semiannual inspections were required of all restaurants with permits for preparing and serving food ; all routine inspections during this period were included in the analysis . special inspections performed in response to customer complaints or to follow - up on deficiencies noted in semiannual inspections were not included . we did not include inspections of schools , correctional facilities , and bars that did not serve food . inspections were performed by state health department employees , or by county health department employees in most metropolitan areas of the state , in accordance with uniform state laws and regulations . all inspectors undergo uniform training and certification by state health department management personnel . to avoid skewing results by including persons performing very few inspections per year , when comparing mean inspection scores by inspector , we included those performing at least 100 inspections during the study period . inspections were performed by using standardized forms including 44 scored items with a possible total score of 100 . of those 44 items , critical items are violations  which are more likely to contribute to food contamination , illness , or environmental degradation and represent substantial public health hazards and [ are ] most closely associated with potential foodborne disease transmission  ( 4 ) . data available for each inspection included overall score , specific violations cited , establishment name and identification number , county , date of inspection , inspector , and time spent on inspection . for comparison purposes , a convenience sample of 19,700 inspections of 2,379 restaurants known to serve distinct types of international or regional cuisine in addition , a convenience sample of 46,700 inspections of 5,300 restaurants were compared on the basis of type of table service . these restaurants were selected based on being well - known to investigators as to type of service or cuisine . fast - food restaurants were defined as establishments where food was paid for before eating . full - service restaurants were defined as establishments where patrons were served at tables and meals were paid for after consumption . data were entered in a centrally maintained database and were analyzed with excel ( microsoft , redmond , wa ) , sas 8.0 ( sas , cary , nc ) , and epiinfo 6.2 software ( 5 ) . all commercial establishments preparing or serving food in tennessee are required to hold a permit from the tennessee department of health . data were available from 167,574 restaurant inspections , involving 29,008 unique restaurants and 248 inspectors during the study period . during this period , individual restaurant scores were 13100 ; the mean was 82.2 , and the median was 83 ( figure 1 ) . among 190 inspectors performing at least 100 inspections during the study period , mean inspection scores of individual inspectors were 6992 , with a median of 82 ( figure 2 ) . mean scores of restaurants within each of the 95 counties in tennessee were 7588 . from 1993 to 2000 , the mean inspection score rose steadily from 80.2 to 83.8 , and the mean number of violations cited per inspection fell from 11.1 to 9.9 . distribution of scores of restaurants inspected statewide from july 1993 to june 2000 , based on a standardized inspection with 44 scored items and a maximum score of 100 . mean score of all restaurants inspected by each inspector , for inspectors performing at least 100 inspections during the study period . during routine restaurant inspections , the most commonly cited violations were for unclean surfaces of equipment that did not contact food and floors or walls appearing unclean , poorly constructed , or in poor repair ( table ) . none of the 12 most commonly cited violations were among those designated as  critical the critical violation most commonly cited was the improper storage or use of toxic items ( for example , storing cleaning fluids on a shelf next to food ) , which was the 13th most commonly cited violation during routine inspections . among restaurant inspections with a total score of > 80 , at lease one critical violation was cited in 44% of those inspections ( mean number of critical violations was 0.6 , mean number of noncritical violations was 6.3 ) . a critical violation was cited in 9,127 inspections with a final score > 90 . among inspections with scores of 60 to 80 , a mean of 2.4 critical and 11.4 noncritical violations were cited ; for inspections with a score < 60 , the means were 5.4 and 16 , respectively . in 1,698 inspections with a score of 60 to 80 , restaurants with a score > 60 tended to have fairly stable scores on subsequent inspections , with a mean drop of 2 points on the subsequent inspection ( figure 3 ) . establishments scoring < 60 had a mean improvement of 16 points on the subsequent routine inspection , with an additional mean increase of 5 on the next inspection . mean change in scores in subsequent two inspections , for restaurants with an initial score on routine inspection of < 60 , 6080 , or > 80 . restaurant inspection data were available from 49 restaurants that were identified as the source of foodborne disease outbreaks investigated by health departments in tennessee from 1999 to 2002 . the mean score of the last routine inspection before the reported outbreak was 81.2 , and the mean score of the inspection previous to the most recent inspection was 81.6 . these scores do not differ significantly from the mean scores of all restaurant inspections during the study period . the rank order of most commonly cited critical violations on routine inspections of restaurants subsequently involved in outbreaks was similar to restaurants not involved in outbreaks . while the two most common critical violations ( proper storage of toxic items and good handwashing and hygienic practices ) were more likely to have been cited during the two routine inspections before an outbreak occurred at a restaurant , the number of reported outbreaks is small , and the conclusions that can be drawn from this observation are limited . under state law , restaurants in tennessee are inspected once every 6 months . the median time between successive inspections during this period was 175 days ; 88% of inspections were performed from 90 to 270 days after the previous inspection . mean scores were similar in restaurants inspected less than or more than 180 days since the previous inspection ( 81.7 and 82.7 , respectively ) and in restaurants inspected within 200 days compared to > 270 days since the previous inspection ( 81.9 and 83.7 , respectively ) . fast - food restaurants ( mean score = 79.9 ) had mean scores similar to independent ( 80.9 ) or chain ( 82.1 ) full - service restaurants . small variations were noted in mean scores of restaurants serving specific types of cuisine , such as thai ( 83.1 ) , barbeque ( 82.9 ) , pizza ( 82.3 ) , italian ( 81.0 ) , chinese ( 77.7 ) , mexican ( 77.4 ) , japanese ( 76.4 ) , and indian ( 74.8 ) foods . these data demonstrate that , during a 7-year period in tennessee , routine restaurant inspection scores varied substantially over time , by region , and by person performing the inspection . while regional variations in the general quality of food service establishments are possible , this factor is unlikely to account for a substantial proportion of the observed differences . restaurant inspections performed by a single observer are difficult to standardize and easily influenced by subjective interpretation . further analyses can be performed that examine