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PubMed1992

Effect of the mosquito repellent DEET and long-wave ultraviolet radiation on permeation of the herbicide 2,4-D and the insecticide DDT in natural rubber gloves.

Studies were conducted to determine the effect of a commonly used insect repellent, DEET (N,N-diethyl-m-toluamide), on the permeability of rubber gloves used as chemical protective clothing (CPC) by pesticide applicators. Glove permeation analysis was conducted with an automated in vitro diffusion analysis (AIDA) method employing an in-house, flow-through permeation cell design. Permeation of 14C-ring-labeled 2,4-D (2,4-dichlorophenoxyacetic acid) in natural rubber glove material was 2.4 +/- 1.81% at 48 hr after treatment of the glove with 2,4-D applied with DEET; this was not significantly different (Student's t-test; p less than 0.05) from 3.2 +/- 3.46% permeation of 2,4-D observed without DEET. Similarly, there was no significant difference between the permeation of pp'-DDT (1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane) applied with DEET (11.7 +/- 5.02%) and without DEET (11.4 +/- 4.86%) to natural rubber glove material. Scanning electron microscopy of the natural rubber glove material, however, demonstrated disruption of the surface ultrastructure following a 24-hr treatment with DEET. The AIDA analysis also suggested that exposure of the glove material to long-wave ultraviolet (UVA) radiation enhanced the glove permeability to 2,4-D (6.2 +/- 0.73% [+UVA]; 0.3% +/- 0.14% [-UVA]) but had no effect on the permeation of DDT. Because the CPC of pesticide applicators is commonly exposed to solar UVA, this finding may raise concerns about the efficacy and safety of CPC in general.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2001

Prevention of Lyme disease: a review of the evidence.

The Healthy People 2010 public health goals targeted a 44% decrease in the incidence of Lyme disease, the most commonly reported tick-borne illness in the United States. To review Lyme disease prevention, clinical trials, epidemiological and experimental studies, and predictive models were evaluated. Geographic distribution of ixodid vectors and local landscape predict Lyme disease risk. Density of infected ticks correlates with incidence and prevalence of Lyme disease, but risk quantitation is made uncertain by tick aggregation and inability to predict tick-human interactions. Outdoor activities are inconsistently or weakly associated with risk, and most infections likely occur in residential areas during routine activities. Tick control (burning or removing vegetation, acaricide use, and deer elimination) reduces Ixodes scapularis populations by up to 94%, and acaricide application to wildlife decreases nymphal I scapularis populations by up to 83%. The effect of these strategies on incidence of Lyme disease in humans is unknown. Studies show that only 40% to 50% of adults take precautions against tick bites even when they are aware of Lyme disease. Effective protection afforded by personal precautions (wearing protective clothing, avoiding ticks, and using insect repellant) has not been shown prospectively. Antimicrobial prophylaxis of tick bites is not warranted. Clinical trials showed vaccines containing recombinant OspA of Borrelia burgdorferi to be efficacious and well tolerated. Currently, vaccination is the only empirically demonstrated method to prevent Lyme disease. The best evidence supports prevention efforts focused on practices that encourage immunization, Lyme disease awareness, and possibly treatment of deer.

Adult↗
PubMed2026

A high-quality chromosome-level genome assembly of apple of Peru (Nicandra physalodes).

Nicandra physalodes, a member of the Solanaceae family, is known for its medicinal potential and strong natural insect-repellent properties, which are mainly attributed to its bioactive withanolides and alkaloids. Despite its ecological and pharmacological significance, genomic information for this species has remained limited. Here, we generated a chromosome-level reference genome for N. physalodes based on PacBio high-fidelity (HiFi) long-read sequencing and Hi-C scaffolding. The assembled genome is 933.97 Mb in size, with a contig N50 of 87.37 Mb, and 99.95% (933.54 Mb) of the sequences anchored to 10 pseudochromosomes. Repetitive elements account for 73.06% of the genome, and 27,925 protein-coding genes were predicted, 97.81% of which were functionally annotated. This genomic resource provides a valuable foundation for investigating the genetic basis of specialized metabolite biosynthesis, insect resistance, and environmental adaptation in N. physalodes, as well as for comparative studies within the Solanaceae family.

Genome, Plant↗
PubMed1998

Deployed US Army soldiers' knowledge and use of personal protection measures to prevent arthropod-related casualties.

