Because vegetables and wood is located closer to the people. If you can avoid the use of chemicals to get rid of the pest is much much better? but if you need to use pest control should be done in the open, and avoid very dangerous drugs. With a long residual effect and what is very important, and should use the correct medication to get rid of the insects, with taken strictly, because in general there are insecticides and are not dangerous to people, it is less. If used correctly, the more dangerous.