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PubMed1982

Diethyltoluamide-containing insect repellent: adverse effects in worldwide use.

During the summer of 1978, ten soldiers were seen because of an eruption in the antecubital fossae. All of them had used an insect repellent containing 50% diethyltoluamide a few hours before the eruption had appeared. The symptoms and clinical findings in these cases were those of a burning sensation, erythema, and blisters at the onset, followed in some cases by ulceration and scarring. Precautions in the use of this commonly used repellent should be advised.

Adolescent↗
PubMed1989

Toxicity and metabolism of a new insect repellent N,N-diethylphenylacetamide in mice, rats and guinea pigs on cutaneous application.

Cutaneous LD50 of N,N-diethylphenylacetamide (DEPA), a new multi insect repellent was 2200, 3200 and 7100 mg/kg body weight in female mice, rats and guinea pigs; and 1600 and 4000 mg/kg in male mice and rats indicating a high degree of safety on skin contact. Dermal application of DEPA to young growing rats for 21 days at a dose of 50 mg/kg did not exert any adverse effects while massive doses of 500 and 1000 mg/kg caused marked reduction of body weight gain and lowering of activities of serum alanine aminotransferase, aspartate aminotransferase and cholinesterase. Along with DEPA, N-ethylphenylacetamide, phenylacetamide and phenylacetic acid were detected in the urine of DEPA treated mice, rats and guinea pigs.

Acetamides↗
PubMed1988

N,N-diethylphenylacetamide, an insect repellent: absence of mutagenic response in the in vitro Ames test and in vivo mouse micronucleus test.

N,N-diethylphenylacetamide (DEPA), a promising new insect repellent, was tested for mutagenicity in the in vitro Ames Salmonella/microsome mutagenicity test and the in vivo mouse micronucleus test. For the Ames test, DEPA was assayed both in the presence and absence of Aroclor 1254-induced rat-liver S-9 mix (5 and 20% S-9 fraction), using five tester strains of Salmonella typhimurium--TA97a, TA98, TA100, TA102 and TA104. For the micronucleus test, mice were exposed to DEPA through ip injection for 2 and 5 days in separate experiments, and bone marrow and peripheral blood were sampled 6 and 48 hr after the final injection, respectively. DEPA did not induce a mutagenic response in the Ames test, and mouse bone marrow and peripheral blood micronucleus tests. DEPA was not considered cytotoxic, as a depression of the percentage PCE was not observed at any dose in the range of 1 to 100 mg/kg body weight with either treatment protocol of the micronucleus test.

Acetamides↗
PubMed1999

Carcinogenicity testing in the CD-1 mouse of a prospective insect repellent (KBR 3023) using the dermal route of exposure.

The carcinogenic potential of 1-(1-methyl-propoxycarbonyl)-2-(2-hydroxyethyl)-piperidine (KBR 3023), a prospective new insect repellent intended for human use, was studied in mice using the dermal route of application. Relying upon the toxicology profile that emerged in the subchronic rat bioassay that was conducted using dermally applied dosages of 0, 80, 200, 500, and 1000 mg KBR 3023/kg body weight per day, it was determined, in concert with the EPA, that dermally applied dosages of 0, 50, 100, or 200 mg KBR 3023/kg body weight per day would be used in the conduct of all definitive forms of subchronic, chronic, and lifetime descriptive testing performed with the chemical. Using this testing approach, the specific results of this 18-month study are as follows. All in-life parameters, which included body weight, food consumption, clinical observations, survival, and hematology were unaffected by exposure to KBR 3023. Similarly, postmortem analyses, which included organ weights and gross pathology, and histopathology were also unchanged following exposure to KBR 3023. No evidence of a compound-induced neoplasia was suggested in this bioassay.

Administration, Cutaneous↗
PubMed1999

Chronic toxicity and carcinogenicity testing in the Sprague-Dawley rat of a prospective insect repellant (KBR 3023) using the dermal route of exposure.

