Examining and Challenging PFAS-specific Sampling Guidance for Cross-contamination

- K.Bowles (Jacobs), A.Wightwick (EPA Victoria), A.Nolan (Ramboll), M.Clough (GHD)

Introduction

In the last five years, various guidance has been written providing rigour and consistency for environmental site investigations where per- and polyfluoroalkyl substances (PFAS) are contaminants of potential concern (e.g. HEPA 2018, 2020, ITRC 2020). This includes guidance on quality control measures to reduce the potential for cross-contamination.

Initial guidance for field sampling was prepared when there was relatively little understanding of what materials PFAS may be found in and in what concentrations. As such, initial guidance on quality control measures was understandably conservative. This was to enable sufficiently low limits of reporting to enable comparison to PFAS human health and ecological threshold values. Some sampling efforts, notably the Department of Environment and Science, Queensland (DES) ambient PFAS survey, have demonstrated that by rigorously following quality control recommendations, cross contamination can be minimised to below the limits of reporting (DES 2021). However, more recent information suggests that the potential for cross-contamination from PFAS containing materials is not as great as initially thought and re-evaluation of conservative quality control measures is warranted.

In Australia, the Western Australian Department of Water and Environmental Regulation (DWER) interim guidance (DWER 2016 and 2017) adopted recommendations in a consultant report on methods for soil, sediment, groundwater and surface water sampling for PFAS (Geosyntec 2016). Materials recommended to avoid on-site during sampling included:

• Clothing: new clothing; clothing with stain-resistant, rain-resistant, or waterproof coatings/ treated fabric (for example GORE-TEX®); Tyvek® clothing
• Food wrappers: fast food wrappers and containers; pre-wrapped foods and snacks (for example chocolate bars, energy bars, granola bars and potato chips
• Sampling equipment: Teflon® containing or coated field equipment (tubing, bailers, tape and plumbing paste); Teflon® lined lids on containers (for example sample containers, rinsate water storage containers); glass sample containers with lined lids
• Other products: aluminium foil; self-sticking notes and similar office products (for example 3M Post-It notes); waterproof paper, notebooks, and labels; drilling fluid containing PFAS; detergents and decontamination solutions (for example Decon 90® Decontamination Solution); reusable chemical or gel ice packs (for example BlueIce®).

Other recommendations included avoiding use of detergents to clean equipment, avoiding reusing equipment from sites with known or suspected presence of PFAS, and use of new nitrile gloves for each monitoring location.

The Australian PFAS NEMP (HEPA 2018, 2020) largely adopted these recommendations. Additional items to be excluded from use during sampling were recommended, including cosmetics and sunscreen. The PFAS NEMP also made useful suggestions for improving quality assurance/quality control (QAQC) practices such as increasing the rate of field QC measures from 1 in 20 samples to 1 in 10 samples.

In the USA, the Interstate Technology Regulatory Council (ITRC 2020) provided similar guidance to that in the PFAS NEMP or referred to various State-based guidance including the WA DWER 2016 guidance. They also provided additional detail and clarifications, such as ‘In the case of Tyvek® PPE, plain Tyvek® does not contain PFAS while coated Tyvek® does.’ The ITRC guidance usefully noted that not all PFAS containing materials may be able to be eliminated from site, meaning a thorough QAQC program is needed to ensure data quality indicators for cross-contamination are met. For example, rather than avoiding detergents altogether, ITRC recommended that ‘The SDSs of detergents or soaps used in decontamination procedures should be reviewed to ensure fluoro-surfactants are not listed as ingredients.’

While many of these practices are self-evident, questioning whether all these measures are necessary is reasonable and practicable. This is especially so for items required for personal safety such as sunscreen, wet-weather gear and hazmat suits. For this reason, various organisations have tested a range of materials to understand the potential for PFAS to be released from the materials. In most cases the information has not been compiled for publication or remains in industry reports that are not publicly accessible. The discussion below summarises results from a range of sources that have been collected opportunistically. It is not a rigorous review of all available relevant information but is intended to be sufficient to indicate whether more detailed examination of PFAS-specific sampling guidance is warranted, particularly in relation to environmental site investigations.

Studies examining PFAS or fluorine in sampling related materials

Rodowa et al. (2020) systematically investigated potential cross-contamination from field materials. They analysed 66 materials for a suite of PFAS using both conventional LC-MSMS and total fluorine by particle-induced gamma ray emission (PIGE). Very few materials had detectable PFAS (reported LOQ 0.45 µg/m3) despite many having significant fluorine as measured by PIGE (10s to 100s mg F/m3). The authors pointed out that many of the materials with detectable PFAS should not come into direct contact with samples (for example paper towel and notebooks) as has also been noted by others (Bartlett and Davis 2018). Rodowa et al. (2020) concluded that cross-contamination of samples to reach the then EPA health advisory limit of 70 ng/L was not plausible. It is worth considering that the same calculation to contaminate to a lower limit, for example 1 ng/L, might not lead to the same conclusion for all materials, and this could be relevant in some situations. Nevertheless, the Rodowa et al. (2020) study usefully demonstrates few of the materials had conventionally measurable PFAS at all.