the variation in scores on the basis of such things as demographic characteristics of inspectors and time since last standardized training ; these analyses can also be done prospective studies of interobserver variability at the same establishments . all restaurant inspections in tennessee during this period were performed under the same laws and procedures and using standard data collection forms . new inspectors undergo standardized training before performing inspections alone , though during this study period no mechanism for formal periodic restandardization after initial training existed . since this study period ( and independently of this study ) the health department has instituted statewide retraining of all inspectors , regardless of length of experience . whether periodic standardized retraining affects the variables assessed in this study is yet to be determined . despite the ubiquity of restaurant inspections , few studies have been published about the correlations between restaurant inspection scores or violations and foodborne illness , and the conclusions are conflicting ( 612 ) . methodologic problems , including the rarity of reported foodborne outbreaks in relation to the number of restaurants and the small percentage of suspected foodborne illnesses linked to epidemiologically confirmed , restaurant - associated outbreaks , make such analyses difficult . the intensity of surveillance for foodborne disease can markedly influence the number of foodborne disease outbreaks reported in a jurisdiction , and a substantial proportion of restaurant - associated foodborne illnesses probably goes unreported . this study did not assess foodborne illness as an endpoint but rather examined characteristics of an inspection system that would be expected to be associated with a consistent , predictable , and reliable foodborne illness prevention system . the limited data available on outbreaks in tennessee suggest that restaurant inspection scores alone do not predict the likelihood of a foodborne outbreak occurring in a particular establishment . we are not aware of published data addressing which items on a routine restaurant inspection are demonstrated to lead to improved food safety within an establishment . the tennessee department of health inspection protocol and the federal food code ( 4 ) after which it is modeled include assessment of a variety of factors of limited importance in directly preventing foodborne illness . these items include condition surfaces that do not contact food , floors , walls and ceilings , lighting , and ventilation . such factors would be expected to substantially influence an observer s impression of overall cleanliness and safety of an operation , but isolated characteristics have not been shown to correlate with food safety . a substantial number of inspections with a final score of > 90 also had critical violations ; likewise , some restaurants with scores < 80 had no critical violations . while most common violations are noncritical items , these data serve as a reminder that overall score alone is not necessarily a sufficient measure of restaurant safety . a number of studies have examined the effect of inspection frequency on restaurant sanitation ( 9,1316 ) . we did not observe a meaningful difference in scores on the basis of time since previous inspection , although because of state laws requiring inspections every 6 months , the variation in intervals was limited . data from other programs with more variation in inspection frequency might be helpful in assessing the potential effect of time since last inspection . restaurant inspections serve an additional goal of ensuring immediate physical safety of patrons and workers in the environment . further studies to determine the most efficient and effective methods for assessing factors associated with food safety will be important to help improve the inspection system . recent introduction of hazard analysis and critical control points systems in many areas of the foodservice industry are an attempt to focus proactively on issues important to food safety ( 4 ) . given the universal performance of restaurant inspections in the united states , no large group of identical restaurants under similar social conditions exist to compare as  controls  to assess the direct effects of inspections . simply the anticipation of routine inspections probably improves compliance with food safety guidelines and laws ( 17 ) . the most appropriate mechanism for measuring restaurant sanitation and sharing the results remains a subject of much debate ( 1821 ) . recent regular dissemination of local restaurant scores in print and broadcast media in tennessee may have increased establishments attention to addressing deficits . many businesses may improve compliance with regulations to avoid bad publicity and negative economic repercussions . while no studies have been done to show that these types of negative reproductions have led to decreased foodborne illness in tennessee or elsewhere , the restaurant inspection system may be an effective mechanism to motivate change within the industry . public perception about the relative cleanliness or safety of particular types of restaurants may not reflect reality . many voluntary interventions , such as strict corporate policies on establishment design , equipment , and hygiene within a particular company can affect a large number of restaurants over a wide geographic area . such policies and procedures within large multistate corporations are unlikely to be substantially affected by local inspection policies . in contrast , restaurants serving specific ethnic or otherwise easily categorized cuisines are more likely to be locally owned and operated and may be more influenced by local management policies . this study suggests that a variety of factors influence the uniformity and reliability of routine restaurant inspections in preventing foodborne disease . some of these factors might be modified by policies designed to ensure periodic retraining and systematic standardization among inspection evaluations within a jurisdiction . further evaluating factors important in food safety and how best to control them will be important in improving the system . the centers for disease control and prevention , in collaboration with the food and drug administration and other agencies , has recently launched an environmental health specialist network project in seven states . this program will systematically address issues of restaurant inspections and their relationship to food safety and might contribute to our understanding of this system and efforts to improve it .
restaurants in the united states are regularly inspected by health departments , but few data exist regarding the effect of restaurant inspections on food safety . 
 we examined statewide inspection records from january 1993 through april 2000 . 
 data were available from 167,574 restaurant inspections . from 1993 to 2000 , mean scores rose steadily from 80.2 to 83.8 . 
 mean inspection scores of individual inspectors were 6992 . 
 none of the 12 most commonly cited violations were critical food safety hazards . 
 establishments scoring < 60 had a mean improvement of 16 points on subsequent inspections . 
 mean scores of restaurants experiencing foodborne disease outbreaks did not differ from restaurants with no reported outbreaks . 
 a variety of factors influence the uniformity of restaurant inspections . 
 the restaurant inspection system should be examined to identify ways to ensure food safety .