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

Association of N, N-diethyl-m-toluamide (DEET) with hyperuricemia among adult participants

BACKGROUND

N,N-diethyl-m-toluamide (DEET) is a widely used active ingredient in insect repellents, and its effects on human health have been a matter of debate. This study aims to investigate the relationship between DEET exposure and hyperuricemia in the adult population.

METHODS

Our study utilized a cross-sectional design and analyzed data from adult participants of the National Health and Nutrition Examination Survey (NHANES) conducted between 2007 and 2016. 3-diethyl-carbamoyl benzoic acid (DCBA) was used as a specific indicator of DEET exposure. DCBA was categorized using quartiles based on its distribution within the study population. Multiple linear regression models were employed to examine the association between DCBA exposure and serum uric acid (SUA) levels in adults. The relationship between DCBA and the prevalence of hyperuricemia in adults was assessed using multiple logistic regression models. Dose-response relationships were analyzed using restricted cubic spline regression.

RESULTS

A total of 8708 participants were included in the study. The mean age of the participants was 46.49 years, and the total number of male participants was 50.93%. The median levels of DCBA and SUA were 2.07 ng/mL and 5.40 mg/dL, respectively. Hyperuricemia was found in 19.99% of the participants. In multivariate-adjusted linear regression models, it was found that higher SUA levels were associated with the highest quartile of DCBA compared with the lowest quartile of DCBA (β [95% CI]: 0.19 [0.08, 0.30], Ptrend<0.001). After adjusting for confounders, a positive association was found between the prevalence of hyperuricemia and DCBA levels (OR [95% CI] quartile 4 vs. 1: 1.41 [1.14-1.74], Ptrend<0.001). Furthermore, linear associations were observed between DCBA concentrations and SUA levels (P for nonlinearity = 0.479) and the prevalence of hyperuricemia (P for nonlinearity = 0.755).

CONCLUSION

Higher DCBA concentrations were found to have a positive association with the prevalence of hyperuricemia in the general adult population.

Insect repellents: An updated review for the clinician

Malaria, Zika virus, West Nile virus, Dengue fever, and Lyme disease are common causes of morbidity and mortality around the world. While arthropod bites may cause local inflammation and discomfort, a greater concern is the potential to develop deadly systemic infection. The use of insect repellents (IRs) to prevent systemic infections constitutes a fundamental public health effort. Cost effectiveness, availability, and high efficacy against arthropod vectors are key characteristics of an ideal IR. Currently, numerous IRs are available on the market, with N,N-diethyl-3-methylbenzamide (DEET) being the most widely used. DEET has an excellent safety profile and remarkable protection against mosquitoes and various other arthropods. Other Environmental Protection Agency-registered IR ingredients (eg, permethrin, picaridin, IR3535, oil of lemon eucalyptus, oil of citronella, catnip oil, and 2-undecanone) are alternative IRs of great interest because some of these ingredients have efficacies comparable to that of DEET. These alternative IRs possess low toxicity and favorable customer experiences in use (eg, cosmetically pleasant, naturally occurring). This review summarizes the currently available Environmental Protection Agency-registered IRs, including their origins, mechanisms of action, side effect profiles, and available formulations. This review will enable the clinician to select the best IR option to meet a patient's needs and provide the greatest protection from arthropod bites and their sequelae.

Exposure to N,N-diethyl-m-toluamide and cardiovascular diseases in adults

Although growing evidence suggests that N,N-diethyl-m-toluamide (DEET) has adverse effects on public health, the relationship of DEET with cardiovascular disease (CVD) is still largely unknown. The purpose of this study was, therefore, to evaluate the association between DEET exposure and total and specific CVD among the US adults. In this cross-sectional study, a total of 5,972 participants were selected from the National Health and Nutrition Examination Survey (NHANES) 2007-2014. CVD was defined as a combination of congestive heart failure (CHF), coronary heart disease (CHD), angina, heart attack, or stroke. Logistic regression models were used to evaluate the association between DEET metabolites and the risks of total and specific CVD. Compared to the lowest quartile, 3-(diethylcarbamoyl) benzoic acid (DCBA) in the highest quartile was associated with the increased risks of CVD (odds ratio [OR]: 1.32, 95% CI: 1.03-1.68, P for trend = 0.025) and CHD (OR: 1.57, 95% CI: 1.10-2.25, P for trend = 0.017), after adjustment for potential covariates. Nevertheless, exposure to DCBA was not significantly associated with heart attack, CHF, angina, and stroke. Further studies are required to confirm these findings and identify the underlying mechanisms.

Is DEET a dangerous neurotoxicant?

Controversies surrounding the safety of N,N-diethyl-meta-toluamide (DEET) when used as an insect repellent are centered around conflicting findings in the scientific literature and inaccurate reporting in the public media. Lethal cases of DEET poisoning are few, and usually due to deliberate or other overdoses that ignore product label instructions. Deleterious effects of DEET typically involve skin reactions and even when encephalopathies, such as seizures, occur they often abate without sequelae. Recent mode-of-action studies prove it has little direct effect on acetylcholinesterase, and have identified G protein-coupled receptors as a site of action deserving of further investigation. Studies with pregnant women found that DEET had no effect on the developing fetus from proper use and its continued deployment as a repellent is endorsed by both the Centers for Disease Control and Prevention and the Environmental Protection Agency, with specific recommendations of how it should be used on children. © 2019 Society of Chemical Industry.