Unpublished results for sampling related materials have been presented in conferences and webinars. Lisa Graham from AsureQuality presented results at an ALGA event in New Zealand (Graham 2018). For that study, qualitative determination of fluorine was done using Fourier Transform Infra-Red Spectroscopy (FTIR) and Scanning Electron Microscopy with Energy Dispersive X-ray Spectrometry (SEM-EDX). Fluorine was not detected in a range of materials in the WA DWER guidance including some waterproof clothing, Tyvek, food wrappers, tubing, aluminium foil, detergents (Liquinox and Decon 90) and ice packs. The advice to not use glass containers was also questioned, as has been questioned by other findings (Lath 2019). While this doesn’t rule out PFAS in all such products, it is further evidence that PFAS is not ubiquitous in all materials. Graham (2018) reported PFOA was detected from PTFE plumber’s tape (presumably determined by LC-MSMS) consistent with findings of Rodowa et al. (2020). Graham (2018) also highlighted poor outcomes (wetting of samples) from the common practice of using ice in plastic bags as a means of avoided ice packs.

A presentation by Elizabeth Denly of TRC (Denly 2019) looked at a related suite of materials using LC-MSMS. She reported significant PFAS, especially short chain PFCAs from a range of materials including both PTFE and LDPE tubing, PTFE bladders, field notebook pages and covers, bailer line, water level tape, silastic tubing and nitrile gloves. PFAS were not detected in a range of other products including silicone tubing, aluminum foil, polyethylene bladder, adhesive notes, passive diffusion bag, resealable plastic storage bags, bubble wrap, bentonite and a protein bar wrapper. A similar unpublished study by Envirolab Services found PFAS in some materials previously associated with PFAS, such as waterproof clothing and some, but not all, Tyvek and food wrappers (D. Springer pers. comm. 2022). In that study, PFAS were not detected in sticky notes, waterproof labels and icepacks.

Other investigations are available addressing more specific sets of materials. A study by Bartlett and Davis (2018) provides commentary on issues surrounding PFAS cross contamination during sampling. This study included results of analysis for 17 PFAS in three personal insect repellents. All PFAS were reported as non-detect (<2.5 ng/L) in all three products. These results contrast with findings for agricultural pesticides where PFAS has been reported. For example, Lasee et al. (2022) reported primarily PFOS in a range of insecticides, where a PFAS was not the primary active ingredient, at concentrations up to about 20 mg/kg. Whilst there is potential for PFAS to exist in pesticides, there is indication that personal insect repellents may be less problematic. Confirming by analysis may still be warranted.

A report by GHD (Cooke and Ewing, 2018) provided measured data for a suite of 29 PFAS in a range of sunscreens chosen to include metal spray-cans, plastic spray-bottles and ‘natural’ products. No PFAS were detected in any sample. A report from ADE Consulting (ADE 2020) addressed cross contamination between soil samples collected using a jaw crusher. They concluded that cross contamination was unlikely to be sufficient to change classification of waste soil.

Other studies not aimed at sampling for contaminated sites have identified PFAS and organofluorine in materials that may be relevant to sampling in some situations. This includes cosmetics (e.g. Whitehead et al. 2021) and sprays used for cleaning glasses (Herkert et al. 2022).

Summary

The information complied for this article was not obtained from systematic review. Nevertheless, the information suggests that some materials recommended to be excluded from sampling sites may not have PFAS at such concentrations to be a risk for cross contamination. Some materials were found to have PFAS, and many of these materials, such as PTFE, can be identified and reasonably excluded. Importantly there was evidence that products such as a personal sunscreen and insect repellent are unlikely to contain PFAS and do not need to be avoided. Similarly, the use of water ice in plastic bags, to avoid freezer packs, may not be warranted.

While the information provides some comfort that field quality control measures may potentially be relaxed, there are caveats that need to be noted. Some of the studies involved targeted analyses for set suites of PFAS using LC-MSMS. There is potential for precursor PFAS to be present in products. This may become relevant where other analytical techniques are used such as Total Oxidisable Precursor (TOP) Assay or Total Organic Fluorine (TOF) are used. Also, the finding of PFAS in some relevant materials again stresses the need for strong QAQC practices to identify PFAS cross contamination at concentrations approaching the current limits of reporting. In particular, collecting field blanks and rinsates (and other materials such as drilling fluids) at an appropriate rate is critical, and non-compliances should be investigated, where appropriate.

