They may be tiny, but they are deadlier than dynamites. Mosquitoes are the carriers of some of the most dangerous diseases in the world. In olden times, people used natural extracts from plants to keep these enemies at bay. Today, mosquito repellents, in the form of mats, liquid vaporisers, sprays or lotions have made the daunting task easy. Ever wondered how these repellents are made? Or how they work?
Mosquitoes are attracted to a particular scent from the human body. So, the simple principle behind a repellent is to confuse the senses of a mosquito so that it is unable to ‘find’ the human skin and bite it. The manufacturing process is two-fold:
Compounding: This is the first step in the production of a repellent. Alcohol (for aerosols), a chemical compound N, N-Diethyl-meta-toluamide, abbreviated DEET, emollients (for skin moisturising) and fragrance are mixed manually to make the repellent formula. Every batch of the formula is tested and then sent to be filled and packaged in the containers.
Working: The vaporiser contains a rod which is immersed in the repellent formula. The device is contained within a plastic-like bottle which can be plugged into a socket. When switched on, the graphite rod heats up, and turns the liquid into fumes that spread into the air. These fumes disable the senses of the mosquito thus preventing you from getting bitten. However, liquid repellents do only that – repel the insects. They don’t kill them.
What happens when the repellent is used up?
Normally, when the liquid is used, we dispose the bottle and attach a refill bottle that can be bought separately. But what happens to the disposed bottle? Both, the plastic cover that contains the repellent, and the graphite rod inside it, can be recycled in metal industries.
Are there any environmental impacts?
Yes, there are. DEET, the most common active ingredient in insect repellents, is harmful not only to the environment but also to animals and humans. Prallethrin, the main ingredient of repellents, can cause headaches and dizziness, and deodorised kerosene, used as a solvent, can cause harm if inhaled regularly. The leftover liquid contents of the vaporiser can affect aquatic life too, if it gets in contact with water resources.