Modified Efficient and Simple Method for Biological Spill Cleanup

Abstract

Introduction:

Spill response procedures are an important aspect of laboratories where infectious materials are handled. The decades-old conventional method of spill cleanup uses paper towels to cover the spill. It requires 2 staff and involves a considerable amount of bending and squatting and being able to balance in those positions while wearing personal protective equipment (PPE). In this article, we describe a method that simplifies spill cleanup and compares it to the conventional method. The simplified method can be easily conducted by 1 person, takes about half the time, generates less waste, and reduces the amount of time spent in contaminated areas.

Objective:

The objective is to describe a modified, simple method of spill cleanup.

Methods:

A mock spill was created and a spill response initiated per the institution’s procedure. The simplified procedure uses a pail filled with decontaminant and a household mop dripping with the decontaminant. Mopping is done from the noncontaminated area toward the contaminated area so the spill does not spread. Mopping is done more than once, and all the materials used, including the mop(s), are disposed as biohazardous material.

Results:

The simplified spill cleanup process described here can be performed by just one person and does not require bending and squatting while wearing PPE. The kit is very simple, consisting of a pail and a mop, which are common household tools familiar to most people.

Conclusion:

The mop-and-pail methodology is simple, requires only one staff member, generates less biological waste, and requires less training and practice while effectively cleaning the spill.

Biological spills are of concern in laboratories because they have the potential to cause illness to laboratory workers or be released into the environment and cause health risks to the community, animals, and plants. The spilled biological material can contain virus, bacteria, or other infectious agents that are either wild type or genetically manipulated in the laboratory. Laboratory manipulation of infectious agents usually involves culturing the agent, and this is often in a liquid form, hence involving higher risk of exposure and potential disease transmission if spilled. In animal laboratories, the excreta and dander from the infected animals contain residues of infectious agents and are also biological materials that can potentially cause infection in humans. Such infections that are acquired as a result of laboratory-related activities are called laboratory-acquired infections (LAIs).^{1 -4}

LAIs can occur in research or diagnostic facilities where infectious biological materials are handled. The actual risk of LAIs is difficult to calculate due to the lack of a systematic, integrated, worldwide reporting system. In addition, LAIs are underreported as not all inadvertent exposures are likely to be symptomatic and they go unnoticed, ⁵ and often determining the specific exposure event that led to the LAI is not possible. ⁶ The common known causes of LAIs have been tabulated, and splashes and sprays account for a quarter of them. ¹

Most often, microbiology laboratory work involves cell cultures. This requires transporting flasks of liquid cultures between the workstation (often the biosafety cabinet) to another location, usually to the microscope or incubator. Since this is a very frequent process, mishaps arise from such activities. In fact, a Flemish survey ⁷ conducted in 2012 showed that spills (at 93%) represent the majority of bioincidents with inadequate spill management contributing to a likely possible cause of LAIs. In these instances, it is believed biosafety compliance was not adhered to due to insufficient knowledge of the risk involved. Personnel conducting work with Risk Group 3 (RG3) and Risk Group 4 (RG4) agents can be at risk of contracting a severe illness following an exposure. This fact mandates the need for very robust biosafety and biosecurity measures in high- and maximum-containment laboratories. Often identifying when a laboratory exposure has occurred and whether an illness is an LAI or the result of an environmental exposure is difficult. Therefore, training and education are necessary to prevent exposure and potential subsequent LAIs. ⁸ Spill response is a key emergency management process that needs to be written into a standard operating procedure (SOP), and regular training needs to be conducted to ensure that staff are properly trained in spill management. ⁹

Fortunately, LAIs from exposure to RG3 and RG4 pathogens are relatively rare. However, with the notable global increase in the number of biosafety level 3 (BSL-3) and biosafety level 4 (BSL-4) laboratories, the number of workers at risk for potential exposure to RG3 or RG4 pathogens has also increased. Concern arises if the workers are not aware of or do not adhere to biosafety practices, as those affected may extend beyond the laboratory worker and may involve the community at large.^10,11 The incident from the Pirbright Institute where the animals in the local vicinity were infected with foot and mouth disease when infected liquid waste leaked from the old plumbing system shows that proper management of equipment and infrastructures associated with biological material in the laboratory is crucial. ¹² While transmission of infection can occur through several routes of exposure, the inhalation of infectious aerosols is the most difficult to control and potentially the most dangerous. Using a good spill cleanup response aimed at preventing exposure and recognizing the importance of spill cleanup are repeatedly noted as best practice in the Centers for Disease Control and Prevention and National Institutes of Health biosafety guidelines. ¹³

