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Abbot JM, Byrd-Bredbenner C, Schaffner D, Bruhn CM, Blalock L. Comparison of food safety cognitions and self-reported food-handling behaviors with observedfood safety behaviors of young adults. Eur J Clin Nutr. 2009 Apr; 63 (4): 572-579. Epub 2007 Nov 14.  

PubMed ID: 18000516
Study Design:
Cross-sectional study.
D - Click here for explanation of classification scheme.
NEUTRAL: See Research Design and Implementation Criteria Checklist below.
Research Purpose:

To examine the relationship between food safety, self-reported food-handling behaviors and cognition of young adults to observed food-handling behaviors.

Inclusion Criteria:


  • Young adults (age 18 to 26 years)
  • Attending Rutgers University
  • Not at risk for foodborne disease (FBD)
  • Available for multiple sessions (observed meal preparation, home visit, complete online survey)
  • Have a kitchen available in their dwelling
  • Not have sanitation certification
  • Be in good to excellent health
  • Live within 25 miles of campus.


Exclusion Criteria:
  • Less than 18 years or older than 26 years of age
  • Not a Rutgers student
  • At risk for FBD
  • Not available for multiple sessions
  • Not have a kitchen available in their dwelling
  • Have sanitation certification
  • Be in poor health
  • Lives more than 25 miles from campus.
Description of Study Protocol:


  • Rutgers students were recruited through official university student e-mail listserves and advertisements in the campus newspaper
  • Each recruitment method described the time commitment the study required, the payment offered for the time spent participating and that this was a food study. Food safety was not mentioned
  • Interested participants completed an online screener questionnaire
  • Those who met the criteria for participation were invited via e-mail to sign up for scheduled study participation times. 


Each subject prepared a meal under observation in a controlled laboratory setting, permitted researchers to observe their home kitchen and completed an online survey assessing their food safety knowledge, behavior and psychosocial measures, as follows: 
  • Meal preparation under observation in a controlled laboratory setting:
    • Conducted by trained observers using a food preparation observation instrument that assessed how closely participants followed safe food handling procedures while preparing a meal
    • Instrument assessed practices consistent with Fight BAC! food safety recommendations:
      • Clean hands, produce and cutting boards
      • Separate dirty form clean and raw poultry from produce to be served raw
      • Cook foods to safe temperatures
      • Chill promptly and thaw properly
      • Prevent cross-contamination
  • Observation by researchers of home kitchen preparation in current living situation:
    • Utilized a home kitchen observation checklist administered by a trained auditor
    • Assessed compliance of home food storage and rotation practices (e.g., time, temperature), sanitation and chemical storage, general kitchen condition (e.g., pest control)
    • Included seven scales [kitchen cleanliness, appliance cleanliness, cleaning supplies availability, temperatures (food thermometer access and refrigerator/freezer temperatures), cold food storage, dry food storage and poisons storage] 
  • Completion of multipart online survey:
    • Online survey administered as part of a larger study (4,343 young adults)
    • Examined self-reported: 
      • Food-handling behaviors (best practices and risky food consumption)
      • Psychosocial factors (beliefs, self-efficacy, locus of control and stage of change)
      • Food safety knowledge (five scales, including cross-contamination prevention and disinfection procedures; safe times and temperatures for cooking and storing food; groups at greatest risk for FBD; foods that increase the chance of FBD; common food sources of FBD pathogens).


No intervention was implemented. This was an observational study comparing self-reported food safety behaviors and cognition with observed behaviors.


Statistical Analysis
  • Used SPSS 15.0 statistical program
  • Descriptive statistics (including means and standard deviations): Demographic characteristics, self-reported food handling behaviors, psychosocial characteristics, knowledge, food preparation observations and home kitchen observations
  • Backward regression models: Examine determinants of food-handling procedures while preparing and storing foods (including rotation practices)
  • Stable models: Created for the sample size, using the independent variables found to a P-value less than 0.10 in relationship to the dependent variables
  • Correlation analyses: Examine relationships between independent and dependent variables [including Pearson’s or Spearman’s (depending on distribution normalcy)]; T-tests or analyses of variance
  • Regression calculations: Excluded P-values higher than 0.10 to avoid eliminating marginally significant variables early in the regression that may become more significant later in the analysis
  • 10% of food handling observations of participants were independently coded at random by two trained researchers and showed interrater reliability of 90%
  • 10% of home kitchen audits were independently double-coded at random by two trained auditors with an interrater reliability of 0.95
  • Reliabilities of questionnaires (on best practices, risky food consumption, beliefs, food safety, self efficacy) were assessed by Cronbach’s α coefficients. The knowledge portion of the questionnaire was assessed using Livingston’s coefficient for criterion-referenced tests.


