Struggles in Strengthening the Food Safety Chain

For better, or more likely, for worse, food-borne illness outbreaks are something to which we have all become accustomed. Whether it’s the recent McDonald’s salad recall linked with Cyclospora parasites or a Salmonella outbreak linked with Kellogg’s Honey Smacks cereal, food safety is an ongoing struggle. The aforementioned outbreaks may be thought of as naturally-occurring; however, there is also the concern that we may be hit with intentional acts of bioterrorism against the agricultural and food industry—so much so, that many consider it America’s soft underbelly.

At the Biodefense World Summit 2018, the topic of food safety was heavily discussed. Perhaps what makes this field so challenging isn’t just the ability to identify pathogens and differentiate between natural or intentional outbreaks, but the sheer speed at which food moves throughout the industry. From farm to table (or processing plant to table), there are a million different points at which contamination to occur. Moreover, the rapid pace of globalization means that the time between processing and consumption has been cut down exponentially. People want their food quick and fresh, which does not leave a lot of room for error when it comes to food-safety measures.

Implementing tracking mechanisms are one strategy, but we also need to establish testing mechanisms that are precise and quick to help identify contamination at the source or early on in the food chain. Two such presentations on these topics are discussed below.

Robert L. Buchanan, PhD, from the University of Maryland’s Center for Food Safety & Security Systems, presented on an all-too-forgotten aspect of testing—sampling. Dr. Buchanan underscored a painful truth about microbial testing; that it is one of the most investigated and used aspects of food microbiology, but also one of the most poorly understood. Part of the challenge is to pick the right tool for the job, as microbial testing involves a set of technological and statistically-based tools that focus on the safety of batches, process control, surveillance, and investigational sampling.

There are 2 kinds of sampling plans for microbiological tests when evaluating the microbial safety (or quality) of food in high quantities: attribute and variables. The hard part is finding the balance between utility, effectiveness, and the cost of testing, which can depend on defect rates, sensitivity required, sample unit size, degree of confidence required, and more.

Dr. Buchanan gave an example of how defect rates can have a large impact on testing confidence and precision. He explained defect rates by showing the calculation for how many tomatoes would be needed if you wanted to be 95% confident that you would be able to detect contaminated tomatoes if the defect rate was 30%, or 99% confident. (FYI—it’s 7 tomatoes for a 30% tomato defect if you want 95% confidence or 10 tomatoes if you want 99% confidence).

He further elaborated on the challenges of refining microbiological testing, noting the 2 primary factors for determining the lower limit of detection for microbiological methods. The following can change the accuracy of detection: the number of target microorganisms needed to distinguish from a signal versus noise—especially when considering the particulate nature of microorganisms—and the sheer likelihood that the pathogen you are looking for is even present in the sample being studied.

Dr. Buchanan ended with a discussion on the future of microbial testing against microbial criteria. He noted that we’ve made a great deal of progress in microbiological testing for food-borne disease and that today’s world of whole genomic sequencing means we are able to identify smaller outbreaks to combat an increased scale of food production, but we still have room for improvement in food sampling capabilities.

Pramod Pandey, PhD, of the University of California, Davis, discussed microbial contamination in surface water, which peaked my interest for obvious infection control reasons. Interestingly, he noted that in the United States, only 23% of the total streams/rivers are actually assessed and of those, 53% are impaired! Moreover, pathogen contamination—mostly from animal waste through manure application and drainage from cropland on farms—is the main cause of impairment in these ambient waters.

Guidelines and protocols are often only as good as our understanding of the science involved and often, we see differences in what is deemed acceptable between countries and international agencies. For example, Dr. Pandey highlighted a difference between the US Environmental Protection Agency (EPA) and the World Health Organization (WHO) in how they define water pollution in ambient water (hint: the WHO has more stringent expectations). Understanding how contamination and pollution occurs is part of the problem in defining it, which is where Dr. Pandey’s research comes in. The hurdle of such work, though, is in the understanding of particle-attached pathogen transport from cropland to surface waters, which makes control measures more difficult. Predicting pathogen transport throughout water and how it moves from croplands into ambient water, like streams, is pivotal for prevention and control measures. Dr. Pandey noted that the challenges in understanding pathogen transport reside in nonpoint sources (ie, pathogens released from cropland receiving manure as fertilizers, etc.), and other complex interactions. Currently, his research focuses on pathogen monitoring, such as monitoring Escherichia coli transport in cattle access to streams, feedlots, floods, and low flows. Ultimately, he noted that hydrological models can enhance our understanding of pathogen transport and we need to improve prediction methodology.

The 2018 Biodefense World Summit covered an immense array of topics when it comes to pathogen detection and the challenges of responding to biological threats. Food safety is increasingly a vital component to biodefense and although we traditionally think of biological threats in the form of bioterrorism, it was humbling to see these efforts to strengthen the safety of US food supply.