In BSL-3 and BSL-4 laboratories that handle high-risk infectious agents, reporting potentially infectious spills is mandatory in most countries. In the United States, agents that are potentially weaponizable and can cause severe danger to the public are called select agents and are covered by the Public Health Security and Bioterrorism Preparedness and Response Act of 2002. Select agents are regulated under the Federal Select Agent Program (FSAP), which is jointly administered by the Centers for Disease Control and Prevention/Division of Select Agents and Toxins and the Animal and Plant Health Inspection Service/Agriculture Select Agent Services. The FSAP enhances US oversight of the safety and security of select agents that have the ability to pose a severe threat to public, animal, or plant health and their products. In Singapore, such agents are classified as First Schedule Part II and are controlled under the Ministry of Health’s Biological Agents and Toxins Act as well as the Ministry of Home Affair’s Infratrsucture Protection Act. These legislations ensure that high standards of safety and security are in place for facilities handling such agents.

In Singapore, every BSL-3 laboratory must have sufficient staff trained in spill cleanup procedures, and they practice a few times a year in mock exercises. Every year when the laboratory is certified by the Singapore Ministry of Health, the staff in the facility must demonstrate proficiency in handling spills to the satisfaction of the ministry. In the United States, entities registered with the FSAP are required to have a site-specific biosafety plan, incident response plan, and security plan. Typically, spill response is covered in both the biosafety and incident response plans, and these plans require that an annual exercise be conducted and documented. The plans and exercises are reviewed by FSAP inspectors every 3 years (sometimes more frequently) before approving the renewal of the entity’s FSAP registration. In addition, all “releases” of select agents must be reported to the FSAP. FSAP defines the release of a select agent as an occupational exposure to an agent or when an agent or toxin is no longer contained within a primary containment barrier.

Most laboratories have SOPs for remediating spills. The conventional method that is practiced by most laboratories was developed decades ago and consists of using paper towels to cover the spill. Briefly, such spill management traditionally involves the steps listed on the left side of Table 1. This method typically requires 2 trained staff, 1 working in the contaminated area and 1 providing support from the noncontaminated area (Figure 1). The 2 areas are often demarcated with decontaminant-soaked paper towels. The person outside the contaminated area helps to prepare and provide all the necessary items during cleanup so the person inside the contaminated area does not need to move over to the noncontaminated side and cause the spill to spread. Spill management is dependent on the institutional SOP and risk assessment of the spillage. In discussions of best practices with colleagues and in conducting spill cleanup demonstrations, we found that typically at least an hour is required to remediate a small-scale laboratory spill. The cleaning process involves a considerable amount of bending and squatting and being able to balance in those positions while wearing PPE when the paper towels are placed over the spill and spatter, wetted gently with decontaminant, and then removed using tongs or other tools. The paper towels often fray and tear, complicating and slowing the cleanup process.

Table 1.

Comparison of Spill Cleanup Methods.a

Step No.	Conventional Method	Simplified Method
1	Isolate spill area.	Isolate spill area.
2	Vacate the spill area for at least 30 minutes (if necessary).	Vacate the spill area for at least 30 minutes (if necessary).
3	Assemble spill management team and spill kit.	Assemble spill management team and spill kit.
4	Don personal protective equipment (PPE).	Don PPE.
5	Prepare disinfectant and spill cleanup equipment.	Prepare disinfectant and spill cleanup equipment.
6	Establish a hot-cold line with paper towels soaked in disinfectant and work as a team.	Establish a hot-cold line with a cloth towel soaked in disinfectant; work as a team or individually.
7	Find and cover the spill and spatter areas with paper towels.	Mop inward toward the spatter and spill, and after appropriate contact time, dispose solid waste into biohazard bags or a rigid container.
8	Pour disinfectant over paper towels and allow for contact time.
9	Collect paper towels with tongs and dispose paper towels into biohazard bags.
10	Clean the spill area with disinfectant using a mop.	Mop the floor a second time with fresh disinfectant and mop head.
11	Wipe down contaminated equipment with a disinfectant-soaked towel.	Wipe down contaminated equipment with a disinfectant-soaked cloth towel.
12	Package and treat all waste per standard operating procedure (SOP).	Package and treat all waste per SOP; disinfectant may be poured down the drain after contact time and flushed with water.
13	Remove PPE, wash hands, and follow the exit protocol.	Remove PPE, wash hands, and follow the exit protocol.

a

In the conventional method, steps 7 to 9 could take at least 30 minutes for even a small spill and involve finding dried spatter, bending, squatting, and maintaining balance while wearing PPE. Step 6 in the simplified method reduces this time to 5 minutes, covers more area than where spatter is visible, and does not require strenuous physical effort.

Figure 1.

The conventional method for spill cleanup requires 2 trained staff, 1 on the clean side and 1 on the contaminated (spill) side, laying paper towels on the spill and pouring disinfectant on the paper. This picture was taken during a mock spill cleanup drill and the regulatory inspectors can be seen in the picture without the full personal protective equipment. In the event of a real spill, only the 2 trained staff cleaning the spill should be in the area.

