Mosquito repellent and mosquito repellent every year, why am I still bitten every year? Today we have intimately launched a mosquito repellent product selection guide, which can make you less fooled when choosing mosquito repellent products - you know, less fooling means less bites.
A mosquito that sucked a mouthful of blood: this blood is not fresh (Image source: watermark)
Why do you need chemical mosquito repellent?
There are two ways to get mosquitoes, one is to kill them directly, and the other is to repel mosquitoes.
Obviously, mosquitoes have been fighting humans for millions of years, and trying to kill them all is tantamount to dreaming. Although there are many types of insecticides today, there is still no way to extinct the mosquito species. Can't kill mosquitoes, we can drive away mosquitoes. The method of physical mosquito repellent has been used by ancestors, and in the Spring and Autumn period more than 2,000 years ago, we Chinese used mosquito nets. It has been used to this day, and the effect is still good. But the problem is, no one can carry mosquito nets around. Therefore, chemical mosquito repellent is still needed.
Whether it is the WHO (World Health Organization) or the CDC (Centers for Disease Control and Prevention), NPIC (National Pesticide Information Center), these authorities recommend chemical mosquito repellent compounds including the following three: DEET, Icaridin and IR3535.
The most famous DEET
In terms of fame, DEET should be the largest.
DEET chemical formula (Image: wiki)
DEET chemical name is N,N-diethyl-3-methylbenzamide, also known as Ethyl Beta, commonly known as DEET, DEET, is currently the world's largest mosquito repellent chemical. Verified by many countries around the world for more than 50 years, it is a highly effective and low-toxicity mosquito repellent product.
In 1944, Samuel Gertler, who worked for the U.S. Department of Agriculture, invented DEET, originally intended to help American soldiers repel mosquitoes in jungle warfare. The compound was patented in 1946 to protect U.S. troops from mosquitoes as they roamed through Vietnam's dense forests. In 1957, because of DEET's outstanding mosquito repellent effect, it was turned to civilian use and benefited people all over the world.
Full text of DEET's patent (Image source: National Patent Office)
Initially, scientists thought that the mechanism of action of DEET affected the ability of mosquitoes to feel carbon dioxide, but this claim was later overturned by a research team at Rockefeller University in the United States. Their 2008 paper in Science showed that DEET is a mosquito fog of war, masking 1-octen-3-ol in people's sweat and breath, keeping mosquitoes out of the north — assuming you already know mosquitoes have poor eyesight.
Follow-up studies have shown that DEET's mosquito repellent mechanism is very complex, and until now, humans have not actually fully understood why DEET can repel mosquitoes.
Despite being popular around the world for more than 50 years, DEET is not perfect. DEET has a certain solubility in plastics and will destroy plastic products. In 1998, the U.S. EPA reported 14-46 episodes of brain disorders that may be related to DEET use, but the association was unclear. Cornell University also reported that employees at Everglades National Park experienced insomnia, low mood and impaired cognitive function due to long-term DEET use.
Everglades National Park (Image: Pixabay)
Because DEET has certain risks in use, many mosquito repellent products that claim to be pure natural plant extracts advertise themselves as DEET-FREE. Interestingly, when labeling the main ingredients of such products, DEET is not mentioned, and of course, all the compounds that have been verified to be effective later in this article are not mentioned. As for whether these plant extracts are really effective, haha, you know.
More scholars believe that practice is the only test of truth. After more than 10 billion tests around the world, the safety of DEET has been recognized by all countries in the world. Of course, security is based on fair use. The mainstream view is that DEET mosquito repellent products below 30% are absolutely safe, but it is still not recommended for infants under 2 months of age. Safety first, for such an older child, there are very few things that can be used, and it is better to physically repel mosquitoes.
Icaridin: The Oolong Incident of the WHO
Icaridin chemical formula (Image: wiki)
Icaridin, whose chemical name is 1-(1-methylpropoxycarbonyl)-2-(2-hydroxyethyl)piperidine, is a CDC-certified most effective mosquito repellent other than DEET.
Icaridin's Chinese name is Ekaridin, and it also has the name Picaridin, which is also an oolong event of the WHO.
In 1998, Bayer in Germany first synthesized this compound. When recommending the WHO International Nonproprietary Name, the name used was Picaridin, but the WHO eventually approved Icaridin, so it was misused that name.
Mosquito repellent products containing Picaridin (Image: Courtesy of the author)
This good thing is officially launched in the new century, in general, Icaridin and DEET's mosquito repellent effect is not much different, but the safety has been greatly improved, not only solves the problem of DEET dissolving plastic, but also has less irritation to the skin after testing. However, it is also not recommended for infants under 2 months of age.
Interestingly, commercially available Icaridin is actually a mixture of four optical isomers, all of which are active in mosquito repellent.
Icaridin's optical isomer (Image: wiki)
Safer IR3535
IR3535's fame is actually not small.
