IFT Expert Report BackgrounderMaking Decisions about the Risks of Chemicals in Foods with Limited Scientific Information
Backgrounder
When food safety managers detect an undesirable chemical contaminant or unanticipated chemical substance in a food commodity, ingredient, or finished product, they must quickly assess human health impact, often with limited scientific information. Timely decisions about appropriate actions, such as whether to implement a food product recall, can be complicated by the interactions of a number of issues. Interpretation of scientific and public policy can cause confusion as a result of insufficient risk assessment data, conflicting data, uncertainty arising from toxicological issues or temporal constraints, emerging nature of the state of the science, and regulatory constraints (for example, zero tolerance).
An extensive legal framework in the United States provides a foundation for U.S. food safety policy, and decision-making and international institutions and measures (for example, Codex standards) govern the safety of foods in international commerce. Risk science has emerged as a powerful tool to aid safety assessment decision-making. Application of the techniques of risk analysis (risk assessment, risk management, and risk communication) is progressing around the world. European laws have been harmonized and often influence other countries and discussions on global standards. The Precautionary Principle, a basic component of European food law, is a provisional risk management tool that developed in response to incomplete science.
At one time the mere presence of a chemical in a food, which related to the limits of detection, was often considered adverse to health and resulted in prohibition of the substance from food. With increasing sensitivity of analytical techniques, food safety professionals have needed a new approach to using available data in conducting risk-based evaluations of the potential exposure, hazard, and toxicity of low levels of chemicals, some of which may have always been an inherent component of the food supply.
Most toxicologists now realize that the mere presence of a chemical in a food does not mean that the substance necessarily poses a risk to health. In addition, there is broad agreement, reflected in regulation, that there is a dose below which the risk is so low that it may be disregarded. This concept of specifying human exposure thresholds relies on knowledge of the range of toxicological risks for structurally related substances and toxicological potency of relevant classes of chemicals for which good toxicity data exist.
During the past several decades, scientists have developed sophisticated decision tree models to address risks from very low level chemical exposures. Some describe a Threshold of Toxicological Concern (TTC) concept, a principle allowing for consideration of establishment of a human exposure threshold value below which there is no appreciable risk to human health. The IFT Expert Panel supports the TTC conceptual framework to manage low level detections of chemicals in foods when available data are limited.
The TTC approach provides an acceptably high probability of health protection as well as practicality. Using the TTC may lead to a decision that, for some chemicals, further work and risk mitigation steps are necessary while for others, further work is not necessary and a decision about risk can be made. The TTC approach has been applied by regulatory agencies and other organizations to indirect additives, flavors, pharmaceuticals, and personal and household products and has been proposed for application to any low-level detection of a chemical in foods with some product exceptions (for example, heavy metals and highly potent carcinogens).
To facilitate use of the concept as a screening and prioritizing approach to risk-based hazard evaluations, the panel visualized and illustrated a Toxicological Priority Grid that is based on toxicological potency, thresholds of toxicological concern, and potential consumer exposures. The prevailing scientific opinion, supported by solid scientific evidence, is that there is insignificant risk associated with chemical substances occurring in foods at levels below 0.5 ppb in the total diet (food and beverage), equivalent to a total dietary exposure of 1.5 µg/day. As a rule of thumb, the Expert Panel agrees with this threshold.
In assessing the risks of an unforeseen, newly discovered and undesired substance in food, interaction of the substance with other food components must be considered. The most appropriate decision involves comparing potential risks with the benefits of the whole food(s) in which the substance is found. Although regulatory and health authorities assessing food safety are obliged to focus great attention on the occurrence and potential risk of suspected toxicants and carcinogens in foods, they should also be encouraged to systematically investigate the health benefits of whole foods, such as those of heated foods and beverages.
Characterization of the effects of the food matrix on risks and benefits associated with various chemical substances in food is complex. Information about critical variables that are intrinsic to the individual, such as gender, age, health status, alcohol consumption, and customary food consumption, must be considered. Given the complexity of the food matrix and its role in altering how dietary chemicals are handled in the body, extrapolating observations to the general population is difficult. The paradoxical role of soy isoflavones in breast cancer is illustrative of the effects of food matrix components and interaction with other variables to influence bioavailability and impact on health and disease. The behavior of phytoestrogens in the life cycle may depend on a number of factors (including timing of exposure, absorption and individual metabolism, hormonal status, previous and current health condition, amount and profile of phytoestrogens in foods or supplements, and individual genetics). Current scientific evidence is insufficient to identify dietary supplements and dietary sources of phytoestrogens as either harmful or beneficial.
In reality there is never a perfect data set on which to base definitive conclusions on the safety of chemicals in food. Considering how far to pursue different options to manage the assessed risks will always be necessary. Regardless of whether there are scientific uncertainties, good production practices should never be compromised. Effective risk communication and education are important to help provide balanced perspectives on the benefits and potential risks of food chemicals.