How to Verify Microplastics Lab Data for Defensible Claims

Written by: Scott Steveson, Specialist, Wellness Quality Institute

Key Takeaways for Plastic-Related Claims

• Raw lab reports record instrument results within specific boundaries, and independent review is required to determine what claim the data can support.
• Verification means reviewing a dataset against published criteria to confirm whether the data supports a specific claim, which is different from laboratory testing or product certification.
• Defensible claims require complete documentation, accredited laboratories, validated methods for the product type, and clear scope limits tied to tested products and production periods.
• Common failures include incomplete records, methods that do not fit complex products, overextended conclusions, non-accredited results, and old data that no longer reflects current manufacturing.
• Companies that want to turn existing lab data into verified claims can contact The Wellness Quality Institute about Plastic-Free Pathway Verification.

Who Needs Verification and How It Works

Any company making or planning a plastic-related product claim, such as “no microplastics detected” or “low plastic content,” needs an independent process to determine what its existing data actually supports. This applies whether the data was commissioned recently or several years ago.

Several terms have specific meanings in this context and benefit from plain-language explanations.

• Verification: an independent review of a dataset against defined, published criteria to determine whether the data supports a specific claim. Verification is different from laboratory testing and is not a certification that a product is free of plastic.
• Detection limit (also called the method floor or reporting limit): the smallest particle size or lowest concentration an instrument can reliably identify. A result of “none detected” means none found above this floor, not none present at any size.
• Chain of custody: the documented record of who collected a sample, how it was handled, and how it moved from collection to analysis. Without this record, a result cannot be traced back to the product it is supposed to represent.
• Accreditation: independent recognition, by a body such as a national accreditation authority, that a laboratory has demonstrated technical competence for a defined set of methods and product types. ISO/IEC 17025:2017 accreditation applies only to the specific tests, methods, ranges, and product types listed on the laboratory’s current certificate, not to testing in general.
• Scope: the precise boundaries of what a result covers, including the product tested, the particle-size range examined, the polymers screened, the production lot sampled, and the period during which sampling occurred. A claim can only extend as far as its scope.

The FTC Guides for the Use of Environmental Marketing Claims (16 CFR Part 260) require that environmental claims, including absence claims about plastics, be truthful, supported by evidence at the time they are made, and clearly qualified so they do not overstate the benefit the evidence supports. A raw lab report, on its own, does not meet that standard.

Step 1: Gather Every Piece of the Dataset

A reviewable dataset includes far more than a single results page. Independent review can only begin when the following documents are available.

• The full laboratory report, including all raw data pages, not only the summary
• The sampling plan and sample collection records, identifying who collected samples, when, and from which production lot
• Chain-of-custody documentation covering the sample from collection through analysis
• The laboratory’s method documentation, identifying the specific analytical procedure used
• Blank results, which show what the instrument detected in control samples containing no product and help identify contamination introduced during analysis
• Spike recovery data, which show how well the method recovered known quantities of target polymers added to the product type being tested
• Replicate results, which are repeated analyses of the same sample used to assess consistency
• A clear record of the production period the sampled lot represents

A Certificate of Analysis is valid only for the specific batch identified by its lot number. A result from one production run provides no assurance about any other run. The dataset must link to a defined production period, and that link must be documented.

Step 2: Confirm Laboratory Accreditation and Qualification

Laboratories that offer microplastics testing vary widely in their ability to produce results that can support a product claim. Procurement teams should independently verify a laboratory’s accreditation status directly from the accreditation body’s public directory, rather than relying on a supplier-provided PDF or logo.

Three qualification tiers matter when assessing whether a laboratory’s results are reviewable. These tiers reflect increasing levels of demonstrated competence, and each tier requires different levels of documentation during verification.

• Preferred: A laboratory accredited by an environmental laboratory accreditation program for the applicable microplastics method. These programs provide one of the most stringent public references currently available, and accredited laboratories have demonstrated method-specific competence.
• Accepted: A laboratory holding ISO/IEC 17025:2017 accreditation, with the specific microplastics method and the product type explicitly within the accredited scope.
• Conditional: Other qualified independent laboratories, where method equivalence can be documented and independently reviewed.