Data Collection Summary:

Timing of Measurements


All measurements were completed during a seven-month study period. Detailed timing of measurements were not provided.


Dependent Variables

  • Scores of the five food preparation observation scales
    • Clean
    • Separate
    • Cook
    • Chill
    • Cross-contamination
  • Seven home kitchen observation scales
    • Kitchen facilities cleanliness
    • Appliance cleanliness
    • Access to cleaning supplies
    • Thermometer access and temperature control
    • Cold food storage practices
    • Dry food storage practices
    • Poisons storage practices.

Independent Variables

  • Best practices scores
  • Risky food consumption score
  • Beliefs scale scores
  • Self-efficacy score
  • Predominant locus of control
  • Stage of change
  • Knowledge scale scores
  • Demographic characteristics: 
    • Gender
    • Race
    • Age
    • Year in college
    • Whether they had held a job as a food server or preparer
    • Prior food safety instruction (e.g., completed at least one nutrition, food science or microbiology college course vs. those who had not).
Description of Actual Data Sample:
  • Initial N: Initially, 1,228 individuals completed the online screener questionnaire, of these 432 (35%) met the inclusion criteria and were subsequently invited to participate. A total of 167 individuals agreed to participate and scheduled appointments.
  • Attrition (final N): The data analyses were conducted on 153 participants (56% female, 67% white, 97% never married, 85% juniors or seniors in college). Of the 167 participants, 153 (91.6%) honored their appointments and completed the seven-month study period. 
  • Mean age: 20.74±1.30 years standard deviation; Range 18 to 26 years
  • Ethnicity: 67% were self-identified as white
  • Other relevant demographics:
    • Participants were from a wide variety of college majors
    • Most (78%) prepared one to 10 meals weekly
    • Most had not held a job as a food server (60%) or food preparer (79%)
    • Most (86%) had not had taken a food science, nutrition or microbiology course
  • Location: Rutgers University, New Brunswick, NJ.
Summary of Results:

Key Findings

  • Mean best practices scale scores were poor, with study participants reporting they engage in less than half of the recommended safe food-handling practices evaluated by this instrument
  • The majority of study participants reported they or a household member had had food poisoning (86%) and had not changed their eating behavior in response to a publicized food poisoning outbreak
  • The authors stated that few significant differences in mean scores for best practices, risky food consumption, beliefs, self-efficacy, knowledge or observations were noted among demographic groups. However, no data was provided in the article
  • The knowledge scale of groups at greatest risk of foodborne disease and cross-contamination prevention self-report behavior scale tended to be significant predictors of actual food preparation behaviors
  • Food preparation observation mean scores were suboptimal, with highest mean compliance score for the “separate” scale (67%) (to prevent cross-contamination) and lowest for the Cook scale (29%) (involving following recommended procedures for safe chicken cooking), such that two-thirds of subjects kept raw animal protein separated from ready-to-eat food; whereas 97% did not use a thermometer to determine that that protein was cooked to safe temperature;  only half practiced adequate hand and kitchen sanitation
  • On the positive side, these three home kitchen observation mean scale scores exceeded 81% compliance:
    • Kitchen facilities cleanliness (e.g., most kitchen were clean to touch and sight)
    • Dry food storage (e.g., most dry foods were stored in a clean, cool, dry location and their packages were in good condition)
    • Poisons storage (e.g., poisonous substances were stored in a safe manner, away from food)
  • The temperatures mean scale score was especially low (e.g., mean refrigerator temperature was higher than 40oF and few had a food thermometer)
  • Study participants were primarily in the pre-action (pre-contemplation, contemplation or preparation) stage of change for safe food handling (78%). Participants had a predominantly internal locus of control for safe food handling (65%) (that is, they felt that protecting themselves from foodborne illness was a personal responsibility) and they had high levels of food safety self-efficacy, but their observed food handling practices do not indicate that these health-promoting cognitions are translated into actually performing safe food-handling practices.

Other Findings

  • Overall, participants correctly answered two-thirds of the food safety knowledge items. They were most knowledgeable about foods that increase risk for foodborne disease (FBD) and least knowledgeable about common food sources of FBD pathogens
  • Nearly everyone self-rated their food safety knowledge level and food safety skill (food poisoning prevention) level as at least fair (95% and 91%, respectively)
  • Regression models, including any one of the home kitchen observation scales as the dependent variable, generated R2 values too low (ranging from 0.02 to 0.10) to warrant further discussion. In contrast, the regression models for the food preparation observation scales revealed stronger, albeit still fairly low R2 values, ranging from 0.17 to 0.20
  • Only 39% of subjects reported washing their hands with soap and water all the time before they began preparing food. Subjects were observed performing only 25% of recommended hand-washing practices despite reporting that they perform half of these practices and correctly answering nearly three-quarters of the handwashing knowledge questions
  • Subjects tended to eat few risky foods, have positive food safety beliefs and high mean self-efficacy scores
  • Regression model results indicate that two measures help predict compliance with established safe food handling practices: Self-reported compliance with prevention of cross-contamination and disinfection procedures and knowledge of groups at greatest risk for FBD. 


