One of summer's best-loved foods--hot dogs--may pose a health threat to consumers if left uncooked or undercooked, according to laboratory tests conducted for The Times.
The tests found that 20% of the major brand hot dog products tested contained bacteria that most commonly cause flu-like symptoms but can cause serious illness. The presence of the bacterium, Listeria monocytogenes, is troubling because hot dogs are often not thoroughly heated and some people eat them straight out of the package.
Hot dogs are classified by the federal government as a "processed" meat item, meaning that they are required by law to be fully cooked and ready to eat at the time of purchase. Thus, the government does not require cooking instructions on hot dog packaging. As a result, some manufacturers provide cooking guidelines and others do not.
Last year, an advisory issued jointly by the Food and Drug Administration, the U.S. Department of Agriculture and the Centers for Disease Control and Prevention warned people considered to be in high-risk groups to avoid eating delicatessen-type foods, soft cheeses and undercooked chicken because of the listeriosis risk.
The advisory specifically recommended that hot dogs be cooked to "steaming hot"--160 degrees for several minutes--in order to destroy harmful organisms that may be present. Still, food service outlets and consumers often undercook hot dogs. Federal officials caution that extra care be taken when microwaving hot dogs because the fast-cooking ovens may heat unevenly.
Typically, a healthy adult can consume small doses of the bacterium and not develop any illness, although heavily contaminated food may infect otherwise healthy adults. Medical officials do not yet know how many organisms constitute an ineffective dose. The allowable amount of Listeria monocytogenes in fully cooked, ready-to-eat foods, such as hot dogs, is zero in the United States.
Several groups are especially vulnerable to Listeria infection, including pregnant women, infants, the elderly, those with compromised immune systems--such as cancer or AIDS patients--and individuals suffering from cirrhosis, diabetes and ulcerative colitis. According to the CDC, AIDS patients have 300 times the risk of infection than the general population; pregnant women have 20 times the risk of acquiring listeriosis.
When infection does occur, the early symptoms are flu-like, including fever, nausea, vomiting and diarrhea. In advanced stages, listeriosis can cause meningitis and blood infections.
The laboratory tests were conducted for The Times by a federally accredited food laboratory that performs testing for the U.S. Department of Agriculture. USDA-approved laboratory procedures were used to detect this particular pathogen. Testing procedures indicate only whether L. monocytogenes is present, but not the amount of bacteria in the product.
The hot dogs tested for The Times were bought in May and June from six Southern California supermarkets--four chains and two independents--over a two-week period. Five out of 30 hot dog products, from a sample that included 19 brands, tested positive for the Listeria monocytogenes bacteria. A sixth product tested positive for Listeria innocua, a related strain that indicates it is possible for Listeria monocytogenes to grow in the product.
Virtually all varieties of meat and poultry hot dogs were tested by the laboratory. Each of the contaminated samples contained beef as a principal ingredient. The shelf life of a hot dog product is 60 to 100 days, depending on the manufacturer.
In the contaminated group were a 16-ounce package of Bar S Jumbo Franks containing chicken, pork and beef (package expiration code, JUN 23 B1); a 16-ounce package of Hoffy Franks containing pork, beef hearts, beef and turkey (package expiration code, JUN 14); a 16-ounce package of Farmer John Beef Franks (package expiration code, JUN 24-1); a 12-ounce package of Wilson Beef Franks (package expiration code, JUL 03 EB3 ESI 26L), a 16-ounce package of Hoffy Beef Wieners (package expiration code, JUL 24), which contained the related L. innocua, and a 12-ounce package of Mogen David Skinless Kosher Beef Frankfurters (package expiration code, NOV 18), which a company spokesman said expired last November and which should have been taken off the shelf.
Three of four Farmer John products analyzed in the Times study were negative for Listeria and a second Wilson brand hot dog product tested negative.