Alternative Methods for Acute Inhalation Toxicity

Acute inhalation systemic toxicity tests identify substances that could cause illness or death after a single inhaled exposure. NICEATM facilitates interactions among stakeholder groups interested in developing and promoting alternatives to animal use for these tests.

Several NICEATM presentations at the 2024 annual meeting of the Society of Toxicology focus on inhalation toxicity:

  • A poster presentation (Allen et al., Respiratory Toxicology I session) provides an overview of development and curation of an acute inhalation toxicity database.
  • A poster presentation (Gwinn et al., Respiratory Toxicology II session) discusses evaluation of an air-liquid interface model.
  • A poster presentation (Johnson et al., New Approach Methods: In Vitro I session) presents preliminary data on an in vitro model for respiratory sensitization hazard.
  • An oral presentation (Chang et al., Symposium Session on "Current Status, Challenges, and Future Considerations: Advancing NAMs for Assessing Inhalation Toxicity") provides case studies of how in vitro to in vivo extrapolation can be used to develop estimates of inhalation toxicity hazard and risk from in vitro data.

EpiAirway Validation Study

A cooperative agreement under the NIEHS Phase IIb Small Business Innovation Research provided funding to MatTek Corporation to validate its EpiAirway™ in vitro human bronchial tissue model to predict the toxicity of inhaled chemicals. Several ICCVAM agency representatives are members of the cooperative agreement steering committee. Testing of reference chemicals to determine the usefulness and limitations of EpiAirway for this purpose has been completed. 

Webinar Series and Workshop on Inhalation Toxicity

A 2016 webinar series and workshop on inhalation toxicity co-organized by NICEATM is summarized in a report published in Toxicology In Vitro (Clippinger et al. 2018a).

NICEATM and the PETA Science Consortium International (PSCI) offered a webinar series from March to September 2016 on Alternative Approaches for Acute Inhalation Toxicity to Address Global Regulatory and Non-regulatory Data Requirements. Webinar presenters:

  • Reviewed regulatory guidelines relevant to assessing inhalation toxicity hazard potential.
  • Described alternative approaches for identifying substances likely to cause acute systemic toxicity through inhalation.
  • Identified mechanisms of acute toxicity that may constitute key events in adverse outcome pathways for acute inhalation toxicity.

More information and links to webinar recordings

At a 2016 workshop that expanded on the webinar series, experts from industry, government, academia, and nongovernmental organizations shared experiences using alternative approaches for acute inhalation toxicity testing and considered how to develop strategies acceptable to regulatory agencies. Workgroups were established to address the four primary workshop recommendations:

  • Develop a database of acute inhalation toxicity data.
  • Prepare a state-of-the-science review on mechanisms and assays for acute inhalation toxicity (Clippinger et al. 2018b).
  • Develop an in silico decision tree for determining when acute inhalation testing should be performed.
  • Optimize in vitro assays and standard protocols to be used across laboratories.

These workgroups have been meeting as needed to continue progress toward implementation.

In Vitro Testing Strategies to Assess Inhalation Toxicity of Nanomaterials

NICEATM collaborated with PSCI, EPA, and industry scientists to support a workgroup focused on inhalation toxicity. In 2014, NICEATM published a request for information (79 FR 35176, June 19, 2014) about devices and/or technologies currently used for identifying potential inhalation hazards.

Subsequently, the workgroup met in 2015 to define specifications for the development and evaluation of an in vitro system to assess the toxicity of multi-walled carbon nanotubes when inhaled. The workgroup determined that the proposed in vitro system should include different lung cells co-cultured at an air-liquid interface and consider relevant human dosimetry and nanomaterial lifecycle changes. Presentations from the meeting and a list of publications developed by meeting participants are available on the PSCI website.

PSCI used these recommendations in a request for proposals to develop an appropriate testing system; funding was awarded in September 2015.

Responses Received to the June 2014 Request for Information