Chemical formula of IR3535 (Image: wiki)
IR3535 is commonly known as mosquito repellent ester or mosquito repellent ester, the chemical name is ethyl 3-(N-n-butyl-N-acetyl)-aminopropionate. Because the name is too long, many ingredients use the name ethyl butyl acetylaminopropionate in the label, and its Chinese name Immonin is used less.
A mosquito repellent product uses IR3535 as a mosquito repellent (Image source: photo by the author)
The biggest advantage of this compound invented by German Merck is safety! Safe! Safe! Among the mosquito repellents recommended by WHO and CDC, IR3535 is the only one that can be used in infants, pregnant and lactating women. Its safety has also been widely verified in its nearly 40-year history of use worldwide. In fact, if we take a closer look at its structure, we should also guess that it is safe. The compound itself is a derivative of β-alanine, which biodegrades relatively thoroughly and has negligible toxicity to the human body and the environment.
Plant extracts VS new chemical mosquito repellent
Some people may ask: Can our ancestors' methods work? In addition to these three compounds, are there no other mosquito repellent products?
In July 2002, a paper in the New England Journal of Medicine, comparing the effects of different mosquito repellents, found that plant extracts of citronella, cedar cedar, eucalyptus, peppermint, lemongrass, geranium geranium were almost useless in mosquito repellent, and the mosquito repellent time was less than 20 minutes. Whether extracts from other plants are useful or not depends on luck.
The methods of the ancestors may not work, but chemical mosquito repellent methods are endless, such as SS220 is a promising mosquito repellent compound.
(Image source: wiki)
This compound was developed in 2002 by the USDA's Chemicals Affecting Insect Behavior Laboratory and has a broad-spectrum insect repellent effect. In 2009, a study from Queensland, Australia, claimed that DEET outperformed SS220 in the lab, but in the wild, DEET was far less effective than SS220 — the former could only provide 2 hours of mosquito repellent protection under the same conditions, while the latter lasted up to 5 hours.
SS220 has a light fruity aroma, little irritation to the skin, and a low probability of triggering allergies; It also stays on the skin longer and does not damage the plastic. But SS220 has only one isomer that is active, which means that the cost of synthesis will be high.
(Image source: Pixabay)
Do you think this is the end of it?
The human exploration of the unknown is endless, SS220 is obviously not the end of mosquito repellent compounds, and more technologies and ruthlessness are constantly being developed.
The popular mosquito repellent compound in the past decade is VUAA1, which is indeed very complex in terms of structure, but because there is no chiral center, the cost of synthesis is basically controllable.
Image source: Courtesy of the author
In 2011, a team of researchers from Vanderbilt University first reported the compound in PNAS. Initially looking for ways to control the spread of malaria, which is mainly transmitted through mosquito bites, the researchers turned to mosquito repellent, discovered VUAA1, and named it after the two letters that began with the university.
Image source: screenshot of the journal's official website
VUAA1 is an agonist that overactivates the mosquito's sense of smell and causes insects to repel it. Simply put, its smell can make mosquitoes smell uncomfortable, and mosquitoes are smoked away.
VUAA1 is not only a new mosquito repellent compound, but also updates the human understanding of mosquito smell in mosquito repellent research. Previously, it was widely believed that mosquitoes' olfactory mechanism was similar to that of mammals, which were exposed to different gas molecules through the nerve cells of odor receptors, and then transmitted information to the brain. But now we know that mosquitoes' odor receptors also rely on a co-receptor whose role is to tell the nerve center which odor receptors have been activated and which odor is detected.
VUAA1 is 1,000 times more effective at repelling mosquitoes than DEET, and it also stimulates sperm motility in mosquitoes — male mosquitoes are afraid of smoking even if they don't suck blood — proving that there is a connection between mosquitoes' sense of smell and reproduction.
conclusion
Q: What to see when choosing mosquito repellent products?
A: Look at the ingredients! As long as the ingredients are labeled to contain one of the "three giants of chemical mosquito repellent" mentioned above, the mosquito repellent effect is guaranteed.
Q: Which of these three compounds is better at mosquito repellent?
A: As long as the concentration is sufficient, the mosquito repellent effect is good enough.
Q: So what's the difference?
A: There is a difference in safety for people and the environment, but don't panic, each compound is safe enough when used reasonably.
Q: In addition to identifying the Big Three ingredients, are there any other principles for purchasing mosquito repellent products?
A: Do what you can. For example, the cost of the new SS220 is very high, which leads to the price is also very ...
Q: Can I buy products called "natural pure plant extract"?
A: The effect of plant extracts is very limited, and those mosquito repellent products that are called "pure plant extracts" are secretly added with mosquito repellent chemicals; Others simply do not add it, relying on faith and probability to repel mosquitoes.
I wish everyone a cool and mosquito-free summer~