Checking food nutrients How can one check if the food does not have excess levels of pesticides?

The need of the hour is to have some machine/tool that checks what is the composition of the food that we are eating and advices us to stop or go ahead with it. I am not sure if there is anything created like that? To take the examples of the news: Salmonella in eggs 

How can we ensure that the food that we eat is not unhealthy?
Practically, you can't. You should clean produce appropriately to remove surface pesticides, and cook food thoroughly to prevent illness from food-borne pathogens.

Checking for levels of pesticides or presence of pathogens would have to occur in a lab, involving microscopes, chemistry techniques, and bacterial cultures. This is impractical to do in the home, plus it would likely destroy the food you were testing.