A laboratory claiming to be “ISO 17025 compliant” without holding a current accreditation certificate from a recognized body makes a self-declared assertion with no independent verification. That distinction matters when the results must satisfy retailers, buyers, or regulators.

Step 3: Match the Method to the Product and Particle Sizes

The analytical method must fit the specific product being tested. A method validated for drinking water may not work for a functional beverage with suspended solids, a flavored liquid, or any product with a complex formulation. An unsuitable method produces results that cannot be defended, regardless of what those results show.

Two standard operating procedures currently serve as validated reference methods for microplastics in drinking water.

• SWB-MP1-rev1: infrared spectroscopy, validated for particles greater than 50 micrometers (µm) through 5,000 µm
• SWB-MP2-rev1: Raman spectroscopy, validated for particles greater than 20 µm through 5,000 µm

Micro-FTIR has a size floor of approximately 10 µm below which it stops identifying particles, while micro-Raman reaches a routine resolution of roughly 0.5–1 µm, which still sits well above the nanoplastic range. The definition reaches down to 1 nanometer, while the best validated methods begin at 20 or 50 micrometers. That gap, where the 1–20 µm fraction is not validated and everything below it is beyond reliable commercial measurement, explains why no product can be claimed to be free of plastic.

No single technique can yet provide comprehensive characterization of microplastics across all environmentally relevant particle-size classes and product types. Beyond particle size, method suitability also depends on which polymer types the test can identify. The polymer panel tested must therefore be assessed. A minimum panel for a defensible review typically includes polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), polyvinyl chloride (PVC), polyamide (PA), polycarbonate (PC), and polymethyl methacrylate (PMMA), with required reporting for any other confirmed polymers and for unidentified particles with no spectral match.

ISO 16094-2:2025, the first international standard for microplastic analysis of clean water using vibrational spectroscopy, and ISO 24187:2023, which sets general principles for microplastics analysis in the environment, can serve as analytical references where method, product type, laboratory validation, and equivalence are reviewed and accepted. Neither standard automatically replaces the reference methods.

Step 4: Check Controls and Supporting Evidence

A result is only as reliable as the controls around it. Current gaps in microplastics standardization, including limited reference materials and incomplete harmonization of methods and data, make the quality of individual laboratory controls even more critical.

The following elements must be present and adequate before a dataset can support any claim.

• Blank results: procedural blanks run alongside samples to detect contamination introduced during analysis. A dataset without blank data cannot show that detected particles came from the product rather than the laboratory environment.
• Spike recovery data: confirmation that the method successfully recovered known quantities of target polymers from the product type, which shows that the method works for that specific product.
• Replicates: repeated analyses that demonstrate results are consistent rather than artifacts of a single measurement.
• Chain of custody: an unbroken documented record from sample collection through analysis and reporting.
• Reporting limits: explicit statements of the lowest concentration or particle count the method can reliably report, so that a “none detected” result can be interpreted correctly.
• Particle counts by size fraction: results reported separately for different size ranges, not as a single aggregate figure, so the scope of the result stays transparent.

A COA that states only “conforms to specification” without per-parameter numeric results, or that lacks test method references or an authorized signature, provides materially weaker evidence. Visual identification of particles alone never suffices, because particles must be chemically confirmed by spectroscopy rather than counted by appearance.

Step 5: Lock the Claim to a Clear Scope

The final step before making any claim is tying that claim tightly to the evidence that supports it. A scope-locked claim specifies exactly what was reviewed and avoids any assertion beyond that boundary.

A complete verification scope includes all of the following elements.

• The specific product or SKU reviewed
• The product type, such as still water, sparkling water, or a specific liquid formulation
• The production or sampling period the dataset represents
• The tested particle-size range and the lower method limit
• The polymer panel screened
• The reporting limits applied
• The analytical method used and the laboratory that performed the analysis

A result from one product cannot be extended to a product line. A result from one production period cannot be extended to subsequent lots. Lot-to-lot variability means a COA matching one batch provides no assurance for a visually identical but untested subsequent batch. Scope lock protects a defensible claim from turning into an indefensible one.

