The Federal Communications Commission’s radio frequency exposure limits, unchanged in substance since 1996, are under court-ordered review after the U.S. Court of Appeals for the D.C. Circuit ruled the agency failed to justify its standards. Device manufacturers, public health advocates, and wireless carriers face regulatory uncertainty as the FCC has yet to produce the reasoned explanation the court demanded in August 2021. The 1.6 W/kg SAR limit remains legally in force, but without the legal foundation the agency supplied when it declined to update its rules in 2019.
The 1996 Exposure Limits and What They Measure
The FCC adopted its current RF exposure framework in 1996, drawing on standards the American National Standards Institute (ANSI) and the Institute of Electrical and Electronics Engineers (IEEE) published in 1991 and 1992. The central metric is the Specific Absorption Rate (SAR): the rate at which biological tissue absorbs radio frequency energy, expressed in watts per kilogram (W/kg).
For mobile devices held against the body, the FCC set the general population SAR limit at 1.6 W/kg averaged over any 1 gram of tissue, per 47 C.F.R. § 1.1310. The occupational exposure limit is 5 W/kg. Both figures derive from a thermal model: tissue heating is treated as the primary mechanism of biological harm, and 1.6 W/kg is calibrated to provide a 50-fold safety margin below the temperature-rise threshold. The standard applies to all devices emitting RF energy between 300 kHz and 300 GHz: smartphones, tablets, Wi-Fi routers, and cellular base stations alike.
Compliance testing relies on the Specific Anthropomorphic Mannequin (SAM), a physical phantom modeled on a large adult male with defined tissue conductivity parameters. Every device sold in the United States must demonstrate SAR compliance through an FCC-authorized test laboratory before receiving a grant of equipment authorization. Critics have noted since the standard’s adoption that SAM does not represent children: thinner pediatric skulls, lower bone density, and higher tissue conductivity produce elevated localized absorption at equivalent field strengths, a gap the FCC’s 2019 review did not close.
ET Docket 03-137: Thirteen Years of Rulemaking
The FCC opened ET Docket 03-137 in 2003 to evaluate whether its RF exposure rules required revision in light of developments since 1996. The proceeding moved slowly across two decades of technological change. A Notice of Proposed Rulemaking published June 4, 2013 (78 FR 33654) solicited public comment on whether scientific or technological evidence justified changes to the existing standards.
The 2013 NPRM generated more than 1,000 formal comments. Environmental and health organizations submitted peer-reviewed studies documenting non-thermal biological effects, oxidative stress responses, altered cell membrane permeability, neurological markers, at field levels below the SAR threshold. Industry commenters and the Food and Drug Administration maintained the existing limits were protective and that the non-thermal literature did not meet the evidentiary bar for regulatory action.
On December 4, 2019, the FCC voted 3-2 to close the inquiry and retain the 1996 limits, issuing its Second Memorandum Opinion and Order (FCC 19-126). The commission made targeted procedural updates: SAR disclosure requirements in device documentation, revised measurement procedures for body-worn accessories, but left the substantive 1.6 W/kg limit intact. Petitions for review followed from Environmental Health Trust, Children’s Health Defense, the Electromagnetic Safety Alliance, and individual petitioners. The D.C. Circuit consolidated the cases under No. 20-1025.
What the D.C. Circuit Found
On August 13, 2021, a three-judge D.C. Circuit panel vacated the FCC’s 2019 order in part and remanded the proceeding in Environmental Health Trust v. FCC, No. 20-1025. The panel applied the arbitrary-and-capricious standard of review under 5 U.S.C. § 706(2)(A), which requires an agency to articulate a rational connection between the facts in the record and the action it takes.
The court identified three specific failures. First, the FCC did not address record evidence that children absorb RF energy at higher rates than adults under equivalent field conditions. Multiple submissions documented the SAM phantom’s adult-male bias and proposed child-specific testing modifications; the order acknowledged these submissions but did not explain why they did not require a change in approach. Second, the agency failed to address long-term and cumulative exposure scenarios. The 1991–1992 ANSI/IEEE standards modeled acute, short-duration exposures; commenters submitted data on hours-long daily smartphone use and persistent Wi-Fi background exposure that did not map onto that framework. Third, the FCC did not engage with dozens of peer-reviewed studies in the record reporting non-thermal biological responses at sub-threshold SAR values.
