A UK-based medical device manufacturer.


As part of a large programme of work in evaluating the safety of a new endotracheal tube device, bibra was asked to evaluate the health risks posed by exposure to potentially hazardous substances that may be transferred to the patient via the gas stream during device use.

Project goals

Using the results of suitable analyses for particulate matter (PM), volatile organic compounds (VOCs) and potential condensate leachables, and by applying the evaluation approach outlined in ISO 18562-1, bibra assessed whether any of these substances could be expected to pose a health risk to adult patients being treated with the endotracheal tube device for up to 4 weeks.

Approach and outcome

In-line with ISO 18562-2, testing for PM was conducted by passing air through the endotracheal tube and capturing any particulates using a suitable filter. Levels of PM did not exceed 12 micrograms per cubic metre, the allowable limit defined by ISO 18562-2. On that basis the device was considered not to introduce pulmonary or respiratory health risks to patients as a result of exposure to PM.

As proposed in ISO 18562-3, Thermal Desorption-Gas Chromatography-Mass Spectrometry (TD-GC-MS) analysis was used to identify any potential VOCs that may be released from the device during use and subsequently inhaled by the patient. In accordance with the evaluation framework outlined in ISO 18562-1, relevant expert-derived inhalation safety limits were identified for all of the identified VOCs and compared with the worst-case patient exposure values. Highly reassuring margins were estimated, and thus it could be concluded that potential inhalation exposure to these VOCs as a result of treatment with the device would be highly unlikely to pose any significant health risks to patients.

In order to identify potential leachables that could leach into any water that condenses within the breathing tube and subsequently reaches the lungs of patients, the endotracheal tube was extracted, under exhaustive conditions, in water. To address ISO 18562-4, the resulting extractables were then formally evaluated in a toxicological risk assessment (TRA), in accordance with ISO 10993-17. For all potential leachables, relevant toxicity and ADME data were identified, the critical effects were defined, and Tolerable Intake (TI) values were derived. Comparing the worst-case patient exposure with these TI values demonstrated that treatment with the device and potential exposure to these leachable substances would be highly unlikely to pose any significant health risks to patients.

Bibra project team

Charles Johnson

Charlie Johnson

Senior Toxicologist

RSB/BTS and European Registered Toxicologist

Charlie joined the bibra team in mid-2015 after he completed his MChem degree. He is now a senior toxicologist and manages a large variety of projects.

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Pete Watts

Pete Watts

Toxicology Director

RSB/BTS and European Registered Toxicologist

Pete, one of our two Toxicology Directors, has an impressive 42 years of experience as a desk-based, bibra toxicologist and hazard/risk assessor. His special interest is in the pragmatic application of risk assessment methodology to toxicity data sets.

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