Ok so diving in, The Guardian is reblogging a blog "lead safe mama".<p>"lead safe mama" is an activist and filmmaker, who does not appear to have a scientific background, and who may primarily be motivated by taking on legal cases. [0]<p>Furthermore, in the toothpaste (informal, blogger-led) study it appears that the testing was performed by "Purity Laboratories" using "ICP-MS" instrumentation. [1]<p>According to "Purity's" own marketing it's admitted the "ICP-MS" may cause interferences, though they aren't specifically quantified. [2] Other laboratories primarily market the technique <i>specifically</i> for testing <i>raw</i> for contamination[3] and discusses "dynamic range", rather than what I speculate is "a complex matrix" though I myself am not technical enough to recognize the meaning there.<p>According to an instrument vendor, Agilent, there are other considerable number of other constraints and variables where the laboratory process itself could introduce issues[4] and alarmingly, I'm unable to locate any details regarding specificity or FPRs, and there's some evidence of targeted advocate edits on Wikipedia regarding the viability of this application of this technique. Furthermore these advocate edits specify a different methodology for health-related detection, rather testing wastes for result of contamination than testing products themselves. Even furthermore Agilent, one vendor that has strategically been selected for my review of technical details about the technique specifies "ICP-MS is an elemental analysis technique, meaning it is used to measure elements, rather than the molecules" but it's difficult to determine whether the technique can avoid creating FPs with molecules. The process itself seems like it is not fool-proof, it would take some expertise in plasma chemistry to understand and predict completely which I cannot provide, or probably some pretty intricate calibration details which are not available for this study.<p>It's conceivable that testing products represents a misuse of the technique, it at least differs in scope from the use-case described throughout the Wikipedia article. There's a section on Wikipedia regarding use of the technique for Pharmaceuticals but it is vague, speculative, and drifts substantially from the actual topic at hand into usage for forensics.<p>[0] <a href="https://tamararubin.com/2023/07/lead-safe-mama-llc-rates-for-consulting-with-law-firms/" rel="nofollow">https://tamararubin.com/2023/07/lead-safe-mama-llc-rates-for...</a><p>[1] <a href="https://tamararubin.com/2025/04/orajel-kids-anti-cavity-toothpaste-with-fluoride-in-fruity-bubble-flavor/" rel="nofollow">https://tamararubin.com/2025/04/orajel-kids-anti-cavity-toot...</a><p>[2] <a href="https://www.puritylabsinc.com/heavy-metals-testing" rel="nofollow">https://www.puritylabsinc.com/heavy-metals-testing</a><p>[3] <a href="https://www.eag.com/wp-content/uploads/2023/11/High-Purity-Raw-Materials-Brochure.pdf" rel="nofollow">https://www.eag.com/wp-content/uploads/2023/11/High-Purity-R...</a><p>[4] <a href="https://www.agilent.com/en/product/atomic-spectroscopy/inductively-coupled-plasma-mass-spectrometry-icp-ms/what-is-icp-ms-icp-ms-faqs" rel="nofollow">https://www.agilent.com/en/product/atomic-spectroscopy/induc...</a>