The National Health and Medical Research Council (NHMRC) has issued a policy statement on smoke inhalation procedures in mice and rats, recommending that:
‘Due to the significant adverse impacts of the nose-only exposure procedure on animal wellbeing and the potential confounding effects of these impacts on scientific outcomes, the use of this procedure can no longer be justified in accordance with the Australian code for the care and use of animals for scientific purposes and its use must be phased out as soon as practicable.’
The nose-only method is a contentious research method used by a research group at the Centenary Institute, Sydney, in which mice are constrained in a tube and attached to a smoking machine, where they are forced to smoke up to 12 cigarettes twice a day for up to 18 weeks before being killed to measure disease indicators. The national funding body, until this point a significant funder of nose-only smoke inhalation research, has determined that the nose-only exposure procedure must not be used in any new projects and must be reviewed for existing projects. The announcement follows years of campaigning by Animal-Free Science Advocacy (formally known as Humane Research Australia) and responds to the foremost recommendation of a 2022 NSW Inquiry into animal experimentation for a rapid phase-out of the cruel test; the Inquiry Committee concluding that the harm caused by this research is greater than the human health benefits gained.
The use of the whole-body exposure procedure, where unrestrained animals are placed in a chamber into which smoke is introduced, will continue to be funded under exceptional circumstances, with additional conditions imposed.
Under both methods, mice suffer from irritation to the eyes and respiratory tract, nicotine withdrawal and from the debilitating effects of the chronic lung disease that the procedures are designed to model. During the nose-only exposure procedure, the animals are at a heightened risk of injury or mortality, they suffer stress as a result of being restrained and kept in isolation, and there is the potential for hypothermia and weight loss.
Released documents, obtained by the Animal Justice Party through a NSW Parliament order for papers, revealed shocking unexpected deaths and adverse outcomes arising from the nose-only exposure method specifically, with over 100 mice having died (commonly from suffocation) during or immediately after ‘being smoked’ at the University of Newcastle between April 2018-June 2020. The University of Newcastle ended the practice in 2022, but the research group re-established at the Centenary Institute, where forced smoking research continues under funding via NHMRC and others.
The ban will not obstruct medical research, with many replacement methods based on human and not mice biology available. Besides the cruelty caused, HRA questions the validity of results obtained via animal smoke inhalation models. There are severe limitations to the translation of findings due to biological differences between humans and mice and differing responses to interventions between species. It is impossible for a mouse to accurately mimic human inhalation, and time that new approach methods, such as the lung-on-a-chip or advanced computer modelling and simulation be utilised.
It is rare that for regulatory or funding agencies to take such a bold position, with a preference for self-regulation by institutional animal ethics committees. Animal-Free Science Advocacy Chief Executive Officer Rachel Smith states.
‘This is a long overdue prohibition of a cruel and invalid research method which is objectionable to the public and scientific community alike. For too long, researchers at the Centenary Institute have caused unnecessary suffering to mice without justification to human health, and were this funding decision not taken, this research would continue unabated. The decision marks a victory for the many advocates, politicians, scientists, animal ethics committee members and individuals who spoke up against cruel smoking towers’.