Indiana PFAS Screening Levels
IDEM published levels for PFAS compounds across soil, groundwater, and indoor air. Includes MCLs for PFOA, PFOS, PFHxS, HFPO-DA, PFNA, and PFBS added in 2025.
Overview
Indiana’s PFAS published levels appear in the IDEM Remediation Closure Guide (WASTE-0046-R2), effective March 28, 2025. The 2025 R2 update added PFAS compounds to the published levels tables for the first time, incorporating the federal MCLs finalized in April 2024 and Indiana’s own risk-based calculations.
35 PFAS chemicals are included, covering individual acid and salt forms of the same compounds (for example, Perfluorooctanoic acid and Perfluorooctanoate are listed separately with identical values). This reflects how PFAS are listed in the federal MCL rule and ensures CAS number-specific matching with laboratory results.
Risk basis: Indiana’s published levels use a 1E-05 cancer risk (1 in 100,000) and HQ of 1.0. For PFAS compounds where the MCL is more protective than the risk-based value, the MCL governs (qualifier M).
No indoor air values: None of the 35 PFAS compounds have Indiana indoor air published levels. PFAS compounds are non-volatile and do not present a vapor intrusion pathway under standard site conditions.
Qualifier key:
- C = Carcinogenic - cancer risk-based
- N = Noncarcinogenic - HQ-based
- M = MCL-based - the federal MCL is more restrictive than the risk-based calculated level
- S = Soil saturation cap
Key PFAS Published Levels
The table below shows the primary regulatory PFAS compounds. For the complete 35-chemical list, contact IDEM or download the IDEM Remediation Closure Guide directly.
| PFAS Compound | CAS Number | Soil Residential (mg/kg) | Q | Soil C/I (mg/kg) | Q | Soil Exc. (mg/kg) | Q | Groundwater (µg/L) | Q |
|---|---|---|---|---|---|---|---|---|---|
| Perfluorooctanoic acid (PFOA) | 335-67-1 | 0.0003 | C | 0.0008 | C | 0.04 | C | 0.004 | M |
| Perfluorooctanoate | 45285-51-6 | 0.0003 | C | 0.0008 | C | 0.04 | C | 0.004 | M |
| Perfluorooctanesulfonic acid (PFOS) | 1763-23-1 | 0.009 | N | 0.08 | N | 0.2 | N | 0.004 | M |
| Perfluorooctanesulfonate | 45298-90-6 | 0.009 | N | 0.08 | N | 0.2 | N | 0.004 | M |
| Perfluorohexanesulfonic acid (PFHxS) | 355-46-4 | 2 | N | 20 | N | 30 | N | 0.01 | M |
| Perfluorohexanesulfonate | 108427-53-8 | 2 | N | 20 | N | 30 | N | 0.01 | M |
| Perfluorononanoic acid (PFNA) | 375-95-1 | 0.3 | N | 3 | N | 5 | N | 0.01 | M |
| Perfluorononanoate | 72007-68-2 | 0.3 | N | 3 | N | 5 | N | 0.01 | M |
| Hexafluoropropylene oxide dimer acid (HFPO-DA / GenX) | 13252-13-6 | — | — | — | — | 6 | N | 0.01 | M |
| Perfluorobutanesulfonic acid (PFBS) | 375-73-5 | 30 | N | 300 | N | 500 | N | 6 | N |
| Perfluorobutanesulfonate | 45187-15-3 | 30 | N | 300 | N | 500 | N | 6 | N |
| Perfluorodecanoic acid (PFDA) | 335-76-2 | 0.0002 | N | 0.002 | N | 0.003 | N | 0.00004 | N |
Note: ”—” indicates no published level for that compound/pathway combination.
Structure of the PFAS Table
Acid and salt pairs: Most PFAS compounds appear in two forms - the free acid (e.g., Perfluorooctanoic acid, PFOA) and the anion/salt form (e.g., Perfluorooctanoate). Both forms have identical published levels. Laboratory results may be reported under either CAS number depending on the analytical method and reporting convention; either form can be compared to the same threshold.
MCL-governed groundwater values: PFOA, PFOS, PFHxS, PFNA, and HFPO-DA (plus their salt forms) have groundwater published levels set by the federal MCLs finalized in April 2024. PFBS has a risk-based groundwater value of 6 µg/L (qualifier N), not an MCL. See the PFAS State Comparison page for current federal MCL status.
Soil values reflect risk-based calculations: Soil published levels for PFOA and related long-chain PFAS are very low (sub-part-per-million range) because these compounds are highly persistent, bioaccumulate, and have low toxicological thresholds. PFBS and shorter-chain PFAS have higher soil values reflecting their lower bioaccumulation potential.
Excavation levels: All 35 PFAS compounds have excavation screening levels in the Indiana system. These are substantially higher than the long-term soil direct-contact values and apply to short-term worker exposure during excavation or soil handling. See Indiana Excavation Screening Levels.
Practical Guidance
Sampling for PFAS: Use EPA Method 537.1 or Method 533 for aqueous samples (groundwater, drinking water). Avoid fluoropolymer-containing equipment (PTFE fittings, some bladder pump materials) that can introduce PFAS contamination. Use PFAS-free HDPE or stainless steel sampling equipment. See our PFAS Sampling Best Practices guide.
Laboratory reporting: PFAS laboratory results are commonly reported as both the acid and ionic forms, especially for PFOA and PFOS. Ensure your laboratory identifies which CAS numbers are reported to avoid double-counting when comparing to published levels.
Indiana vs. Ohio comparison: Ohio does not currently have state-specific enforceable PFAS soil standards. Indiana’s published levels provide more complete multi-media PFAS guidance than Ohio’s current framework. See Ohio PFAS Standards for Ohio’s current groundwater values.
Federal MCL status as of March 2026: The PFOA (4 ppt) and PFOS (4 ppt) MCLs remain in effect. Federal MCLs for PFHxS, PFNA, and HFPO-DA are subject to a pending D.C. Circuit challenge and potential rescission. Indiana’s published levels incorporate the MCL values as of the March 2025 R2 update; monitor IDEM communications for future revisions.