Identifying Hazardous Drug Residue via Wipe Analysis

July 2013 - Vol. 10 No. 7 - Page #42

Occupational exposure to hazardous drugs remains a serious risk to health care personnel, with potential exposure occurring at numerous points of hazardous drug handling from receiving the manufacturer’s vials at the loading dock through disposal of the corresponding waste.1-3 Formal wipe analysis has revealed that hazardous drug residue occurs throughout hospitals, including in areas outside of the pharmacy and oncology units.4 Given this risk, facilities handling hazardous drugs should consider establishing a formal wipe analysis plan to identify potential environmental residues and prevent health care worker exposure.

The National Institute for Occupational Safety and Health (NIOSH) Alert,Preventing Occupational Exposures to Antineoplastic and Other Hazardous Drugs in Health Care Settings, recommends conducting environmental sampling and/or biological monitoring when exposure is suspected or symptoms have been noted.5 Preemptive environmental monitoring, however, can identify potential staff exposure risks prior to any concerns arising. At the time of publication of the NIOSH Alert (2004), there were few commercial options for hospitals to conduct environmental sampling. As a result, for some hospitals this monitoring did not become typical practice. Since the NIOSH publication, multiple environmental hygienist companies have introduced environmental sampling kits for hazardous drugs, making it straightforward for hospital pharmacies to adopt this practice (see Table 1). 

It may be prudent for clinicians to partner with a vendor noted in the primary literature as having expertise and experience measuring hazardous drug residues in specific settings for sampling. While there are no standards defining which drugs to test for, the number of samples to collect, or the locations of sampling, there are many helpful investigative publications that can assist clinicians with making these decisions.6 Working closely with an experienced environmental sampling partner will help ensure health care workers are protected from the harmful effects of hazardous drug exposure, and developing a robust wipe analysis procedure will assist in identifying areas of potential contamination.

Establish Sampling Locations
Be sure to choose a vendor whose offerings match the needs of your practice. Once a vendor has been selected, the next step is to define the specific hazardous drug residues that will be tested for and determine the sampling locations. These are important considerations, as testing costs are determined by the number of drugs tested and the number of sampling locations specified. When evaluating which drugs to test for, consider the site’s compounding history, with the most frequently compounded drugs serving as representative agents. Sampling is not universally available for every hazardous drug, and each vendor tests for different drugs. To determine the number of sample locations, consider historical practice at the site, previous spills, and areas of high contact with hazardous drug products. It may be particularly advantageous to map out the hazardous product flow from receiving to disposal (see Figure 1). Sample locations should include areas noted to have the highest chance of residue as identified in the literature.6 These locations may include: 

Click here to view a larger version of this Figure

  • Work surfaces within biological safety cabinets/compounding aseptic containment isolators (BSCs/CACIs)
  • BSC/CACI airfoils/vents
  • Floors directly below the opening of the BSC/CACI
  • Counter tops where hazardous drugs are stored 
  • To establish secondary sample locations, review areas outside of the normal compounding and administration locations where residue may reside, such as:
  • Door handles to the compounding area
  • Refrigerators storing hazardous drugs 
  • Drug storage areas on oncology units
  • Infusion chairs where patients receive hazardous drugs
  • Buttons on intravenous pumps used for hazardous drug infusions
  • Exterior of hazardous drug waste containers 
  • Investigate each vendor’s sampling requirements and kit contents to ensure you order a sufficient number of kits for your site based on the number of sampling locations identified.

Testing Kit Contents
The vendor will provide a kit customized to their testing standards and available assays for drugs; the contents of these kits will vary (see wipe analysis step Photos). However, most of the kits are similar in nature and may include the following basic items:

  • User manual, company brochure, and site map 
  • Disposable measuring tape
  • Removable colored dots for marking sampling areas
  • Swab tissues for sampling
  • Sampling diluent (eg, 0.03M NaOH [sodium hydroxide] solution)
  • Sample collection containers with individual labels and plastic overbags to prevent cross contamination
  • Hazardous drug nitrile gloves
  • Pen for documentation and disposal after sampling
  • Return shipping box
  • Return FedEx or UPS package label/envelope

Click here to view a larger version of these Photos

Wipe Analysis Procedures
It is important to note that the process of collecting hazardous drug surface samples should be considered high risk, and every precaution recommended by NIOSH for compounding should be employed for sampling as well. Prior to beginning the sampling process, read the vendor’s instruction sheet, paying particular attention to the sections on the collection to shipping time, interim storage prior to shipping, and shipping requirements. Some vendors require samples to be shipped on dry ice. However, the vendor may not provide the dry ice or the dry ice shipping containers, in which case these items should be acquired prior to sampling. As a general rule, plan to use one pound of dry ice for every six samples. Because some vendors may not provide shipping containers, ensure the proper container is on site prior to collecting. 

Although the process for collecting samples varies among the different vendors, the basic steps are similar.

