A Portuguese technology company has developed a new treatment process for clothes to repel mosquitos that it claims is far superior to traditional technology. Mosquitos spread malaria. The process involves impregnating textiles with amorphous silica (silicon dioxide) nanoparticles. Immobilized in the pores of these particles is a non-toxic active substance. In tests performed by a third party, that substance repelled 81 percent of Anopheles gambiae mosquitoes, while keeping 89 percent of them from feeding. By contrast, textiles treated with microencapsulated DEET (which is a toxic substance) had a repellency index of 40 percent, and a feeding inhibition of 65 percent. While the company is keeping the identity of the active substance quiet, they claims that it has been in use for over 30 years, and is proven biocompatible and is classified by EPA with the lowest degree of toxicity (grade IV) in all categories. The silicon dioxide is essentially just sand, and is environmentally innocuous. The particles are larger than 100 nanometers, which puts them well above the size of permeability of human skin. In a conventional finishing process which can be conducted at regular fabric-dying facilities, the nanoparticles are reportedly deposited into the material, as opposed to just adhering to the outer surface of its fibers. In lab tests, this allowed the particles to remain in the material for up to 90 washes. Although by that point, the repellant content was down to 35 percent. www.nanolabel.pt/anti-mosquito.html
