Use of Probabilistic Exposure Models in the Assessment of Dietary Exposure to Chemicals 

Risk Sciences International CEO, Greg Paoli and RSI senior experts Emma Hartnett and Paul Price, have co-authored a new peer-reviewed publication highlighting the critical role of probabilistic exposure assessments (PEAs) in protecting public health. Supported by the Institute for the Advancement of Food and Nutrition Sciences (IAFNS), the study demonstrates how PEAs provide a more accurate picture of dietary chemical exposures, helping regulators and other stakeholders avoid the pitfalls of “compounding conservatism” and make more evidence-based decisions. Paoli noted that the publication was praised by reviewers as both “comprehensive” and “de-mystifying,” reflecting the team’s goal of creating a single resource that captures the history, methods, regulatory guidance, and practical applications of PEA techniques.

The Institute for the Advancement of Food and Nutrition Sciences released the following news release earlier today.

Newswise — Washington D.C. – Decision-makers consider both the potential hazards of, and exposure to, chemicals when protecting public health. Increasingly they are seeking to accurately describe population-level exposures to chemicals in our diet to better convey the risks, if any, that are posed by these chemicals.

That’s where a type of analysis called “Probabilistic Exposure Assessment” (PEA) comes in. Regulators and other stakeholders use PEAs to combine exposure data with mathematical models to arrive at better risk management decisions.

In a new study supported by the IAFNS Food & Chemical Safety Committee, researchers point out how PEAs support the understanding of dietary exposures to support decision-making using a variety of established computer software packages and techniques. 

PEAs are important tools because they help in accurately assessing health exposures and risks. Probabilistic techniques are particularly required to estimate what fraction of the population may be consuming higher doses. The publication demonstrates that techniques that are not probabilistic will often dramatically overestimate exposures without providing the context of how unlikely these estimated exposures really are. This occurs through a well-known process referred to as ‘compounding conservatism.’

But where do the chemicals in foods come from? Chemicals can enter the growing, processing and marketing of foods at multiple points. Chemical compounds from different sources may be intentionally added to, or inadvertently become present in, a food. Thus, considering these multiple points and processes is important when weighing food chemical safety decisions.

The most common approach to PEA makes use of Monte Carlo simulation techniques, using commercial off-the-shelf software add-ins to Microsoft Excel™ like @Risk™ or Analytica™, as custom-written software, or freely available food-specific on-line software tools like FDA-iRISK™.

Approaches are quite diverse, ranging from acute (intense or sudden) to chronic (persistent), from life-stage to lifelong exposures and can explicitly demonstrate longitudinal variation, the authors conclude.

PEAs can be used to estimate cumulative ingested dose (exposure to a chemical via multiple foods) and aggregate exposures (from multiple routes such as food, air and consumer products). In these assessments, the daily exposure to a chemical from each source is modeled separately and then summed to provide the individual’s total dose.

The study’s lead author, Greg Paoli of Risk Sciences International in Ottawa, notes: “We were particularly pleased that the peer reviewers characterized the publication as both ‘comprehensive’ and ‘de-mystifying.’ Our goal was to have one publication that covers the history of use and the who, what, why, when and how of PEAs. We also characterized available regulatory guidance as well as potential barriers and solutions to yield more widespread use.”

The paper is available here.

The Institute for the Advancement of Food and Nutrition Sciences (IAFNS) is committed to leading positive change across the food and beverage ecosystem. This paper was supported by IAFNS Food & Chemical Safety Committee. IAFNS is a 501(c)(3) science-focused nonprofit uniquely positioned to mobilize government, industry and academia to drive, fund and lead actionable research. iafns.org