Two of the top questions I get as an agriculture reporter for Harvest Public Media are:

2. What are pesticides, actually?
4. How are they used on my food?

From foodies to farmers, pesticides are a sensitive subject.

First: Pesticides are chemical concoctions used to control, destroy or regulate pesky weeds and insects. Herbicides kill weeds. Insecticides kill bugs. For most purposes, we use the umbrella term "pesticides" to cover both types, which falls in line with the Environmental Protection Agency's definition.

Some of the most popular pesticides are atrazine and glyphosate, which is the active ingredient in the weed killer Roundup, produced by agribusiness giant Monsanto.

Farmers often spray pesticides over crops like corn or soybeans, the vast majority of which in the U.S. have been genetically modified to withstand those chemicals.

Pesticides are also often used in growing tomatoes, apples and other fruits and vegetables we eat directly. For farmers, the goal is to get more results from the crops they plant and efficiently grow more food. Fewer weeds and bugs mean more of a chance for extra tomatoes and melons.

The government does require farmers to follow rules that dictate how much of each chemical they can use, and when they can use it. It's often referred to as the ‘label law:' applicators must abide by the instructions on the label, as approved by the EPA, or risk fines and lawsuits.

Think you're free from pesticides if you buy organic? Not always. Organic producers can also use organic pesticides derived from naturally occurring sources like soil bacteria or other plants.

Chemical pesticides can drift over to neighboring farms and kill crops and honeybees, or run off into waterways, seeping into groundwater. Federal regulators like the EPA, the Food and Drug Administration and the U.S. Department of Agriculture test pesticide levels in waterways and residue on produce. And they set standards to protect human health.

Conflicting interpretations of scientific research have led various authorities to issue different levels of concern over pesticide use. Whether synthetic or organic, however, pesticides in the wrong amount can be dangerous to health.

So while the chemicals are ubiquitous in our food supply, their impact remains a question of much debate.