How To Verify Lab Data on Plastic Content Before Any Claim

Written by: Scott Steveson, Specialist

Key Takeaways

Verifying existing laboratory data on plastic content means checking accreditation, particle-size range, polymer panel, blanks, chain of custody, and product scope before any public claim.
A raw lab report is not the same as a defensible claim. Verification against defined criteria is needed to meet FTC Green Guides standards and withstand regulatory scrutiny.
Key verification steps include confirming ISO/IEC 17025 accreditation, mapping tested particle sizes and polymers against validated method limits, checking blanks and contamination controls, and ensuring complete chain-of-custody documentation.
Common data-quality gaps such as missing blanks, unsuitable methods, or over-extended scope must be identified and fixed before a dataset can support an independent review decision.
The Wellness Quality Institute offers independent verification of existing laboratory data through its Plastic-Free Pathway Verification program so brands can substantiate defensible plastic-content claims.

Why a raw lab report does not equal a defensible claim

Many brands have already paid for independent laboratory testing on plastic or microplastic content. The report exists, it cost real money, and it may even read “none detected.” A laboratory result and a market claim remain two different things, and the distance between them is where legal and reputational exposure lives.

Four terms matter here, and defining them plainly keeps the rest of this process clear.

Verification means an independent review of existing data against defined criteria to determine what that data supports. Validation means confirming that a method itself is fit for purpose, meaning it measures what it claims to measure in the product tested. Detection limit (also called the reporting limit) is the smallest particle size or concentration a given instrument and method can reliably find. Anything below that floor is invisible to the method, not confirmed absent. Chain of custody is the documented, unbroken record of who handled a sample, when, and under what conditions, from collection through analysis. Scope defines exactly what the data covers, including product, production lot, particle-size range, polymers, and time period.

Under the FTC Green Guides (16 CFR Part 260), environmental marketing claims must be truthful, not misleading, and backed by scientific evidence that qualified people can evaluate objectively. A raw laboratory report can contribute to that substantiation file, but it does not constitute it on its own. A scope-locked, independently verified statement is more defensible than relying on raw analytical data alone when substantiating plastic-content claims, particularly as state attorneys general are actively pursuing companies whose environmental marketing claims cannot withstand scrutiny.

The six steps below describe how to review an existing dataset before drawing any public conclusion from it, and where independent verification from the Wellness Quality Institute can convert that dataset into a claim that holds up.

Step 1: Confirm laboratory qualification and accreditation for your product

The first task is confirming whether the laboratory that produced the report is qualified to produce it. Accreditation provides the clearest proxy for that qualification.

ISO/IEC 17025:2017, the international standard for testing and calibration laboratory competence, is the baseline accreditation reference for microplastics work. Accreditation under this standard means the laboratory has demonstrated technical competence and a quality management system that produces reliable results. The specific method and the specific matrix, such as bottled water or a liquid beverage, must fall explicitly within the laboratory’s accredited scope. A laboratory accredited for environmental water testing is not automatically qualified for bottled water or functional beverage testing.

Scientists in white coats working with samples and microscopes in a laboratory. — Only a small number of laboratories can genuinely test for microplastics, and capability varies by instrument and method. WQI reviews a company’s existing third-party laboratory data against a defined standard — it does not run the tests itself.

For US-based brands, California’s Environmental Laboratory Accreditation Program (ELAP) offers one public laboratory qualification reference for microplastics in drinking water, tied to the state’s published standard operating procedures. Accreditation under ELAP for the applicable method serves as one reference point among several a brand may consider.

If the report does not identify the laboratory’s accreditation status, or if the method and matrix are not within the accredited scope, the dataset’s defensibility is immediately limited regardless of what the results say. At that stage, independent verification from the Wellness Quality Institute can highlight the accreditation gap and help you decide whether to supplement or repeat testing before making any claim.

Step 2: Match particle-size range and polymer panel to validated method limits

This step separates data verification from data validation for plastic content in practical terms. Verification asks what the data shows. Validation asks whether the method was capable of showing it reliably.

