The challenge of investigating PFAS contamination: Current strategies and innovations

PFAS is an industry hot topic, often called ‘forever chemicals’ because they don’t break down naturally and is increasingly linked to serious environmental and human health risks. It’s widespread use in everyday products such as non-stick cookware, shampoos, paints, textiles, fast food packaging, stain-resistant products, and firefighting foams, has made it an emerging area of concern.

Because PFAS is used in so many consumer and industrial products, there is high potential for external PFAS sources to show up during field sampling. To mitigate cross-contamination from these external sources, PFAS sampling guidance generally takes a precautionary approach. This places restrictions on the behaviours of field personnel by introducing controls for “outside the workspace”, such as avoiding fast food or using cosmetics during field sampling.

This article shares three case studies from a research project conducted to understand the importance of sampling precautions when collecting environmental data. These findings are intended to support more reliable outcomes in projects that benefit the Canadian contaminated sites community.

Case Study 1

Before 2015, there was limited guidance on PFAS-specific sample collection. Existing guidance had primarily focused on preventing direct contact between PFAS-containing materials and samples, rather than identifying all potential external sources of PFAS in a field environment. This first study looked at PFAS detections in field blanks (samples prepared in the field by transferring PFAS-free water to an analytical bottle) collected before and after 2015, when PFAS-specific procedures were introduced to help reduce contamination from sources outside the sampling area. The study focused on a single site with sampling data going back to 2007.

Of the sixteen field blanks collected before PFAS-specific protocols were in place, two showed PFAS detection. In contrast, none of the six field blanks collected after the protocols showed any detection. However, it is likely that the detections weren’t due to the lack of PFAS-specific protocols. One of the field blank detected parameters was not found in any of the native samples, suggesting cross-contamination was unlikely. Two field blank detected parameters fell within the lab’s acceptable limits, and three others had very high concentrations in the native samples (which created difficulties for commercial laboratories at the time).

Overall, this study found that the PFAS sampling precautions likely had little-to-no impact on detectable PFAS concentrations at this site.

Case Study 2

The second study surveyed Canadian commercial laboratories accredited for PFAS analysis to understand the precautions used in lab settings when analyzing PFAS samples. Historical Quality Assurance/Quality Control (QA/QC) samples were also reviewed to support the evaluation.

The results showed that four of six surveyed labs focused mainly on controlling their immediate workspace when handling PFAS samples – for example using PFAS-specific fume hoods or cleaning surfaces with methanol and paper towels. Only two labs implemented additional controls to limit contamination from outside the workspace, such as avoiding the use of personal care products on exposed skin or wearing water repellant clothing. Similarly, only a select number of labs followed field-specific sampling precautions for controls outside the workspace.

Laboratories appear to focus more on controlling the environment where samples are handled, rather than restricting an individual’s behaviour. To identify background PFAS contamination, labs use method and environmental blanks to monitor accuracy of the handling protocols. A review of SLR project data showed PFAS detections in 44 of 546 method blank samples. Of these, only three were water samples and the remaining 41 were soil samples. The levels detected were similar to the concentrations observed in the first case study, despite labs and field sites using sampling and handling measures.

While laboratory environments are better equipped to minimize background contamination than outdoor field sites, PFAS were still being introduced in one of every twelve laboratory method blanks.

Case Study 3

The third case study reviewed PFAS detections in different field QA/QC samples, specifically field blanks, trip blanks, equipment blanks, and equipment rinsates, collected after 2015. The purpose was to determine any patterns in how PFAS may be introduced to field samples from external sources, and whether specific PFAS parameters detected could provide further insight.

From 2017 onward the data showed six of 372 field blanks (1.6%), nine of 248 trip blanks (3.6%), zero of 51 equipment blanks, and 31 of 126 rinsate blanks (24.4%) had detectable PFAS concentrations.

Interestingly, trip blanks – which are prepared in a lab and not handled in the field – had a higher detection rate than field blanks, despite laboratory environments being more conducive to minimizing background introduction of PFAS. Another notable finding was how common PFAS detections were in equipment rinsates – samples collected after decontaminating field equipment, such as drill rigs. This highlights that cleaning large equipment in the field is challenging and can result in major PFAS detections from cross-contamination in equipment rinsates.

Conclusion

PFAS impacted media sampling precautions are in place to keep concentrations as low as reasonably achievable and should continue to be used as best practice. However, when working with PFAS – especially in a source zone – focus may need to be placed on decontamination rather than on controlling an individual’s behaviour outside the workspace. These precautions do reduce the risk of cross-contamination and are beneficial for projects requiring low level PFAS detection, such as testing tap water. Conversely, they may be less relevant when analyzing samples from a heavily contaminated source zone.

The field of knowledge on PFAS is in a period of growth, with new findings emerging from both laboratory-scale and field-scale practices. SLR strives to remain at the forefront, continually advancing our expertise in this space.