Restaurants and food service facilities are subject to periodic inspections for cleanliness by federal, state or country health inspectors. But no authority keeps track of how tidy your home kitchen is -- save your mother or neat-nik spouse.

And for your peace of mind, that is probably a good thing. By the standards of commercial public health regulations, it probably isn't as clean as you think.

To test that theory, we called in an expert. In three local home kitchens last week, Ellen Schroth stuck a thermometer through the bars of refrigerator racks, crouched beside cabinets with a flashlight and gave the white-glove test to pots, pans and dishware. Schroth is a health inspector, a professional clean freak.

However, there is a difference between unclean and unsafe, as Schroth acknowledges. Not all poor hygiene practices carry the same risk.

For example, the chain reaction that would have to occur for you to get sick from an unclean refrigerator door is far less likely than the circumstances it would take for you to get sick from eating improperly thawed and cooked chicken.

When it comes to unsafe food practices, what is unsafe in a food service establishment is generally unsafe in a home. Time/temperature abuse and cross-contamination of raw and cooked foods -- two major causes of foodborne disease -- can occur in either setting.

The difference is the potential for error. A public facility has a larger number of food handlers whose mistakes would affect a larger amount of food and a greater number of people than in a home.

There has been increasing concern in the past few years over an upsurge in microbial contamination and foodborne disease, whatever the location.

The Centers for Disease Control reported 29,000 cases of salmonella in 1980, 56,000 in 1985 -- the most marked increase among foodborne diseases. And the reporting system picks up only a small percentage of actual cases; Julie Parsonnet, an epidemic intelligence service officer at CDC, estimates that there may be currently between 2 and 4 million cases of salmonella per year.

There are many causes of this wave of microbial contamination, including poultry industry practices, the size of the distribution chain and trendy foods (e.g. sushi).

Improper sanitation principles in the home kitchen have been implicated, too. So we asked Schroth, a local food sanitarian for over 10 years who now owns her own sanitation consulting and training firm, Foodsense, to inspect three home kitchens.

We visited a diversity of living situations during the dinner hour: a group house, a family and a single-person household. We didn't give the subjects enough advance notice to do a major clean-up.

The Group House Kitchen "John and Leslie's Shelf," "Rudd's Drawer," "This Area for Tall Items Only." Whenever seven unrelated adults between the ages of 24 and 29, two cats and a dog share a small kitchen, the refrigerator has to have a system. This Mt. Pleasant house was no exception.

It was also no exception to the general rule that group house kitchens often have sanitation problems similar to restaurant kitchens', stemming from a number of unrelated people with different levels of hygiene awareness sharing equipment and food preparation areas. The lines of responsibility for sanitation get fuzzy (and sometimes furious).

As roommates Dominique and Louise made spaghetti and the cats roamed the kitchen, Schroth noted a number of areas that could use cleaning. A pull-out ice cube drawer in the freezer was speckled with dirt. The ice is "not in a wholesome condition for consumption" wrote Schroth in her inspection report.

Schroth spotted in a gold paper bag in the refrigerator some old, discolored and soft potatoes belonging to an unspecified roommate, and told the women to ditch them.

Soon Matt came home from work and joined the women in the kitchen to make his spanish omelet for dinner. Now the room was filled with a food inspector, a reporter, the cats and three cooks.

In the confusion, Matt committed a double case of cross-contamination. He dropped the carton of eggs on the floor, wiped off the mess with a rag and then immediately used the rag to wipe off a cutting board. Secondly, he didn't wash his hands after the incident and before he returned to preparing his dinner.

Matt not only transferred bacteria from the floor to the cutting board, but also onto his hands, Schroth commented later. Nevertheless, bacteria need enough time and the proper temperature in which to grow (two hours between 45 and 140 degrees). Matt eliminated both variables by eating dinner immediately.

After a lot of pulling, peeking and acting professionally nosy, Schroth told the good-natured but embarrassed group the good news: their food stored in cabinets was stored in tight containers with little possibility for insect infestation or spoilage. The fact that they air-dried their dishes rather than towel-drying was a positive. Towel drying, explained Schroth, can spread bacteria from a contaminated cloth to a clean dish.

The bad news, as Schroth later wrote in her report, included mouse droppings under the sink cabinet, several dead roaches and a live roach on the cabinet above the stove. Rodents and insects harbor bacteria that can be transferred to food.

