Trace levels of food pathogen do not always translate to health risk, says study

(Press-News.org) These food safety measures and ultra-sensitive tests may drive edible food being thrown away, excessive packaging, and extra costs for consumers. 

The international team of researchers make it clear that food safety is an important concern, as foodborne pathogens account for approximately 420,000 deaths and 600 million cases of illness each year. However, the authors argue that food systems will be more sustainable, while continuing to protect public health, if “zero-detection” expectations are replaced with evidence-based targets for “sufficiently safe” food. 

Their new article sets out how regulators might find trade-offs with other important factors, such as food supply security, sustainability, and nutritional health. 

“Although the public expects food to be completely safe, there will always be some risk of foodborne illness. Zero risk doesn’t exist, and we shouldn’t be aiming for that either. Just as we don’t limit highway speeds to 10 miles per hour to minimize road deaths, we need to take a balanced approach that considers possible negative consequences of extreme food safety measures,” said lead author Prof Martin Wiedmann from Cornell University. 

Impact of aiming for zero risk 

The study’s authors highlight several situations where excessive caution can cause harm. 

Many rules and purchasing standards rely heavily on detecting a pathogen, sometimes treating any detection as unacceptable without fully considering dose, exposure, the food’s ability to support microbial growth, or who is most at risk. 

For example, a food product might be considered contaminated if it tests positive for the bacterium Listeria monocytogenes, regardless of levels. 

These alarms can result from ultra-sensitive tests detecting small amounts of microbes unlikely to cause disease in humans. In some cases, the concerns may come from bacteria that are not harmful themselves, but are an indirect indicator of contamination. 

Throwing away such food reduces the available food supply and wastes resources. Similarly, recalling food products from consumers can damage consumer trust, pushing people away from otherwise healthy products. 

Other protective measures, such as storage temperatures, packaging, and heat treatment, can waste energy, increase costs, and reduce nutritional content. While these are all important safety measures, they should only be applied if needed and associated trade-offs should be considered. 

“A tremendous amount of food is wasted that would have been sufficiently safe to eat. Too often, trade-offs such as environmental or economic costs are only considered after a traditional microbial risk assessment. We cannot afford to carry on like this at a time when we desperately need to reduce our impact on the planet and assure not only food safety but food security,” said co-author Prof Sophia Johler at Ludwig Maximilian University of Munich, Germany. 

Focus on risk rather than hazard 

The current situation is driven by an emphasis on hazard-based assessments, according to the authors, where regulations focus on detecting pathogens, regardless of the threat to consumers. The researchers argue that the food system should move towards more flexible risk-based approaches, which assess the probabilities of harms and adjust the safety measures accordingly. 

Regulations that overemphasize stringent corrective actions (such as recalls) when swab samples from a food-processing facility test positive for an indicator, for example, could lead to undue corrective actions in areas that are unlikely to contaminate the food. The authors explain that this could be an opportunity cost that diverts resources away from more effective interventions and control strategies in high-risk areas. 

“There’s well-established evidence that focusing on end-product testing is generally ineffective to ensure safety. Overemphasis on end-product testing may distract from other food safety measures (e.g., applying validated and verified process controls), which can provide greater public health benefits,” said co-author Dr Sriya Sunil at Cornell University. 

Better tools to assess priorities 

Computational tools that incorporate vast amounts of information across the food production system could help with establishing acceptable risks. 

One challenge is how to prioritize different hazards. For example, in the US, norovirus causes thousands of times more cases than Listeria monocytogenes, yet Listeria monocytogenes causes more deaths per year.  

While there are trade advantages to having consistent international food safety standards, the balance between competing interests may vary between regions. This can become even more complex when factoring in the health and environmental implications of greenhouse gas emissions. 

“Specialists across social sciences, economics, and life sciences must work together to establish values that align with consumers’ priorities. Together with advanced models that build on geographic information, AI, and genomics, we can assess, manage, and communicate risks far more accurately,” said Wiedmann. 

 

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