Current analytical methods have hard detection floors. California’s SWB-MP1-rev1 (infrared spectroscopy) is validated for particles greater than 50 µm through 5,000 µm. SWB-MP2-rev1 (Raman spectroscopy) is validated for particles greater than 20 µm through 5,000 µm. ISO 24187:2023 outlines general principles for microplastics analysis in environmental matrices. The 1–20 µm fraction is not validated under either California method, and everything below 1 µm, the nanoplastic range, currently sits beyond reliable commercial measurement.

Colorful plastic fragments in water inside a laboratory petri dish. — Microplastics are particles smaller than five millimeters. Current methods can count and identify them at the upper end of that range, but reliable measurement falls away as particles get smaller — a limit that shapes every honest claim.

A result of “none detected” from a method starting at 50 µm means none were found above 50 µm using that instrument on that lot. It says nothing about smaller particles. Current microplastics standards predominantly address particles larger than 20 µm, with minimal guidance available for nanoplastics below 1 µm in water matrices.

The polymer panel, meaning the list of plastic types the method screened for, matters equally. Commonly detected polymers in water matrices include polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and polystyrene (PS), while broader panels including PVC, polyamide (PA), polyurethane (PU), and polyethersulfone (PES) are often needed for more complex matrices. A report that screened for only two or three polymer types cannot support a claim about plastic content in general.

Check the report for an explicit statement of the particle-size range tested and the polymer panel covered. If either is absent, the scope of the result is undefined and needs clarification before any public statement.

Step 3: Use blanks and controls to separate real particles from contamination

Blanks are the single most important quality-control element in microplastics analysis and the most commonly missing from reports that brands receive.

Because microplastics are present in laboratory air, on surfaces, in reagents, and on equipment, contamination can occur at every analytical step, making blanks and contamination controls essential for credible results. Three types of blanks serve distinct functions, each targeting a different contamination pathway in the analytical chain.

Fragments of plastic suspended in blue water below the surface. — Plastic doesn’t disappear — it fragments. These secondary microplastics are the breakdown products of everyday objects, and independent research now detects them across the water supply. Detection, though, establishes presence, not absence.

Field blanks detect contamination introduced during sample collection.
Procedural blanks identify contamination introduced during laboratory processing.
Air blanks monitor airborne fiber deposition during open-vessel handling.

Results should include both raw and blank-corrected data, the average and standard deviation of particles found in blanks, and a clear statement on whether blank correction was applied. A report that presents only a final particle count, with no blank data, cannot distinguish particles genuinely present in the product from particles introduced during analysis.

Spike recoveries, which are tests where a known quantity of standard microplastic particles is added to a sample to verify the method recovers them accurately, provide a further indicator of method reliability, particularly for fibers and particles smaller than 100 µm.

Visual identification alone never suffices. Simple visual microscopy cannot prove that a particle is plastic, and false positives are common without chemical confirmation. Every counted particle, or an approved statistically valid subsample, must be chemically confirmed by spectroscopy.

Step 4: Confirm chain-of-custody integrity and data recency

Microplastics testing chain of custody is the documented record that connects the sample collected from a product to the result reported by the laboratory. Without that record, no one can confirm that the analyzed sample was the product it was represented to be or that it was handled in a way that preserved its integrity.

A complete chain-of-custody record must capture a unique sample identifier, custodian identity, timestamp of each event, action taken, condition and environment at handoff, and signature or electronic authentication. Any unexplained gap in a sample’s chain of custody prevents verification of sample location or handling during that interval and undermines confidence in results derived from the sample.

Common gaps include verbal handoffs without documentation, shared logins that prevent attribution to a specific custodian, undocumented courier legs during transport, and retroactive edits to the log.

Data recency matters separately. A result from a production lot sampled two or three years ago does not describe current production. Lot-to-lot variability in plastic content is real, because packaging materials, filling equipment, and processing conditions change. A dataset’s age directly limits the scope of any claim drawn from it.

