Who doesn't love picnics and barbecues? Thing is, if you don't practice safe food preparation, outdoor eating can also set the stage for foodborne illness.
Every year approximately 1 in 6 Americans gets sick, and 128,000 are hospitalized from foodborne diseases, according to the CDC. Among 31 known pathogens, most deaths occur from Salmonella, Toxoplasma, Listeria, and norovirus.
"The rule of thumb is that no food should be left out for four total hours," said Amy Goodson, RD, a dietitian at Ben Hogan Sports Medicine in Fort Worth, Texas. "This refers to not just four hours at a time, but four accumulated hours." The following foods are most likely to ruin your good time.
Undercooked meat puts you at risk for potentially life-threatening illness from a subtype of E. coli bacteria called O157:H7. An outbreak in 2014 linked to ground beef contaminated with this type of E. coli sickened 12 people from four different states.
"Your risk largely depends on the number of cows making up your ground beef," said Michael Schmidt, PhD, professor at the department of microbiology and immunology at the Medical University of South Carolina (MUSC). "The greater the number of cows the greater chance of having something that was not intended to be in the meat."
Ground beef is riskier than specific cuts of meat that come from a single cow. Regardless, cook burgers or any beef to an internal temperature of at least 160 degrees to kill E. coli.
Topping your burger with a handful of raw sprouts could set the stage for food poisoning. Seeds and beans need warm and humid conditions to grow, which also happen to be ideal conditions for the growth of bacteria, including Salmonella, Listeria, and E. coli. Even homegrown sprouts grown under sanitary conditions can produce harmful bacteria because seeds have been known to be contaminated.
"If you are putting sprouts in a salad or on a sandwich/burger, consider sautéing them first," Goodson said. "Sprouts can easily harbor bacteria and when that is mixed with moisture, food poisoning risk multiplies."
Eating a Caesar salad can make you sick if the dressing is made the traditional way—with raw eggs. (Store-bought bottled dressing is pasteurized; it's homemade dressing you need to watch out for.)
"Pay close attention to anything that could be made with raw or undercooked eggs, especially if they are not pasteurized," said Lori Zanini, RD, a Los Angeles-based dietitian.
The Food and Drug Administration recommends cooking eggs thoroughly and washing all equipment that comes in contact with eggs and your hands with hot soapy water.
Leafy green salads
Once you know the dressing's safe, you also want to consider the lettuce itself—and the hygiene habits of the person who prepared it. A CDC report revealed that salad greens—such as lettuce, escarole, endive, spinach, cabbage, kale, arugula, and chard—caused 262 outbreaks involving 8,836 reported cases of foodborne illness between 1998 and 2008.
There are a few ways greens can be contaminated: at the farm by manure or dirty water rinses; when a sick person preps a salad without washing their hands; and by cross-contamination at home (for example, by using the same cutting board for raw meat and salad prep, which spreads bacteria from meat to produce.) Wash greens before eating by placing them in a large colander and tossing them under your faucet, or by using a salad spinner.
If a summertime trip to the shore always includes a stop at a raw oyster bar, consume with caution: Vibrio parahaemolyticus and Vibrio vulnificus can both can be contracted by eating raw shellfish, especially oysters. In fact, the CDC reported a 52 percent increase in Vibrio poisonings between 2011 and 2013. Both of these bacteria cause diarrhea, vomiting, and abdominal pain in healthy people. For people with liver disease, diabetes, cancer, stomach disorders, or any other condition that affects the immune system, Vibrio vulnificus is extremely dangerous: it can invade the bloodstream, causing a life-threatening illness. Half of all Vibrio vulnificus bloodstream infections are fatal.
Homemade ice cream
It sounds like a luscious treat, but homemade ice cream prepared with raw eggs could contain Salmonella, said Leigh Tracy, RD, dietitian at the Center for Endocrinology at Mercy Medical Center in Baltimore, MD. "The FDA recommends using a custard base or pasteurized eggs."
Cooking and pasteurization kills Salmonella. Store-bought ice cream can contain harmful bacteria as well, but it's much more rare. In 2015, both Blue Bell Creameries of Texas and Jeni's Ice Cream of Ohio produced ice cream contaminated with Listeria. The Blue Bell ice cream was linked to 10 illnesses, including three deaths. All that said, you generally shouldn't worry about the safety of store-bought ice cream; Listeria is rarely found in the sweet stuff because it can't grow at cold temperatures.
