Does your occupation affect your PFAS levels? Yes, according to a recent large-scale study. Of course, this may not be news to a lot of people. For many years, firefighters have warned that their job exposes them to high levels of PFAS. And that consequently they have higher levels of PFAS in their blood. But this study seems to provide additional proof. It also suggests that healthcare workers may have higher levels of PFAS too.
What is the context?
This new paper is from a large-scale biomonitoring study launched during the COVID-19 pandemic. The Arizona HEROES project (Arizona Healthcare, Emergency Responder, and Other Essential Worker Study) collected multiple blood serum samples over a 3 year period. This paper explores serum PFAS levels for 14 different PFAS compounds in order to test whether there is any correlation between PFAS levels and occupation. In total, samples from 1,960 participants were included in the paper.
What are the headline results?
The paper authors report two main results based on their statistical analysis of the samples.
- Firefighters had higher levels of 4 PFAS compounds. Specifically, they are more likely to have higher levels of total PFOS (both branched and linear), PFHxS and PFHpS. These 3 compounds are all closely related, differing only in the number of carbon atoms in the central chain.
- Healthcare workers had higher levels of 2 PFAS compounds. Specifically, PFDoA and branched PFOA. PFDoA is a relatively uncommon compound and branched PFOA is usually found in smaller concentrations than linear PFOA.
The first result is broadly in line with previous studies that looked into PFAS blood levels for firefighters,
Were there any other observations?
One interesting observation the authors made was that for the majority of PFAS compounds, the estimated serum level declined steadily throughout the 3 year study. This was true for all 4 groups in the study (firefighters, other emergency responders, healthcare workers, and other essential workers).
There were a couple of exceptions to this, which could be significant. Firefighters and healthcare workers both saw increased levels of PFHpS during the study (and this was especially significant for healthcare workers). And for PFDA, the level of exposure for firefighters remained relatively flat (while it declined for all other workers).
Was this a robust study?
There are a couple of caveats that the authors highlight in the study.
- Exposure sources. The study didn’t assess whether there may have been any non-occupational exposure to PFAS, for instance in drinking water.
- Limited data. The study didn’t take any account of duration of employment. This means they were unable to see if longer exposure at work led to any change in PFAS level. Likewise, the study took no account of aspects like the specific role done by each firefighter.
- Limited cohort. The study only looks at people who were part of the HEROES study. This group may well not be representative of people in Arizona as a whole, let alone the US general population.
That being said, this was a well designed and robust study overall. It is also relatively large compared to other studies looking at PFAS.
Comparison with NHANES
The authors did make some comparison with the general population. When the data is compared with the results of the most recent public NHANES dataset from 2017 - 2018, the HEROES results are actually lower. However, the study authors point out that this may reflect a general steady decline in PFAS levels over time. That would align with other studies and with the long-term analysis from the NHANES study itself.
What does this mean for you?
If you are a firefighter or healthcare professional, you might find this study quite worrying. It strongly suggests that workers like you have higher occupational PFAS exposure than others. However, it’s important not to over-interpret the significance of the results.
The average level of PFAS actually declined over the course of the study for individuals that submitted more than one serum sample. This is in line with other studies and reflects two things: firstly, the manufacture and use of many PFAS has declined over recent years. Secondly, there has been a move towards more short-chain PFAS that break down much more rapidly in the body.
Also, while the levels of some PFAS were significantly higher, the actual difference was under 30% in all cases. This is high enough to be concerning, but it is impossible to say how much this actually increases the risk. Moreover, for many of the compounds with increased exposures, the absolute exposure was still quite low, especially in the context of NASEM’s guidelines on PFAS risk.
If you are worried about your own PFAS levels, you can take one of our at-home PFAS blood tests. This will let you compare your results against the NHANES data and give you an idea of your own risk according to the NASEM guidelines.