The recommendation to use personal protection measures (PPMs) to prevent arthropod-related diseases and nuisance bites is a common element of travel medicine consultation.1-3 Prevention of arthropod-related casualties is especially important to the military, given the often intense exposure of service members to biting arthropods and the threat of personnel losses to mission success. In the 1980s, 75% deet (N,N-diethyl-m-toluamide) was the US military-issue insect repellent for use on skin and clothing. Collaboration between military and civilian researchers led to the implementation in 1991 of the current US military system of PPMs which has three components: topical application of 33% extended-duration deet, treatment of field uniforms with permethrin, and proper wearing of field uniforms.4-6 Compared to military-issue 75% topical deet, 33% extended-duration deet prevents bites up to three times longer (as long as 12 hours), is less greasy, and has lower plasticizing properties. Field uniforms treated with the contact toxicant, permethrin, are also necessary to minimize bites from crawling arthropods such as ticks and chiggers. Implementation of all three components of this system is a safe and effective means of reducing the threat posed by biting arthropods.7 We conducted a questionnaire survey to assess the degree of deployed soldiers' knowledge of the US military's system of PPMs and use of PPMs in general. Survey results may promote the development of better ways to advise and teach military and civilian travelers about the proper use of PPMs given the multitude of available products and practices.

Adolescent↗
PubMed2006

Prevention of malaria in long-term travelers.

CONTEXT: Long-term travelers, defined here as those traveling for periods of 6 months or longer, face particular challenges regarding malaria prevention. Current guidelines for malaria prevention primarily address prevention of Plasmodium falciparum infections in short-term travelers. OBJECTIVES: To examine the risk of malaria in long-term travelers, recent developments in personal protective measures, and the safety and tolerability of malaria chemoprophylaxis during long-term use and to consider prevention strategies including continuous chemoprophylaxis, stand-by emergency self-treatment, seasonal prophylaxis, and strategies to prevent primary infection and relapses from P vivax malaria. EVIDENCE ACQUISITION: Comprehensive search of scientific publications including MEDLINE via both OVID and PubMED for relevant studies and articles with a cutoff date of July 2006, using the search terms long-term travel and malaria prevention, long-term malaria chemoprophylaxis, and insect repellent and malaria. Additional references were obtained from searching the bibliographies of the selected articles, from dissertations, and from the proceedings of relevant conferences on travel medicine. There were no language restrictions. EVIDENCE SYNTHESIS: Long-term travelers have a higher risk of malaria than short-term travelers. Long-term travelers underuse personal protective measures and adhere poorly to continuous chemoprophylaxis regimens. A number of strategies are used during long-term stays: discontinuation of chemoprophylaxis after the initial period, sequential regimens with different medications for chemoprophylaxis, stand-by emergency self-treatment, and seasonal chemoprophylaxis targeting high-incidence periods or locations. All strategies have advantages and drawbacks. Counterfeit drugs sold in countries endemic for malaria pose serious concern for long-term travelers who purchase their medications overseas. Vivax malaria causes significant illness in travelers, but relapses of vivax malaria are not prevented with the current first-line chemoprophylaxis regimens. Consensus guidelines are needed for prevention of malaria in long-term travelers. CONCLUSIONS: Prevention of malaria in long-term travelers is a complex issue and requires expert advice from travel medicine specialists. Recommendations for prevention of malaria in long-term travelers must be individualized.

Algorithms↗
PubMed1999

Efficacy of the topical skin protectant in advanced development.

A topical skin protectant (TSP) (ICD 2289) is being developed to protect service members from exposure to chemical warfare agents (CWA). The TSP is designed for use on the skin at the overgarment closures and other vulnerable areas to enhance protection. The TSP, which is in phase II clinical studies, is a cream containing two chemically inert substances: perfluoroalkylpolyether and polytetrafluoroethylene. Animal data showed that the TSP was effective against percutaneous penetration of a blister agent, sulfur mustard (HD), by reducing the size of skin lesions and against T-2 mycotoxin by preventing the development of erythema and edema. The insect repellent N,N-diethyl-m-toluamide (DEET) reduced the TSP protection against HD regardless of the order of application on rabbit skin prior to dosing of HD. The protection was sustained when DEET was removed with a dry gauze prior to TSP application. The TSP was also effective against percutaneous exposure of nerve agents-thickened (with 5% methyl methacrylamide) soman (TGD) and VX (O-ethyl-S-[2-(diisopropylamino)ethyl]methylphosphonothioate )-by reducing the mortality rate and protecting the red blood cell acetylcholinesterase activity. The TSP was effective against VX when DEET was applied prior to TSP application. Because human efficacy studies using CWA cannot be conducted, the efficacy will be demonstrated by the level of protection against poison ivy (urushiol) contact dermatitis in humans.