The chronic toxicology and carcinogenic potential of 1-(1-methyl-propoxycarbonyl)-2-(2-hydroxyethyl)-piperidine (KBR 3023), a prospective new insect repellent intended for human use, was studied in rats using the dermal route of application. Relying upon the toxicology profile that emerged in the subchronic rat bioassay that was conducted using dermally applied dosages of 0, 80, 200, 500 and 1000 mg KBR 3023/kg body wt/day, it was determined, in concert with the Environmental Protection Agency (EPA), that dermally applied dosages of 0, 50, 100 or 200 mg KBR 3023/kg body wt/day would be used in the conduction of all definitive forms of subchronic, chronic, and lifetime descriptive testing performed with the chemical. Using this testing approach, the specific results of this 2-year study are as follows. All in-life parameters, which included body weight, food consumption, clinical observations, survival, ophthalmology, clinical chemistry, hematology, and urinalysis, were unaffected by exposure to KBR 3023. Similarly, postmortem analyses, which included organ weights and gross pathology, were also unchanged following exposure to KBR 3023. Histopathology at the dose site/skin was characterized by a pattern of acanthosis and/or hyperkeratosis across all doses in 1- and 2-year rats. Beyond the dosing site, cystic degeneration of the liver was described in 2-year 200-mg KBR 3023/kg body wt/day males. No other compound-related non-dosing site lesion was identified at any dose tested. No evidence of a compound-induced neoplasia was suggested in this bioassay.

Administration, Cutaneous↗
PubMed1988

Some cardiovascular effects of the insect repellent N,N-diethyl-m-toluamide (DEET).

Initial toxicological safety evaluations of the insect repellent N,N-diethyl-m-toluamide (DEET) indicated a potential hypotensive effect. The current study was initiated in order to pursue this aspect of DEET toxicity and to elucidate potential mechanisms for this response. Sublethal intraperitoneal injections of DEET in anesthetized rats were found to decrease mean blood pressure and heart rate in a dose-related fashion. Doses ranged from 56 to 225 mg/kg. Dogs treated with 225 mg/kg of DEET exhibited a similar hypotension and bradycardia. Cardiac output was also significantly reduced but stroke volume and total peripheral resistance were not altered. Lead II ECG changes included small increases in P-R and Q-T intervals. In a series of pharmacological studies in rats, DEET was found to decrease the hypotension and bradycardia associated with acetylcholine injection; epinephrine, norepinephrine, and histamine responses were not altered. Atropine pretreatment reduced but did not eliminate the hypotensive effects of DEET.

Acetylcholine↗
PubMed2001

Insect repellent activity of diterpenoid alkaloids.

Diterpenoid and norditerpenoid alkaloids were tested against Tribolium casteneum (Herbst.) in order to assess their repellent activity. Of 29 tested alkaloids, 21 compounds showed promising insect repellent activity, while eight of them were not found to be active. The alkaloids were obtained from Delphinium, Consolida and Aconitum species. The highest activity was found in hetisine, a diterpene alkaloid (59.37%) and the lowest activity in another diterpene alkaloid venulol (31.25%).

Animals↗
PubMed2000

Performance of GC-MS and MOSES II, a hybrid modular sensor system, for the quantitative detection of the evaporation of the insect repellent N,N-diethyl-m-toluamide from two different matrices.

The purpose of this work was to determine the evaporated amount of N,N-diethyl-m-toluamide (DEET), a commonly used insect repellent, from two different matrices medium chain triglycerides (MCT) and Polyethylene glycol 400 (PEG), with GC with mass sensitive detection (GC-MS) and a hybrid modular sensor system (MOSES II). Thus, the binary mixtures are equilibrated at 80 degrees C for 45 min and then an aliquot of this headspace is analyzed by GC-MS and a sensory system consisting of an array of eight metal oxide sensors and eight quartz crystal microbalances. Both analytical methods allow a sensitive detection of even small amounts of DEET in the headspace from binary mixtures with the MCT or PEG, respectively. The two additives are found to be very different concerning their behavior to the vapor phase; i.e., the lipophilic (MCT) delivers an almost constant headspace of DEET, while the hydrophilic matrix PEG releases smaller amounts of DEET, which continuously decrease when a multiple headspace extraction is performed. Furthermore, the results reveal that both analytical methods lead to comparable results with the MCT/DEET mixtures whereas differences were seen with mixtures containing PEG. This can be attributed to the interaction of volatile portions of PEG with the sensors of the MOSES II.