Turn real lab data into a claim you can support. Talk to the Wellness Quality Institute about Plastic-Free Pathway Verification.

Evidence Framework: Checklist for Neutral Decisions

Before any plastic-related product claim is made, specific criteria should be satisfied. This checklist reflects minimum requirements for a dataset to support a defensible claim. It does not guarantee that a claim will survive all scrutiny, but a dataset that fails any item cannot support a claim at all.

• The laboratory holds current ISO/IEC 17025 accreditation, or equivalent recognized accreditation, with the specific method and product type explicitly within the accredited scope
• The analytical method is validated for the product type being tested
• The tested particle-size range is explicitly stated, with a defined lower method limit
• The polymer panel is identified and covers at minimum PE, PP, PET, PS, PVC, PA, PC, and PMMA
• Blank results are reported and show no contamination above the reporting limit
• Spike recovery data confirm the method performed adequately in the product type
• Replicate analyses are included
• Chain of custody is documented from sample collection through final report
• Particle counts are reported by size fraction, not as a single aggregate
• All detected particles are chemically confirmed by spectroscopy, not identified by visual inspection alone
• The dataset is linked to a defined production lot and sampling period
• The proposed claim does not extend beyond the tested product, size range, polymer panel, or production period

Common Problems and How to Fix Them

Several recurring problems prevent raw laboratory data from supporting a defensible claim. Recognizing them early reduces the cost and time needed to correct them.

Incomplete documentation. The most common failure is a dataset that includes results but lacks blanks, spike recoveries, chain-of-custody records, or method documentation. Without these controls, the result cannot be independently verified, because reviewers cannot confirm that detected particles came from the product rather than contamination. The corrective action is to return to the laboratory for the missing records before any claim is made, or, if records were not generated, to commission new testing with complete documentation requirements specified in advance.

Unsuitable method for the product type. A method validated for drinking water may produce unreliable results in a flavored beverage, a product with added minerals, or a liquid with suspended solids. Particle-resolved vibrational spectroscopy and thermal analysis methods each have method-dependent limitations in size and polymer coverage that affect data quality. The corrective action is to confirm method and product-type suitability before commissioning testing, not after receiving results.

Overextended conclusions. A result showing “no microplastics detected” in one product, from one lot, using one method, is sometimes presented as evidence that an entire product line or brand is free of microplastics. Environmental claims may only cover the environmental impacts or performance that were actually assessed. The corrective action is to restrict every claim to the exact scope the data covers.

Non-accredited laboratory results. Results from a laboratory without current, relevant accreditation carry less weight and may be rejected by retailers, procurement teams, or regulators. ISO/IEC 17025 accreditation of the issuing laboratory is often required for a COA to carry regulatory or commercial weight in many industries. The corrective action is to verify accreditation status before commissioning testing.

Stale data. A dataset from a production period that no longer reflects current manufacturing conditions cannot support a current claim. Batch-specificity and recency are essential because a COA is only meaningful if it corresponds to the exact batch the customer is receiving, tested reasonably close to the point of sale. The corrective action is to establish a re-testing schedule tied to production changes and claim renewal.

How to Track Progress Toward a Defensible Claim

Progress toward a defensible plastic claim can be measured through objective indicators. The following markers show that a dataset is moving toward reviewability.

• Complete documentation: all required records exist and are retrievable
• Laboratory qualification confirmed: accreditation status verified against the accrediting body’s public directory, not the laboratory’s own materials
• Method and product-type suitability confirmed: written confirmation that the method is appropriate for the specific product
• Blank and control data present: procedural blanks and spike recoveries included in the dataset
• Scope defined in writing: the claim boundaries are documented before any public statement is made
• Auditability: a third party with no stake in the outcome could examine the dataset and reach the same conclusion

Of all these markers, auditability is the practical test that encompasses the others. If an independent reviewer, such as a retailer’s technical team, a journalist, or a litigator, could not reconstruct the basis for a claim from the documentation provided, the claim is not yet defensible.

Frequently Asked Questions

What is the difference between a lab report and a verified claim?

