question: Why is deet in insect repellents bad for us humans?
comment: It seems to have a low but existent correlation with neurological effects like seizures and mood disorders and in extreme cases brain damage. However, this generally comes from high exposure and appears to be rare. I don't believe the mechanism of action is known.
passages: Insect repellents containing DEET are the most effective. The concentration of DEET in products may range from less than 10 percent to nearly 100 percent. The benefits of DEET reach a peak at a concentration of 30 percent, the maximum concentration currently recommended for infants and children. DEET should not be used on children under 2 months of age.
   DEET is commonly used in combination with insecticides and can strengthen the toxicity of carbamate insecticides, which are also acetylcholinesterase inhibitors. These findings indicate that DEET has neurological effects on insects in addition to known olfactory effects, and that its toxicity is strengthened in combination with other insecticides.
  
  Section::::Effects on health.:Detection in body fluids.
   The authors of a 2002 study published in The New England Journal of Medicine wrote, "DEET has a remarkable safety profile after 40 years of use and nearly 8 billion human applications. When applied with common sense, DEET-based repellents can be expected to provide a safe as well as long-lasting repellent effect. Despite the substantial attention paid by the lay press every year to the safety of DEET, this repellent has been subjected to more scientific and toxicological scrutiny than any other repellent substance."
   Citing human health reasons, Health Canada barred the sale of insect repellents for human use that contained more than 30% DEET in a 2002 re-evaluation. The agency recommended that DEET-based products be used on children between the ages of 2 and 12 only if the concentration of DEET is 10% or less and that repellents be applied no more than 3 times a day, children under 2 should not receive more than 1 application of repellent in a day and DEET-based products of any concentration should not be used on infants under 6 months. Some experts recommend against applying DEET and sunscreen simultaneously since that would increase DEET penetration; Xiaochen Gu, a professor at the University of Manitoba’s faculty of Pharmacy who led a study about mosquitos, advises that DEET should be applied 30 or more minutes later. 
   DEET
  
  "N","N"-Diethyl-"meta"-toluamide, also called DEET () or diethyltoluamide, is the most common active ingredient in insect repellents. It is a slightly yellow oil intended to be applied to the skin or to clothing and provides protection against mosquitoes, ticks, fleas, chiggers, leeches and many biting insects.
  
  Section::::History.
   In the DEET Reregistration Eligibility Decision (RED) the United States Environmental Protection Agency (EPA) reported 14 to 46 cases of potential DEET associated seizures, including 4 deaths. The EPA states: "... it does appear that some cases are likely related to DEET toxicity," but observed that with 30% of the US population using DEET, the likely seizure rate is only about one per 100 million users.
   DEET is often sold and used in spray or lotion in concentrations up to 100%. "Consumer Reports" found a direct correlation between DEET concentration and hours of protection against insect bites. 100% DEET was found to offer up to 12 hours of protection while several lower concentration DEET formulations (20–34%) offered 3–6 hours of protection. Other research has corroborated the effectiveness of DEET. The Centers for Disease Control and Prevention recommends 30–50% DEET to prevent the spread of pathogens carried by insects.
  
  Section::::Effects on health.
   Within countries of the European Union, implementation of Regulation 98/8/EC, commonly referred to as the Biocidal Products Directive, has severely limited the number and type of insect repellents available to European consumers. Only a small number of active ingredients have been supported by manufacturers in submitting dossiers to the EU Authorities.
   Section::::Mechanism and effectiveness.
  
  DEET was historically believed to work by blocking insect olfactory receptors for 1-octen-3-ol, a volatile substance that is contained in human sweat and breath. The prevailing theory was that DEET effectively "blinds" the insect's senses so that the biting/feeding instinct is not triggered by the chemicals present in the sweat and breath of humans or other animals. DEET does not appear to affect the insect's ability to smell carbon dioxide, as had been suspected earlier.
   Section::::Prevention.
  
  Prevention can be partially achieved through limiting contact with vectors through the use of DEET and other repellents, but due to the predominantly relatively mild symptoms and the infection being generally asymptomatic, little has formally been done to control the disease.
  
  Section::::Treatment.
   In 2015, Researchers at New Mexico State University tested 10 commercially available products for their effectiveness at repelling mosquitoes. On the mosquito "Aedes aegypti", the vector of Zika virus, only one repellent that did not contain DEET had a strong effect for the duration of the 240 minutes test: a lemon eucalyptus oil repellent. All DEET-containing mosquito repellents were active.
   A 2011 structural study (PDB: 3N7H) revealed that DEET binds to "Anopheles gambiae" odorant binding protein 1 (AgamOBP1) with high shape complementarity, suggesting that AgamOBP1 is a molecular target of DEET and perhaps other repellents.
  
  A 2013 study suggests that mosquitoes can at least temporarily overcome or adapt to the repellent effect of DEET after an initial exposure, representing a non-genetic behavioral change. This observation, if verified, has significant implications for how repellent effectiveness should be assessed.
  
  Section::::Concentrations.
   Over-the-counter repellents with high concentrations of DEET or picaridin are proven to work, but may not be suitable for some people, e.g. people with sensitive skin and pregnant women. However, the effectiveness of DEET and picaridin products seems to differ among individuals with some people reporting better results with one product over another while other people finding neither product effective for them. This may be partially due to various species living in different areas.
  
