SWAB AND TAPE LIFT SAMPLING Sterile swabs are most often used to collect biological materials such as powders or fungal material from surfaces. ASTM International has two standard methods. ASTM D7789 was developed for swab sampling for fungal materials and can be used for analysis by direct microscopy, culture, or biochemical analysis. ASTM E2458 addresses swab sampling of nonporous surfaces for “residual suspicious powders that are suspected biological agents and toxins from solid nonporous surfaces.” In addition, NIOSH has posted a swab sampling procedure for use in collecting culturable samples for Bacillus anthracis spores on its website.  Prepared swabs, as test kits, can be useful when collecting a sample of or for testing for contaminants in small or hard-to-reach places. Swab testing kits for lead and other metals and drugs are commercially available, and a web search for the analyte of interest as a test kit could produce an appropriate product. For example, when dealing with lead-based paint and lead-based paint hazards, see the EPA website for the list of EPA-recognized test kits. Tape lift sampling is typically used for microscopic examination rather than instrumental analysis. Standard methods include ASTM E1216, which focuses on sampling for particulate contamination by tape lift, and ASTM D7910. ASTM E1216 can be used for microscopic examination of metal, metalloid, or organic particulates, while ASTM D7910 is used for fungal materials. VACUUM SAMPLING Vacuum sampling is often a good choice for obtaining samples from carpeted floors and similar surfaces, and for collecting bulk samples. Standardized vacuum sampling protocols include ASTM D7144, which uses a personal sampling pump for micro-vacuum sampling on soft surfaces including carpets, and ASTM D5438, which uses a modified stand-up “high-volume sampler” (HVS) vacuum cleaner to perform carpet sampling. Collection efficiencies of both methods have been investigated and performance data published in peer-reviewed literature (see two articles from the Journal of Occupational and Environmental Hygiene in the resources section on page 28 for more information).  In ASTM D7144, dust collected is captured in a sample cassette fitted with a collection nozzle. The collection efficiency varies widely with the surface being sampled; also, material gets caught in the collection nozzle. Despite these limitations, micro-vacuum sampling is viewed as a practical design-based method that enables data comparisons if the standard method is used. Collection efficiency of the D5438 method is enhanced due to high sampling flow rate and rigorous agitation of the surface, is demonstrably high (overall mean 88 percent), and supports the ASTM standard.  DERMAL SAMPLING A number of dermal sampling techniques are outlined in ISO Technical Report 14294, Workplace Atmospheres — Measurement of Dermal Exposure — Principles and Methods. The report describes methods such as wiping using a cotton fabric; dermal patches for selected organics; smear tabs for polychlorinated biphenyls, or PCBs; and in situ methods using clothing as the collection medium. Gloves have also been used to collect the sample by intercepting it before it reaches the hand. Most of these methods have not been validated. ASTM D7822, which applies to sampling for metals and metalloids, is based on methodologies developed by NIOSH and utilizes a wipe (either premoistened or moistened in the field) with a wiping pattern starting from the perimeter and moving to the interior of the area being sampled. It includes a protocol for estimating the surface area of a hand when the entire hand is being wiped. SARS-COV-2 CORONAVIRUS Surface sampling for viruses, including the new SARS-CoV-2 virus (cause of COVID-19), has typically been done in the same way as sampling for fungi and bacteria: with a pre-wetted swab. The wetting agent is often phosphate buffered saline. Analysis is by reverse transcription polymerase chain reaction (RT-PCR) in which a specific ribonucleic acid (RNA) sequence is converted to DNA for amplification and detection. RT-PCR can be used to indicate just presence/absence, but it may also be used quantitatively (qRT-PCR) to track the rate of amplification. The swab should be analyzed very quickly as RNA is not as stable as DNA. Some protocols require overnighting refrigerated samples; others require placing the swab in a viral transport medium or chaotropic lysis buffer in the field, the latter being preferred for long-term storage.  While data on the limits of quantitation is available for analytical procedures, no data exists regarding the efficiency or uncertainty in the transfer of virus from different surfaces to swab, or the stability, recovery, or uncertainty of the transfer from swab to analyzer. Hence, the qRT-PCR procedure is semi-quantitative at best, and studies should be performed to improve knowledge in this area. Swabs are currently scarce due to the pandemic and wipes can cover much greater areas, potentially improving the sensitivity. Research into suitable wiping procedures is ongoing. See the U.S. Food and Drug Administration’s frequently asked questions on testing for SARS-CoV-2 for information regarding SARS-CoV-2 test kits. WHAT THE LAB NEEDS TO KNOW Communication with the lab is key to the success of the sampling program. It’s important that the OHS practitioner understands what the lab can and cannot do; the lab knows what it is getting and the desired data quality objectives; and the OHS practitioner understands what the data from the lab mean. Thus, the lab needs to know:

Wipe material is especially important for the laboratory. Certain wipe materials may not be compatible with some methods used in the laboratory, so it is important to check in advance to make sure the laboratory can handle what you plan to send. In return, the lab should provide:

Call the lab! They are there to help. (Editor’s note: More tips for improving collaboration between field IHs and laboratory professionals can be found in an article from the August 2016 Synergist.) 

A full-day professional development course titled “Surface Sampling – Issues, Methods, and Strategy for Metals, Metalloids, Organics, and Biologicals” was presented at AIHce EXP 2019 and included much of the information contained in this article with more detail and discussion. The PDC was accepted for this year’s conference, but it was not presented online at AIHce EXP 2020 because it does not lend itself to virtual presentation. The same PDC will be proposed for AIHce EXP 2021. In addition, a Sampling Quality Assurance Manual compiled by the AIHA Sampling and Laboratory Analysis Committee is scheduled for release next year.    MICHAEL J. (MIKE) BRISSON, MS, PMP, FASTM, is a fellow technical advisor at Savannah River National Laboratory, Aiken, South Carolina. He is a past chair of the AIHA Sampling and Laboratory Analysis Committee, on the Board of Directors of ASTM International and past chair of Committee D22 (Air Quality), chair of ISO Technical Committee 146, Subcommittee 4, on Air Quality General Aspects, and convener of four ISO working groups. KENNETH T. (KENN) WHITE, MS, MM, CIH, CSP, FAIHA, FASTM, is the principal of Consultive Services in Virginia Beach, Virginia. He is a three-time recipient of the AIHA Edward J. Baier Technical Achievement Award, chair of the ASTM International Subcommittee D22.12 on Sampling and Analysis of Lead for Exposure and Risk Assessment, and a member of the AIHA Sampling and Laboratory Analysis Committee, serving as chair of the Environmental Lead Subcommittee. The following applies to Mike Brisson: This manuscript has been authored by Savannah River Nuclear Solutions (SRNS), LLC under Contract No. DE-AC09-08SR22470 with the U.S. Department of Energy (DOE) Office of Environmental Management (EM). Disclaimer: The United States Government retains and the publisher, by accepting this article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for United States Government purposes. Acknowledgements: The authors gratefully acknowledge Eric Esswein, Lisa Rogers, and Martin Harper for providing their valuable inputs.

Send feedback to The Synergist.