Perfluorooctanesulfonic acid (PFOS) (Cancer & Developmental)
Perfluorooctanesulfonic acid (PFOS) is listed under California Proposition 65 for the Cancer & Developmental endpoint. Its established safe harbor level is 0.2 µg/day as a NSRL, determined for exposure primarily via the ingestion route. CAS registry number: 1763-23-1.
Safe Harbor Level
| Field | Value |
|---|---|
| Chemical | Perfluorooctanesulfonic acid (PFOS) |
| CAS Number | 1763-23-1 |
| Toxicity Endpoint | Cancer & Developmental |
| Safe Harbor Basis | NSRL |
| Safe Harbor Level | 0.2 µg/day |
| Primary Exposure Route | Ingestion |
What this level means
A NSRL is a daily exposure level for Perfluorooctanesulfonic acid (PFOS) that — at or below 0.2 µg/day per day — does not require a Proposition 65 warning because it poses no significant risk for the Cancer & Developmental endpoint. This is the No Significant Risk Level (NSRL) — the daily intake for the cancer endpoint.
- Level: 0.2 µg/day per day (NSRL).
- Endpoint: Cancer & Developmental.
- Route: exposure is assessed primarily through the ingestion route.
- CAS: 1763-23-1.
Businesses that expose consumers to more than the safe harbor level for Perfluorooctanesulfonic acid (PFOS) must provide a clear and reasonable Prop 65 warning. Compliance is assessed against the applicable OEHHA safe harbor level above; where no safe harbor level is established, an exposure assessment may be required.
Compliance notes
- Compare the daily exposure to the NSRL of 0.2 µg/day.
- If exposure exceeds the level, a Prop 65 warning is generally required.
- Confirm the current OEHHA listing and any updates to the level before relying on it — safe harbor levels are amended periodically.
Frequently Asked Questions
What is the Prop 65 safe harbor level for Perfluorooctanesulfonic acid (PFOS)?
0.2 µg/day per day (NSRL).
What is the CAS number for Perfluorooctanesulfonic acid (PFOS)?
1763-23-1.
What endpoint is Perfluorooctanesulfonic acid (PFOS) listed for?
Cancer & Developmental.
What is the primary route of exposure for Perfluorooctanesulfonic acid (PFOS)?
The ingestion route.
What is the difference between an NSRL and a MADL?
An NSRL (No Significant Risk Level) applies to cancer endpoints; a MADL (Maximum Allowable Dose Level) applies to reproductive and developmental endpoints.