  • Choose a day when all samples can be collected in the morning for afternoon shipping. Some vendors have strict timing requirements for the samples once they are collected
  • Select a time in the day when access to the sample sites will not be disrupted
  • Allow approximately ten minutes for the collection of each sample
  • Pre-label all collection vessels with the drug to be analyzed and the location of the sample
  • Individuals collecting the samples should wear proper personal protective equipment (PPE) according to NIOSH recommendations.5 Gather sufficient hazardous drug rated gloves to replace two pairs after each sample is collected (ie, six samples require 12 pairs of gloves)
  • Following vendor specifications, measure the area required for sampling (eg, one company specifies a 0.5m2 area for sampling). It is best to use a disposable measuring tape or a strip of paper the length of the sampling requirements 
  • Mark the sampling area with removable, disposable colored tape or dots; some vendors provide site markers to assist with this process
  • Use the vendor-provided solvent to wet the sampling area in order to collect the sample for analysis (eg, a dropper vial with approximately 17 mL of sodium hydroxide [NaOH] for each sample). Note that the steps for prepping the solution and conducting the swabbing are vendor-specific. Follow the vendor’s instructions on wetting the sample area
  • Use the sample collection wipe provided by the vendor (eg, tissues, cylindrical swabs, towelettes, cotton swabs) and collect the sample in the manner outlined by the vendor (eg, single swipe of the area using vertical and horizontal strokes). Some vendors require a second wipe with a new wipe for each area to be added to the sample; this too is vendor-specific
  • Place the samples in the pre-labeled vial and seal
  • To minimize the possibility of cross contamination, replace gloves between each sample; also replace PPE if suspected contamination has occurred.  Dispose of gloves and any PPE in the hazardous waste container
  • Between sampling, the collected products may need to be stored in a refrigerator or on dry ice per the vendor’s specifications. To minimize cross contamination of the storage environment and the sample, each sample vial must be in a zip lock bag during temporary storage
  • Thoroughly wash hands with soap and water upon completion of sample collecting
  • Once all samples are collected, complete the vendor-supplied sample log enumerating the location(s) tested and the drugs to be analyzed
  • Place the samples and corresponding paperwork into the recommended shipping container following the vendor’s packing specifications
  • If shipping with dry ice, a Department of Transportation hazard class 9 label UN1845 and an airway bill are required documentation. The vendor may or may not provide these documents. FedEx and UPS will ship dry ice samples
  • All remaining materials used in the sampling process but not required by the vendor (eg, pens, measuring tapes, paper, PPE), must be disposed in hazardous waste containers

Wipe Analysis Reports
Each vendor provides a basic report listing the collection locations and any residue of the sampled drug identified in a quantity of residue per quantity area (see Table 2). As previously noted, there is no standard reporting metric for quantifying hazardous drug residue, and result reports differ by vendor; however, each report identifies existing residue and its concentration. The goal of testing is to not find residue; however, there are many opportunities for residue to contaminate an area beyond the compounding and drug administration process.7

Some vendors provide a comparative analysis to similar facilities at an additional cost. Remember that these comparisons do not correlate to best practices; they only relate to the moment in time that each site conducted the sampling. These types of reports should not be used to measure the effectiveness of a site’s hazardous drug program against other facilities; rather, they are best used for internal benchmarking until national standards are established by a reputable, non-profit organization. The data from these reports provides valuable information to practitioners regarding hazardous drug residue. Unlike in the radiology department, where personal dosimeters and Geiger counters provide practitioners with immediate, continuous data on radiation exposure, hazardous drug sampling does not provide immediate results. In addition, because the reports only provide a snapshot in time within the hazardous drug flow process, they should not be construed as defining practices at a site. Information garnered from sampling should be used by sites to denote gaps and improve processes. 

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Given the serious consequences of occupational exposure to hazardous drugs, establishing a formal wipe analysis program for hazardous drug residue gives pharmacy leadership the opportunity to identify specific risks throughout their facilities, and in response, develop practices to continually avert these risks. Since numerous vendors now offer wipe analysis kits, establishing such a program can be simple; however, it is important to note that sampling for hazardous drug residue itself is a hazardous process, and the same precautions used for drug compounding and administration should be heeded during the sampling process. This approach will add an additional layer of safety to sterile compounding, thus allowing pharmacy to assert control over what has traditionally been a nebulous area to manage. 

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  1. Anderson RW, Puckett WH Jr, Dana WJ, Nguyen TV, Theiss JC, Matney TS. Risk of handling injectable antineoplastic agents. Am J Hosp Pharm. 1982;39(11):1881-1887.
  2. Davis J, McLauchlan R, Connor TH. Exposure to hazardous drugs in healthcare: an issue that will not go away. J Oncol Pharm Practice. 2011;17(1):9-13.
  3. Occupational Safety and Health Administration. Controlling occupational exposure to hazardous drugs. OSHA technical manual, TED 1-0.15A. Section VI. Chapter 2. (accessed 2012 February 22)
  4. Connor TH, McDiarmid MA. Preventing occupational exposure to antineoplastic drugs in health care settings. CA Cancer J Clin. 2006;56(6):354-365.
  5. National Institute for Safety and Occupation (NIOSH) Alert. Preventing Occupational Exposures to Antineoplastic and Other Hazardous Drugs in Health Care Settings. DHHS (NIOSH) Pub No. 2004-165, September 2004.
  6. Connor TH, DeBord DG, Pretty JR, et al. Evaluation of antineoplastic drug exposure of health care workers at three university-based US cancer centers. J Occup Environ Med. 2010;52(10):1019-1027.
  7. Powers LA. Demand clean vials. Am J Health Syst Pharm. 2005;62(5):471.
  8. Sessink PJM. Reference values for environmental contamination with cyclophosphamide (CP) in the Netherlands. Safety Consideration in Oncology Pharmacy. Special Edition; Fall 2011:3-5.

Firouzan “Fred” Massoomi, PharmD, FASHP, received his doctorate from the University of Kansas School of Pharmacy and is the pharmacy operations coordinator at the Nebraska Methodist Hospital in Omaha. 

Kelly L. Knolla, PharmD, is a clinical pharmacist at Penrose Hospital in Colorado Springs, Colorado. 


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