California's Proposition 65 is enforced in an unusual way: alongside the state Attorney General, private individuals and law firms can serve a public "60-day notice" on a seller and pursue penalties. Because a share of any settlement can go to the party who files, an entire ecosystem of professional enforcers — sometimes called "bounty hunters" — has grown around the law. Hundreds of notices are filed every month, and many of them begin long before anything appears in the public record: with an ordinary-looking buyer message.

Below is an exchange based on patterns we've seen across multiple Amazon sellers, anonymized and composited to protect all parties involved. It's worth reading closely, because sellers report similar patterns across marketplaces.

The message that starts it

A few days after a purchase, a buyer sends the seller a polite message. They've noticed the item might contain DEHP — a phthalate on the Prop 65 list — and ask whether the seller can confirm the material composition, often mentioning a baby or young child at home. A follow-up tends to arrive shortly after, asking for the product's safety data sheet (SDS), the material data sheet from the factory, and sometimes whether the product was imported under a particular HS customs code.

Read as a consumer inquiry, it sounds reasonable. Read as a sequence, it's unusual. Ordinary buyers rarely know which plasticizers occur in styrene-butadiene rubber, rarely ask for SDS documents by name, and almost never reference HS codes — that's customs-broker vocabulary. Messages with this profile are consistent with someone assembling documentation, not someone deciding whether to keep a purchase.

Five patterns that appear again and again

  • Chemical specificity. The message names a specific listed chemical (DEHP, lead, cadmium, acrylamide) and connects it correctly to the product's likely material — knowledge that usually comes from testing or from studying past notices, not from using the product.
  • Document requests. Asks for SDS/MSDS sheets, factory material declarations, or lab test reports. These documents are discovery material; a refund request doesn't need them.
  • Supply-chain vocabulary. References to HS codes, import records, or the country of manufacture suggest the sender has already looked at customs data for the product or the seller.
  • Sympathy framing. "I have a baby at home" or similar wording raises the emotional stakes and encourages a fast, unguarded reply.
  • Two-step escalation. A soft opening question, then a more technical follow-up once the seller engages. Each reply becomes another document in a growing file.

The reply that creates a problem

In this pattern, a seller often answers quickly and honestly — and writes that products of this type "can contain trace amounts of DEHP." That single sentence transforms the situation. Before the reply, the sender had a theory; after it, they have a written statement from the seller acknowledging the possible presence of a listed chemical. In past enforcement matters, statements like this have been used to support the "knowingly exposed" element that Prop 65 claims are built on.

What makes this instructive: even when the product already carries a Prop 65 warning — sometimes the buyer attaches a photo of the label to the message — a hedging reply can still weaken the seller's position. That's worth unpacking, because the same message plays out very differently depending on which situation a seller is in.

Scenario 1: the product has no Prop 65 warning

Here the sender's theory is that a listed chemical is present and no warning was given. Any reply that speculates about composition ("it might," "trace amounts are possible," "our supplier says it's fine") supplies in writing the one thing the sender didn't have. What actually answers a composition question is data: supplier material declarations and accredited-lab test reports for the product. Sellers without that documentation on file often use exactly this kind of moment to request it from their factory or commission testing — because the 60-day notice window, when it comes, is the period in which a seller can still act on solid information: substantiate the product, add a compliant warning where one is required, or pull the listing. A seller who first learns what is in their product from a plaintiff's lab report has spent that window blind.

Scenario 2: the product already carries a Prop 65 warning

Counterintuitively, this seller can also lose ground with one reply. The label on the box is a definitive statement: this product may expose you to a listed chemical, and we have said so as the law prescribes. A reply that hedges — "it can contain trace amounts", or simply restating what the sticker says as if it were news — reads as a seller who doesn't actually know what is in their own product. In writing, that impression can be collected and combined with other materials. The label was already doing its job; the strongest thing a written reply can do is not undercut it.

The common thread is not that sellers should be evasive. It is that a marketplace message thread is a permanent written record, and factual claims about chemical composition are significant statements that most sellers are not in a position to make accurately in a chat window — with or without a warning label, composition questions are answered by test data, not by message-thread speculation.

What the public record shows

None of this is speculation about shadowy actors: the entire 60-day notice system is public. Every filed notice names the noticing party and their counsel, and the same names appear over and over. You can see this yourself in our free Prop 65 notice checker — search any well-known noticing party and you'll find hundreds of filings, often concentrated in a handful of product categories and chemicals. The chemical × category heatmap shows where filing activity is currently concentrated.

Filed notices also lag the investigation phase. A notice citing lab results implies earlier test purchases and analysis — so by the time a brand name appears in the public database, the documentation work may have been under way for weeks or months. That's why sellers who go through an exchange like this often set up a daily watchlist on their brand and company names afterward: the public record is the earliest reliable signal available.

If a message like this lands in your inbox

We are not a law firm and can't tell you what to do in your specific case. What we can say factually: marketplace message threads are written records; statements about chemical composition are evidence-grade claims; product testing by an accredited lab is how composition questions are actually answered; and questions about legal exposure, warning obligations, or settlement are the territory of a licensed attorney experienced with Prop 65. Several state resources, including the California Attorney General's Prop 65 pages, describe the notice process in detail.

What you can do today, for free: search California Prop 65 60-day notices for free for your brand, company, and shop names — and set up a watchlist so you hear about a filing that may reference you while the response window is still open.

And if your question is the bigger one — can professional filers be stopped at all? — we've written the honest answer up separately: Why Prop 65 bounty hunters exist — and how to be a bad target.

This article describes a composite pattern, built from anonymized observations across multiple sellers, and public-record information for general awareness. It is not legal advice, and it does not assert that any particular message sender is engaged in enforcement activity.