Autoanalysis↗
PubMed2000

Acute effects of an insect repellent, N,N-diethyl-m-toluamide, on cholinesterase inhibition induced by pyridostigmine bromide in rats.

Acute lethal interactions have been previously described between a cholinesterase (ChE) inhibitor, pyridostigmine bromide (PB), and the insect repellent, N,N-diethyl-m-toluamide (DEET). The mechanism of toxic interaction between these agents is unknown. Alterations in membrane permeability caused by DEET could facilitate or enhance absorption, or alter the distribution of peripherally restricted PB, causing increased inhibition of ChE at a given dose. Studies were conducted to investigate PB-induced ChE inhibition in the presence of DEET. Rats received ip injections of PB (1, 2, or 3 mg/kg), DEET (200 mg/kg), or PB + DEET at doses that potentiated acute lethality. ChE activity was measured in heart, diaphragm, blood, whole brain, or specific brain areas using a modified spectrophotometric assay. DEET did not alter PB-induced inhibition of ChE activity in rat diaphragm, heart, or blood. Administration of DEET alone had no effect on ChE activity. PB alone did not inhibit ChE in whole brain, but PB (3 mg/kg) + DEET (200 mg/kg) caused significant inhibition of whole brain ChE activity to approximately 60% of controls. In specific brain areas, (cortex, cerebellum, medulla, hypothalamus, hippocampus, midbrain, and striatum) PB alone did not inhibit ChE activity. PB (3 mg/kg) + DEET (200 mg/kg) reduced ChE activity to approximately 65-75% of controls in each brain area, but those results were not statistically significant. In conclusion, DEET did not alter PB-induced inhibition of ChE activity in the periphery. While DEET may have facilitated the access of PB into the CNS at high doses, it is doubtful that the resulting minor reduction in ChE activity would have resulted in death. It is unlikely that the lethal interaction between PB and DEET is mediated through a cholinergic effect resulting from increased inhibition of ChE.

Animals↗
PubMed1996

Solid-phase extraction and liquid chromatographic quantitation of insect repellent N,N-diethyl-m-toluamide in plasma.

A sensitive and reliable method based on solid-phase extraction and reversed-phase liquid chromatography was developed and validated for the quantitation of insect repellent N,N-diethyl-m-toluamide (DEET) in plasma. N,N-diethyl-2-phenylacetamide was used as internal standard in the extraction which employed C18 solid-phase extraction cartridges. The wash solvent was 3 ml acetonitrile-ammonium acetate (pH 4.5; 0.03 M) (10:90, v/v), and the eluting solvent was 1 ml acetonitrile-ammonium acetate (pH 4.5; 0.03 M) (40:60, v/v). The eluent obtained from the extraction cartridge was directly analyzed on a reversed-phase C8 column with UV detection at 220 nm. A clean chromatogram and high sensitivity were achieved at this wavelength. The mobile phase was acetonitrile-ammonium acetate (pH 4.5; 0.03 M) (36:64 v/v). The retention time was 7.9 min for the internal standard and 9.6 min for DEET when the mobile phase was delivered at 1.0 ml min-1. The overall absolute recovery was 97.7% with a standard deviation (SD) of 3.9 (n = 9) for DEET and 100.2% with a SD of 3.4 (n = 3) for the internal standard. The limit of quantitation was found to be 15 ng ml-1 with a relative standard deviation of 12%. For the analyses of DEET-spiked plasma samples with five replicates each at 50, 500 and 1500 ng ml-1, the overall intra- and inter-day precisions were 5.7% and 5.5% respectively, and the overall intra- and inter-day accuracies were 2.0% and 2.4% respectively. The correlation coefficient for calibration plots in the concentration range 15-1500 ng ml-1 was typically 0.999. The method was applicable to both dog and human plasma samples and was successfully used in pharmacokinetic studies of DEET in beagle dogs after intravenous bolus and topical routes of administration.

