Microplastics Testing For Retailers: Labs, Methods & Claims
The Wellness Quality Institute helps retailers choose labs, interpret results, and make honest microplastics claims. Start testing with confidence.
Read articleTurn Lab Data into Defensible Plastic-Free Claims
The Wellness Quality Institute evaluates your lab data against 5 criteria so plastic-free claims hold up to regulators and retailers. Get verified.
Written by: Scott Steveson, Specialist, Wellness Quality Institute
Key Takeaways
- Raw laboratory reports that show “none detected” describe what the method could see for that test, not a guarantee of zero plastic.
- U.S. regulators and retailers now expect detailed proof for plastic-reduction claims, with California SB 343 and AB 2253 setting documentation standards likely to spread.
- Five technical checkpoints determine whether existing data can support a defensible claim: lab qualification, method and particle-size range, polymer panel and reporting limits, contamination controls, and scope of findings.
- Independent review against WQI-CS-01 from The Wellness Quality Institute converts third-party lab data into a scope-locked, registry-listed verification that stands up to legal and retailer review.
- Contact The Wellness Quality Institute to turn your existing laboratory data into a Plastic-Free Pathway Verified claim you can defend.
Why Regulators and Retailers Now Scrutinize Plastic-Reduction Claims
Regulatory and litigation pressure on environmental marketing claims has increased sharply in recent years. At the federal level, 16 CFR 260.13, known as the FTC Green Guides, requires that recycled-content and related environmental claims rest on a reasonable factual basis before they appear in the market. Broad, sweeping claims require stronger evidence than narrow, specific statements. The FTC is revising the 2012 Green Guides, with a final version expected in 2026 that will likely tighten proof and disclosure rules for sustainability claims.
At the state level, California is setting documentation expectations that other states are likely to follow. California SB 343, effective for products manufactured on or after October 4, 2026, prohibits recyclability statements on products and packaging unless the item meets statewide criteria and requires manufacturers to keep written records that back up those claims. Building on that foundation, California AB 2253 requires manufacturers making recycled-content claims for plastic food container products to maintain documentation showing that recycled content was diverted from the solid waste stream, with these requirements expanding to all products that make such claims. Together, these California laws show where national expectations are heading: documentation standards are tightening, and self-reported results are treated as marketing, not proof.
Legal exposure adds another layer of risk. Morgan Lewis identifies “plastic-free” as a high-risk environmental marketing term that should always go through legal review before use. A growing wave of class-action lawsuits now targets companies whose plastic-related claims cannot be backed up with solid evidence.
Why Raw Laboratory Reports Alone Do Not Support Defensible Claims
A laboratory report that reads “none detected” describes a limited finding, not a blanket guarantee. “None detected” means no particles were found above the method’s detection threshold, which is the lowest level the instrument can reliably see, for the polymers it screened in the lot it tested. If the report does not state an explicit limit of detection, that result should not be used to support plastic-reduction claims.
ISO 14021:2026, the international standard for self-declared environmental claims, requires documented methods behind those claims. A raw lab report, quoted directly, supplies a number but not the independent interpretation needed to explain what that number actually means for marketing language.
No laboratory today can confirm the complete absence of plastic across every particle size, polymer type, and production lot. This limit reflects current science, not a lack of effort. Detection methods can show that plastic is present, but they cannot prove that plastic is entirely absent. Any claim of total absence goes beyond what current methods can support.
Given these limits, companies need a structured way to decide what their data can honestly support. Evaluating each dataset against five clear technical criteria separates bounded, supportable findings from broad marketing claims that invite challenge.