Author Conclusion:

Findings strengthen the assessment that young adults lack optimal food safety knowledge, behavior and skill, and regression model results highlight two important considerations for the future of food safety education in this population:

  • Educational efforts focused on increasing knowledge of both overall foodborne illness awareness and correct cross-contamination prevention procedures could translate into better compliance with actual safe food-handling practices
  • Using these two measures as part of a baseline assessment could provide valuable information for evaluating where individuals fall on the continuum of food safety behaviors. This screening method could help educators focus their efforts more effectively by tailoring intensity and message topics to meet the needs of their specific audience.





Reviewer Comments:

 Authors noted the following limitations: 

  • The low P-values for the significant predictor variables in the regression models present as a limitation of this analysis; however, these results should be looked upon as new and exploratory
  • Similar evaluations should be done with larger sample sizes that can further define stronger predictor variables and better descriptions of the disconnect between what young adults report know about food safety and what they are observed practicing.  
Other possible limitations to the study are:
  • Authors did not assess the socioeconomic status of participants, which could impact the observations made. It could potentially limit the applicability of these findings to other young adults (e.g., working young adults, community college students, etc.).
  • Study had a low response rate. Of 432 young adults that met the criteria for participation, only 167 (39%) individuals accepted the invitation and scheduled a time to begin the study and, of these, 153 completed the study. Thus, it is unclear that the study sample was a representative sample of the relevant population.
There are some questions regarding the implementation of the study.
  • Was enrollment continuous or was there a specific start and stop date? The authors state a seven-month study period, but what was the average length of enrollment for participants?
  • What was the time span between the three time points (e.g., food preparation observation, home visit, and online survey)? Was this consistent between participants?
  • When scheduling the home visits, how did researchers control for last-minute cleaning efforts by participants?
  • Were participants asked not to research information on food and food safety while enrolled in the study or asked about if they sought additional information? This could have impacted outcome measures during the seven-month study.

Research Design and Implementation Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to nutrition or dietetics practice?
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies)
Validity Questions
1. Was the research question clearly stated?
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated?
  1.3. Were the target population and setting specified?
2. Was the selection of study subjects/patients free from bias?
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?
  2.2. Were criteria applied equally to all study groups?
  2.3. Were health, demographics, and other characteristics of subjects described?
  2.4. Were the subjects/patients a representative sample of the relevant population?
3. Were study groups comparable?
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?
  3.3. Were concurrent controls used? (Concurrent preferred over historical controls.)
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?
  3.5. If case control or cross-sectional study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable. Criterion may not be applicable in some cross-sectional studies.)
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?
4. Was method of handling withdrawals described?
  4.1. Were follow-up methods described and the same for all groups?
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for?
  4.4. Were reasons for withdrawals similar across groups?
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study?
5. Was blinding used to prevent introduction of bias?
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status?
  5.5. In diagnostic study, were test results blinded to patient history and other test results?
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied?
  6.2. In observational study, were interventions, study settings, and clinicians/provider described?
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured?
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described?
  6.6. Were extra or unplanned treatments described?
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?
  6.8. In diagnostic study, were details of test administration and replication sufficient?
7. Were outcomes clearly defined and the measurements valid and reliable?
  7.1. Were primary and secondary endpoints described and relevant to the question?
  7.2. Were nutrition measures appropriate to question and outcomes of concern?
  7.3. Was the period of follow-up long enough for important outcome(s) to occur?
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?
  7.5. Was the measurement of effect at an appropriate level of precision?
  7.6. Were other factors accounted for (measured) that could affect outcomes?
  7.7. Were the measurements conducted consistently across groups?
8. Was the statistical analysis appropriate for the study design and type of outcome indicators?
  8.1. Were statistical analyses adequately described and the results reported appropriately?
  8.2. Were correct statistical tests used and assumptions of test not violated?
  8.3. Were statistics reported with levels of significance and/or confidence intervals?
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?
  8.6. Was clinical significance as well as statistical significance reported?
  8.7. If negative findings, was a power calculation reported to address type 2 error?
9. Are conclusions supported by results with biases and limitations taken into consideration?
  9.1. Is there a discussion of findings?
  9.2. Are biases and study limitations identified and discussed?
10. Is bias due to study’s funding or sponsorship unlikely?
  10.1. Were sources of funding and investigators’ affiliations described?
  10.2. Was the study free from apparent conflict of interest?