P450 enzymes, with only 10%–14% recovered unchanged in the urine.

Toxic effects

Adults
Most of the data on DEET's toxic effects in humans stem from case reports of ingestion of the chemical. Such ingestion may lead to hypotension, seizures and coma within as little as 1 hour.12 Deaths have been associated with serum concentrations of 1 mmol/L.11

The mechanism leading to seizures is unknown. They may occur as soon as 1 hour and as long as 48 hours after ingestion.11 Although seizures may theoretically occur more often in people using DEET who are concurrently using drugs that lower the seizure threshold (e.g., bubropion, antipsychotic agents, systemic steroids and antimalarial agents), no interactions have been confirmed.

Psychosis was described in an adult who had applied a product containing 70% DEET to the skin.11

Immediate contact dermatitis following dermal application has been described, as have generalized pruritus and generalized angioedema.11 Conjunctival damage may result from application to the eye.

Children

Extrapolating from data on toxic effects in adults, one might expect seizures to be a major adverse effect in children. However, we found only 10 reports describing seizures in children following dermal application of DEET that were published in the almost 50 years since DEET has been available;1,3,4,5,6,7,8 none was published after 1992. Nevertheless, these case reports have been widely quoted and have led regulatory agencies and pediatric societies to limit the use of DEET in young children.

However, because seizure disorders occur in 3%–5% of children13 and an estimated 23%–29% of children in this continent are exposed to DEET,2 it would not be surprising to see an association just by chance in some cases. Epidemiologically, when 2 events (i.e., DEET application and seizures) are both prevalent, case reports are not useful in determining causation.

In addition, other features of these case reports are not very helpful because they do not appear to be pathognomonic. For example, viral encephalitis was not ruled out in any of the cases. The differential diagnosis of encephalitis was entertained in 3 cases, and there was "nonspecific rash" reported in 1 case. In another case, the clinical picture resembled Reye's synDrOme, which on its own could predispose a child to seizures.14 In 1989, the CDC, after discussing 5 pediatric cases of seizures associated with dermal application of DEET, cautioned against the use of these cases as proof of causation.1 Specifically, the CDC wrote that "DEET should not be accepted as the cause of a seizure until appropriate evaluation has reliably excluded other possible etiologies." Yet, appropriate evaluation has not been conducted in any case before or after 1989, whereas the causation has been implied by authorities numerous times.

A large-scale population-based study on the safety of DEET was published in 2002 based on data collected by the American Association of Poison Control Centers between 1993 and 1997.15 This study refutes the long-held, unproven perception that young children are more sensitive than adults to the adverse effects of DEET. After collecting data on 20 764 pediatric and adult cases of accidental DEET exposure, the authors analyzed the cases by severity of adverse events (from none to fatal) and by age. A total of 1151 infants and children and an additional 101 adolescents were accidentally exposed to DEET dermally. Analysis of the severity of adverse events revealed that the infants and children had lower rates of each of moderate, severe and fatal events than did the adults. The authors summarized that, "overall, children experienced more of the less severe outcomes and adults experienced more of the worst outcomes associated with an exposure."

Pregnant and lactating women

Women are often concerned about using DEET during pregnancy, but the available data on toxic effects in humans and animals are reassuring. An animal study published in 1994 reported no adverse effects in the offspring of rats and rabbits force fed different concentrations of DEET at different times of gestation, with one exception.16 The highest DEET dose (325 mg/kg daily), by orders of magnitude higher than the normal human dose, resulted in maternal toxic effects and low birth weights of offspring. There was no evidence of fetal toxic effects or malformations in the offspring of exposed animals, regardless of the dose used. No observations on behaviour or neurologic development were reported.16

The first study of the safety of DEET when used regularly during the second and third trimesters was a randomized, double-blind trial involving 897 pregnant women in Thailand who continuously applied therapeutic doses of DEET topically (1.7 g/d) — a dose similar to that recommended to prevent malaria17 — or placebo to prevent malaria.17 The DEET group received a median cumulative dose of 214.2 g. DEET levels were measured in cord blood samples in a subgroup of 50 women; it was detected in 4 (8%), which provides evidence that the chemical crosses the placenta. In the group as a whole, no adverse neurological, gastrointestinal or dermatological effects were observed in the women exposed to DEET, and no adverse effects on survival or growth and development at birth and at 1 year of age were detected in the babies whose mothers used DEET.