Call for information

Based on the findings above, further information from industry would be valuable to (i) identify any similar on studies rigorously assessing PFAS in sampling related materials, and (ii) record expert experience for how often blanks and rinsates are returning results above LOR (or even better, LOD) and therefore suggesting false positives are occurring in samples. The ALGA Emerging Contaminants SIG would value your feedback on any of the following questions:

1. Does your organisation implement the full list of sampling recommendations in the DWER guidance and/or the PFAS NEMP?
2. Has your organisation conducted any studies/analyses to assess PFAS in relevant materials used for PFAS sampling?
3. Has your organisation conducted any studies/analyses to assess PFAS in materials/consumables used for drilling and well installation?
4. Has your organisation relied on any studies (either your own or from other organisations’) to justify not following the full list of recommendations in DWER or the PFAS NEMP?
5. How often (as a percentage) do you observe detects of PFAS above LOR in blanks or rinsates?
6. Do you observe any trends in detects in blanks or rinsates according to materials being used or matrices being sampled?
7. How often do you observe PFAS detections in samples where there are no known source(s) of PFAS? Have these detections ever been linked to sampling practices or lab contamination?

Answers can be provided using the button below.

Depending on the strength of any information provided for the above questions, a more detailed analysis may be possible to provide guidance for consultants and regulators.

References

Bartlett SA and Davis KL, 2018. Evaluating PFAS cross contamination issues. Remediation. 28:53–57.  

Cooke E and Ewing J, 2018. PFAS in Sunscreen NEMP or NOPE. CleanUp Conference Proceedings 2018. GHD, Sydney, Australia.

Denly, E, 2019. PFAS Leachability from Sampling Materials: Results of a Recent Study.  New Hampshire Hazardous Waste & Contaminated Sites Conference, September 2019.

DES 2021 https://www.qld.gov.au/environment/management/environmental/incidents/pfas/monitoring-program-report

DWER 2016. Interim Guideline on the Assessment and Management of Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) Contaminated Sites Guidelines. February 2016.

DWER 2017. Interim Guideline on the Assessment and Management of Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) Contaminated Sites Guidelines, v2.1. January 2017.

Geosyntec (2016) Methodology for soil, sediment, groundwater and surface water sampling and analyses for PFAS investigations

Graham, LA, 2018. Sample Collection for PFAS – Debunking Sampling Guidance Curiosities.  AsureQuality Ltd. Wellington Laboratory.  ALGA Contaminated Land Conference NZ 2018.

HEPA, 2018. PFAS National Environmental Management Plan v1.0, Heads of EPAs Australian and New Zealand, January 2018

HEPA, 2020. PFAS National Environmental Management Plan v2.0, Heads of EPAs Australian and New Zealand, January 2020.

Herkert NJ, Kassotis CD, Zhang S, Han Y, Pulikkal VF, Sun M, Ferguson PL and Stapleton HM 2022. Characterization of Per- and Polyfluorinated Alkyl Substances Present in Commercial Anti-fog Products and Their In Vitro Adipogenic Activity. Environ. Sci. Technol. 56, 1162−1173.

ITRC, 2020. Site Characterization Considerations, Sampling Precautions, and Laboratory Analytical Methods for Per- and Polyfluoroalkyl Substances (PFAS).  ITRC Washington, DC USA.  April 2020.

Lasee S, McDermett K, Kumar N, Guelfo J, Payton P, Yang Z and Anderson TA, 2022 Targeted analysis and Total Oxidizable Precursor assay of several insecticides for PFAS J. Haz. Mat. Letters 3 (2022) 100067.

Supriya, L, Knight ER, Navarro DA, Kookana RS, McLaughlin MJ, 2019. Sorption of PFOA onto different laboratory materials: Filter membranes and centrifuge tubes.  Chemosphere 222:671-678.

Rodowa AE, Christie E, Sedlak J, Peaslee GF, Bogdan D, DiGuiseppi B and Field JA, 2020 Field Sampling Materials Unlikely Source of Contamination for Perfluoroalkyl and Polyfluoroalkyl Substances in Field Samples. Environ. Sci. Technol. Lett. 7, 156−163

Whitehead HD, Venier M, Wu Y, Eastman E, Urbanik S, Diamond ML, Shalin A, Schwartz-Narbonne H, Bruton TA, Blum A, Wang Z, Green M, Tighe M, Wilkinson JT, McGuinness S and Peaslee GF, 2021. Fluorinated Compounds in North American Cosmetics. Environ. Sci. Technol. Lett. 8, 538−544.

Article Published on 20/04/2023

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