Five-Criterion Framework for Evaluating Laboratory Datasets
This five-part framework gives sustainability leaders and procurement teams a practical checklist for judging whether existing laboratory data can support a plastic-reduction claim. It aligns with ISO 14021:2026 and the FTC Green Guides. Each criterion includes a pass condition, a common gap seen in practice, and a reference standard.
| Criterion | Pass Condition | Common Gap | Reference |
|---|---|---|---|
| Laboratory Qualification | State-accredited for the applicable method (preferred), or ISO/IEC 17025-accredited with the method and matrix explicitly in scope (accepted) | Laboratory holds general accreditation but the microplastics method or product matrix is not within the accredited scope | ISO/IEC 17025:2017; state accreditation programs |
| Analytical Method and Particle-Size Range | SWB-MP1-rev1 (infrared, >50 µm) or SWB-MP2-rev1 (Raman, >20 µm); validated range documented; 1–20 µm fraction acknowledged as unvalidated | Method not validated for the product matrix; detection floor not stated; particle-size range not specified in the report | California SWB-MP1-rev1; SWB-MP2-rev1; ISO 16094-2:2025 |
| Polymer Panel and Reporting Limits | Minimum panel of PE, PP, PET, PS, PVC, PA, PC, PMMA tested; reporting limits meet WQI-CS-01 thresholds; unidentified particles reported | Panel covers only a few polymers; reporting limits not stated or below required threshold; unidentified particles omitted | WQI-CS-01; ISO 14021:2026 §8.6 |
| Chain-of-Custody and Contamination Controls | Documented procedural blanks, spike recoveries, replicates, and custody records present in the dataset | Blanks not run or not reported; spike recoveries absent; chain-of-custody records missing or incomplete | WQI-LAB-01; ISO/IEC 17025:2017 |
| Scope of Findings | Findings locked to the reviewed product, dataset, particle-size range, polymer panel, and production period; no company-wide or product-line extension | Single product result extended to a product line or the company as a whole; production period not specified | WQI-CS-01; FTC Green Guides |
How WQI Evaluates Laboratory Qualification
Not every laboratory that offers microplastic testing generates data that can support a defensible claim. The Wellness Quality Institute’s review standard recognizes three tiers of laboratory qualification.
The preferred tier is a laboratory that holds state Environmental Laboratory Accreditation Program accreditation specifically for the applicable state microplastics method. The accepted tier is a laboratory that holds ISO/IEC 17025:2017 accreditation, the global standard for testing laboratory competence, with the microplastics method and the specific product matrix clearly listed in its accredited scope. A conditional tier covers other independent laboratories that may qualify after a documented method-equivalence review and technical approval.
The difference between general accreditation and method-and-matrix-specific accreditation has real consequences. Laboratory instruments for true microplastic identification cost between $30,000 and $300,000 and require trained operators and strict contamination control. A laboratory may hold ISO/IEC 17025 accreditation for unrelated work while lacking validated capability for microplastics in a beverage or similar matrix. Confirming laboratory qualification before commissioning testing helps avoid paying for data that cannot support a verification decision.
How Method and Particle-Size Range Shape Your Claim
The California State Water Board has published two validated analytical methods for microplastics in drinking water, and these methods serve as the technical reference for The Wellness Quality Institute’s review criteria.
SWB-MP1-rev1 uses infrared spectroscopy and is validated for particles larger than 50 micrometers up to 5,000 micrometers. SWB-MP2-rev1 uses Raman spectroscopy and is validated for particles larger than 20 micrometers up to 5,000 micrometers. ISO 16094-2, published in September 2025, is the first international standard for microplastic analysis of clean water and can serve as an analytical reference where method, matrix, laboratory validation, and equivalence are reviewed and accepted, although it does not automatically replace the California methods.
The 1–20 micrometer particle-size fraction remains unvalidated under both California methods. The California drinking-water definition reaches down to 1 nanometer, while the best validated methods begin at 20 or 50 micrometers, which are thousands of times larger. Any dataset that does not clearly state its particle-size range and detection floor cannot credibly support a claim about what was or was not found.
Polymer Panels and Reporting Limits That Support Real Claims
A microplastic test only screens for the polymer types included in its analytical panel. A “none detected” result applies solely to the polymers the method was configured to find. WQI-CS-01 sets a minimum target polymer panel that a dataset must cover before review.