  A particular extract of Lemon Eucalyptus oil (not the essential oil) has now been shown to be as effective as DEET in various studies.
   Though DEET is not expected to bioaccumulate, it has been found to have a slight toxicity for fresh-water fish such as rainbow trout and tilapia, and it also has been shown to be toxic for some species of freshwater zooplankton. DEET has been detected at low concentrations in water bodies as a result of production and use, such as in the Mississippi River and its tributaries, where a 1991 study detected levels varying from 5 to 201 ng/l.
  
  Section::::See also.
  
  BULLET::::- Beautyberry
  
  BULLET::::- Citronella oil
  
  BULLET::::- DDT, another means of disease vector control
  
  BULLET::::- Icaridin
  
  BULLET::::- Lemon eucalyptus
   A test of various insect repellents by an independent consumer organization found that repellents containing DEET or picaridin are more effective than repellents with "natural" active ingredients. All the synthetics gave almost 100% repellency for the first 2 hours, where the natural mosquito repellent products were most effective for the first 30 to 60 minutes, and required reapplication to be effective over several hours.
   Regardless of which repellent product used, it is recommended to read the label before use and carefully follow directions. Usage instructions for repellents vary from country to country. Some insect repellents are not recommended for use on younger children.
   One example of the consequences of the exposure of developing animals, including humans, to hormonally active agents is the case of the drug diethylstilbestrol (DES), a nonsteroidal estrogen and not an environmental pollutant. Prior to its ban in the early 1970s, doctors prescribed DES to as many as five million pregnant women to block spontaneous abortion, an off-label use of this medication prior to 1947. It was discovered after the children went through puberty that DES affected the development of the reproductive system and caused vaginal cancer. The relevance of the DES saga to the risks of exposure to endocrine disruptors is questionable, as the doses involved are much higher in these individuals than in those due to environmental exposures.
   There are also products available based on sound production, particularly ultrasound (inaudibly high frequency sounds) which purport to be insect repellents. However, these electronic devices have been shown to be ineffective based on studies done by the United States Environmental Protection Agency and many universities.
  
  Section::::Repellent safety for humans.
  
  Regarding safety with insect repellent use on children and pregnant women:
  
  BULLET::::- Children may be at greater risk for adverse reactions to repellents, in part, because their exposure may be greater.
  
  BULLET::::- Keep repellents out of the reach of children.
  
  BULLET::::- Do not allow children to apply repellents to themselves.
   BULLET::::- Use only small amounts of repellent on children.
  
  BULLET::::- Do not apply repellents to the hands of young children because this may result in accidental eye contact or ingestion.
  
  BULLET::::- Try to reduce the use of repellents by dressing children in long sleeves and long trousers tucked into boots or socks whenever possible. Use netting over strollers, playpens, etc.
  
  BULLET::::- As with chemical exposures in general, pregnant women should take care to avoid exposures to repellents when practical, as the fetus may be vulnerable.
   The Environmental Protection Agency has determined that exposure levels from eating crops treated with Naled are below the level of concern. With higher exposures, however, naled can cause cholinesterase inhibition in humans, which in turn can overstimulate the nervous system causing nausea, dizziness, confusion, and at very high exposures, respiratory paralysis and death. It has the UN hazard classification of "6.1" (inhalation hazard) and is prohibited for use as an insecticide within the EU.
   Chemical repellents mimic natural substances that repel or deter animals, or they are designed to be so irritating to a specific animal or type of animal that the targeted animal will avoid the protected object or area. Some chemical repellents combine both principles.
   Two mutations, the valine to leucine mutation (V419L) and the leucine to isoleucine mutation (L925I) in voltage-gated sodium channel α-subunit gene, have been identified as responsible for knockdown resistance to deltamethrin in bed bugs. One study found that 88% of bed bug populations in the US had at least one of the two mutations, if not both, meaning that deltamethrin resistance among bed bugs is currently making this insecticide obsolete.
  
  Section::::Poisoning.
  
  Section::::Poisoning.:In humans.
   BULLET::::1. Aldrin, an insecticide used in soils to kill termites, grasshoppers, Western corn rootworm, and others, is also known to kill birds, fish, and humans. Humans are primarily exposed to aldrin through dairy products and animal meats.
   According to the American Mosquito Control Association's Web site, N,N-diethyl-3-methylbenzamide (DEET) remains the standard by which all other repellents are judged. DEET was developed by the U.S. Department of Agriculture and was registered for use by the general public in 1957. It is effective against mosquitoes, biting flies, chiggers, fleas and ticks. These insect repellents slowly evaporate into the air, producing an invisible chemical barrier around the areas on the body and clothes where it is applied, repelling incoming insects.
   BULLET::::- Research has shown that cinnamon oil, clove oil, and eugenol are effective snake repellents. Snakes will retreat when sprayed directly with these oils and will exit cargo or other confined spaces when these oils are introduced to the area.
  
  BULLET::::- In ancient times the Greek historian Herodotus noted that Arabian harvesters of frankincense used burning resin from "Styrax" trees to repel poisonous snakes that lived in the trees.
  
  BULLET::::- Camphor
  
  BULLET::::- Moth balls
  
raw_presuppositions: Deet in insect repellents is bad for us humans.
raw_corrections: Neurological effects due to high exposure to DEET are rare and only from high exposure.