Health risk assessment of a polyester thread in a wound dressing


A medical devices manufacturer.


The company manufactures wound dressings (for short-term use) that were found to contain, at very infrequent intervals, a joining polyester thread in one of the layers.

Project goals

Bibra was asked to assess the possible health impact of the occasional presence of the thread in the wound dressing.


Bibra calculated a “worst-case” occurrence of the thread in a dressing, and used this to estimate patient exposure. It was considered that exposure to the thread would consist of single isolated instances, and thus the health risk assessment was limited to an evaluation of acute general systemic toxicity, genotoxicity, skin irritation and skin sensitisation endpoints. The full composition of the thread was not defined so, in a health-precautionary approach, it was assumed that the thread might contain a small proportion of undefined low molecular weight organic compounds. Toxicity data on the monomers were used to supplement (in a very conservative manner) available data on the polyester. The hypothetical) organic unknowns were considered by application of the Threshold of Toxicological Concern (TTC) approach.

Project outcome

Bibra’s health risk assessment provided reassurance that the presence of the polyester thread in the very occasional dressing would not be expected to pose any significant toxicological risks to patient health.

Project Team

Daniel Threlfall

Pete Watts


Medical devices

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