Schroth was also concerned that Dominique did not wash her hands between handling the cats and preparing food. Cats are known harbingers of bacteria called campylobacter, according to Doug Archer, director of microbiology at the Food and Drug Administration. That doesn't mean that you definitely will get a foodborne infection if you touch a cat and then your dinner without washing your hands. It simply means you increase the chance of spreading bacteria, Archer said. You may or may not have added the time element that's crucial to allow the bacteria to multiply enough to cause sickness.

Storage of chemicals in the kitchen bothered Schroth. Foil, plastic wrap and bags were stored under the sink along with chemicals instead of being separated. Schroth was concerned that chemicals from already-leaking containers would reach the food-contact surfaces.

The Family Kitchen As in many houses with two toddlers, their presence is obvious in Sarah and Rick Glassco's Alexandria kitchen. Playdoh was inside the refrigerator, magic wands were on top of the refrigerator and a sudden change in dinner plans occurred when daughter Sylvia, 4, ran into the room demanding macaroni and cheese instead of chicken.

Schroth was impressed with several of Sarah Glassco's hygiene techniques: She frequently washed her hands between touching nonfood contact surfaces and food. She uses an old toothbrush to clean hard-to-reach crevices. Her blender, pots and dishes were quite clean. And she dates the frozen food in her freezer ("Large bluefish fillet, 10/23/87").

Schroth also noted that Glassco's dishwasher was properly stacked. Many people overstack their dishwashers, commented Schroth, and the dishes are not cleaned completely.

Since temperature control is crucial in eliminating the growth and spread of bacteria, all areas of a refrigerator should be maintained at 45 degrees or below. Schroth took the Glasscos' refrigerator temperature in three places and got three different temperatures, all below 45. (Typically the back will be colder, the door warmer. The back was 33 degrees, the door was 41 degrees and the hydrator was 36 degrees.)

Schroth's concerns centered primarily on two food storage techniques. Although Glassco stored her raw chicken in a bottom hydrator (a good practice so the blood and juices don't drip and contaminate other foods beneath it), she had placed chunks of wrapped cheese and ham on top of it. Schroth said that while the cheeses were hand wrapped, she would rather not see raw poultry, a potentially hazardous product, stored with a product it could contaminate.

Glassco was also concerned about cooking chicken in the microwave, fearing that it did not cook evenly or properly. Schroth recommended, as she did at all the inspections, that Glassco buy a thermometer and insert it into the center of several of her chicken pieces. Salmonella is killed at 165 degrees.

In the interests of ecology, Glassco does not use her garbage disposal, preferring not to add waste to the water supply. Instead, she puts food garbage such as chicken skins and fruit peels into a cut-down plastic milk carton and stores it on her kitchen counter next to a food preparation area. Every night she dumps it outside, but returns the carton to the kitchen.

In this instance, Schroth was concerned that Glassco could be transmitting bacteria from the trash to food in the food preparation area. Since the milk carton had only a small cut-out area, Glassco pushed the trash into the opening, permitting bacteria to possibly rub off on her hands. And since Glassco reused the carton, Schroth was concerned that bacteria would have time to grow and multiply.

The Single-Person Kitchen Nelson Canton "freaks" if he sees a bug. But, says Canton, "if they don't get what they want, they go somewhere else." Canton doesn't give them what they want. The self-admitted and now publicly confirmed neat-nik keeps an A-plus kitchen.

A 41-year-old speech writer for the National Education Association who lives in a Southwest Washington high-rise, Canton cooks dinner for himself nearly every night. He shops every other night, which permits him to buy on his whim of the evening and also minimize food wastage. This particular evening, Canton had bought salmon from the Maine Avenue market (frozen from the cold air; he defrosted it in a dish of water), fresh string beans and brown rice.

His counters, cabinets, refrigerator and appliances passed Schroth's white glove test and his food sanitation practices seemed to fit all the codes. To minimize any risk of cross-contamination, he cuts vegetables on a cutting board and cuts his chicken on a counter top covered with paper towels.

He uses paper towels routinely instead of cloth towels, thaws his chicken in his 28-degree refrigerator instead of on the counter and hates it when dinner hosts taste food from a large pot and then replace the spoon without washing it.

The secret to Canton's success -- and the secret to clean restaurants' success, Schroth said -- is that things don't get out of hand to begin with. Thus, it doesn't take him long to clean up. (Of course, Canton's advantage is that he has only his own mess to clean up, not the clutter caused by roommates or children.)

The only possible slight error Canton committed was storing a nonfood item in the refrigerator, a faux pas in a restaurant setting but not in a home, Schroth conceded. And Canton's reasoning was strong. On a bottom shelf, safe from fire, sat Canton's finished, but as yet unpublished novel.