A roach scurries across a cutting board. Raw chicken juices mingle with cooked shrimp as ready-to-serve sushi decomposes nearby in a faulty cooler.

Those unappetizing scenes were among the potentially hazardous food-safety violations discovered by restaurant inspectors in Pittsburgh and unveiled in a new report by the Center for Science in the Public Interest.

The Washington, D.C.-based consumer watchdog examined a sampling of inspection reports in Pittsburgh and 19 other cities, finding dangerous food handling practices at two-thirds of the 539 restaurants it studied.

Perhaps best known for its efforts to ban artery-clogging trans fats and rid schools of junk food, the center is now pushing for food safety inspectors nationwide to post letter grades in restaurant windows reflecting how those businesses did on their latest inspections as a warning to diners about hidden hazards.

"If you can walk by a restaurant and see what credit cards it takes and how Zagat rates it, you certainly should be able to see what the health department thinks about the cleanliness of the restaurant," said staff attorney Sarah Klein, one of the authors of the report "Dirty Dining: Have reservations? You will now."

The center decided to analyze data on restaurant inspections because of the growing number of Americans eating out.

The average consumer eats restaurant food at least five times per week, Ms. Klein said, while the average household spends half of its food dollars on restaurant food.

"Americans are really relying on restaurants to provide safe food," she said.

Nevertheless, 40 percent of foodborne illnesses can be traced to restaurants compared with 22 percent linked to in-home cooking, she said. All told, an estimated 76 million Americans get sick from unsafe food each year.

Among the 20 cities examined for the report, just two -- Las Vegas and St. Louis -- displayed grade cards in restaurant windows. Restaurants earn an "A," "B," or "C," depending on the number and severity of food safety violations. Restaurants earning less than a "C" can be shut down.

"A letter grade in the window has proven to be one of the most powerful incentives for restaurants to perform well on inspections," Ms. Klein said. She cited Los Angeles County, which has used a grading system for the last 10 years that is credited with cutting hospitalizations from foodborne illnesses by 20 percent.

But a spokesman for the Allegheny County Health Department, which conducts restaurant inspections across the county, said such scoring systems were unfair.

"Our position is that it is difficult to reduce all the information from an inspection into a letter grade or numerical score that is a true picture of the establishment," the department's Guillermo Cole said. "At this point, we don't buy into that."

Mr. Cole said county inspectors close restaurants that "are not making adequate progress" fixing serious problems. The last mandatory closing was in July 2007 when the Cotton Club in the Hill District was shut down for operating without hot water and other uncorrected critical violations.

But Ms. Klein said that approach was not enough to adequately inform the public.

"We argue there is a big gray area between an 'A' and an 'F,' and that gray area is what consumers should have access to," she said.

"Would Pittsburgh consumers want to eat at a 'C' restaurant if a restaurant next door gets an 'A'?"

"We are not asking for additional regulations or additional money to be spent," Ms. Klein said. "We are just saying, 'Please translate your results into a letter grade so people can see it.' "

Mr. Cole said county health inspectors can post a yellow "Consumer Alert" decal for repeated, uncorrected critical food safety violations. Restaurants have 10 days to solve the problems or they could be shut down, he said.

Last year, three such alerts were issued among some 7,500 food facilities in the county, which includes establishments such as caterers, mobile vendors and grocery store deli counters. So far this year, there have been four alerts: at The New Oriental Wok in Lawrenceville; Plum Convenience Store in Plum; My Ngoc, Strip District; and Moby Fish and Chicken, Downtown. All four alerts have been lifted.

"We feel the current system does notify consumers whenever a restaurant may pose a significant health risk," Mr. Cole said.

But the Dining report said health officials should be more transparent about what's going on behind the closed doors of restaurant kitchens.

"Consumers are given little choice, and little information, about how to judge the safety of what and where they eat," the report said.

Seventy percent of the violations chalked up by Pittsburgh- area restaurants were among the infractions considered the most dangerous to public health by the U.S. Centers for Disease Control and Prevention, the report found. They include hand-washing violations, which can result in infected workers passing along the potentially deadly Hepatitis A virus and staph bacteria, and temperature violations, which can allow pathogens that cause botulism and salmonella poisoning and other illnesses to grow in foods not kept hot or cold enough.

Overall, 21 of the 30 Pittsburgh restaurants in the study had at least one critical violation.

Ms. Klein called those findings "significant" and something Pittsburgh consumers should know about.

Among the 20 cities, Pittsburgh ranked sixth for the highest rate of critical violations. But Ms. Klein cautioned that comparisons between cities could be misleading because it was unclear whether areas with the most violations had dirtier restaurants or tougher inspectors.

A number of the cities examined allow the public to view inspection reports online. Allegheny County does not post reports online, but expects to start doing so sometime next year, Mr. Cole said.

For now, people who want to see an inspection report must come to the health department's office in Oakland, or make a written request for copies by mail at 50 cents per page.

The report criticized the county's system as "useless" because it requires diners who want the information to help choose a restaurant to act in advance, perhaps months ahead.

"Keeping results that people can only get if they work for it doesn't make much sense to me," Ms. Klein said.

She said posting inspections online would be a good first step, but would not be as useful as implementing an easily understood scoring system.

Consumers looking at full reports tend to focus on the "rats and roaches" violations, which are troubling but should not overshadow less sensational offenses that can be even bigger health threats, Ms. Klein said.

In other words, not properly sanitizing a cutting board between pounding the hamburger patties and shredding the lettuce can be worse than flies in the soup.

Inspection reports also can be filled with technical jargon, making them hard to interpret.

"You might as well not have anything if it's something you can't recognize," Ms. Klein said.

Mr. Cole said this region fared better in a February report in Men's Health magazine that ranked Pittsburgh fourth best out of 101 cities for fewest outbreaks per capita of three of the most common foodborne illnesses. Los Angles, which uses the grade card system, placed 62nd.

In Allegheny County, inspectors are supposed to visit full-service restaurants twice a year. But it doesn't always work out that way.

The inspector who spotted the scampering cockroach -- at Rico's Restaurant in Ross during a November 2006 inspection -- left his job, and no one else from the health department followed up.

"We'll probably get out there sometime this month," Mr. Cole said Wednesday.

Indeed, an inspector showed up at Rico's Thursday afternoon, turning up several serious refrigeration, food temperature and hand-washing violations. The roaches were still hanging out, too, although this time they were hiding behind a cooler and all but one appeared to be dead.

As for the festering fish, it was discovered in May at South Side's Nakama Japanese Steakhouse & Sushi Bar.

The "Dirty Dining" report is available at www.cspinet.org. It includes a section on Pittsburgh and a list of the 30 local restaurants examined, ranging from fast-food chains to white tablecloth eateries.

For more information on the four restaurants hit with a "Consumer Alert" by Allegheny County health inspectors this year, visit the food safety section of the health department's Web site at www.achd.net/food/food.html and click "Consumer Alerts" along the right side or call the department at 412-578-8044.