Although this study shows that DEET-based products
can be depended on for long-lasting repellent
effect, they are not perfect repellents. DEET may be
washed off by perspiration or rain, and its efficacy
decreases dramatically with rising outdoor temperatures.
19,30,34
DEET is also a plasticizer, capable of dissolving
watch crystals, the frames of glasses, and certain
synthetic fabrics.