Step 5: Tie results to a specific product scope and production period

A dataset covers what it covers, and nothing more. An environmental claim must clearly define its scope, specifying whether it applies to the full product, a specific component, a single SKU, or a particular production period.

Before drawing any public conclusion from a lab report, map the result precisely to the product tested. Confirm the specific SKU or product variant, the production lot or sampling date range, the product matrix, such as still water in a 500 mL PET bottle versus sparkling water in glass, and the fill and packaging conditions at the time of sampling. A result from one SKU does not extend to a product line. A result from one production period does not cover subsequent lots.

This point is not a technicality. Overbroad or unqualified wording increases deception risk in consumer class actions, and brands are expected to use clear, specific, and prominent qualifications when the evidence is narrower than the claim.

Step 6: Decide whether the dataset is ready for independent review

After completing the five steps above, assess whether the dataset, taken as a whole, is complete enough to support an independent review and whether the results, within the reviewed scope, meet a defined standard.

A dataset is reviewable when it includes all the quality-control elements that establish both technical reliability and traceability. On the technical side, you need a qualified laboratory with accreditation covering the method and matrix, an explicit particle-size range and polymer panel, blank data with blank-corrected results, and spike recovery data to confirm the method performed as expected. On the traceability side, you need a complete chain-of-custody record, a clearly defined product scope and production period, and data recent enough to reflect current production, because even strong analytical work loses value if you cannot prove what was tested or when.

A dataset that meets all of those criteria can be submitted for independent review. One that does not tells the brand specifically where the gap is, which is useful information because it identifies what additional testing or documentation would be needed before any public claim is defensible.

Common data-quality problems and how to fix them

Several data-quality problems appear consistently in lab reports that brands bring to independent review. Recognizing them early prevents a brand from building a claim on a foundation that will not hold.

Incomplete or absent blanks. This is the most common gap and it prevents separation of product particles from contamination. The practical fix is to request blank data from the laboratory directly. If it was not collected, the testing may need to be repeated with proper controls.
Method unsuitable for the matrix. A method validated for surface water or wastewater may not be appropriate for bottled water or a functional beverage with dissolved solids, and the matrix affects what the method can reliably detect, as discussed in Step 2. Companies must be able to explain what their test methods can and cannot detect to avoid overstating conclusions from tests that do not capture the full range of potentially relevant particles. The fix is to confirm that the method was validated specifically for the product matrix.
Visual identification without chemical confirmation. Nile Red staining can stain non-plastic hydrophobic materials and generate false positives; one 2026 study reported 1,891 particles/m³ with Nile Red but only 161 confirmed microplastics/m³ by µRaman. Any report relying on visual or staining methods without spectroscopic confirmation functions as a screening result, not a defensible finding, so follow-up testing with spectroscopy is needed.
Over-extended scope. A result from one product or one lot applied to an entire brand or product line stretches the data beyond its limits. The fix is to restrict any claim language precisely to the tested product and production period or commission additional testing for broader coverage.
Missing chain-of-custody documentation. If the laboratory cannot produce a complete custody record, the integrity of the sample cannot be confirmed. This is a fundamental gap that cannot be repaired after the fact, so new sampling and testing may be required.
Aggregate particle counts without size-fraction breakdown. Counts reported only as a single aggregate figure prevent meaningful interpretation of what the method detected and where. The fix is to request size-fraction data from the laboratory or ensure that future testing reports counts by size range.

Measuring progress: indicators that your dataset is complete and auditable

A dataset is complete and auditable when it satisfies the following indicators. These reflect the quality-control expectations embedded in published analytical standards and regulatory guidance.

