How To Substantiate Sustainability Claims: Step-By-Step

Written by: Scott Steveson, Specialist, Wellness Quality Institute

Key Takeaways

• Third-party review turns existing lab data into a defensible sustainability claim by checking the dataset, method, scope, and controls against clear criteria.

• A lab report alone does not become a market claim. Self-reported results count as marketing and face FTC Green Guides scrutiny and class-action risk.

• Independent reviewers need real independence, with no role in testing, no financial stake in the outcome, and published criteria that anyone can inspect.

• Approved claim language must match the reviewed evidence exactly, including particle-size range, polymer panel, and reporting limits, to avoid greenwashing exposure.

• Talk to the Wellness Quality Institute (WQI) about Plastic-Free Pathway Verification and turn real lab data into a defensible claim.

Who This Guide Helps And How It Fits The Rules

This guide speaks to quality leaders, sustainability leads, compliance teams, brand operators, procurement stakeholders, and founders at US consumer brands that make or plan to make plastic-related claims.

A few terms used throughout this guide, explained in plain language:

• Verification: an independent review of evidence against defined criteria, not a guarantee that a product is free of any substance.

• Review / assessment: the work an independent body does when it examines a dataset and the claim that dataset is meant to support.

• Scope: the specific product, method, particle-size range, polymer panel, and production period covered by a dataset or a claim.

• Detection floor / reporting limit: the smallest particle size or lowest concentration a method can reliably find. Anything below this floor is invisible to the instrument rather than confirmed absent.

• Chain of custody: the documented record of who handled a sample, when, and how, from collection through analysis.

• Accreditation: formal recognition by an independent body that a laboratory meets defined competence standards, for example ISO/IEC 17025:2017, the international standard for testing laboratory competence.

• Blank controls: clean samples run through the full analytical procedure to measure how much contamination the procedure itself introduces.

• Substantiation: the documented evidence that supports a claim before it is published.

• Polymer panel: the specific list of plastic types, such as polyethylene, polypropylene, or PET, that a method screens for.

On the US regulatory environment, there is no federal standard for plastic content in consumer goods. The FTC Green Guides (16 CFR 260.2) set a reasonable-basis standard for environmental claims. A brand must hold competent and reliable scientific evidence before making a claim. ISO 14021:2026 covers self-declared environmental claims, and ISO/IEC 17025:2017 sets the accreditation basis for testing laboratory competence. These standards are optional examples that organizations may choose to adopt. They still shape how regulators and courts think about substantiation. Only a small number of laboratories can genuinely test for microplastics, detection capability varies between and within laboratories, and no single methodology has achieved consensus across the field. That uncertainty is exactly why the process starts with the claim itself.

The Step-By-Step Substantiation Sequence

Step 1 — Define The Claim Precisely

The specificity of a claim determines whether anyone can substantiate it. A claim about a named product, a named tested particle-size range, and a named polymer panel is reviewable. A company-wide “sustainable” claim fails that test. That distinction matters because a reviewer can only decide whether evidence supports a claim when the claim is written in specific, testable terms. So before any evidence is assembled, the claim must be narrowed to those terms.

Step 2 — Build The Evidence Package

A dataset must contain more than a single result. For a dataset to support a defensible claim, it typically needs to document:

• Laboratory qualification and accreditation

• Analytical method and its validated range

• Product matrix, meaning what was actually tested, such as bottled water or a beverage

• Sampling protocol and sample count

• Tested particle-size range

• Target polymer panel

• Reporting limits for each polymer

• Blank results that show contamination introduced by the procedure itself

• Spike recoveries that confirm the method can find what it is looking for

• Replicates, or repeat runs, to confirm consistency

• Chain of custody documentation

• Data recency relative to current production

• Product scope, including which SKU and which production period

Missing any of these elements does not always mean the testing was poor. It may simply mean the documentation is incomplete. A reviewer can only evaluate what is documented, so an incomplete dataset cannot support a complete claim.

Step 3 — Choose An Independent Reviewer You Can Explain To Stakeholders

A qualified independent reviewer brings structural independence, not just technical skill. That means no role in the testing, no commercial interest in the outcome, published criteria, and a record that can be checked. A reviewer who helped design the study, who is paid based on the outcome, or whose criteria are not public cannot provide the independence that makes a review credible.

