Traditionally, NOAELs from subchronic toxicity studies have been used to determine margins of safety for food ingredients and contaminants. The use of NOAELs from such studies is not ideal, because the NOAEL for the same substance may vary between studies due to choice of dose, control, species and/or strain used for the study. For macroingredients, the actual NOAEL may be higher than the highest dose tested. Further, NOAELs have not been established for some food ingredients that have been in the food supply for decades, due to lack of testing or reporting. Which dose, then, should be used as the point of departure for the purpose of risk assessment? The approaches that have been used to determine safe levels of exposure to food ingredients (e.g. NOAEL, benchmark dose, threshold of toxicological concern) are discussed, in hopes of generating discussion about the best method to assess risk of food ingredients and contaminants.
Implementation of the BMD in food safety
Since the suggestion by the FDA in the early 1950s, the No Observed Adverse Effect Level (NOAEL) has been used to develop “safe” doses or margins of safety for food ingredients and contaminants. However, NOAELs may not be available, and use levels of macroingredients may be higher than NOAELs from studies using low doses. In part to resolve problems, the benchmark dose (BMD) was developed in the early 1980’s. The BMD is defined as a dose associated with a predetermined response, such as 10%, for the critical effect, which is the first adverse effect in the dose scale as dose increases. Several examples are given for food ingredients and contaminants with different choices of BMD and critical effect.
The Threshold of Toxicological Concern (TTC) Approach in Food Safety
Exposure to some substances in the diet (e.g. flavorings, environmental contaminants, packaging migrants, process or metabolic intermediates and degradation products) is often extremely low, and requiring the generation of specific toxicological information may be time consuming and logistically complex. The TTC approach provides a pragmatic solution to some of these difficulties. It is based on use of the large body of existing information on those chemicals that have already been extensively tested, using distributional analysis to identify exposure levels below which there is a very low probability of harm for any chemical of unknown toxicity. Chemicals can be grouped into broad categories based on structure, leading to a tiered TTC approach. The suitability of the approach has been confirmed in several evaluations. The TTC approach can provide assurance that the levels of a substance in food are so low that no further data are necessary to complete the risk assessment.
Harmonization of Approaches for Food Ingredients and Constituents; Is It Possible?
The basic principles of safety can apply to all constituents in foods and beverages whether they are present purposefully or not. However, numerous factors can influence the approaches utilized for hazard characterization and risk assessment for various food and beverage constituents. These factors can include: the regulatory and legal framework being followed, what is and what is not known scientifically about the safety of a constituent, what the substance is, its function in a food or beverage, and consumer perception of the substance in the food or beverage., Food safety organizations around the world have adopted a variety of different approaches for addressing the safety of constituents in foods and beverages, which complicates, rather than simplifies, the risk assessment process. The ability to adopt and adapt various scientifically valid approaches for evaluating safety is important for ensuring the safety and continuity of supply of foods and beverages.
A symposium discussing these topics, called Risk Assessments: Which is Best for Food Ingredients? will take place on Sunday, July 12th at 1:30 PM at the Institute of Food Tehcnologist’s IFT15. Speakers will include Ray A. Matulka, Ph.D., Burdock Group, Alan R. Boobis, BS, Ph.D., Imperial College London, and Michael L. Dourson (or potential substitute speaker), Toxicology Excellence for Risk Assessment (TERA).
You can register for IFT15 at http://www.am-fe.ift.org/cms/.