One of the issues I see with PFAS testing is that the legal limit is right at the lower limit of detectability for most test equipment. Signals at that level are difficult to read reliably and the accuracy of detection at that level is worse than at higher levels.
It's almost like legislators saw that the machines could ostensibly detect 4 parts-per-trillion and decided that should be the limit without continuing to read the machine manual to describe the reduction in accuracy at that threshold level.
The levels in this test were close to this threshold and there was one outlier sample that severely changed the average results. The testing methodology also involved several laboratory steps where contamination could have occurred.
Did they wear gloves when installing the samplers?
One of the issues I see with PFAS testing is that the legal limit is right at the lower limit of detectability for most test equipment. Signals at that level are difficult to read reliably and the accuracy of detection at that level is worse than at higher levels.
It's almost like legislators saw that the machines could ostensibly detect 4 parts-per-trillion and decided that should be the limit without continuing to read the machine manual to describe the reduction in accuracy at that threshold level.
The levels in this test were close to this threshold and there was one outlier sample that severely changed the average results. The testing methodology also involved several laboratory steps where contamination could have occurred.
https://media.sciltp.com/articles/2603003293/2603003293.pdf