When you buy mosquito repellent, you may want to pay attention to the ingredient description picture / Wang Xi

Mosquito repellent is talked about every year, but why are we still bitten by mosquitoes every year? The "Mosquito Repellent Product Purchasing Guide" launched today must be read carefully, which can help you avoid being deceived when purchasing mosquito repellent products--you know, less deception means less bites.

Why use chemical mosquito repellent?

There are two ways to deal with mosquitoes, one is to kill them directly, and the other is to drive them away.

Obviously, mosquitoes have been fighting with humans for millions of years, and it is tantamount to a fool's dream to want to kill them all. Although there are many types of insecticides today and their effects are outstanding, humans still cannot exterminate the mosquito species.

Some people say that if you can't kill mosquitoes, you can drive them away. The physical method of mosquito repellent has been used by our ancestors. In the Spring and Autumn Period more than 2,000 years ago, the Chinese were using mosquito nets. The mosquito nets have been used until today, which shows that the effect is still good. But the problem is that no one can carry a mosquito net around. So, chemical mosquito repellents are still needed.

In fact, whether it is WHO (World Health Organization), CDC (US Centers for Disease Control and Prevention), or NPIC (US National Pesticide Information Center), the chemical mosquito repellent compounds recommended by these authoritative organizations include the following three: DEET, Icaridin, and IR3535.

The safety of "DEET" is questioned

DEET is the most famous. It has been verified by many countries around the world for more than 50 years and is a highly effective and low-toxic mosquito repellent product. Its chemical name is N,N-diethyl-3-methylbenzamide, also known as DEET, commonly known as "DEET" and "DEET".

In 1944, Samuel Gertler, who worked for the US Department of Agriculture, invented DEET. It was originally used to help American soldiers in jungle warfare repel mosquitoes. This compound was patented in 1946 to protect US troops from mosquitoes while traveling through the dense jungles of Vietnam. In 1957, because of its outstanding mosquito repellent effect, DEET was converted to civilian use, benefiting people all over the world.

Initially, scientists believed that the mechanism of action of DEET was to affect the ability of mosquitoes to sense carbon dioxide. Later, this statement was overturned by a research team at Rockefeller University in the United States. In 2008, they published a paper in the professional magazine "Science" showing that DEET is a mosquito's fog of war, which can cover up 1-octen-3-ol (1-octen-3-ol) in human sweat and breath, making it difficult for mosquitoes to find their targets - you know, mosquitoes have poor eyesight.

However, subsequent studies have shown that the mosquito repellent mechanism of DEET is very complicated. 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. Many people are worried that "DEET repellent" is unsafe. One of its disadvantages is that it has a certain solubility in plastics and will damage plastic products. In addition, in 1998, the US EPA reported 14-46 cases of brain disease attacks that may be related to the use of DEET, but the connection is not clear. Cornell University in the United States also reported that employees of the Everglades National Park suffered from insomnia, depression, and impaired cognitive function due to long-term use of DEET.

Interestingly, because DEET has certain risks in use, many mosquito repellent products claiming to be "pure natural plant extracts" are advertised as "DEET-FREE (without DEET)". When labeling the main ingredients of such products, DEET is not mentioned, and of course, all the proven effective compounds described later in this article are not mentioned. As for whether these so-called "pure natural plant extracts" are really effective, it is unknown.

But more scholars believe that practice is the only criterion for testing the truth. After more than 10 billion people worldwide have used it, the safety of DEET has finally been recognized by all countries in the world. Of course, safety is still based on reasonable use. The current mainstream view is that mosquito repellent products with a content of less than 30% DEET are absolutely safe, but it is still not recommended for infants under 2 months old. After all, safety comes first. For such a young child, there are few things that can be used. Physical mosquito repellent is more suitable.

"Icaridin" is safer than "DEET"

The chemical name of Icaridin is 1-(1-methylpropyloxycarbonyl)-2-(2-hydroxyethyl)piperidine. Its Chinese name is Icaridin, and it also has another name called Picaridin. It is the most effective mosquito repellent certified by the CDC besides DEET.

Sometimes, the ingredients marked on some products are Icaridin, and sometimes Picaridin. Speaking of which, this is a "oolong" incident of WHO. In 1998, Bayer of Germany first synthesized this compound. When applying for the "International Nonproprietary Drug Name" of WHO, the name used was Picaridin, but the name finally approved by WHO was Icaridin, which was missing a P, so they had to make the best of it.

This good thing was officially used in the new century. Generally speaking, the mosquito repellent effect of Icaridin and DEET is not much different, but the safety is greatly improved. It not only solves the problem of DEET dissolving plastic, but also has been tested to be less irritating to the skin. But it is also not recommended for infants under 2 months old.

Interestingly, the Icaridin sold on the market is actually a mixture of four optical isomers, all of which have mosquito repellent activity.

The safest one is "repellent"

But it is even safer - IR3535. IR3535 is commonly known as "repellent" or "repellent", and its chemical name is 3-(N-n-butyl-N-acetyl)-aminopropionic acid ethyl ester. Because the chemical name is too long, the name "butylacetylaminopropionic acid ethyl ester" is used in the ingredient labels of many related products, and its Chinese name "рад╛дЧ" is less used.

Merck of Germany invented this compound. Its biggest advantage is safety. Among the various mosquito repellents recommended by WHO and CDC, IR3535 is the only one that can be used for infants, pregnant women and breastfeeding women. Its safety has also been widely verified in its nearly 40 years of use around the world. Because this compound itself is a derivative of beta-alanine, it is biodegraded more thoroughly and its toxicity to humans and the environment is negligible.

Plant extracts are basically unreliable

Some people may ask: 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 compared the effects of different mosquito repellents and found that plant extracts of citronella, cedar, eucalyptus, peppermint, lemongrass, and geranium were almost useless in repelling mosquitoes, with a mosquito repellent effect of less than 20 minutes. Whether the extracts of other plants are useful or not seems to depend on luck.

Natural methods don't work, but other chemical methods of repelling mosquitoes are emerging in an endless stream. For example, SS220, developed by the Chemicals Affecting Insect Behavior Laboratory of the U.S. Department of Agriculture in 2002, has a broad-spectrum insect repellent effect. In 2009, a study from Queensland, Australia stated that DEET performed better than SS220 in the laboratory, but in field conditions, DEET was far less effective than SS220 - under the same conditions, the former could only provide 2 hours of mosquito repellent protection, while the latter provided up to 5 hours of protection.

In addition, SS220 has a light fruity scent, is less irritating to the skin, and has a low probability of causing allergies; it also stays on the skin longer and does not damage plastics. However, only one isomer of SS220 is active, which means that the cost of synthesis will be very high.

Conclusion

Look at the "ingredients" before purchasing mosquito repellent products

Speaking of this, the so-called guide to purchasing mosquito repellent products is nothing more than "looking at the ingredients".

Be sure to check whether the product's ingredient label contains the chemical names of the "three giants in the chemical mosquito repellent world" mentioned above, DEET, Icaridin and IR3535. As long as one of them is present, the mosquito repellent effect is guaranteed.

As long as the concentration of these three compounds is sufficient, the mosquito repellent effect is good enough. Although there are differences in safety to humans and the environment, each compound is safe enough as long as it is used reasonably.

In addition to identifying the "three giants" in the ingredients, it is also good to buy new products-those containing SS220, but due to cost issues, the cost is high. And those products claiming to be "natural pure plant extracts" have very limited mosquito repellent effects, and some of them are still secretly added with mosquito repellent chemical ingredients to be effective. (Wang Xi)

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