California Prop 65 for Supplements: What It Is, Why You’re Getting Sued, and How to Stay Compliant
California Proposition 65 (“Prop 65”) touches almost every supplement brand—whether you sell DTC, on Amazon, or via retail. It’s not a product ban; it’s a right-to-know law. If a listed chemical (e.g., lead, cadmium, arsenic, certain phthalates, BPA, TiO₂) is present above its “safe harbor” exposure level, you must warn California consumers with a very specific on-label notice. Miss it, and you’re squarely in the sights of private enforcers—and costly settlements.
Below is a plain-English walkthrough of how Prop 65 works, why powders and botanicals get hit so often, and what you can do now to reduce your exposure (pun intended).
Prop 65 in one minute
What it is: A California state law requiring clear warnings when a product exposes consumers to listed chemicals known to cause cancer or reproductive harm.
Who it hits: Anyone selling into CA (yes, your Shopify/Amazon counts), regardless of where you’re based.
How it’s enforced: Private plaintiff firms send Notices of Violation (NOVs) and sue for civil penalties + attorneys’ fees. Most cases settle.
What it’s not: A purity standard. Prop 65 doesn’t ban chemicals; it compels disclosures above specific exposure limits.
Why supplements get targeted
Powders = larger daily intake. Even tiny parts-per-billion of heavy metals can exceed safe-harbor exposure when the serving size is big (e.g., protein/greens blends).
Botanicals concentrate soil metals. Plants naturally uptake lead, cadmium, and arsenic; extracts can further concentrate them.
Complex supply chains. Variability across farms, lots, and processors makes consistency hard without a tight supplier and testing program.
Label gaps. Brands either don’t know Prop 65 applies, or avoid warnings for fear of consumer backlash—until an NOV arrives.
Reality check: Many whole foods (spinach, mushrooms, root veg) can contain background metals at levels that would exceed Prop 65 safe harbors on a per-serving exposure basis. The issue isn’t “unsafe product”; it’s legal exposure math plus a highly active plaintiff bar.
Common chemicals in supplement NOVs
Lead, cadmium, arsenic (heavy metals) — most frequent for protein, botanicals, and “greens.”
Phthalates (e.g., DEHP) — often from packaging components or process contact materials.
BPA — legacy in some packaging lines.
Titanium dioxide — when used as a colorant, warning can be implicated depending on form/exposure route.
Note: Prop 65 doesn’t care that you’re a “dietary supplement.” If the exposure threshold is exceeded, the warning obligation attaches.
How warnings actually work
You don’t warn just because a chemical is detected; you warn if exposure per day (after realistic product use) exceeds the safe-harbor level.
Exposure = concentration × serving size × default absorption (simplified).
If there’s no established safe harbor, you must do a defensible risk assessment or default to warning.
Warnings must follow format, icon, and placement rules and be conspicuous on product and e-commerce PDPs for California consumers.
E-commerce & “one label for all” headaches
Maintaining CA-only packaging is tough. Many brands either:
Add the on-pack warning globally (risking consumer perception outside CA), and/or
Implement state-aware warnings online (CA PDP banner/modal + cart messaging), and/or
Reformulate and tighten specs to avoid warning altogether.
There’s no one right answer—choose what best fits your channel mix, margins, and brand position.
What plaintiff firms look for
Category heuristics (powders, botanicals, kids’ products).
Missing or non-compliant warning text/format.
COAs that cover micro only (no metals/DEHP/BPA) or testing gaps across lots.
Packaging or supply changes without updated exposure assessments.
Once an NOV lands, you’ll be asked to: (1) pay a settlement (often six figures all-in), (2) reformulate and/or add warnings, (3) implement a testing/monitoring program, and (4) cover plaintiff fees. It’s expensive, distracting, and avoidable.
A practical mitigation plan
1) Engineer exposure down at the formula level
Prefer low-metal botanical sources and extraction methods; require supplier spec ceilings aligned to safe-harbor math.
Watch serving sizes—they drive exposure. Split doses or right-size scoops where possible.
Audit excipients, flavors, colors, and contact materials (liners, seals, tubing) for phthalates/BPA/TiO₂ contributions.
2) Lock a real testing strategy (not just micro)
Raw materials: ID + targeted metals (Pb/Cd/As/Hg) for high-risk inputs per lot or statistically justified skip-lot plan.
Finished goods: Verify metals by serving, plus any packaging-related chemicals where risk is identified.
Method readiness: Ensure detection limits are low enough to be meaningful against safe-harbor math.
3) Do the math and document it
Maintain a Prop 65 exposure worksheet per SKU (assumptions, calculations, safe-harbor references).
Decide “warn vs. reformulate” SKU-by-SKU; keep your rationale in the data room.
4) Get the warnings right (if you must warn)
Use current icon, signal word, and chemical naming conventions.
Match on-pack, PDP, and marketplace listings for California visibility.
Train CX to answer “why is there a cancer warning?” with calm, accurate context.
5) Fix your contracts
Add supplier reps & warranties on Prop 65 chemicals, lot-level test evidence, and indemnities.
Scrutinize co-man MSAs: most push Prop 65 risk to the brand—negotiate shared obligations where feasible.
What about protein powders specifically?
Expect to manage lead/cadmium/arsenic via source selection (dairy origin for whey; soil history for plant proteins), blending, and lot segregation.
Safe-harbor exceedances often hinge on scoop size and total daily use directions (“2 scoops daily” doubles exposure).
Build a lot release spec that back-solves from your exposure target, not just a generic “meets USP heavy metals.”
Practical messaging if you add a warning
Keep it factual and consistent across PDP, FAQ, and CX scripts:
Prop 65 is a California right-to-know law, not a product safety rating.
Many nutrient-dense foods naturally contain trace metals from soil.
We use strict supplier standards and testing; this warning is required when CA exposure math exceeds very low thresholds.
FAQ
Do I need a Prop 65 warning if I only sell online?
If you ship to California residents, Prop 65 applies. You’ll need a compliant online warning and, for CA shipments, on-pack if warning is required.
How often should I test for heavy metals?
At minimum: Every finished batch for SKUs likely to exceed thresholds. Use skip-lot only with strong historical data and supplier control.
Are “natural” foods exempt?
Whole produce at retail is treated differently than manufactured products like supplements. Your finished goods are in scope.
Is titanium dioxide banned?
Prop 65 focuses on exposure warnings, not outright bans. Evaluate your colorant’s form, use level, for your dosage form.
Can I just slap the warning on and call it a day?
You can, but you’ll still want to know where you land from batch to batch. Better to run the exposure math and control inputs so warning is a choice—not a surprise.
Next steps
New to market?
Book a Signature 1-on-1 Consultation to turn your idea into a real go-to-market plan (regulatory framework, lawful claims, spec/test plan, and contract-manufacturer search strategy). We’ll map the fastest compliant path so you don’t rebuild at launch.
DIY builder / want fundamentals?
Enroll in SSET (Supplement Startup Essentials Training). Learn what regulations apply, how to draft a market brief, evaluate claims, and find/vet a co-man—so your drafts slot into a real compliance workflow.
Established brand?
Contact us and we can look at an Operator-Level Compliance Health Check. We’ll assess GMP/SOPs, supplier files, Prop 65 testing strategy, and contracts, then deliver a prioritized CAPA plan for retailer audits, investor diligence, etc..
About Blue Ocean Regulatory
Blue Ocean Regulatory helps supplement and functional-food brands launch and scale the right way—from lawful claims and label compliance to GMP systems, supplier qualification, test plans, and retailer/Amazon readiness. We support founder-led startups and established operators through growth, audits, and investor/M&A diligence.