Cardiorespiratory effects following acute exposure to pyridostigmine bromide and/or N,N-diethyl-m-toluamide (DEET) in rats

The acute lethal interaction that occurs in rodents when high doses of a peripherally restricted cholinesterase inhibitor, pyridostigmine bromide (PB), and the insect repellent N, N-diethyl-m-toluamide (DEET) are combined was first described during studies of chemical mixtures that were targeted as potential causative agents of Gulf War illnesses. This study was intended to provide insight into possible mechanisms of that lethal interaction. Following a single intraperitoneal injection of PB (2 mg/kg) and/or DEET (300 or 500 mg/kg), respiratory activity was measured in conscious freely moving rats using whole-body plethysmography. Cardiovascular function was also monitored simultaneously through an arterial catheter. PB (2 mg/kg) given alone stimulated respiration and increased blood pressure. Arterial pH levels were decreased, whereas pO(2) and pCO(2) remained at control levels. Administration of DEET (300 mg/kg) alone increased tidal volume and decreased blood pressure. Blood gases and pH levels were unaltered. A higher dose of DEET (500 mg/kg) also decreased respiratory and heart rate. Coadministration of PB (2 mg/kg) and DEET (300 mg/kg) increased tidal volume, decreased arterial pH, and elevated pCO(2). Heart rate and blood pressure declined progressively after drug coadministration. Pretreatment with atropine methyl nitrate (AMN), a peripherally selective competitive antagonist at nicotinic and muscarinic receptor sites, reduced the individual effects of PB or DEET, and significantly increased survival after coexposure to these agents. Although changes in respiratory function may have contributed to the lethal interaction, it was concluded that the primary cause of death was circulatory failure.

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.

Duration of repellency of various synthetic and plant-derived preparations for Culicoides imicola, the vector of African horse sickness virus

Objectives of the study were threefold: to find a safer and longer lasting repellent of the biting midge Culicoides imicola than di-ethyl toluamide (DEET), to examine whether the current recommendations in Israel for application of repellents during an outbreak of C. imicola-borne pathogens are justified; and to examine whether plant-derived preparations that have no known detrimental side effects are potential replacements of synthetic repellents. Of the seven repellents tested, those inferior to DEET were: oregano and Herbipet which showed a slight non-significant repellency for 2 h and 1 h respectively and Stomoxin which showed significant (P < 0.05) repellency for only 1 h. As the active ingredient of Stomoxin is permethrin, this suggests that recommendations to spray animals with this insecticide to prevent the spread of C. imicola-borne pathogens are not useful. Tri-Tec14 showed significant (P < 0.05) repellency with respect to controls for 2 h only, but performed similarly to, or slightly better than DEET. The repellents clearly superior to DEET were: the plant-derived material Ag1000 that repelled significantly (P < 0.05) with respect to controls for up to 4 h following a similar pattern to but somewhat more strongly than DEET, and pyrethroid-T which exerted significant (P < 0.05) repellency for 9 h. Pyrethroid-T proved to be the best repellent tested and if sprayed nightly it might provide protection from C. imicola-borne pathogens.

Insect repellent (N,N-diethyl-m-toluamide) cardiovascular toxicity in an adult

OBJECTIVE

To describe a case of N,N-diethyl-m-toluamide (DEET)-induced cardiovascular toxicity in an adult and reviews other cases that have been reported in the published literature. Human and animal data available on DEET pharmacokinetics are reviewed and factors that predispose an individual to DEET toxicity are identified.

DATA SOURCES

Case report information was obtained through personal contact with the patient during hospitalization and by telephone, and also from the patient's medical records. Computerized literature searches were conducted with the following systems to obtain medical literature on DEET toxicity: TOXLINE, International Pharmaceutical Abstracts, and MEDLINE. Index Medicus was searched manually.

STUDY SELECTION

All reported cases of DEET toxicity in children and adults were reviewed.

DATA EXTRACTION

Case reports were evaluated for the quantity of the DEET exposure (topical or oral), the clinical manifestations of the exposure, and the outcome of the exposure.

DATA SYNTHESIS

This case is similar in some aspects to those already in the literature; however, very few cases of DEET toxicity in adults have been reported. Cardiovascular toxicity in humans related to DEET application has not been previously reported in the published medical literature. DEET exposure (topical or oral) results in a highly variable clinical course. Whether the outcome is death or recovery without sequelae is difficult to predict.

CONCLUSIONS

Adults, as well as children, are at risk for toxicity from insect repellents. The use of highly concentrated DEET-containing insect repellents should be avoided to reduce the risk of toxicity in both children and adults. The consequences of DEET toxicity are variable and unpredictable.