Cantaloupes have been linked to Listeria outbreaks, and watermelon can also cause problems. Listeria traced back to a North Carolina farm and another outbreak in Colorado sickened more than 140 people and resulted in 30 deaths. Unlike other germs, Listeria can grow in refrigerator-level temperatures. It has no smell or taste and only heat can kill it. But if heated food cools, the Listeria may grow again, according to the FDA. Since the germs live on the outside peel, rinse all melons under running water and scrub with a produce brush before eating or cutting the fruit, even if you peel it first. Cutting into the rind can spread bacteria from the outside of the fruit to the inside.
Chicken is commonly contaminated with Salmonella and needs to be thoroughly cooked to kill the germs. A 2014 Consumer Reports analysis found that 97 percent of all chicken breasts, including organic, were contaminated with harmful bacteria. Use a food thermometer when cooking meats and chicken to ensure you've heated them to a safe temperature. Chicken should be cooked to an internal temperature of 165 degrees and held at between 140 and 145 degrees, Goodson said.
"Plus, be careful of storage practices before it's grilled," she said. "For example, don't put raw chicken or beef, even if wrapped in foil, above the salad or fruit bowl when you are transporting it to the BBQ or party, as fluids can drip and cross-contaminate other foods without you knowing."
Tomatoes are super healthy, and can be tossed into salads or sliced as a burger topping. But because they aren't cooked (which generally kills bacteria) they have been linked to foodborne illness outbreaks. Cases of Salmonella poisoning in 2006 were traced to a packinghouse in Ohio. Overall, 190 people were sickened across 21 states before the source of the outbreak was discovered. Salmonella is found in the feces of animals or in some habitats including ponds as drainage ditches.
"It is important to wash your tomatoes thoroughly under running water," Tracy said. "Additionally, discard any bruised or spoiled tomatoes."
The risk of Salmonella is highest in deviled eggs when they're not held at the right temperature (at or below 40 degrees Fahrenheit), Goodson said. Salmonella can live on both the inside and outside of eggs and the egg can still appear perfectly normal, according to the CDC. Deviled eggs are cooked, of course, which should kill any germs in the eggs. But because you combine a bunch of eggs together for the filling, and then it sits for hours at room temperature, bacteria can grow to dangerous levels if an egg is undercooked or contaminated after cooking. Buy eggs only from stores or other suppliers that keep them refrigerated at or below 40 degrees Fahrenheit, and serve deviled eggs on ice at all times.
Staphylococcal aureus is type of bacteria found primarily on skin and hair, and can cause food poisoning when a person prepping a dish contaminates it and then fails to refrigerate it properly. It's most common in foods that require handling, but no cooking—like macaroni salad. Some strains of Staphylococcal aureus are capable of producing a highly heat-stable protein toxin, and unlike some germs that can take up to two weeks to cause symptoms, S. aureus can make you sick within 6 hours and sometimes as little as 30 minutes. Any food that should be held either hot to cold, left in the danger zone (40 to 140 degrees F), puts you at risk for foodborne illness.
Leftovers should be handled properly as well. Once everyone has eaten, put the food in its appropriate hot or cold environment, Goodson said. "Food left out becomes a problem because it enters the temperature danger zone, between 40 and 140 degrees Fahrenheit."
Count how many hours the food has been left out overall. If it's close to or over four hours, trash it, Goodson said.
"Do this especially if the food was left out a good part of the day, and at the hottest part of the day, just get rid of it," Goodson said. "Don't take the risk of getting sick."
Though most summer food hazards come from food poisoning germs, here's one danger you may not have thought of: Grilling meats has been shown to form cancer-causing substances, according to the American Institute for Cancer Research (AICR). Studies have also demonstrated that one of the possible cancer-causing substances could be reduced when the meat, poultry, or fish has been marinated for at least 30 minutes with a mixture of vinegar, lemon juice, or wine with herbs and spices. "Cooking the meat over a low flame as well as trimming off the fat and flipping it frequently can help reduce the formation of the cancer-causing substances," Tracy said.
When you see potato salad on a picnic table, you can probably assume that it's safe to eat, but there's one instance in which it can become dangerous: when the potatoes are baked ahead of time and then stored in foil. Spores of Clostridium botulinum—the group of bacteria that causes botulism—can survive the potato-baking process. Leaving the cooked potatoes wrapped in foil at room temperature produces perfect conditions for those spores to germinate and grow, and release their deadly toxin. In 1994, an El Paso, Texas Greek restaurant kept baked potatoes at room temperature for several days before using them in a dip; 30 people contracted botulism. Botulism is exceedingly rare, but even still, you're best off prepping potatoes the same day you plan on making them into a salad.