Acetylcholinesterase↗
PubMed2000

Fur rubbing behavior in free-ranging black-handed spider monkeys (Ateles geoffroyi) in Panama.

Members of the population of black-handed spider monkeys (Ateles geoffroyi) on Barro Colorado Island, Panama, use the leaves of three Rutaceae species in a behavior that resembles fur rubbing in the white faced capuchin (Cebus capucinus). This behavior has not been reported from other sites where Ateles has been studied. During more than 1,200 hours of observation, 30 episodes of this behavior were recorded ad libitum. Adult males engage in this behavior more than adult females. Season did not impact the frequency of the behavior. The behavior described here differs in many respects from that reported for Cebus capucinus, and does not fit the hypotheses that the behavior functions in repelling insects or other antiseptic purposes. It is proposed that fur rubbing in this group of spider monkeys is a modification of a behavior previously recorded in Ateles and may function in scent marking.

Animal Communication↗
PubMed2003

In vitro human phase I metabolism of xenobiotics I: pesticides and related compounds used in agriculture and public health, May 2003.

This is the first revision of a database covering human phase I enzymes and their isoforms that metabolize pesticides and related compounds. The original version included enzymes that metabolize chloroacetamide and triazine herbicides, and organophosphorus insecticides. This revision also includes carbamate, nicotinoid, and pyrethroid insecticides and insect repellents.

Agriculture↗
PubMed2002

Coleonema album: studies of the pharmacological action on smooth muscle in vitro and antimicrobial action of its essential oil.

The mode of action of the essential oil of Coleonema album, a South African species from the Cape region, was studied on smooth muscle in vitro using field-stimulated guinea-pig ileum. The oil produced an initial spasmogenic activity followed by spasmolysis, both actions being dose-dependent. The spasmolytic action was post-synaptic and not atropine-like and was unaffected by the adrenoceptor blockers phentolamine and propranolol. There was no evidence for the involvement of either cyclic guanosine monophosphate or cyclic adenosine monophosphate in the spasmolytic activity. The oil had some calcium channel blocking activity but this is not the primary explanation for its spasmolytic response. Antimicrobial activity against Pseudomonas aeruginosa, Escherichia coli, Staphyloccocus aureus and Saccharomyces cerevisiae was very low and totally absent against Enterococcus hirae, suggesting that the oil has no worthwhile potential in this area. However, as the oil has a very disagreeable odour in its undiluted form, it could be a powerful insect repellent, as its local usage suggests, and this remains to be investigated.

Animals↗
PubMed1999

Association of low PON1 type Q (type A) arylesterase activity with neurologic symptom complexes in Gulf War veterans.

Previously Haley et al. described six possible syndromes identified by factor analysis of symptoms in Gulf War veterans and demonstrated that veterans with these symptom complexes were more neurologically impaired than age-sex-education-matched well controls. They also uncovered strong associations (relative risks 4-8) suggesting that these symptom complexes were related to wartime exposure to combinations of organophosphate pesticides, chemical nerve agents, high concentration DEET insect repellant, and symptoms of advanced acute toxicity after taking pyridostigmine. Here we have shown that compared to controls, ill veterans with the neurologic symptom complexes were more likely to have the R allele (heterozygous QR or homozygous R) than to be homozygous Q for the paraoxonase/arylesterase 1 (PON1) gene. Moreover, low activity of the PON1 type Q (Gln192, formerly designated type A) arylesterase allozyme distinguished ill veterans from controls better than just the PON1 genotype or the activity levels of the type R (Arg192, formerly designated type B) arylesterase allozyme, total arylesterase, total paraoxonase, or butyrylcholinesterase. A history of advanced acute toxicity after taking pyridostigmine was also correlated with low PON1 type Q arylesterase activity. Type Q is the allozyme of paraoxonase/arylesterase that most efficiently hydrolyzes several organophosphates including sarin, soman, and diazinon. These findings further support the proposal that neurologic symptoms in some Gulf War veterans were caused by environmental chemical exposures.

