###### Abstract  
Although biological monitoring is beneficial as it assesses all possible routes of exposure, urine sampling of healthcare workers exposed to hazardous drugs is currently not routine. Therefore, a scoping review was performed on this subject matter to understand what is known about exposure and identify knowledge gaps. A literature search was performed on three databases: ProQuest, Web of Science, and PubMed. Articles published between 2005 and 2020 and written in English were included. Overall, this review consisted of 39 full-text articles. The studies varied with respect to design, sample sizes, sample collection times, and drugs examined. Many articles found at least one sample had detectable levels of a hazardous drug. Studies reported urinary drug contamination despite controls being employed. Knowledge gaps included a lack of an exposure limit, lack of a standardized sampling method, and lack of correlation between health effects and urinary contamination levels. Due to differences in sample collection and analysis, a comparison between studies was not possible. Nevertheless, it appears that biological monitoring via urine sampling is meaningful to aid in understanding healthcare workers' exposure to hazardous drugs. This is supported by the fact that most studies reported positive urine samples and that case-control studies had statistically significant findings.  
hazardous drugs; biological monitoring; urine samples; healthcare workers; occupational exposure +
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or biomonitoring, evaluates worker exposure by measuring the concentration of a chemical or its metabolite in biological specimens [11; 12]. From an occupational health and safety perspective, biological exposure monitoring is beneficial as it assesses a worker's uptake through all possible routes of exposure, such as skin absorption, inhalation, and ingestion, resulting in a more accurate assessment of risk [11]. Urine is often used as a specimen for biological exposure monitoring because it is non-invasive, is readily available, and large volumes are possible [13]. In essence, by analyzing the concentration of hazardous drugs and/or their metabolites in urine from healthcare workers, it is possible to identify exposure risk factors as well as evaluate the effectiveness of control measures intended to reduce occupational exposure [14; 15].  
In their best practice document intended to prevent healthcare workers' exposure to hazardous drugs, the National Institute for Occupational Health and Safety (NIOSH) suggests that biological monitoring should be conducted \"when exposure is suspected, or symptoms have been noted\" [16]. This is especially important as dermal contamination has been reported despite gloves being worn by healthcare workers [17; 18] and, therefore, uptake is likely. In addition, there is no known correlation between environmental contamination and urinary contamination levels. Despite the above, employing biological urinary monitoring to assess healthcare workers' exposure to hazardous drugs is currently not a common practice--most likely because there is little guidance surrounding the matter. This study sought to provide some clarity on the issue of biological monitoring of healthcare workers who may be exposed to hazardous drugs.  
Therefore, the objective of this study was to conduct a scoping review of the current body of literature surrounding biological monitoring via urine samples for healthcare workers occupationally exposed to hazardous drugs. A scoping review is ideal to establish how urinary contamination studies were conducted, what the data to date indicate about exposure and, subsequently, identify knowledge gaps [19]. The goal was to understand what information is still required for biological monitoring via urine samples to become a more common or routine practice to protect the health and well-being of healthcare workers exposed to hazardous drugs.