Multicenter study of environmental contamination with antineoplastic drugs in 33 Canadian hospitals

No occupational exposure limit exists for antineoplastic drugs. The main objective of this study was to describe environmental contamination with cyclophosphamide, ifosfamide and methotrexate in pharmacy and patient care areas of Canadian hospitals in 2012. The secondary objective was to compare the 2012 environmental monitoring results with the 2008-2010 results.

Six standardized sites in the pharmacy and six sites on patient care areas were sampled in each participating center. Samples were analyzed for the presence of cyclophosphamide, ifosfamide and methotrexate by UPLC-MS-MS. The limit of detection (LOD) was 1.8 pg/cm² for cyclophosphamide, 2.2 pg/cm² for ifosfamide and 8.0 pg/cm² for methotrexate. The comparison of surface contamination between the 2008-2010 and 2012 studies was made with the 75th percentile of cyclophosphamide concentration.

A total of 33 hospitals participated in the study and 363 samples were collected. Overall, 40 % (147/363) of the samples were positive for cyclophosphamide, 18 % (68/363) were positive for ifosfamide and 5 % (17/363) were positive for methotrexate. In 2012, the 75th percentile value of cyclophosphamide surface concentration was of 9.4 pg/cm², which is four times lower than the 2008-2010 75th percentile of 40 pg/cm². In both studies, the 75th percentile for ifosfamide and methotrexate concentration was lower than the LOD.

Surface contamination by cyclophosphamide, ifosfamide and methotrexate in Canadian hospitals is improving both in terms of the proportions of positive samples and in terms of the surface concentration of antineoplastic drugs. A local 75th percentile value should be use to assess local contamination and interpret local results.