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We develop a model for bacterial cross‐contamination during food preparation in the domestic kitchen and apply this to the case of Campylobacter‐contaminated chicken breast. Building blocks of the model are the routines performed during food preparation, with their associated probabilities of bacterial transfer between food items and kitchen utensils. The model is used in a quantitative microbiological risk assessment (QMRA) of Campylobacter in the Netherlands. Using parameter values from the literature and performing elementary sensitivity analyses, we show that cross‐contamination can contribute significantly to the risk of Campylobacter infection and find that cleaning frequency of kitchen utensils and thoroughness of rinsing of raw food items after preparation has more impact on cross‐contamination than previously emphasized. Furthermore, we argue that especially more behavioral data on hygiene during food preparation is needed for a comprehensive Campylobacter risk assessment.

A quantitative microbiological risk assessment model describes the transmission of Campylobacter through the broiler meat production chain and at home, from entering the processing plant until consumption of a chicken breast fillet meal. The exposure model is linked to a dose‐response model to allow estimation of the incidence of human campylobacteriosis. The ultimate objective of the model is to serve as a tool to assess the effects of interventions to reduce campylobacteriosis in the Netherlands. The model describes some basic mechanistics of processing, including the nonlinear effects of cross‐contamination between carcasses and their leaking feces. Model input is based on the output of an accompanying farm model and Dutch count data of Campylobacters on the birds' exterior and in the feces. When processing data are lacking, expert judgment is used for model parameter estimation. The model shows that to accurately assess of the effects of interventions, numbers of Campylobacter have to be explicitly incorporated in the model in addition to the prevalence of contamination. Also, as count data usually vary by several orders of magnitude, variability in numbers within and especially between flocks has to be accounted for. Flocks with high concentrations of Campylobacter in the feces that leak from the carcasses during industrial processing seem to have a dominant impact on the human incidence. The uncertainty in the final risk estimate is large, due to a large uncertainty at several stages of the chain. Among others, more quantitative count data at several stages of the production chain are needed to decrease this uncertainty. However, this uncertainty is smaller when relative risks of interventions are calculated with the model. Hence, the model can be effectively used by risk management in deciding on strategies to reduce human campylobacteriosis.

To reduce consumer health risks from foodborne diseases that result from improper domestic food handling, consumers need to know how to safely handle food. To realize improvements in public health, it is necessary to develop interventions that match the needs of individual consumers. Successful intervention strategies are therefore contingent on identifying not only the practices that are important for consumer protection, but also barriers that prevent consumers from responding to these interventions. A measure of food safety behavior is needed to assess the effectiveness of different intervention strategies across different groups of consumers. A nationally representative survey was conducted in the Netherlands to determine which practices are likely conducted by which consumers. Participants reported their behaviors with respect to 55 different food‐handling practices. The Rasch modeling technique was used to determine a general measure for the likelihood of an average consumer performing each food‐handling behavior. Simultaneously, an average performance measure was estimated for each consumer. These two measures can be combined to predict the likelihood that an individual consumer engages in a specific food‐handling behavior. A single "food safety" dimension was shown to underlie all items. Some potentially safe practices (e.g., use of meat thermometers) were reported as very difficult, while other safe practices were conducted by respondents more frequently (e.g., washing of fresh fruit and vegetables). A cluster analysis was applied to the resulting data set, and five segments of consumers were identified. Different behaviors may have different effects on microbial growth in food, and thus have different consequences for human health. Once the microbial relevance of the different consumer behaviors has been confirmed by experiments and modeling, the scale developed in the research reported here can be used to develop risk communication targeted to the needs of different consumer groups, as well as to measure the efficacy of different interventions.

Cross‐contamination and undercooking are major factors responsible for campylobacteriosis and as such should be incorporated in microbiological risk assessment. A previous paper by van Asselt et al.(1) quantified cross‐contamination routes from chicken breast fillet via hand, cutting board, and knife ending up in a prepared chicken‐curry salad in the domestic kitchen. The aim of the current article was to validate the obtained transfer rates with consumer data obtained by video observations and microbial analyses of a home prepared chicken‐curry salad. Results showed a wide range of microbial contamination levels in the final salad, caused by various cross‐contamination practices and heating times varying from 2′44″ to 41′30″. Model predictions indicated that cooking times should be at least 8 minutes and cutting boards need to be changed after cutting raw chicken in order to obtain safe bacterial levels in the final salad. The model predicted around 75% of the variance in cross‐contamination behavior. Accuracy of the model can further be improved by including other cross‐contamination routes besides hands, cutting boards, and knives. The model proved to be fail‐safe, which implies it can be used as a worst‐case estimate to assess the importance of cross‐contamination in the home.

