June 12, 2012 -- At a farmers market near the White House, Stephanie Roseman prepares a sandwich for the Fish Scales concession -- and demonstrates safe food-handling techniques. Gloves prevent bare-hand contact, and ice keeps condiments cool. The market was about to close for the day, and most of the ice had melted. (SHNS photo by Kris Connor)

Kris Connor/SHNS

June 12, 2012 -- James Smith weighs a bag of produce at his stand, part of the weekly Tuesday market at a U.S. Department of Transportation office in Washington, D.C. The federal government encourages setting up markets on its properties throughout the country to promote healthful eating among its employees and the general public. (SHNS photo by Kris Connor)

Kris Connor/SHNS

June 12, 2012 -- Overhead shelters protect food items and customers from the elements. Shown here is a produce stand at the FreshFarm Market at Dupont Circle in Washington, D.C. (SHNS photo by Carol Guensburg)

Carol Guensburg/SHNS

June 12, 2012 -- Thomas Pearson of Dunham’s Produce offers fresh peach samples at the Market Square Farmers Market in Alexandria, Va., reportedly the nation’s oldest continuously operating market. Pearson also demonstrates proper handling by keeping samples in a covered container, served with toothpicks to prevent bare-hand contact. (SHNS photo by Kris Connor)

Kris Connor/SHNS

June 12, 2012 -- To reduce food-safety risks, keep hot foods hot and cold foods cold. At a farmers market near the White House, Coulter Farms of Coulter, Pa., offers cheese samples in clearly labeled containers set on ice. (SHNS photo by Kris Connor)

Kris Connor/SHNS

June 12, 2012 -- A vendor offers samples of seafood spread, warning customers not to double dip. But customers might reach for crackers from the containers instead of pouring a few into individual cups. (SHNS photo by Carol Guensburg)

Carol Guensburg/SHNS

June 12, 2012 -- A worker arranges summer squash for sale at the Market Square Farmers Market in Alexandria, Va. Gloves reduce the risk of contamination between produce and workers. (SHNS photo by Kris Connor)

Kris Connor/SHNS

June 12, 2012 -- Strawberries beckon at the Market Square Farmers Market in Alexandria, Va. Awnings protect food items from the elements. (SHNS photo by Kris Connor)

Kris Connor/SHNS

June 12, 2012 -- Bare-hand contact while cutting produce -- especially samples -- increases the risk of spreading disease. Instead, vendors should wear gloves -- not fabric, unless they’re washed after each use. (SHNS photo by Kris Connor)

Kris Connor/SHNS

June 12, 2012 -- Jeff Hughes rests with his dog, Hartley, and a basket of rhubarb near the Market Square Farmers Market in Alexandria, Va. Many markets forbid pets or restrict them to tight leashes. (SHNS photo by Kris Connor)

Kris Connor/SHNS

June 12, 2012 -- Many farmers markets -- such as this one in Alexandria, Va. -- forbid pets or restrict them to tight leashes. You don’t want someone petting an animal and then touching food. (SHNS photo by Kris Connor)

Kris Connor/SHNS

June 12, 2012 -- Sam Kass, White House assistant chef and an adviser on first lady Michelle Obama’s healthy-foods initiative, often takes school groups to farmers markets or on tours of the White House’s kitchen garden. (SHNS photo by Emmanuel Tambakakis)

Emmanuel Tambakakis/SHNS