Army and Marines are beginning to use field uniforms that are treated with
insect (mainly mosquitos) repellant (permethrin) during manufacture. This means
the uniforms never have to be treated again. Currently, troops have permethrin
either sprayed on (and last for about six washes), or soak uniforms in it (and
last for 50 washes). The factory level treatment tends to eliminate complaints
that the sprayed or soaked approach makes the uniforms stuffy (they don't
"breathe.") Some troops complain of rashes from the permethrin, but there's no
medical evidence of that. There are also unfounded rumors that permethrin
causes cancer. What permethrin does do is keep mosquitoes away, and in areas
where the insects transmit lots of diseases (like malaria), that is a big deal.
Tests have shown that troops who just rub a mosquito repellant (like Deet) on
their skin, still get bitten about ten times an hour. But with Deet and
permethrin treated uniforms, you'll get bitten maybe once or twice a day. When
permethrin treated uniforms are used, cases of mosquito borne diseases go down
over 80 percent.