Using Wipe Sampling to Detect Contamination

Healthcare workers, such as oncology nurses and compounding professionals handling antineoplastic and other hazardous drugs, are at risk for exposure through inhalation and skin contact. Efforts to limit this exposure are a primary concern of employers. Safety protocols are also mandated by Occupational Safety and Health Administration (OSHA) guidelines.

Wipe sampling is an important method to determine the level of contamination on surfaces from chemotherapy drugs and other hazardous materials. The process for wipe sampling is referenced explicitly in OSHA literature, giving employers essential safety guidance. Even with this documentation, some additional tips can help make the process more efficient and optimize worker safety.

In 2015, the Oncology Nursing Society and others issued a position statement on ensuring healthcare workers' safety when handling hazardous drugs.¹ This statement noted that more than 50 studies discovered hazardous drugs in the urine of healthcare workers, indicating actual, not merely theoretical, exposure to these toxins. Exposure can cause adverse personal health outcomes, such as rashes, reproductive challenges, and cancers such as leukemia.²

Evidence does demonstrate that safety protocols can prevent worker exposure. A 2017 study found that after implementing exposure interventions, contamination levels decreased on surfaces—as indicated by wipe sampling—and that levels in worker urine also went down.³

Wipe sampling is a method to determine the presence and volume of a hazardous drug on a surface. The process is an important part of a "safe handling" program for hazardous drugs, such as those encountered by oncology nurses, pharmacists, and other health care workers. Wipe sampling allows for determining current levels of exposure risk and evaluating the effectiveness of safety protocols.⁴

This wipe sampling procedure also offers essential data about areas at greatest risk for hazardous drug exposure and methodologies that work best to reduce the risk. A 2019 study of 5,842 wipes collected from more than 338 hospital pharmacies over 6 years found contamination was greatest in drug preparation areas.⁵

However, contamination existed elsewhere as well. Surface contamination was significantly lower at institutions that use closed system transfer devices (CSTDs).⁵

Wipe sampling appears to have tremendous benefits. Its effectiveness as a tool, however, depends on its consistent and reliable use. There are several factors that can impact the reliability of results.⁶,⁷ These include:

• Type of wipe and its ability to absorb or contain the hazardous material
• Specific drug or hazardous material recovered
• Size, shape, condition, and material of the sampling surface
• Potential for hazardous material to break down or degrade before analysis, such as with a volatile organic compound lost to evaporation
• Storage environment of samples before analysis, taking into account light, temperature, air pressure, and other factors
• Frequency of sampling and location of sampling surfaces
  

Because of these variables, it is essential to have detailed wipe sampling protocols in place. That can help to ensure results are accurate, consistent, and truly contribute to healthcare worker safety.²

Wipe sampling procedures can reach peak efficiency with certain parameters in place. Below are some recommendations for factors and considerations to review prior to and during your wipe sampling program.⁴

Determine the Goal of Wipe Sampling

Many healthcare settings have multiple goals for wipe sampling. Identifying these can help ensure you have the right tools and processes to achieve them. Some examples include:

• Compliance with occupational health guidelines
• Assessment of baseline levels of contamination of new equipment
• Determination of contamination levels on surfaces of safety equipment like CSTDs
• Evaluation of cleaning and safety program effectiveness
• Establishment of a comprehensive safe handling program

Starting with a goal can help determine your next steps. For example, to establish baseline contamination, one may need only single or single and subsequent wipe samples. However, to support a comprehensive safety program, you may need a regular schedule of wipe sample collection.

Inventory Chemotherapy Drugs and Other Hazardous Materials

Make a list of the hazardous drugs that are present in the facility. Then determine which drugs you want to sample. Your wipes must be able to pick up these drugs and create a sample that accurately reflects their presence in the environment.

Choose a Highly Efficient Sampling Method

Determine the combination of wipe and method that will achieve a high rate of recovery. It may be easier to collect from smooth, nonporous surfaces, but that may not always be possible. Try for a recovery rate of 90% before you approve a sampling method.⁴

Determine the Optimal Sample Size

OSHA guidelines recommend a sample size of 10 cm X 10 cm, or about the size of an individual's palm.⁸ After determining the level of a contaminant in a sample of this size, the health care facility can roughly calculate the amount of exposure during the course of a workday.

However, the 10 cm X 10 cm size may be too small for a large area and require multiple samples. It may miss components that are unevenly distributed across the surfaces. For that reason, you may want to take a series of larger samples, finding a balance between the cost of the process and the usefulness of the results.⁴

Record Sample Information

Before you begin your wipe sampling program, create a database to record the information. Transfer this data regularly after the program begins. Review the data fields with each entry to make sure you are capturing all necessary information.

Photograph or Sketch Sampling Areas

Keep a standard diagram, sketch, or photos of sampling areas. This will help eliminate confusion about the precise location of each sample's origins. This information can help show what parts of the facility are at higher risk for healthcare worker exposure.

Wipe Following Specific Pattern

To ensure accuracy of results, take the wipe sample the same way every time. That involves wiping the sample area in a particular pattern to eliminate changes in data readings that result from a lack of uniformity in sample taking.

Label and Pack Samples

Maintain a set procedure to pack and label samples that go for testing. Follow this procedure regardless of whether you use an external lab or test on-site. Keep a set chain of custody to avoid loss, mishandling, or contamination of samples.

Oncology nurses and other healthcare workers handling chemotherapy drugs need protection on the job. Wipe sampling helps institutions identify areas of surface contamination and implement safety protocols, such as the use of closed system transfer devices (CSTDs). When creating a wipe sampling program, follow set procedures, keep your goals in mind and ensure consistency in sample-taking, storage and testing.