Harmful chemicals are all around us -- in our bodies, in our environment and in our food. Maybe you can tolerate a little bit of pesticide, but, like anything else, you can overdo it. Experts say anything you eat in abundance should be organic in order to avoid overexposure to certain chemicals. While a little bit of pesticide residue in your favorite tortilla chips may be OK, if you eat a bag of them a day, you may be flirting with toxic buildup (not to mention obesity). Same with peanut butter, rib eye steaks, corn and so on. It's especially important to remember this rule for babies and children because their small body size means toxins can accumulate quickly.