Administration, Topical↗
PubMed2004

Insect repellent [correction of repellant] interactions: sunscreens enhance DEET (N,N-diethyl-m-toluamide) absorption.

Toxicology studies are typically performed on single compounds, which we hypothesized would miss adverse synergies from chemical mixtures. This hypothesis was tested using an insect repellant and sunscreens because both groups include known permeation enhancers, with prior pediatric reports of toxicity from highly concentrated DEET (N,N-diethyl-m-toluamide). Using real-time mass spectroscopy in a hairless mouse skin model, we confirmed substantial penetration of a 20% DEET standard. Despite a lower (10%) DEET content, a commercially marketed sunscreen formulation had a 6-fold more rapid detection (5 versus 30 min) and 3.4-fold greater penetration at steady state. We also tested the efficacy of DEET microemulsion products and confirmed that one successfully slowed the onset of absorption, but not the steady-state permeation. Risks from mixtures of potential toxins are worthy of routine testing, which can be accomplished by simple assays, and are of utmost importance for pediatric applications.

Animals↗
PubMed2002

Development and validation of a reversed-phase high-performance liquid chromatographic method for the determination of ethyl-3-(N-n-butyl-N-acetyl)aminopropionate in an insect repellent semi-solid formulation.

A reversed-phase high-performance liquid chromatographic method with detection at 220 nm was developed and validated for the determination of ethyl-3-(N-n-butyl-N-acetyl)aminopropionate, IR 3535, in an insect repellent semi-solid product. A Hypersil ODS RP-C18 column (250 x 4.6 mm), 5 microm particle size, was equilibrated with a mobile phase consisted of water-acetonitrile (60:40, v/v). Its flow-rate was 1.0 ml/min. Excipients did not interfere with the determination of IR 3535 (Rs = 8.663). Intra- and inter-day relative standard deviations for samples were not higher than 0.61 and 1.2%, respectively. Mean recovery was found not lower than 98.5% and not higher than 100.3%. The method of external standard was adopted. Calibration curves were linear in the concentration range between 1.0 x 10(-6) and 5.0 x 10(-4) M. Limits of detection and quantitation were 65 and 196 ng/ml, respectively.

Calibration↗
PubMed1998

Pharmacokinetics, formulation, and safety of insect repellent N,N-diethyl-3-methylbenzamide (deet): a review.

This review is intended to provide the reader with an overview of the all-purpose topical insect repellent N,N-diethyl-3-methylbenzamide (deet), with emphasis on its pharmacokinetics, formulation, and safety aspects. N,N-diethyl-3-methylbenzamide is effective against a variety of mosquitoes, flies, fleas, and ticks, and its protection efficacy depends on factors such as type of formulation, application pattern, physical activity of the user, environment, and species and feeding behavior of the insects. It offers an inexpensive and practical means of preventing the attack of biting insects and, more importantly, the transmission of vector-borne diseases. In both humans and animals, deet skin penetration and biodistribution are rapid and extensive, and metabolism and elimination appear to be complete. As evidenced by over 4 decades of human experience and rigorous animal testing, deet is generally safe for topical use if applied as recommended, although it has occasionally been related to side effects such as toxic encephalopathy, seizure, acute manic psychosis, cardiovascular toxicity, and dermatitis, along with a few cases of death due to extensive skin absorption. N,N-diethyl-3-methylbenzamide may compete in metabolism with and alter the biodistribution properties of other compounds to which a subject is simultaneously exposed, resulting in an added risk of side effects. The appropriate use of formulation techniques and new formulation excipients not only offers a way to extend the duration of protection, but also reduces deet skin penetration. In addition to extended repellency, minimal skin penetration of deet should be an important consideration in the evaluation of a deet formulation during new product development.

