Comparing Chemical Tests to XRF for Lead Detection
How do chemical tests stack up against XRF? To find out, I did a little study where I produced several paint samples by mixing some lead-based paint into modern house paint.
Creating Lead-Infused Paint Samples
It was eggshell finish, indoor paint, and after homogenizing them to the best of my ability, I applied a uniform thickness onto each square that had been taped off on this piece of sheetrock. I allowed it to dry for four days and then tested each one with a variety of chemical tests as well as the XRF.
Lead Detection: Chemical Tests vs. XRF
Both methods successfully detected the lead in each of the boxes. The first box was the only one where the lead content was too low to detect with the chemicals but was detected at a range of about 120 parts per million lead by the XRF unit.
Understanding Lead Limits: CSPC and EPA Regulations
While this would be too high to sell in the U.S. today as the limit is 90 parts per million, the limit set by the CSPC in 1973 was 600, and that persisted until 2008 when they lowered it to 90.
Sodium Rhodizonate Swabs: A Chemical Test I Invented
I tested all the boxes with the sodium rhodizonate-based swabs that I invented in 2019. I currently sell those on Amazon, and they have detected lead on millions of surfaces so far. Conversely, there's a new type of test out which relies on fluorescence. This one is a bit more tricky, and I am always still tweaking the mixture to ensure the highest degree of sensitivity.
EPA Regulations and Chemical Test Sensitivity
Both of these swabs would not meet current EPA regulations, ironically, because they detect lead far below the "limit" of 5,000 parts per million.
XRF’s Advantage: Detecting Over-Painted Lead
The real area where XRF outshines the chemical tests is when the lead is over-painted. While over-painted lead does not cause an immediate threat to the occupants, if it's disturbed without being properly investigated, it certainly will.
RRP Rule Compliance: Ensuring Safety During Renovations
So if you're going to renovate, always adhere to the rules surrounding the RRP rule. Renovation of over six square feet inside a house necessitates inspection by a qualified person. If you use a professional contractor, they should either have RRP certification themselves or know where you can get a professional lead inspection to determine if they need to comply with the laws when they renovate. This is a huge area where people wind up getting poisoned because they don't know that there's lead in the walls, and they do a lot of renovating to buried lead.
Limitations of Current Lead Detection Swabs
Even though the 3M swabs, which are currently unavailable, are able to rule out the presence of lead paint, I think that this rule is a little bit misguided since over-painted lead would not qualify as a net positive result, and therefore people would have a false sense of security.
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