Exposure based waiving: The application of the toxicological threshold of concern (TTC) to inhalation exposure for aerosol ingredients in consumer products

Introduction:
This article discusses the application of the Toxicological Threshold of Concern (TTC) to inhalation exposure for aerosol ingredients in consumer products. The authors propose an exposure-based waiving (EBW) approach to evaluating the potential for adverse effects from such exposures, which could reduce the amount of inhalation toxicology studies required for REaCh implementation.

Key Points:

* The authors reviewed inhalation toxicology studies available in the public domain to establish a database for inhalation toxicology and derive TTCs for effects in the respiratory tract and systemically for Cramer class 1 and 3 chemicals.
* The EBW approach involves measuring consumer exposure in simulated product use and using an evaluation of potential structure activity relationship for toxicity and the TTCs for inhalation exposure to waive undertaking inhalation toxicology studies under REaCh.
* The study design included reviewing over 100 rodent studies, excluding certain types of chemicals, and using inhalation studies conducted to OECD guidelines for inhalation testing.
* The authors derived group NOaECs/NOaELs from the NOaECs for local and systemic effects from inhalation studies.
* The TTC for local and systemic effects was derived using uncertainty factors for interspecies and intraspecies variations.
* The TTCs derived from inhalation data lie between the class 1 and 3 values based on oral studies.
* The authors suggest that this EBW approach, which is consistent with the concept of developing 'intelligent testing strategies' for REaCh, could reduce the amount of inhalation toxicology studies required for REaCh implementation.

Main Message:
The article proposes an exposure-based waiving approach that could reduce the amount of inhalation toxicology studies required for REaCh implementation, while ensuring the safe use of chemicals with respect to human health and the environment. By using TTCs derived from inhalation data, the EBW approach could provide a more efficient and ethical way to evaluate the potential for adverse effects from inhalation exposure to aerosol ingredients in consumer products.

Carthew, P., C. Clapp, and S. Gutsell. “Exposure Based Waiving: The application of the Toxicological Threshold of Concern (TTC) to Inhalation Exposure for aerosol Ingredients in Consumer Products.” Food and Chemical Toxicology 47, no. 6 (June 2009): 1287–95. https://doi.org/10.1016/j.fct.2009.02.024.