One distinction matters here. Certification does not replace evidence, and a marketer remains responsible for substantiating the claim even where a third-party certification exists (16 CFR 260.6(c)). A seal or logo may show that a process took place, yet the brand still owns the claim and its underlying support.

Step 4 — Match Claim Wording To What The Data Supports

The review must connect the evidence to the exact words that will appear on packaging or in marketing materials. A dataset that supports “no reportable target polymers detected above 50 µm using infrared spectroscopy, for the tested polymer panel, in the reviewed production lot” does not automatically support a broader or differently worded claim. Approved claim language tied to the reviewed evidence keeps a brand inside what the data actually supports and outside the territory where greenwashing exposure begins.

Step 5 — Share Enough Detail To Be Checkable

A substantiation package, when published or made available, should typically contain:

• The claim statement itself

• The scope of the claim, including product, production period, and tested range

• The methodology used

• Data sources and their qualifications

• Assumptions and limitations

• A review statement from the independent reviewer

• The reviewer’s qualifications and independence

Transparency converts a claim from a bare assertion into something checkable.

Step 6 — Separate Independent Review From Self-Substantiation

Self-reported results are discounted as marketing because the party with the strongest incentive to make a favorable claim is the least reliable assessor of that claim. A review conducted by a party with no stake in the outcome carries weight that self-reporting structurally cannot. See how WQI’s Plastic-Free Pathway Verification turns existing lab data into a defensible claim.

What An Independent Reviewer Looks For In Your Data

An independent reviewer’s job is to test whether the evidence can carry the claim, so the focus falls on the points where datasets most often fall short. The elements a reviewer typically examines include:

• Method suitability for the matrix: whether the analytical method was validated for the specific product being tested. A method validated for drinking water may not suit a viscous beverage or a food product.

• Reporting limits: whether the detection thresholds are low enough to support the claim. A reporting limit that is too high means the method cannot see particles that may be present.

• Blank and contamination controls: whether procedural blanks were run, meaning clean samples carried through the full protocol to measure contamination introduced by the procedure itself. Without blanks, a result cannot be separated from background noise.

• Spike recoveries: whether the laboratory confirmed that its method can actually find the particles it is looking for, by spiking known quantities into clean samples and measuring recovery rates.

• Replicates: whether multiple runs were conducted to confirm consistency, or the result rests on a single sample.

• Chain of custody: whether a documented record of sample handling exists from collection through analysis.

• Data recency: whether the dataset reflects current production or the product or process has changed since testing.

• Tested particle-size range: which sizes the method actually covered, since this is where the detection-floor problem becomes a claim-substantiation issue.

• Polymer panel: which plastic types the method screened for, because a result is only meaningful for the polymers actually tested.

The detection-floor problem deserves particular attention. A method validated above 50 µm cannot support a claim about particles below that size. “None detected” is a bounded statement. It means none found above that instrument’s floor, for the polymers it screened, in the lot it tested. It does not mean none present.

The two California State Water Board analytical methods show how detection floors limit claim wording. Raman spectroscopy (SWB-MP2-rev1) applies above 20 µm through 5,000 µm, and infrared spectroscopy (SWB-MP1-rev1) applies above 50 µm through 5,000 µm. The 1–20 µm fraction is not validated under either method. A claim based on either method cannot speak to particles below its validated lower bound, and no claim can speak to the nanoplastic range, which current commercial methods cannot reliably reach.

This is where the Wellness Quality Institute’s Plastic-Free Pathway Verification (PFPV) provides structure. The Wellness Quality Institute (WQI) is an independent verification body that reviews a company’s existing third-party laboratory data on plastic and microplastic content against WQI-CS-01, which aligns with the California State Water Board’s drinking-water microplastics reference framework. California serves as a technical reference point rather than a geographic boundary. Verification is available to US companies nationally. California did not create, approve, authorize, or endorse WQI or its standard. WQI does not run laboratory tests and does not certify that any product is free of plastic.

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.

How To Use Evidence, Frameworks, And Decision Tools

Several frameworks help organize the substantiation process. These are optional examples that organizations may choose to adopt, yet they show how structured thinking supports completeness, comparability, and defensibility.

