# NTP rodent carcinogenicity studies of cell phone radiofrequency radiation (2018)

> Two-year whole-body exposure studies found clear evidence of malignant schwannomas of the heart in male rats at exposure levels above the human whole-body limit, with no such finding in female rats or in mice.

- Canonical URL: https://emfbase.com/studies/ntp-2018-cellphone-rfr
- Collection: Research record
- Record id: `studies:ntp-2018`
- Status: verified
- Last verified: 2026-08-12
- JSON: https://emfbase.com/api/studies/ntp-2018-cellphone-rfr

## Key values

- **Authors:** U.S. National Toxicology Program
- **Year:** 2018
- **Design:** animal
- **Exposure studied:** Whole-body GSM- and CDMA-modulated RF at 900 MHz (rats) and 1900 MHz (mice), 1.5–6 W/kg whole-body SAR, roughly 9 hours per day for two years, from before birth
- **Place in the evidence base:** high
- **Primary document:** https://ntp.niehs.nih.gov/whatwestudy/topics/cellphones

## Finding

Clear evidence of carcinogenic activity: malignant schwannoma of the heart in male rats. Equivocal evidence for glioma in male rats. No clear evidence in female rats or in mice of either sex.

## What it cannot establish

Whole-body SAR levels were at or above the human whole-body limit and produced measurable tissue heating at the highest level. Exposed male rats survived longer than controls, complicating interpretation. Rodent heart schwannoma has no clear human counterpart in the epidemiology, and NTP itself stated the findings should not be extrapolated directly to human phone use.

## Related records

- [Ramazzini Institute far-field base-station exposure study (2018)](https://emfbase.com/studies/ramazzini-2018-base-station-rfr): A lifespan rat study at far-field, base-station-like levels reported the same rare heart schwannoma signal as the NTP study, at much lower exposure intensities.
- [IARC classification of radiofrequency fields as Group 2B (2011)](https://emfbase.com/studies/iarc-2011-rf-group-2b): IARC classified radiofrequency electromagnetic fields as possibly carcinogenic to humans (Group 2B) based on limited evidence for glioma and acoustic neuroma from heavy mobile phone use.

## Sources

- `ntp-cellphone` National Toxicology Program, U.S. NIEHS. *Cell Phone Radiofrequency Radiation Studies*. https://ntp.niehs.nih.gov/whatwestudy/topics/cellphones — government, link checked 2026-08-12

Data licence: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Dataset version 2026.08.1. Retrieved from EMFBase, https://emfbase.com.

This record is reference data, not medical or legal advice. Regulatory limits, scientific guidelines and precautionary values are labelled separately and answer different questions.