Although they have been found to be more-or-less safe for mammals in laboratory studies, pyrethroids are known to cause skin irritation, headache, dizziness and nausea.
However, indoors the chemicals in pyrethroid pesticides adhere to cloth, tiled floors and wood differently to how they would to outdoor surfaces.
Researchers found that 70% of cypermethrin, a pyrethroid pesticide found in up to 90% of homes, in dust samples around a test house after a year.
Pesticide exposure requires more research
The extended persistence of this chemical increases the likelihood that residents will be exposed to the pesticide.
This especially worrying for young children and household pets, as they spend more time on the floor and frequently pick up things and put them in their mouths.
So, before you reach for bug spray, consider natural ways to banish pests from your home.