A comprehensive search of the literature shows a lack of peer-reviewed articles that describe spill response methods. It is therefore timely that this article addresses a more efficient method for cleaning biological spills in containment laboratories. The simplified spill cleanup method is described and compared to the conventional method. The simplified method can be easily conducted by 1 person (per a risk assessment), takes about half the time to perform, generates less waste, and reduces the amount of time people spend in areas contaminated with biohazardous agents.

Methods

Performing the Simplified Method of Spill Cleanup

A mock spill was created by dropping a loosely capped test tube with about 15 mL of sterile water from waist height onto the floor, resulting in splashing and spattering on the floor and vicinity. Spill response was initiated per the institution’s simplified spill cleanup SOP. In most institutions, this would consist of evacuating the area for 30 to 60 minutes to allow the aerosol to settle, ensuring the spill response kit has all materials needed specific to the spill, assembling the team to remediate the spill, and entering the spill area to perform the cleanup. These early steps are the same in both the conventional and simplified methods. However, the simplified spill cleanup method described in this article differs from the conventional method from the point at which the spill response team arrives at the spill site. The difference can be seen by comparing the right and left columns in Table 1. Note that many of the peripheral steps involved in dealing with a spill do not change; only the actual cleanup procedure changes. Supplies needed for the simplified method require less storage space (the pail becomes the kit), plus the bulk from paper towels and additional PPE is less compared to the conventional method.

The simplified spill response procedure consists of the steps described hereafter and as shown in Figure 2. A 6 L or larger pail is used to prepare 4 L of decontaminant (appropriate for inactivation of the spilled agent) according to the manufacturer’s instruction or the institution’s SOP. Then, a mop is submerged into the pail to ensure that the mop head is thoroughly soaked and dripping with decontaminant. If a pail with a ringer is used, the mop should not be rung to avoid squeezing out most of the decontaminant. Then the spill area and the clean zone are demarcated by placing a towel(s) (cloth or pad) soaked with decontaminant for zonal and visual reference. Next, the decontaminant-filled pail is placed on the cloth towel before the individual cleaning up the spill steps onto the cloth towel to commence the spill cleanup. Standing on the decontaminant-soaked towel and using the mop, which should be dripping with decontaminant, the individual should start mopping from the clean area demarcation line, covering areas of likely spatter and moving inward toward the center of the spill. The individual may walk back across the mopped area to resoak the mop in the decontaminant pail as needed. The individual should work his or her way around any vials, tubes, or glass pieces that may be on the floor while moving toward the center of the spill, ensuring that each area is exposed to the decontaminant for the contact time required by the SOP. Once the surrounding floor is completely disinfected, the individual should approach the vials, tubes, and glass pieces with the same decontaminant-dripping mop. He or she then douses them with decontaminant and then picks them up using tongs or other tools and places them in a biohazard bag or puncture-proof biohazard container (if sharps are present).

Figure 2.

(A) Personal protective equipment (PPE) should be worn according to the institution’s standard operating procedures (SOPs). Four liters of disinfectant are prepared in a pail as per the manufacturer’s instruction or institution SOP. The spill area is demarcated from the clean area using a disposable pad or cloth towels. Disinfectant is poured onto the pad or cloth towel so it is well soaked. (B) Standing on the soaked pad and (C) using the mop that should be dripping in disinfectant, mop from the location on the pad inward toward the center of the spill, allowing contact time in all the areas. (D) Continue mopping, working around the vials, tubes, glass pieces, and so on that may be on the floor. (E) Once the spill area is disinfected, the vials, tubes, and/or glass pieces should be covered with disinfectant using the dripping mop and then picked up using tongs or paper towels as needed and placed in biohazard bags or sharps container, as appropriate. At this time, since all the spill area is decontaminated, going back and forth within the spill area is possible, taking care not to cross over to the clean side beyond the demarcation pad/cloth towel. (F) Once the pieces are all bagged, a thorough mopping should be done again with fresh disinfectant and a fresh mop if needed. (G) All furniture and surfaces that could have been potentially contaminated by the spill should be cleaned with disinfectant. The mop and all other material should be disposed as biohazardous material. These spill cleanup pictures were taken during a mock spill cleanup drill.

At this time, since the surrounding area has been decontaminated by mopping, going back and forth within the spill area is possible, taking care not to cross over to the clean side beyond the demarcation pad/cloth towel. Once the area is cleared of debris and contact time with the decontaminant has completely elapsed, the cleanup person should thoroughly mop the floor again with fresh decontaminant and optimally with a fresh mop head, from the outer perimeter of the room inward toward the spill. All the casework, equipment, and walls that could have been contaminated should be wiped clean with a fresh decontaminant-soaked cloth towel, and all the materials used, including the mop(s), should be disposed of as biohazardous material. The institution’s SOP should be followed to report the spill, and individuals potentially exposed should seek medical attention per the SOP.

