This document explains the origin of the numeric value currently shown on the Standards page for each method and matrix. It is a proposed starting point for the Scientific Advisory Board to review once constituted (§2b) — not a board determination itself, and it is labeled as such everywhere it appears in the registry, the verify API, and this page.
Pass = no microplastic particles or polymer mass detected by the accredited laboratory at or above that method’s own validated quantification limit, for the applicable matrix.
Setting any specific non-zero count or mass value — e.g. “0.4 particles/L” — would require a published study establishing that exact figure as a meaningful cutoff for that exact matrix. No such figure currently has that kind of backing across the matrices this Standard covers; inventing one would be exactly the failure mode the MPFREE Claims Policy and threshold-governance model exist to prevent.
“Non-detect at the method's own validated floor” is different: it isn't a chosen number, it's a direct consequence of the method characteristics already documented on the Standards page — µFTIR's practical size floor (≈20 µm) [2], Raman's finer resolution (≈1 µm) [3], and Py-GC-MS's nanogram-level mass sensitivity [4], all operating within the microplastic size range this Standard follows (1–1,000 µm) [1]. The specific numeric quantification limit that applies in practice is whatever the certifying accredited lab's own ISO/IEC 17025 scope states for that method — a real, audited, lab-specific figure, not a centrally invented one.
This also mirrors the WHO's own 2019 call for standardized measurement methods as a precondition for a more confident assessment [5] — starting from what the methods can already reliably resolve, rather than from an assumed acceptable exposure level nobody has yet established for these matrices.
The Scientific Advisory Board may adopt this baseline, tighten it, loosen it with evidence, or replace it with a matrix-specific numeric limit entirely — all per the review process in §2b. Whatever it decides, the resulting threshold row’s status field moves from proposed to ratified, and this document will be superseded by the board’s own rationale — not silently edited in place.