Common tools include review checklists that map each element of a dataset against defined requirements, laboratory qualification tiers that distinguish preferred, accepted, and conditional laboratories by accreditation type, and evidence hierarchies that rank data quality from fully documented and replicated down to single-run or undocumented. Scope definitions specify exactly which product, production period, and tested range a dataset covers. Risk-assessment models identify where gaps in the evidence create claim exposure.

A neutral example shows how inputs change the path. Consider two datasets for the same product. Dataset A has adequate reporting limits, a qualified laboratory, and complete chain of custody, but it lacks blank data. Dataset B has complete blanks and spike recoveries, but the reporting limits sit above the threshold required to support the intended claim. Dataset A produces a different review outcome than Dataset B, even though both represent genuine testing effort. Neither outcome reflects a failed product. Both reflect specific gaps in the evidence that can often be addressed with additional documentation or supplementary testing.

The best approach in any case depends on the product, claim, matrix, method, and intended use. Frameworks guide the analysis. They do not replace it.

Common Challenges And Practical Fixes

Substantiation reviews tend to uncover the same issues, which means brands can prepare for them in advance:

• Incomplete documentation: chain of custody records, laboratory accreditation certificates, or method validation reports are missing. An early warning sign appears when the laboratory report exists but supporting documentation was never requested or retained. The fix is to contact the laboratory and obtain the full documentation package before submitting for review.

• Unclear scope: the dataset covers one SKU, but the intended claim references a product line. The fix is to define the claim scope to match the tested scope or commission additional testing for each product in scope.

• Weak or missing blank controls: the laboratory did not run procedural blanks, or blank data was not included in the report. This gap is both common and consequential. The fix is to request blank data from the laboratory or commission a new run with blanks included.

• Methods unsuitable for the matrix: a method validated for drinking water was applied to a viscous beverage or a food product without documented equivalence review. The fix is to confirm method-matrix suitability with the laboratory before commissioning testing.

• Inconsistent terminology: the report uses non-standard size categories or polymer names that do not map to the reviewer’s criteria. The fix is to request a supplementary table from the laboratory that uses standardized terminology.

• Overextended conclusions: the report’s summary states “no microplastics detected” without specifying the detection floor, polymer panel, or particle-size range. The fix is to ensure the claim language reflects the bounded nature of the finding rather than an absolute absence.

Substantiate your plastic-related claims with independent third-party review through WQI’s Plastic-Free Pathway Verification.

What Happens When The Review Does Not Support The Claim

A review that does not support the intended claim remains private. In a well-structured independent review program, a Standard Not Met outcome carries no public claim, no logo rights, and no registry listing.

A Standard Not Met outcome often reflects insufficient data, an unsupported method, or incomplete scope rather than a product problem. The company can request missing documentation from the lab, address the gaps, and resubmit for future review. This structure matters because many brands hesitate to start substantiation out of fear of creating a public issue. A private outcome removes that risk and encourages participation.

In WQI’s program, the two possible outcomes are Standard Met and Standard Not Met. Standard Met requires two conditions together. The dataset must satisfy all applicable technical and data-quality requirements, and no reportable target polymer particles can be detected within the tested particle-size range and approved reporting limits. A non-detect result alone is not enough. The reporting limits themselves must meet WQI’s requirements, or the non-detect has no meaning. Standard Not Met is issued where one or more requirements are unsatisfied, and the company may resubmit with updated information.

How To Measure Progress And Data Quality

Objective indicators of effective execution in the substantiation process include:

• Completeness of records, where every required element of the dataset is documented and retrievable

• Review readiness, where the dataset can be submitted to an independent reviewer without supplementary requests

• Consistency of evidence, where results are reproducible across replicates and align with blank data

• Auditability, where a third party can trace every claim back to its underlying evidence

• Decision traceability, where the path from data to claim wording is documented and defensible

Simple ways to monitor progress include review checklists mapped to defined criteria, periodic documentation audits, and review gates before any claim is published. Early process signals, such as complete blank data and documented chain of custody, differ from longer-term quality outcomes, such as consistent results across re-verification cycles.

WQI’s verification period is 24 months from the sampling date of the most recent accepted dataset. Continued claim use after that period requires re-verification with current data. This reflects lot-to-lot variability. A result reflects the production it was drawn from rather than all future production.

Advanced Planning And Iteration Across Products

Scaling the substantiation process across products requires treating each product, SKU, and production period as a separate scope. Verification is locked to the reviewed product, dataset, tested particle-size range, polymer panel, and production period. A company cannot extend a single dataset to a company-wide or product-line claim. A brand with ten products needs ten datasets if it intends to make claims about all ten.