We found no human studies of exposure to DEET in the first trimester. However, the very high dose administered orally in the animal study16 suggests that DEET is safe when used as recommended. The CDC has advised that pregnant women take precautions to reduce their risk of WNV infection and other arboviral infections by avoiding mosquito bites and using protective clothing and DEET-based repellents.18 There is no evidence that the use of DEET by pregnant or lactating women poses a health hazard to unborn babies or children who are breast-feeding.19

Alternatives to DEET

Insect repellents other than DEET-based ones are available in Canada, although data on their safety are sparse. Products containing citronella oil for topical use are available at concentrations of 5%–15%. Citronella-based candles and incense are also available. Protection time with the dermally applied products is considered to be between 30 minutes and 2 hours, although in a recent study the mean protection time was less than 20 minutes with a product that contained a concentration of 10%.20 Lavender oil at a concentration of 6% applied topically protects for less than 30 minutes.9 Citronella oil and lavender oil are generally considered safe but are not recommended for topical use on children under 2 years of age because of the lack of evidence. Aspiration pneumonia could be a concern if either oil is ingested.

A product containing 2% soybean oil was found to protect for about 90 minutes, a period similar to that of a product containing 4.75% DEET.20 However, DEET at a concentration of 6.65% and 20% protected for a mean of 110 and 230 minutes respectively.9 Although repellents containing soybean oil are registered in Canada, none is currently available on the market. Aspiration pneumonia could be a concern if soybean oil is ingested by a young child.

A new product, containing p-menthane-3,8-diol at a concentration of 10% (OFF! Botanicals Lotion Insect repellent 1), was found to be effective for at least 90 minutes in one field trial.21 It can be applied up to twice a day on children over 3 years old, the age limit merely reflecting lack of data.21,22 Although the manufacturer states that no adverse effects are expected to occur with appropriate use, there are no epidemiological studies of the product's safety after dermal exposure or oral ingestion.

In a controlled study that compared DEET-based repellents with non-DEET-based repellents, the latter failed to show appropriate protection against mosquito bites.20

Areas of potential confusion

Both Health Canada and the Canadian Paediatric Society advise against the use of DEET on children under 6 months of age. Children aged 6 months to 2 years should be limited to one application per day, and children aged 2 to 12 years should be limited to 3 applications per day. The maximum concentration used should be 10% or less for children up to 12 years of age.9,21,22 However, these low concentrations are effective in repelling mosquitoes for only 2–3 hours (Table 1); therefore, young children would theoretically not be protected when outside for extended periods. Moreover, if the child goes swimming, the DEET will be washed away. Given the lack of evidence of increased toxicity of low-concentration DEET in young children, a second application of DEET may be warranted if the child is outdoors for more than 4 hours and WNV infection is a serious concern. Similarly, it may be prudent to reapply DEET after a session of swimming. In areas of high risk where WNV is present and mosquitoes are abundant, the risk of infection must be balanced against potential toxic effects.

Summary
DEET-based insect repellents are relatively safe when used as recommended. The suggestion that young children are more prone than adults to the neurotoxic effects of DEET is not supported by critical evaluation of existing evidence. Non-DEET-based insect repellents are available, but based on a one-time application comparison, a product containing 10% DEET will provide a longer period of protection (3 hours) than any other repellent currently available in Canada.

Footnotes
This paper is sponsored by the Canadian Society for Clinical Pharmacology.
Member:
lindas

Posted on Saturday, Apr 18, 2009 - 10:13 am:

I have always spent a lot of time in the woods, including taking boy scout troops to some of the buggiest places imaginable. DEET has been my best friend! In the boundary waters in Minnesota we still had to wear long sleeve shirts and mosquito netting head covers, but it helped a lot on exposed areas like your hands. I never thought about using it on the horses. I will have to try it, as my mare sometimes gets hives from the stronger pyrethrin formulas.
Member:
mitch316

Posted on Saturday, Apr 18, 2009 - 11:33 am:

Dr. O, your article got my research bug going, and so I started to dig a little. The Army Field Manual I used was published right before the first Gulf War, and the military was using DEET in much higher concentrations than are found in today's preparations. They were soaking tents, mosquito nets, and even washing their clothes in it.

As part of the mysterious Gulf War Illness, the Army took several precautions (mostly to quiet politicians), and one was to lower the concentrations of DEET, along with doing away with some of the other non-tested prophylactic medications they made the troops take during that war. So the switch to pyrethrin for humans, but DEET was and is still used for tents, bedding, etc, but at much lower concentrations than used before.

The field manual might get updated,and might not, as some are still in use from WW2 and Vietnam.

So, I guess I can start using it again, ha. Thanks fro the article, as it definitely teaches a lesson about staying up to date on the latest research on even the smallest things!
Moderator:
DrO

Posted on Sunday, Apr 19, 2009 - 9:00 am:

Yes, I understand when ghosts are pursued, ghosts are often found. The DEET issue is illustrative of our modern day conundrums. We have become so good technically sometimes we loose sight of good sense.

Thousands if not hundreds of thousands develop illness from pest bites, many serious some occasionally life threatening. These diseases could have been prevented with the proper use of DEET and no other product in many cases. DEET like all substances, including pure water, has toxic aspects. It is easy to see why water is not much discussed but the issue with DEET much tougher. These decisions are always a balance of the good vs bad but it does not take much for someone with a agenda that is not based in good sense to present a single side and tip this balance the wrong way.
DrO
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