Laboratory accreditation confirmed, with method and matrix explicitly within accredited scope
Particle-size range stated explicitly, with the method’s lower detection limit identified
Polymer panel listed by name, covering at minimum PE, PP, PET, PS, PVC, PA, PC, and PMMA
Field blanks, procedural blanks, and air blanks reported with raw counts and blank-corrected results
Spike recovery data present, with recovery percentages reported
All counted particles chemically confirmed by spectroscopy, not visual identification alone
Particle counts reported by size fraction, not as a single aggregate
Complete chain-of-custody record with no undocumented gaps
Sampling date and production lot identified, with data recent enough to reflect current production
Product scope defined to a specific SKU and production period

A dataset that satisfies all of these indicators can support an independent review. One that satisfies most of them identifies a clear remediation path.

Frequently Asked Questions

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 polymer types the method screened, in the specific lot tested. It is a bounded statement, not a guarantee of absence. A method that begins at 50 µm cannot see anything smaller, so “none detected” can coexist with particles present below that size. The result is only as meaningful as the method behind it, which is why reviewing the method matters as much as reading the result.

How is data verification different from data validation for plastic content?

Verification reviews what an existing dataset shows and whether it supports a specific claim. Validation confirms that the method itself was fit for purpose, meaning it reliably measures what it claims to measure in the product tested. Both matter. A verified result from an unvalidated method is not defensible, because the method’s reliability has not been established. A brand reviewing an existing report needs to assess both what the data says and whether the method was capable of saying it accurately.

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

No. A dataset covers the specific product, SKU, production lot, particle-size range, polymer panel, and sampling period it was drawn from. Extending a single result to a product line, a brand, or a company as a whole creates a scope overreach that creates legal exposure. Each product and production period requires its own supporting data if a claim is to be made about it.

What happens if the existing dataset does not meet the criteria for an independent review?

A dataset that does not meet review criteria does not automatically indicate a failed product. In many cases, the gap sits in the testing rather than in the product itself. Common gaps include missing blank data, a method not validated for the product matrix, an incomplete polymer panel, or a chain-of-custody record with undocumented intervals. Each gap is specific and addressable. The laboratory may be able to supply missing documentation, or additional testing with proper controls may be commissioned, and the dataset can then be resubmitted for review.

Does independent review replace legal or advertising-claims counsel?

No. Independent review of a laboratory dataset against a defined standard forms one component of a substantiation file. Companies remain responsible for ensuring that all product, packaging, and marketing claims are accurate and properly substantiated under applicable law. Independent review is not legal, regulatory, or advertising-claims counsel, and it does not replace those functions.

Next step: independent review with the Wellness Quality Institute

A laboratory report that has passed the six-step review above is ready to be assessed by an independent third party. That assessment converts a dataset into a defensible market claim, because independent review carries weight that self-reported data structurally cannot. When a brand publishes its own test results, the market reads it as marketing, regardless of how rigorous the underlying testing was.

The Wellness Quality Institute (WQI) is an independent verification body that reviews companies’ existing third-party laboratory data on plastic and microplastic content against a defined standard, WQI-CS-01, so brands can substantiate real progress toward plastic-free standards. WQI’s core program, Plastic-Free Pathway Verification (PFPV), reviews a company’s existing independent laboratory dataset, testing methodology, product scope, and supporting controls against criteria aligned with the California State Water Board’s drinking-water microplastics reference framework. California’s framework serves as a technical reference point, not a geographic boundary, and verification is available to US-based companies nationally.

The review examines every element covered in the six steps above, including laboratory qualification, analytical method, product matrix, particle-size range, polymer panel, reporting limits, blank results, spike recoveries, chain of custody, data recency, and product scope. The outcome is binary. Standard Met carries a verification decision, a scope-locked license to use the WQI mark, a public registry listing, and approved claim language. Standard Not Met is a private outcome that is never described as a failed product and 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. Independent laboratory testing is arranged and billed separately by a qualified independent laboratory. Payment of the assessment fee does not guarantee a verification decision.

WQI does not perform laboratory testing. Its independence from the testing it reviews is the source of the credibility its review carries.

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 California approval, government certification, or health or safety certification.

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