Updating evidence over time keeps a claim honest. Production changes, methods improve, and standards evolve, so the evidence underlying a claim must keep pace. That is why re-review cycles should be planned in advance rather than triggered by expiration.

Adapting to changing standards and methods remains an ongoing responsibility. The microplastics testing field continues to shift. Method detection floors are improving, polymer panels are expanding, and regulatory frameworks are developing. A substantiation process built on today’s best available methods may need updates as the field advances.

Readiness criteria for more advanced practices include three things. A brand needs a complete, documented substantiation package for at least one product, a standing relationship with a qualified independent laboratory, and a defined internal process for reviewing claims before publication. Controlled iteration, where a company tests one product, learns from the review, and applies those lessons to the next, is more reliable than trying to substantiate an entire product line at once.

Explore WQI’s Plastic-Free Pathway Verification to support iterative, product-by-product substantiation.

Frequently Asked Questions

How Does Certification Differ From Review Of Existing Lab Data?

A third-party certification usually involves an independent body awarding a mark or label based on defined criteria that may cover many environmental attributes. Third-party review of existing lab data is narrower and more specific. An independent reviewer examines a dataset a company already holds, checks whether the method, scope, and controls meet defined requirements, and determines what claim the data can support. As noted in Step 3, a certification does not transfer the substantiation obligation. The brand still owns the claim.

What Evidence Must Support A Sustainability Claim?

The FTC Green Guides require that environmental claims be supported by competent and reliable scientific evidence. That phrase means tests, analyses, research, or studies conducted and evaluated objectively by qualified people using procedures generally accepted in the field. For plastic and microplastic claims, that evidence typically includes a qualified laboratory’s analytical report, documentation of the method and its validated range, blank and contamination controls, spike recoveries, chain of custody records, and a clear statement of scope. Scope covers which product, which production period, which particle-size range, and which polymer panel. A result without this supporting documentation is a number without context, and a number without context does not count as substantiation.

What Penalties Apply To Misleading Sustainability Claims?

In the US, the FTC Green Guides establish a reasonable-basis standard under Section 5 of the FTC Act, which prohibits unfair or deceptive acts or practices. The Guides themselves carry no penalties, but FTC enforcement actions under the Act can result in civil penalties, consent orders, corrective advertising requirements, and other remedies. Private plaintiffs can also bring class-action suits under state consumer protection statutes, without waiting for an agency to act. Every US state has its own consumer protection statute, and many states read the FTC Green Guides into their own law formally or in practice. Practical exposure for a brand making an unsubstantiated plastic claim includes litigation costs, settlement costs, corrective advertising, and reputational damage, even without regulatory action.

How Long Does A Review Take, And What Speeds It Up?

Timeline depends on the completeness of the dataset submitted. A complete, well-documented dataset that includes the documentation elements listed in Step 2 can move through review more efficiently than one that needs supplementary requests. Incomplete documentation is the most common cause of delay. Before submitting for review, a brand should confirm that every required element is present and retrievable and that the laboratory can provide supporting documentation on request.

What Should A Brand Do After A Standard Not Met Outcome?

As covered earlier, a Standard Not Met outcome is private and can be resubmitted with corrected data. The practical next steps involve requesting missing documentation from the laboratory, clarifying scope, and scheduling a re-review once gaps are closed. This approach turns an initial shortfall into a roadmap for improvement rather than a public setback.

Does WQI Verification Replace Legal Or Advertising-Claims Review?

WQI Plastic-Free Pathway Verification provides an independent review of a dataset against a defined standard. It does not provide legal counsel, regulatory counsel, or advertising-claims review, and it does not replace any of them. Companies remain responsible for ensuring all product, packaging, and marketing claims are accurate and properly substantiated under applicable law. WQI’s approved claim language and registry listing support substantiation. They do not act as a legal shield or remove the brand’s own compliance obligations.

Read Next

• Retail Sustainability Claim Verification Programs Explained

• Turn Lab Data Into Verified Plastic-Free Claims: 6 Steps

• Third-Party Claim Validation Standards for Product Claims

• Third-Party Verification for Plastic Reduction Claims

• How to Verify Plastic Reduction Claims: A 5-Step Audit