Microbial food safety has been the focus of research across various disciplines within the risk analysis community. Natural scientists involved in food microbiology and related disciplines work on the identification of health hazards, and the detection of pathogenic microorganisms. To perform risk assessment, research activities are increasingly focused on the quantification of microbial contamination of food products at various stages in the food chain, and modeling the impact of this contamination on human health. Social scientists conduct research into how consumers perceive food risks, and how best to develop effective risk communication with consumers in order to improve public health through improved food handling practices. The two approaches converge at the end of the food chain, where the activities regarding food preparation and food consumption are considered. Both natural and social sciences may benefit from input and expertise from the perspective of the alternative discipline, although, to date, the integration of social and natural sciences has been somewhat limited. This article therefore explores the potential of a transdisciplinary approach to food risk analysis in terms of delivering additional improvements to public health. Developing knowledge arising from research in both the natural and social sciences, we present a novel framework involving the integration of the two approaches that might provide the most effective way to improve the consumer health associated with food‐borne illness.

The improvement of food safety in the domestic environment requires a transdisciplinary approach, involving interaction between both the social and natural sciences. This approach is applied in a study on risks associated withCampylobacteron broiler meat. First, some web‐based information interventions were designed and tested on participant motivation and intentions to cook more safely. Based on these self‐reported measures, the intervention supported by the emotion "disgust" was selected as the most promising information intervention. Its effect on microbial cross‐contamination was tested by recruiting a set of participants who prepared a salad with chicken breast fillet carrying a known amount of tracer bacteria. The amount of tracer that could be recovered from the salad revealed the transfer and survival ofCampylobacterand was used as a measure of hygiene. This was introduced into an existing risk model onCampylobacterin the Netherlands to assess the effect of the information intervention both at the level of exposure and the level of human disease risk. We showed that the information intervention supported by the emotion "disgust" alone had no measurable effect on the health risk. However, when a behavioral cue was embedded within the instruction for the salad preparation, the risk decreased sharply. It is shown that a transdisciplinary approach, involving research on risk perception, microbiology, and risk assessment, is successful in evaluating the efficacy of an information intervention in terms of human health risks. The approach offers a novel tool for science‐based risk management in the area of food safety.

It has been established that, to a considerable extent, the domestic hygiene practices adopted by consumers can result in a greater or lesser microbial load in prepared meals. In the research presented here, an interdisciplinary study is reported in which interviews, observations of consumers preparing a recipe, and microbial contamination of the finished meals were compared. The results suggest that, while most consumers are knowledgeable about the importance of cross‐contamination and heating in preventing the occurrence of foodborne illness, this knowledge is not necessarily translated into behavior. The adoption of habitual cooking practices may also be important. Potentially risky behaviors were, indeed, observed in the domestic food preparation environment. Eighteen of the participants made errors in food preparation that could potentially result in cross‐contamination, and seven participants allowed raw meat juices to come in contact with the final meal. Using a tracer microorganism the log reduction as a result of consumer preparation was estimated at an average of log 4.1 cfu/salad. When combining these findings, it was found that cross‐contamination errors were a good predictor for log reduction. Procedural food safety knowledge (i.e., knowledge proffered after general open questions) was a better predictor of efficacious bacterial reduction than declarative food safety knowledge (i.e., knowledge proffered after formal questioning). This suggests that motivation to prepare safe food was a better indicator of actual behavior than knowledge about food safety per se.

Campylobacter bacteria are an important cause of foodborne infections. We estimated the potential costs and benefits of a large number of possible interventions to decrease human exposure to Campylobacter by consumption of chicken meat, which accounts for 20–40% of all cases of human campylobacteriosis in the Netherlands. For this purpose, a farm‐to‐fork risk assessment model was combined with economic analysis and epidemiological data. Reduction of contamination at broiler farms could be efficient in theory. However, it is unclear which hygienic measures need to be taken and the costs can be very high. The experimental treatment of colonized broiler flocks with bacteriophages has proven to be effective and could also be cost efficient, if confirmed in practice. Since a major decrease of infections at the broiler farm is not expected in the short term, additional measures in the processing plant were also considered. At this moment, guaranteed Campylobacter‐free chicken meat at the retail level is not realistic. The most promising interventions in the processing plant are limiting fecal leakage during processing and separation of contaminated and noncontaminated flocks (scheduling), followed by decontamination of the contaminated flock. New (faster and more sensitive) test methods to detect Campylobacter colonization in broilers flocks are a prerequisite for successful scheduling scenarios. Other methods to decrease the contamination of meat of colonized flocks such as freezing and heat treatment are more expensive and/or less effective than chemical decontamination.