In the case for "organic" foods, organic apples and potatoes appear to be worth the extra money as studies have shown apples and potatoes are more susceptible to pesticides leeching into their skin.
Studies have also shown with respect to apples and potatoes; lab animals exposed to a diet of apples and potatoes protected with pesticides grew 10% fatter than those on a diet of organic apples and potatoes.
Studies have also shown with respect to apples and potatoes; lab animals exposed to a diet of apples and potatoes protected with pesticides grew 10% fatter than those on a diet of organic apples and potatoes.