The chances are high that hazardous drug residue exists wherever the drugs are present. What can nurses do to reduce their risks?
Martha A. Polovich, PhD, RN, AOCN
The use of chemotherapy and other hazardous drugs (HD) is increasing each year. With an estimated 1.68 million individuals in the US diagnosed with cancer in 2016,1 the number of patients who are likely to be treated with chemotherapy is quite high. Add the multiple uses of chemotherapy for nononcology indications and the over 100 nonantineoplastic HDs in common use, and HDs can be present anywhere in healthcare settings.2
Most oncology nurses are knowledgeable about exposure; however, results from a study of nurses’ use of safe handling precautions for HD handling found that 15% of those nurses did not know that HDs left behind on surfaces can be a source of exposure.3
The routes of occupational exposure to HDs are absorption, inhalation, ingestion, and injection (Figure). Initially, inhalation was thought to be the main source of occupational exposure to HDs. Aerosols are generated when drugs are withdrawn from vials, which led to the use of biosafety cabinets (BSCs) in the 1980s. Dermal absorption is a common exposure route and is possible during any HD handling activity. The purpose of personal protective equipment (PPE) is to provide barrier protection from HDs.
In the early 1990s,4 the presence of cyclophosphamide residue was first identified on surfaces in pharmacies and chemotherapy administration areas. The presence of environmental contamination was recognized as a source of exposure for healthcare workers who might absorb HD residue when touching workplace surfaces.
Residue can be transferred to other items and surfaces, resulting in exposure of individuals who are not personally involved in HD handling. In a recent study, researchers swabbed workers’ hands and found that a volunteer, oncologist, dietician, and aide who worked in a unit where chemotherapy is administered had exposure that was equal to that of the nurses who directly handled the drugs.5
HD residue has been recovered from surfaces inside BSCs, floors in drug preparation, and administration areas, countertops, sinks, computer terminals, telephones, and elevator buttons. At least 15 studies have demonstrated HD residue on the external surfaces of drug vials when delivered from manufacturers. Handling vials without gloves is a source of skin exposure. If vials are not decontaminated before bringing them into the BSC, drug residue can be transferred to other surfaces.
BSCs capture HD aerosols, but do not prevent the generation of contamination. Drug droplets or aerosols produced during the compounding process can contaminate the outside of IV bags and syringes. Crushing tablets, opening capsules, and other drug manipulation outside of a controlled environment cause contamination of the environment with HD residue. PPE used for HD handling can be a vector for transferring drug residue to other surfaces.
Traditional needle-and-syringe techniques often result in leaking. IV tubing and connectors that are not closed systems can result in HD contamination of numerous surfaces in infusion centers, including IV pumps, IV poles, tables, infusion chair arms, and the floor. Small drops of HDs, if not identified and cleaned, are a source of exposure. Closed system transfer devices (CSTDs) are pieces of equipment that contain HDs when they are transferred from one container to another (eg, from vial to syringe or IV container). Ample evidence exists that CSTDs are effective in reducing environmental contamination.6-8
Oncology nurses may consider their work environment free of HD contamination in the absence of a known spill. The evidence does not support that. In the last 24 years, over 100 studies have documented contamination of many surfaces with chemotherapy.9 The frequency and magnitude of contamination vary from one study to another; however, every published study to date has found HD surface contamination when testing for it.
Because surface contamination is invisible, laboratory testing is required to identify it. Documenting contamination, using surface wipe samples, is usually performed in the context of research, but can be an eye-opening exercise in clinical settings. The US Pharmacopeial Convention (USP) in its General Chapter <800>— Hazardous Drugs Handling in Healthcare Settings,10 recommends baseline and periodic sur- face wipe sampling for environmental contamination with HDs. Positive wipe samples not only identify areas of contamination, but also can be used to determine sources of exposure. Follow-up sampling can measure the effectiveness of practices aimed at decreasing contamination.
Some of the challenges related to implementing routine surface wipe sampling for evaluating environmental HD contamination include: limited laboratories that can perform the analysis; the high cost of the assays; the lack of standards for the level of contamination that might be considered “acceptable,” and the level of contamination that requires action. For these reasons, such monitoring is not yet considered routine.
Several strategies exist for reducing nurses’ risk of HD exposure:
Environmental contamination with HDs is now considered the most likely source of HD exposure for healthcare workers. It is not necessary to wait for laboratory evidence of workplace contamination. The chances are high that HD residue exists wherever the drugs are present. It is time to address the problem of HD residue on work surfaces to minimize nurses’ exposure.