Adult↗
PubMed2002

Pyridostigmine bromide modulates the dermal disposition of [14C]permethrin.

The cause of the Gulf War Syndrome may be related to soldiers being exposed to insecticides (e.g., permethrin (P)), insect repellents (e.g., N,N-diethyl-m-toluamide (DEET)), an organophosphate nerve agent simulant (e.g., diisopropyl fluorpohosphate (DFP)), and/or prophylactic treatment (e.g., pyridostigmine bromide (PB)) against potential nerve gas attacks. The purpose of this study was to assess the dermal disposition of [14C]permethrin in ethanol or ethanol:water (3:2) in the isolated perfused porcine skin flap (IPPSF) model with simultaneous dermal exposure to DEET or DFP. These IPPSFs were also simultaneously perfused arterially with or without PB, DFP, or DFP + PB. The results indicated that DFP + PB significantly increased [14C]permethrin absorption compared to controls (1.06% dose vs 0.14% dose). PB significantly increased [14C]permethrin disposition in the stratum corneum (SC) in aqueous mixtures only (9.40 vs 3.35% dose), while topical DEET or topical DFP reduced [14C]permethrin levels in the SC especially in nonaqueous mixtures. PB also significantly enhanced [14C]permethrin penetration into all skin tissues and perfusate in aqueous mixtures, while DEET reversed this effect. PB appeared to influence [14C]permethrin disposition in flowthrough diffusion cells, suggesting that the mechanism of this interaction may be associated predominantly with epidermal permeability, although muscarinic effects in the vasculature in IPPSFs should not be ruled out and requires further investigation. These experiments suggest that intraarterial perfusion of PB and/or DFP and topical application of DFP or DEET can alter the disposition of [14C]permethrin in skin and possibly its bioavailability in soldiers simultaneously exposed to these chemicals.

Animals↗
PubMed2006

Self-anointing behavior in free-ranging spider monkeys (Ateles geoffroyi) in Mexico.

During 250 h of observation, a total of 20 episodes of self-anointing, that is, the application of scent-bearing material onto the body, were recorded in a group of free-ranging Mexican spider monkeys (Ateles geoffroyi). The animals used the leaves of three species of plants (Brongniartia alamosana, Fabaceae; Cecropia obtusifolia, Cecropiaceae; and Apium graveolens, Umbelliferae) two of which have not been reported so far in this context in any New World primate species. The findings that only two males displayed self-anointing, that only the sternal and axillary regions of the body were rubbed with the mix of saliva and plant material, and a lack of correlation between the occurrence of self-anointing and time of day, season of the year, ambient temperature or humidity do not fit the hypothesis that this behavior functions in repelling insects and/or mitigating topical skin infections in this species. Rather, the data and the observation that the leaves of all three plant species spread an intensive and aromatic odor when crushed, support the hypothesis that self-anointing in A. geoffroyi may play a role in the context of social communication, possibly for signaling of social status or to increase sexual attractiveness.

Animal Communication↗
PubMedDate not supplied

Approaches to vector control: new and trusted. 4. Appropriate technology for vector control: impregnated bed nets, polystyrene beads and fly traps.

There are social, economic and entomological problems with conventional insecticidal spraying methods for vector control. There is therefore interest in alternative technologies, especially the impregnation of bed nets with pyrethroid insecticides against malaria vectors. This method is cheap, socially acceptable and effective where bed nets are already widely used and where malaria transmission is not very intense. In holoendemic areas, and where people consider bed nets unaffordable, there are still unanswered questions. Whether pyrethroid resistance will be selected in anophelines also deserves more attention than it has so far attracted. Where Culex mosquitoes breed in confined sites such as pit latrines, the application of floating layers of polystyrene beads is a long-lasting and effective control method. There is increasing evidence that house flies are important agents in the mechanical transmission of diarrhoea due to Shigella. Simple fly traps can be an effective way of controlling house fly populations and this deserves comprehensive testing in tropical countries.

Animals↗
PubMed1979

Potential halogenated industrial carcinogenic and mutagenic chemicals. IV. Halogenated aryl derivatives.

