Improper food handling during Memorial Day cookouts can lead to serious health risks, including foodborne illnesses caused by bacteria like E. coli and Salmonella. Vulnerable groups, such as children under five, adults over 65, and individuals with weakened immune systems, are at higher risk of severe complications. Symptoms of foodborne illnesses can include dehydration, diarrhea, and abdominal cramps, with potential for kidney failure in severe cases. Additionally, leaving perishable foods out for extended periods, especially in hot weather, increases the risk of bacterial growth, making it crucial to follow safety guidelines.