The required minimum panel includes:
- Polyethylene (PE)
- Polypropylene (PP)
- Polyethylene terephthalate (PET)
- Polystyrene (PS)
- Polyvinyl chloride (PVC)
- Polyamide (PA, commonly called nylon)
- Polycarbonate (PC)
- Polymethyl methacrylate (PMMA, commonly called acrylic)
The dataset must also report other confirmed polymers and unidentified particles with no spectral match, meaning particles the instrument detected but could not chemically identify. Leaving unidentified particles out of the report is a common gap that weakens the dataset. Reporting limits, which are the lowest concentrations the method can reliably measure, must meet WQI-CS-01 thresholds. A non-detect result paired with reporting limits that fall below those thresholds does not support a claim, because the “none detected” finding sits on an inadequate measurement floor.
Contamination Controls and Chain-of-Custody Requirements
Contamination risk sits at the center of microplastic analysis. Plastic particles exist in laboratory air, on work surfaces, and in reagents, so any result that ignores contamination introduced during handling and analysis cannot be separated from background noise.
A reviewable dataset needs documented evidence of four contamination and custody controls.
- Procedural blanks, which are samples processed through the full analytical procedure without the product matrix, measure background contamination from the laboratory environment and reagents.
- Spike recoveries, which are samples spiked with known amounts of target polymers, confirm that the method detects what it should at the stated reporting limits.
- Replicates, which are repeated analyses of the same sample, show that results are reproducible rather than one-off artifacts.
- Chain-of-custody records, which track the sample from collection through analysis, confirm that the tested sample matches what was submitted and that handling procedures were followed.
A 2024 PNAS study reported roughly 240,000 plastic particles per liter of bottled water, and a later PNAS commentary found that the study’s procedural blanks appeared contaminated and its quality control was inadequate. That critique focused on blank controls, the same contamination safeguards WQI-CS-01 requires. Missing blank documentation does not prove that a product is contaminated, but it does mean the result cannot be interpreted with confidence.
Keeping Claims Within the True Scope of the Data
A single dataset can only support a claim about the product, production lot, particle-size range, polymer panel, and time period it actually covers. Extending one product result to an entire product line, brand, or company is one of the fastest ways for credible data to become an indefensible claim.
Scope lock protects truth in advertising. A verified finding that applies to a 500 mL bottled water product from a specific production period does not automatically apply to a 1 L version of that product, to a different SKU, or to other product categories from the same company. Every public claim must stay within the boundaries of the data that supports it.
This principle appears in the FTC Green Guides’ product-specificity requirement and in the scope-definition requirements of ISO 14021 discussed earlier, both of which expect companies to define exactly what each claim covers and what it does not.
How WQI Plastic-Free Pathway Verification Uses Your Data
The Wellness Quality Institute does not operate laboratories or perform testing. Instead, WQI independently reviews a company’s existing third-party laboratory datasets against the five-criterion framework described above, using its published review standard, WQI-CS-01.
The review covers laboratory qualification, analytical method, product matrix, sampling, tested particle-size range, target polymer panel, reporting limits, blank results, spike recoveries, replicates, chain of custody, data recency, product scope, and production or sampling period. Many companies learn through this review what their existing data does and does not prove, including where a “none detected” result reflects the method’s detection floor rather than the product itself.
Each review ends with one of two outcomes. Standard Met means the dataset satisfies all applicable technical and data-quality requirements and that no reportable target polymer particles are detected within the tested particle-size range and approved reporting limits. A non-detect result alone does not qualify; the reporting limits must also meet WQI-CS-01 thresholds. A Standard Met outcome includes a verification decision, a scope-locked license to use the WQI mark (“WQI Plastic-Free Pathway Verified”), a public registry listing, and approved claim language tied to the specific evidence reviewed. Standard Not Met is a private outcome with no public claim, no logo rights, and no registry listing. It does not label the product as a failure and often reflects gaps in testing rather than in the product itself, and the company may resubmit with updated information.