Animals↗
PubMed2002

Naphthalene, an insect repellent, is produced by Muscodor vitigenus, a novel endophytic fungus.

Muscodor vitigenus is a recently described endophytic fungus of Paullinia paullinioides, a liana growing in the understorey of the rainforests of the Peruvian Amazon. This fungus produces naphthalene under certain cultural conditions. Naphthalene produced by M. vitigenus was identified by gas chromatography/mass spectrometry. Its chromatographic and mass spectral properties were identical to authentic naphthalene. Agar plugs supporting growth of the fungus and producing known amounts of naphthalene effectively repelled the adult stage of the wheat stem sawfly, Cephus cinctus, in Y-tube bioassay tests. Authentic naphthalene, at comparable concentrations to those in tests involving the fungus itself, mimicked the insect repellency of the fungus. Although other Muscodor spp. produce volatile antimicrobials, M. vitigenus is unique in its ability to produce naphthalene almost exclusively. This report also describes the potential practical implications of M. vitigenus.

Animals↗
PubMed1999

Short report: prevention of Schistosoma mansoni infections in mice by the insect repellents AI3-37220 and N,N-diethyl-3-methylbenzamide.

N,N-diethyl-3-methylbenzamide (DEET) has recently been reported to kill cercariae of Schistosoma mansoni in vitro. In addition, it blocked cercarial entry into mouse tail skin. We confirmed these results and compared the efficacy of DEET to a second insect repellent, 1-(3-Cyclohexen-1-yl-carbonyl)-2-methylpiperidine (AI3-37220), in preventing S. mansoni infections in mice. Both AI3-37220 and DEET conferred 100% protection against S. mansoni infection via percutaneous exposure to cercariae.

Animals↗
PubMed2001

Safety of the insect repellent N,N-diethyl-M-toluamide (DEET) in pregnancy.

The safety of daily application of N, N-diethyl-m-toluamide (DEET) (1.7 g of DEET/day) in the second and third trimesters of pregnancy was assessed as part of a double-blind, randomized, therapeutic trial of insect repellents for the prevention of malaria in pregnancy (n = 897). No adverse neurologic, gastrointestinal, or dermatologic effects were observed for women who applied a median total dose of 214.2 g of DEET per pregnancy (range = 0-345.1 g). DEET crossed the placenta and was detected in 8% (95% confidence interval = 2.6-18.2) of cord blood samples from a randomly selected subgroup of DEET users (n = 50). No adverse effects on survival, growth, or development at birth, or at one year, were found. This is the first study to document the safety of DEET applied regularly in the second and third trimesters of pregnancy. The results suggest that the risk of DEET accumulating in the fetus is low and that DEET is safe to use in later pregnancy.

Administration, Cutaneous↗
PubMed1992

Carbon dioxide released from human skin: effect of temperature and insect repellents.

Measurement with an infrared analyzer of CO2 given off by the hands of human volunteers under laboratory conditions showed that they continuously produced CO2 at the rate of 1.0-1.8 ml/h. Increased production of CO2 was observed with increase in temperature for all subjects. Treatment of subjects with three insect repellents or ethanol resulted in a short-term drop in CO2 production, after which it returned to pretreatment levels. Olfactometer studies showed no correlation between the amount of CO2 produced by hands and the attractancy of the subjects to host-seeking female Ae. aegypti (L.). The supplemental addition of five times the amount of CO2 given off by the hands did not affect attractancy of subjects to mosquitoes. The amount of CO2 released by hands is negligible compared to ambient levels of 300 ppm, and it is unlikely to be attractive at this level of release by itself.

Animals↗
PubMed2003

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

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.

Animals↗