The Threshold of Toxicological Concern (TTC) is a pragmatic tool for the safety assessment: Case studies of cosmetic ingredients with low consumer exposure

Safety assessment of Paeonia lactiflora root extract for a cosmetic ingredient employing the threshold of toxicological concern (TTC) approach

Botanical extracts, widely used in cosmetics, pose a challenge to safety assessment due to their complex compositions. The threshold of toxicological concern (TTC) approach, offering a safe exposure level for cosmetic ingredients, proves to be a promising solution for ensuring the safety of cosmetic ingredients with low exposure level. We assessed the safety of Paeonia lactiflora root extract (PLR), commonly used in skin conditioning products, with the TTC. We identified 50 constituents of PLR extract from the USDA database and literature exploration. Concentration of each constituent of PLR extract was determined with the information from USDA references, literature, and experimental analysis. The genotoxicity of PLR and its constituents was assessed in vitro and in silico respectively. Cramer class of the constituents of the PLR extract was determined with Toxtree 3.1 extended decision tree using ChemTunes®. Systemic exposure of each constituent from leave-on type cosmetic products containing PLR at a 1% concentration was estimated and compared with respective TTC threshold. Two constituents exceeding TTC threshold were further analyzed for dermal absorption using in silico tools, which confirmed the safety of PLR extract in cosmetics. Collectively, we demonstrated that the TTC is a useful tool for assessing botanical extract safety in cosmetics.

Application of AllerCatPro 2.0 for protein safety assessments of consumer products

Foreign proteins are potentially immunogenic, and a proportion of these are able to induce immune responses that result in allergic sensitization. Subsequent exposure of sensitized subjects to the inducing protein can provoke a variety of allergic reactions that may be severe, or even fatal. It has therefore been recognized for some time that it is important to determine a priori whether a given protein has the potential to induce allergic responses in exposed subjects. For example, the need to assess whether transgene products expressed in genetically engineered crop plants have allergenic properties. This is not necessarily a straightforward exercise (as discussed elsewhere in this edition), but the task becomes even more challenging when there is a need to conduct an overall allergenicity safety assessment of complex mixtures of proteins in botanicals or other natural sources that are to be used in consumer products. This paper describes a new paradigm for the allergenicity safety assessment of proteins that is based on the use of AllerCatPro 2.0, a new version of a previously described web application model developed for the characterization of the allergenic potential of proteins. Operational aspects of AllerCatPro 2.0 are described with emphasis on the application of new features that provide improvements in the predictions of allergenic properties such as the identification of proteins with high allergenic concern. Furthermore, the paper provides a description of strategies of how AllerCatPro 2.0 can best be deployed as a screening tool for identifying suitable proteins as ingredients in consumer products as well as a tool, in conjunction with label-free proteomic analysis, for identifying and semiquantifying protein allergens in complex materials. Lastly, the paper discusses the steps that are recommended for formal allergenicity safety assessment of novel consumer products which contain proteins, including consideration and integration of predicted consumer exposure metrics. The article therefore provides a holistic perspective of the processes through which effective protein safety assessments can be made of potential allergenic hazards and risks associated with exposure to proteins in consumer products, with a particular focus on the use of AllerCatPro 2.0 for this purpose.

Safety assessment of Cnidium officinale rhizome extract in cosmetics using the Threshold of Toxicological Concern (TTC) approach

Cosmetics often contain botanical extracts, which present a challenge for safety assessors due to their complex composition. The threshold of toxicological concern (TTC) approach is considered as a solution for the safety assessment of botanical extracts in cosmetics as part of next-generation risk assessment. In this study, we applied the TTC approach to evaluate the safety of Cnidium officinale rhizome extract (CORE), a widely used botanical extract in skin conditioning products. We identified 32 components of CORE through the USDA database and literature and determined the content of each component through literature or actual analysis where an authentic standard was available. Macro- and micronutrients were also analyzed to exclude them as safe components. The Toxtree® software was used to identify the Cramer class of remaining components. We estimated the systemic exposure of each component from leave-on type cosmetic products containing CORE at a 1% concentration and compared the results to TTC thresholds. All components of CORE had a systemic exposure below the TTC threshold. While batch variations and presence of unknown chemicals in individual CORE materials should be considered, this study demonstrated that the TTC approach can be a useful tool for the safety assessment of botanical extracts in cosmetics.

Lessons Learned from the Grouping of Chemicals to Assess Risks to Human Health

In analogy to the periodic system that groups elements by their similarity in structure and chemical properties, the hazard of chemicals can be assessed in groups having similar structures and similar toxicological properties. Here we review case studies of chemical grouping strategies that supported the assessment of hazard, exposure, and risk to human health. By the EU-REACH and the US-TSCA New Chemicals Program, structural similarity is commonly used as the basis for grouping, but that criterion is not always adequate and sufficient. Based on the lessons learned, we derive ten principles for grouping, including: transparency of the purpose, criteria, and boundaries of the group; adequacy of methods used to justify the group; and inclusion or exclusion of substances in the group by toxicological properties. These principles apply to initial grouping to prioritize further actions as well as to definitive grouping to generate data for risk assessment. Both can expedite effective risk management.