A variety of halogenated aryl derivatives possess significant activity as solvents for pesticides, heat transfer agents, pesticide intermediates, additives for rubber products, intermediates in organic synthesis and as insect repellants and deodorants. Ortho- and para-dichlorobenzenes; 1,2,4-trichloro- and hexachlorobenzene, as well as bromobenzenes and benzylchloride were reviewed principally in terms of their synthesis, areas of utility, stability, distribution, reactivity, levels of exposure, populations at risk, metabolism, carcinogenicity and mutagenicity.

Animals↗
PubMed1993

Relevance of enantiomeric separations in environmental science.

A significant number of all organic chemicals that are released into the environment are racemic mixtures. Most environmental regulations and scientific environmental studies treat racemic mixtures as though they were single, pure compounds. This can lead to incorrect toxicological, distribution, degradation and other data. A series of new enantioselective chromatographic techniques have been developed that allow the facile separation and quantitation of chiral compounds of environmental importance. Nineteen racemic compounds that have been or currently are being released to the environment are resolved. These include: rodenticides--Warfarin, Coumachlor and Coumafuryl; insecticides--Crufomate, Bulan, Fonofos, Mitotane; insect repellent--Ethohexadiol; herbicides and fungicides--Ancymidol, Silvex, Napropamide, phenyl mercuric lactate, 2-[3-chlorophenoxy]propionamide, and 2-chloropropionic acid; and halocarbons-1,2-dichloropropane, 2-bromo-1-chloropropane, 1,2-dibromo-3-chloropropane, 2,3-dichlorobutane and alpha-1,2,3,4,5,6-hexachlorocyclohexane. Several examples are given to illustrate the importance of enantioselective measurements of these and other compounds. Choosing the proper chromatographic technique and chiral stationary phase based on analyte structure is also discussed.

Journal Article↗
PubMed1992

A comparison of the acute toxicity, neuropathology, and electrophysiology of N,N-diethyl-m-toluamide and N,N-dimethyl-2,2-diphenylacetamide in rats.

The insect repellent DEET and the structurally related herbicide diphenamid both cause ataxia associated with a spongiform myelinopathy largely confined to the cerebellar roof nuclei. This local myelinopathy was accompanied by the formation of neuronal cytoplasmic clefts and was produced by a single dose of 1 to 3 g/kg N,N-diethyl-m-toluamide (DEET). These dose levels also produced a severe and often fatal prostration and clear electrophysiological signs of prolonged suppressed seizure activity. Diphenamid produced an identical myelinopathy after doses of 0.8 to 1.5 g/kg but without the severe prostration, suppressed seizures, or neuronal clefts. The effects of diphenamid were shown to be reversible over 3 to 7 days by neuropathological, motor, and auditory evoked response indices. Both compounds caused characteristic changes in auditory evoked response which may be useful in clinical diagnosis. Six other alkyl amides, two of which produce signs of CNS excitation, failed to produce myelinopathy at the maximum tolerated doses. Our findings show close parallels with a number of human cases of DEET poisoning and indicate that other amides, like diphenamid, also pose a potential hazard.

Aging↗
PubMed1988

In vitro and in vivo evaluation of the genotoxic potential of 2-ethyl-1,3-hexanediol.

2-Ethyl-1,3-hexanediol (EHD) has intentional human exposure because of its application to skin as an insect repellent and its use in various skin care products. Genotoxicity studies on EHD were conducted to determine mutagenic and clastogenic potential using in vitro and in vivo test systems. In vitro tests were conducted both with and without an Aroclor-induced, rat-liver S9 metabolic activation system and within a range of cytotoxic to non-cytotoxic doses. EHD did not produce dose-related positive increases in gene mutations in the Salmonella (Ames) test or in the CHO/HGPRT forward mutation test. No statistically significant or dose-related increases in sister chromatid exchanges indicative of DNA damage were produced by EHD in CHO cells. Small but statistically significant increases in chromosome aberrations were produced in CHO cells only in tests with S9 activation. However, no evidence of clastogenicity of EHD was obtained in vivo in a mouse peripheral blood micronucleus test or in 2 rat bone marrow chromosome aberration studies using single or repeated dosing procedures. The overall negative pattern of mutagenic and clastogenic results in the majority of tests conducted suggests that EHD is unlikely to pose significant hazard as a genotoxic agent or to possess carcinogenic initiating activity in animals.

Animals↗