Insect sprays with the active ingredients diethyltoluamide (DEET) and Icaridin protect against mosquito bites. However, the substances are suspected of polluting the environment. What alternatives are there without chemistry?

Insect sprays with the active ingredients diethyltoluamide (DEET) and icaridin, which are applied to the skin, can provide effective protection against mosquito bites. Consumer advocates recommend mosquito repellent with the active ingredient Icaridin. It protects for about five hours after application. Agents with DEET prevent up to eight hours. However, this active ingredient can irritate the mucous membranes and eyes. Repellants with this active ingredient are therefore not suitable for small children and pregnant women. Almost all products are water-soluble, which is why they have to be applied several times after bathing or during sweaty activities.

How harmful are mosquito sprays to the environment?

But the biocides contained in the mosquito sprays are obviously problematic for the environment: DEET can damage aquatic organisms and microorganisms, there are indications of this in the case of Icaridin. Consumers should therefore definitely not exceed the dosage recommended by the manufacturer. This is how the chemicals affect the environment:

• Diethyltoluamide (DEET) : The insect repellent DEET was developed by the US Army to protect soldiers from mosquitos. The active ingredient is used in sprays such as Anti Brumm or Nobite with an active ingredient content of 20 to 50 percent. DEET is a chemical that requires authorization and, in higher doses, can damage environmental organisms. The manufacturers of insect repellants must therefore print warning and dosage information on the packaging. The composition in sprays makes DEET a water-soluble substance. However, sewage treatment plants can only remove 70 percent of the amount of DEET from the water. 30 percent go back into the water cycle and decompose over time.

• Icaridin : The insect control agent Icaridin has also recently been subject to authorization in the EU. Conservation groups are of the opinion that Icaridin is not a harmless substance for the environment. An American study from 2018 came to the result that the concentration of an over-the-counter American insect spray with the active ingredient Icaridn can decimate the larvae of amphibians if they are exposed to the substance for a longer period of time. The Federal Environment Agency suggests it’s a serious indication that the environmental properties of Icaridin should be researched further. * (Source: Rafael Almeida (Cary Institute of Ecosystem Studies, Millbrook, NY) et al., Royal Society Biology Letters, doi: 10.1098 / rsbl.2018.0526)

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Carbon dioxide and sweat attract mosquitoes

Not all people are equally attracted to mosquitoes. The strongest stimulus for mosquitoes is the carbon dioxide (CO2) in the exhaled air. The composition of the sweat on the skin also plays a role, as does the breakdown of sweat by skin bacteria.

Protection against mosquito bites without chemicals

In areas where mosquitoes are not abundant and do not spread communicable diseases, consumers may consider alternatives to bug sprays containing DEET and icaridin. How to protect yourself from mosquito bites without chemicals:

• A fan ensures that mosquitoes no longer perceive the smell of people so intensely.
• Close-meshed insect screens – for example made of weatherproof fiberglass fabric – in front of the window openings protect against mosquitoes from entering bedrooms and living rooms.
• Showering before going to sleep or before a barbecue party removes the human sweat that mosquitoes find attractive.
• Proper clothing can deter mosquitoes, such as bright colors and long-sleeved sweaters made from thick fabrics. Black and blue are more likely to attract mosquitoes.
• Put a worn sock near the bed as a distraction – tests have shown that mosquitoes find the smell attractive.
• Avoid lakes and rivers in summer from dusk – they are breeding grounds for mosquitoes.

Plant-based mosquito repellent can trigger allergies

According to experts, natural active ingredients such as the vegetable oil geraniol can trigger allergies in some people. Therefore, try mosquito repellent with herbal active ingredients on a small area of ​​skin before using it for the first time.

Essential oils and anti-mosquito bracelets are not very effective

Essential oils from citrus fruits, lavender, eucalyptus or cedarwood, which are applied directly to the skin, only help for a short time. So-called anti-mosquito bracelets, which are supposed to drive away mosquitoes with essential oils, have also proven to be largely ineffective in tests by Stiftung Warentest.

Biocide vaporizer with harmful side effects

So-called biocide vaporizers, which are plugged into the socket, emit toxic fumes. While they keep mosquitos away, they can cause headaches, dizziness and numbness if the room is not adequately ventilated.

Electronic stitch healer and cool relieves itching

Anyone who is bitten despite mosquito repellent can relieve the itching with a battery-operated sting healer (available from around 20 euros in the pharmacy). The device’s plate, which is around 50 degrees warm, is held on the puncture site. The heat kills the proteins that cause itching. Cooling the puncture site and covering it with a slice of lemon or onion also helps against swelling and itching. Cooling gels from the pharmacy can also provide relief.