Every Standard Met product receives a public registry entry that records the verified party, product scope, matrix, production or sampling period, tested particle-size range, lower method limit, polymer panel, reporting limits, testing laboratory and its accreditation, verification and expiration dates, registry ID, approved result statement, and current status. The verification period lasts 24 months from the sampling date of the most recent accepted dataset, and continued claim use after that point requires re-verification with current data.
A single assessment fee covers review, verification decision, and registry listing, with independent laboratory testing arranged and billed separately by a qualified independent laboratory. Paying the assessment fee does not guarantee a verification decision.
Frequently Asked Questions
What does “none detected” actually mean in a lab report?
“None detected” means no particles were found above the instrument’s detection floor for the polymer types the method was set up to screen in the specific lot that was sampled. It does not mean no plastic is present. A method validated for particles larger than 50 micrometers cannot see anything smaller, so “none detected” can coexist with particles that fall below that size threshold. The result is bounded by the method’s detection floor, the polymer panel, and the production lot, not by the product itself. Recognizing this limit is the first step in deciding what a laboratory report can and cannot support as a market claim.
How do ISO 14021 and the FTC Green Guides differ from waste-credit standards?
ISO 14021 and the FTC Green Guides govern self-declared environmental claims at the product level and spell out what a company must be able to show about the specific product it sells. Waste-credit programs operate at the system or supply-chain level and allow organizations to buy credits that represent plastic removed from the environment elsewhere, without tying that removal to the specific product making the claim. These approaches answer different questions. ISO 14021 and the FTC Green Guides ask what the data for this specific product supports. Waste-credit programs ask what has been removed from the waste stream in total. For a brand making a product-level plastic-reduction claim on packaging or in consumer marketing, the relevant framework is ISO 14021 and the FTC Green Guides, not waste-credit accounting. A waste-credit purchase cannot replace product-level laboratory data when the claim concerns the product itself.
Can a single lab result support a company-wide plastic-reduction claim?
No. A single laboratory result can only support a claim about the product, particle-size range, polymer panel, and production period it covers. Extending that result to a product line, brand, or entire company is not supported by the data and creates the kind of scope mismatch that regulators and class-action litigants look for. Each product that makes a plastic-reduction claim needs its own dataset, reviewed against the criteria that apply to that product’s matrix and production context. This requirement reflects real lot-to-lot variability, where a clean result on one production run does not guarantee the next.
What documentation must be maintained under California AB 2253 for recycled-content claims?
California AB 2253 requires manufacturers or suppliers that make recycled-content environmental marketing claims for plastic food container products to maintain written documentation showing that the recycled content was diverted from the solid waste stream, either during manufacturing as pre-consumer material or after consumer use as post-consumer material. The documentation must follow the FTC Green Guides and must show that the recycled content claimed does not exceed the amount of third-party certified recycled content introduced into the manufacturer’s or supplier’s overall supply stream. Companies must provide this documentation to the public on request. These requirements expand to all products that make recycled-content claims, and companies outside California can treat them as a preview of the documentation standard that is becoming normal nationally.
Next Step: Turn Your Lab Data into a Defensible Claim
Raw laboratory data by itself is not a market claim. The five-criterion framework, covering laboratory qualification, analytical method and particle-size range, polymer panel and reporting limits, contamination controls, and scope of findings, gives you a structured way to decide whether existing data can support a plastic-reduction claim that survives retailer scrutiny, legal review, and class-action risk.
Most companies that apply this framework to their existing datasets discover one of three outcomes. Their data supports a narrower claim than they assumed, their data supports a stronger claim than they were comfortable making without independent review, or their data contains gaps that must be closed before any claim is defensible. In every case, clarity is better than uncertainty.
The Wellness Quality Institute reviews existing datasets against WQI-CS-01, a defined, published standard aligned with the California State Water Board’s drinking-water microplastics reference framework, and issues scope-locked approved claim language for datasets that meet the standard. The review tells you what your data actually supports. The approved language tells the market, backed by a public registry entry that any buyer, retailer, or journalist can check.