The court stopped short of holding that the existing limits are scientifically wrong or must be reduced. The ruling remanded to the FCC with instructions to either supply the missing reasoned explanation or revise its rules, a distinction that preserves the agency’s discretion while imposing a procedural obligation it has not yet discharged.
The Science in Dispute
The scientific literature on RF bioeffects remains actively contested. Consensus exists on thermal effects: RF energy absorbed above a measurable threshold heats tissue and can cause harm at sufficient intensity. The dispute centers on whether biological effects occur through non-thermal mechanisms at levels below the heating threshold, and whether those effects constitute adverse health outcomes.
The National Toxicology Program conducted a $30 million multi-year rodent study exposing animals to 2G CDMA and GSM frequencies at whole-body SAR values ranging from 1.5 to 6 W/kg, the lower bound matching the FCC public limit. Results published in 2018 reported statistically significant increases in malignant schwannomas of the heart and glial cell tumors in exposed male rats. A 2025 systematic review of 52 animal bioassays, applying OHAT risk-of-bias methods and GRADE certainty ratings, found high-certainty evidence of increased glial cell-derived neoplasms and malignant heart schwannomas in chronically exposed male rats. An independent expert panel reviewing the NTP findings characterized them as “equivocal” for human relevance, noting that whole-body rodent exposure differs structurally from the localized, device-proximate exposure patterns typical of human mobile phone use.
The International Agency for Research on Cancer classified RF electromagnetic fields as “possibly carcinogenic to humans” (Group 2B) in 2011, citing limited epidemiological evidence of glioma and acoustic neuroma risk in long-term mobile phone users. IARC has not revised that classification upward since. The World Health Organization maintains that current evidence does not confirm health risks at levels below international guidelines while acknowledging ongoing research. Industry and federal health agencies argue that non-thermal effect studies in the record carry methodological limitations: inadequate controls, small sample sizes, replication failures, that do not support regulatory action. Independent researchers counter that the volume and consistency of non-thermal findings across laboratories and methodologies make the thermal-only model scientifically untenable.
What’s Next: FCC’s Response to Remand
As of the date of this article, the FCC has not issued a new order in ET Docket 03-137 responding to the court’s three-part remand. No Notice of Proposed Rulemaking, Further Notice of Inquiry, or formal procedural document announcing the agency’s compliance path has been published in the docket.
Environmental Health Trust has pressed FCC Chairman Brendan Carr, confirmed to lead the agency in January 2025, to act. In correspondence to Carr, EHT President Joe Sandri argued that complying with a federal court mandate is a ministerial obligation requiring no new policy judgment from the chair. EHT has stated it is actively evaluating a writ of mandamus under 28 U.S.C. § 1651 to compel agency action. A House Energy and Commerce Subcommittee on Communications and Technology oversight hearing held January 14, 2026, examined FCC operations without any member raising the outstanding remand: a silence EHT publicly criticized in post-hearing statements.
The practical stakes for consumer electronics manufacturers are concrete. A revised SAR limit, new testing phantom requirements that account for pediatric anatomy, or mandatory long-term and cumulative exposure disclosures would require manufacturers to retest existing product lines and potentially redesign antenna placement in future devices. Some advocacy filings before the FCC propose a limit of 0.08 W/kg, a 20-fold reduction from the current standard — which would require fundamental changes to how smartphones and wearables are tested, authorized, and marketed in the United States.
Until the FCC acts, the 1996 limits remain legally operative. The D.C. Circuit’s August 2021 order vacated the FCC’s 2019 decision not to update the rules, but it did not vacate the rules themselves. The regulatory status quo holds — but the legal record on which the agency previously rested that status quo has been stripped away.
For a broader examination of FCC spectrum governance and rulemaking procedures, see the FCC Spectrum Policy guide.