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| An example of a lead testing kit from Amazon |
There is legitimate concern about lead content of some glass intendended for culinary use. Surface lead testing kits have become popular and indicate the presence of lead on many glasses. It seemed to me that some evaluation of home lead test kits was in order. I looked at some sites for scientific evaluations and some reviews of testing kits and found these results.
Public Lab, whose mission is “Pursuing environmental justice through community science and open technology”, reports in the paper, “Evaluating Low-cost Lead Screening Products”, by Read Holman that “There are two evaluated [surface lead] test kits, the remaining three for surfaces have not been scientifically evaluated.” The report states that the tests for
“Paint/Surfaces...
- ESCA Tech, Inc. D-Lead Paint Test Kit.
This product was "EPA-recognized" in 2010, but for negative
results only; the rate of finding false-positives is 16% (Source PDF))
- 3M LeadCheck Swabs. This
product was "EPA-Recognized" in 2010, but for negative results
only; the rate of finding false-positives is 98% (Source PDF)). This is an extremely
high false-positive rate.”
There
are seven other scientifically evaluated tests for dust and water, which are
not applicable to glass surfaces.
The
conclusion of a report for the US Dept of Commerce states:
“Currently
available spot test kits cannot be used to determine lead-based paint, which is
defined as a paint having lead at levels equal to, or greater than, 1mg/cm2
[the allowable level]. This finding was consistent with conclusions from
several previously published field studies. As was found in the field studies,
the spot test kits in this controlled laboratory study generally gave
relatively high percents of false positives at the lead-based paint level of 1
mg/cm2. That is, the spot test kits were generally sensitive to lead
in paint at much lower levels” (p61)
The
experience of people using these tests (reviews on Amazon) show that almost all
surfaces show traces of lead, but at much lower concentrations than the allowable
levels.
A sample
review:
“We got a heart attack because what we wanted to test turned positive, we proceeded to then test other stuff as a control, and guess what? All positive. We got suspicious and started testing random objects that couldn’t possibly contain lead. They also turned positive!” JSP Lead Test Kit
The
high levels of false positives (up to 98%) leads me to question their value or
accuracy. Although I am not going to
spend money on any of these tests, I suspect the test kits will show lead on
clear glass too.
My
conclusion is that these tests are not reliable indicators of risky levels of
lead presence on the surface of glass artifacts. Any concern needs a much more reliable test
than the currently available surface lead test kits.
