When Dennis Loo attends a party, you can bet the food is put on ice or kept warm at appropriate temperatures.

"My friends and family know that I’m the health inspector guy," said Loo, a sanitarian at the state Department of Health. "They always need to put things away before I say something. It comes with so many years on the job."

With summer playing host to picnics, outdoor barbecues and lots of parties, the bacteria that cause food-borne illnesses are uninvited guests you want to avoid. Exposed food can be contaminated with bacteria in the air, from utensils or human handling, and if not kept at the proper temperature — hot or cold — the pathogens can multiply to reach infectious levels or produce toxins.

Potato salad, a picnic favorite, is one of the biggest culprits in food poisoning cases, according to Loo. "People put it out and don’t think too much about it. I’m always worried about how long things have set out before being put on the table," he said. "People tend to think more about meats because they don’t want to eat them cold. They tend to cook meats and eat them right away. Things that are cooked on site and eaten immediately are always the safest."

Potato salad and condiments should be placed on ice to ensure they remain at a safe temperature (below 45 degrees), he explained. "I always bring an extra chest of ice" to chill food.

Loo said the smell test is not a reliable way to detect whether food has spoiled. "Food poisoning germs don’t have an odor and can’t be seen," he said.

Rice is another potentially hazardous food, according to Peter Oshiro, a supervisor with the Health Department’s Sanitation Branch. Cooked rice should be kept above 140 degrees or below 45 degrees at all times.

"If the temperature of the rice falls below 140 degrees, it should be discarded after four hours," Oshiro said. "Cooked rice is especially a problem with handmade Spam and other musubi products that have been handled with bare hands. If the rice becomes contaminated through handling, it is an excellent medium for growing staph and carrying other pathogens that may have come into contact with the rice during preparation."

Historically, the food-poisoning outbreaks in Hawaii traced to musubi or bentos involved contaminated rice left out at improper temperatures for more than four hours, Oshiro added.

A good rule of thumb is that "hot foods need to stay hot, and cold foods need to stay cold," said Lynn Nakamura-Tengan, a cooperative extension educator at the University of Hawaii at Manoa. For example, if someone makes a big pot of chili for a picnic, it should be brought chilled and heated on site, until it’s steaming hot.

"We don’t want food to be left out in danger zones because that is when bacteria can grow. If the temperature is over 90 degrees, food should not be left out for more than one hour," she explained. "People should also follow the two-hour rule. We don’t want food sitting at room temperature for more than two hours."

Bread and other foods that can normally be left at room temperature are the safest choices for outdoor picnics, Nakamura-Tengan added. "Most people don’t think about the cut fruit and veggies that need to be kept chilled. We see a lot of problems with cut melons. Whole grapes and cherries are not as problematic because they aren’t cut," she said.

Another concern is keeping raw and cooked foods separated. "Raw food should be kept in a separate cooler from drinks. The raw juice can contaminate beverages," said Nakamura-Tengan. And once meats are cooked, they should be placed on a new clean dish to avoid contamination.

"If raw meats were in a foil pan, you don’t want to put the cooked meat back in that same pan," she said. Ensure that clean utensils are used for serving, and be careful of surfaces used for food preparation, she added.

Hawaii has seen recent outbreaks of salmonella from raw ahi, and peanut butter, ground beef, spinach and an array of other items have been removed from store shelves due to concerns about possible contamination at mainland processing plants.

Food poisoning symptoms include nausea, vomiting, diarrhea and abdominal cramping. In most cases the illness does not require medical attention and will run its course in a day or two. The most significant complication is dehydration, according to Dr. Matthew Ing, medical director for the Emergency Department at the Queen’s Medical Center.

"The majority of food-borne illnesses can be managed at home if symptoms are mild and the person is still able to hold down fluid," Ing said. "Over-the-counter medications for nausea and diarrhea may provide some relief, at least enough to help keep fluids down. Sports drinks and noncitrus juices such as apple juice and grape juice will help to replace lost electrolytes."

Profuse vomiting or diarrhea and the inability to hold down liquids are reasons to see a doctor. "Also, because they become dehydrated easier, the elderly and the very young should have a low threshold to seek medical attention," he said.