Discussion and Conclusion

Mishaps do occur in a laboratory, which is why institutional SOPs that describe responses to various emergencies must be in place well before an accident or incident occurs. Spill management is an important aspect in developing emergency SOPs, especially in laboratories where infectious biological material is handled, because a spill outside primary containment may occur and pose a health concern to the laboratory personnel within, and in the event of agents causing transmissible disease, a subsequent threat may be posed to family, medical personnel, and community members. Hence, the methodology to address spills is critical.

While the conventional method of addressing spillage exists, other elements have to be considered as well when performing the spill cleanup. Factoring in the time needed to address the spill and the logistics involved in preparing a spill kit, we modified a known concept into a modern method of spill management. In our experience, the mop-and-pail methodology requires less training and practice than the more laborious approach of finding spatter trails and the spill (which are often dried by the time the team enters the room), laying down paper toweling, carefully pouring decontaminant on the toweling, and then collecting the shredded paper towels, all of which is done while maintaining balance when bending or crouching in PPE. In our experience using a solution that fluoresces under blacklight, we confirmed that no 2 spills produce an identical spatter pattern (pictures not presented). Differences in the volume of liquid and the way a tube or plate bounces and spins after hitting the floor change the trajectory of the liquid and make identifying dried spatter very difficult. This can be easily replicated by any laboratory by using water and serves as an important training opportunity for all staff.

Demonstrations while conducting mock spill cleanups using a fluorescent solution at numerous facilities across Asia have shown that more often, some spatter is not identified during the primary cleaning step in the conventional method. This resulted in people walking through the spatter and contaminating other areas of the room. In the simplified method, the first action of mopping greatly reduces, if not completely eliminates, the problem (personal observation and knowledge, Dr Barbara Johnson, Biosafety Biosecurity International, December 2018).

Importantly, in the simplified process, we define a clean zone and a spill zone by using a decontaminant-soaked cloth towel and mopped the area carefully from the area that is less contaminated to the area in which the bulk of the spill is located. In between mopping, the mop head is submerged into the pail to be decontaminated chemically as well as to produce a dilution factor. However, once the main spill content is mopped away, the cleanup person has to be mindful that the mop should not be used to mop a less contaminated area. We recommend using a second bucket of decontaminant and a fresh mop head once the primary decontamination is completed. Double-compartment mop buckets are commercially available and are ideal for this application.

Equipment, casework, and walls that may have been splashed by the spill are given a surface wipe with decontaminant while the floor surface is left to dry, allowing the decontaminant to have appropriate contact time. The second round of mopping is performed to address any spots that may have been missed or not adequately wetted with the decontaminant, just as one would do in the conventional method.

This method is very simple and in terms of supplies requires a pail(s), mop heads, decontaminant, biohazard bag(s)/sharps container, spare PPE (gloves, shoe covers), and a couple of cloth towels for demarcation and cleaning of any contaminated equipment. The pails may also serve as the holder for the kit items. This simplifies replenishment of the spill kit as compared to the conventional method that requires bundles of paper towels, which often break down and tear after being wetted, making cleanup that much more difficult and creating more waste for disposal. Regardless of how much paper toweling is used, once the bundle is opened, all the paper is considered contaminated and is disposed of as waste. In addition, it is not uncommon for people to lose their balance while bending or squatting, resulting in contaminating their gloves or overgarment when they fall. This requires supplying the kit with even more additional PPE. The simplified method streamlines not only the cleanup and waste-disposal processes but also the logistics of supplying the kit.

Several surveys have shown that safety standards are not always adhered to,^7,14 with insufficient knowledge of the hazard being the most prevalent reason. In resource-constrained settings, lack of safety knowledge and training, coupled with a lack of resources for disposable cleaning supplies, may contribute to suboptimal spill remediation and place laboratorians and the community at risk. Another benefit of the simplified process we describe is its similarity to how people in many countries (including those that are resource constrained) conduct routine cleaning. A time-, cost-, and effort-efficient methodology like the mop/pail cleaning process is one that is familiar to most everyone globally, making training people easier. Since people more quickly understand how and why to do it correctly, adherence to safety procedures improves.

An effective spill management SOP is necessary for any institution working with infectious biological materials, especially those that are pathogenic or toxic. Employing methods that incorporate simplicity, efficiency, and efficacy in the process will earn the buy-in from the workers and will promulgate increased safety not only for the workers within the laboratory but also for the community as well. Even a small spill in the laboratory if not addressed adequately could have social and economic consequences.