Implementation of measures to reduce chemical contamination by cytotoxics in a centralised Chemotherapy Reconstitution Unit: are they effective?

Introduction
In order to assess the chemical contamination of the surfaces of the Chemotherapy Reconstitution Unit (CRU), we took samples inside and outside the isolators (9 points) in July 2019. These revealed contamination by several molecules, especially on the preparation release bench, and we implemented corrective measures. New samples (12 points) were taken in September 2020 to assess the effectiveness of these measures at one year.

Material and methods
Sampling kits were provided to us by the establishment carrying out the assays. The samples were taken in accordance with their recommendations, and by the same person during the two campaigns. After solid phase extraction, 6 molecules (5-FU, gemcitabine, cyclophosphamide, ifosfamide, doxorubicin, epirubicin) were measured by UPLC-MS/MS.
Corrective measures implemented in October 2019 include: closure of the injection site of the bags at the end of the preparation with a stopper, daily installation of drapes on the release bench, weekly systematic cleaning of the isolators with a detergent in addition to the bactericidal/fungicidal/virucidal/sporicidal product.

Results
The main contaminations (release bench) decreased between 2019 and 2020: from 296.11 to 2.50 pg/cm2 (99.16% reduction), from 112 to 0.8 pg/cm2 (99.29% reduction), from 513.06 to 7.90 pg/cm2 (98.46% reduction), from 22914 pg/cm2 to non-detectable for ifosfamide, gemcitabine, cyclophosphamide, and 5-FU respectively. Only 2 points (in one isolator) had stable contamination: ifosfamide (101.06 to 105.10 pg/cm2) and cyclophosphamide (3.55 to 2.50 pg/cm2). The new points tested in 2020 (telephones, cooler, door handle) are contaminated.

Discussion - Conclusion
As contamination has decreased on most points between 2019 and 2020, our implemented measures have a good efficiency. One improvement was suggested to reduce contamination inside the isolators: cleaning the spikes of the vials with a compress before putting them in the residue bin. A protocolised cleaning schedule was set up, including telephones and door handles, the importance of wearing gloves (nitrile) was reminded to the team, and a systematic annual monitoring of the chemical contamination of the CRU was set up to evaluate its evolution over time.

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