Dinner doesn't feel like prime time for chatting about diarrhea-inducing toxins.
But E. coli is a serious matter. Dozens of people have been sickened by bad beef in the past month, many of them hospitalized and a major meat producer has recalled enough beef to feed the greater Cleveland area.
Here's what Doug Powell does: He whips out the thermometer he's recently taken to carrying with him.
You might wonder how the food-safety expert finesses such a potentially awkward social situation.
"I go into it very academic, professor-ish like," he said.
"I try not to be a jerk."
Powell runs the Food Safety Network and teaches at Kansas State University. He is having people visit his place for the holiday and is thinking of "some good old American Fourth of July" fare.
But nobody will eat a burger off his grill that hasn't been stabbed in the side with a tip-sensitive digital thermometer and is cooked to a minimum of 160 degrees.
Jose Rodriguez has tallied for weeks the human toll of E. coli O157:H7 bacteria that naturally lives in cow intestines but can kill people.
The guy's a carnivore, but forget serving him a burger over the holiday weekend. He'll be polite, that's his way; he's in public relations for the city health department.
"I am choosing to eat no ground beef, regardless of where it came from, by the way," he said.
His coworker, Vince Fasone, who spends his workdays inspecting restaurants and teaching proper food safety to people in the business, said he thinks he'll be dining on steak.
Dinners out, whether at a restaurant or a friend's house, can be informative, even frightening, experiences for Fasone.
There are nice ways to speak up, he said.
"One tries to be gracious, but at the same time you're looking after the health of other folks. "I might say, ‘Let me help you, and let me put this back in the fridge.' "
Rodriguez once invited Fasone to dinner.
"I was nervous the whole time," Rodriguez said.
Vickie Vaclavik, who teaches clinical nutrition at University of Texas Southwestern Medical Center in Dallas, says those in the know should absolutely share their wisdom.
"It's a good thing to do. A guest does not want to be annoying, however a reference to food safety in the news and taking proper precautions seems to be a must," she wrote in an e-mail.
Most cooks don't consider that their food might be poisonous, said William Marler, a Seattle lawyer who represents people sickened by contaminated food.
But Marler doesn't have to worry much about etiquette at the barbecue.
He's never invited.