A laboratory report records what an instrument detected under specific conditions, for a defined particle-size range, a specific set of polymers, and a particular production lot. It does not, on its own, determine what claim that result can support. A verified claim has been reviewed by an independent party against published criteria, confirming that the method was appropriate, the controls were adequate, the scope is defined, and the proposed claim does not exceed what the data shows. Many companies hold lab reports that say “none detected” without realizing that the finding is bounded entirely by the instrument’s detection floor, meaning none found above a certain size using a specific method on a specific lot, not none present at any size or in any later lot.

Can a single lab result support a claim about an entire product line?

No. As explained in Steps 1 and 5, lot-to-lot variability means results are valid only for the specific product, lot, and sampling period tested. Any broader claim about a product line, a brand, or future production runs extends beyond what the data supports.

What happens if a company’s existing data does not meet the criteria for a verified claim?

The most common outcome is that the dataset is incomplete, missing blanks, spike recoveries, chain-of-custody records, or method documentation, rather than that the product itself is problematic. In that case, the corrective path is to identify the specific gaps, return to the laboratory for missing records where possible, or commission new testing with complete documentation requirements specified in advance. A dataset that does not currently support a claim can often reach a reviewable standard with targeted additional work. The Wellness Quality Institute’s (WQI) Plastic-Free Pathway Verification program issues a private Standard Not Met outcome in these cases, which carries no public claim and can be resubmitted with updated information.

Why does laboratory accreditation matter for plastic claims specifically?

Accreditation under ISO/IEC 17025:2017 means an independent body has assessed the laboratory’s technical competence for a defined set of methods and product types. For microplastics testing, this matters because the instrumentation is expensive, the methods are technically demanding, and capability varies significantly between laboratories and even between instruments within the same laboratory. As noted in Step 2, laboratories claiming compliance without actual accreditation present the same structural problem as self-reported product claims, because they make assertions with no independent verification. Accreditation status should always be verified directly from the accrediting body’s public directory, not from the laboratory’s own marketing materials.

What does “none detected” actually mean on a microplastics lab report?

“None detected” means no particles were found above the instrument’s detection floor, for the polymers included in the test panel, in the specific lot sampled. It does not mean no plastic is present at any size, in any polymer type, or in any other production lot. As discussed in Step 3, validated methods can only detect particles down to 20–50 micrometers, which are thousands of times larger than the 1-nanometer lower bound of the microplastics definition. A “none detected” result is a bounded statement about a specific measurement, not a guarantee of absence, and any claim built on it must reflect those boundaries explicitly.

Conclusion: Turning Lab Data into Defensible Claims

A clean lab result does not equal a defensible product claim. It serves as the starting point for one. The distance between a raw dataset and a claim a company can stand behind is covered by five sequential steps: collecting the complete dataset, confirming laboratory qualification, assessing method and product-type suitability, evaluating completeness and controls, and defining the verification scope. Each step is necessary. Skipping any one of them leaves the claim exposed to retailer pushback, legal challenge, or simple uncertainty about what the data actually proves.

The Wellness Quality Institute (WQI) exists to close that gap. The Wellness Quality Institute’s core program, Plastic-Free Pathway Verification (PFPV), governed by the standard WQI-CS-01, independently reviews a company’s existing laboratory dataset, testing methodology, product scope, and supporting controls against defined criteria. These criteria align with a drinking-water microplastics reference framework as a technical reference point and are available to companies nationally. The Wellness Quality Institute does not run laboratory tests. It reviews the data companies already hold, or data they commission from a qualified independent laboratory, and issues one of two outcomes: Standard Met, which carries a verification decision, a scope-locked license to use the WQI mark, a public registry listing, and approved claim language; or Standard Not Met, a private outcome that can be resubmitted with updated information. A single assessment fee covers review, verification decision, and registry listing, with no separate mark-license or registry fee.

WQI Plastic-Free Pathway Verification does not certify that a product contains zero plastic, microplastics, or nanoplastics. It shows that the company is on a verified pathway toward plastic-free standards. Verification applies only to the reviewed products, submitted datasets, tested ranges, polymer panels, production or sampling periods, and supporting controls. WQI verification is not a government certification, or health or safety certification.

Ready to verify your plastic claims? Contact the Wellness Quality Institute to review your existing laboratory data.