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Cancer & Tumors

Lack of promoting effects of the electromagnetic near-field used for cellular phones (929.2 MHz) on rat liver carcinogenesis in a medium-term liver bioassay.

No Effects Found

Imaida K, Taki M, Yamaguchi T, Ito T, Watanabe S, Wake K, Aimoto A, Kamimura Y, Ito N, Shirai T · 1998

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Cell phone radiation at high SAR levels (7.2 W/kg) showed no cancer-promoting effects in rat liver tissue over 6 weeks.

Plain English Summary

Summary written for general audiences

Japanese researchers exposed rats to 929.2 MHz cell phone radiation for 90 minutes daily over 6 weeks to test whether the radiation could promote liver cancer development. The study used relatively high SAR levels (up to 7.2 W/kg) and found no difference in pre-cancerous liver lesions between exposed and unexposed rats. This suggests that cell phone radiation at these levels does not accelerate liver cancer progression in this animal model.

Why This Matters

This 1998 study represents an important early investigation into whether cell phone radiation acts as a cancer promoter - meaning it could accelerate existing cancer processes rather than initiate them. The researchers used SAR levels significantly higher than current safety limits (2 W/kg), making this a fairly robust test of the promotion hypothesis. However, the study's focus on liver cancer promotion using a specific chemical carcinogen model has limited relevance to the broader question of whether RF radiation can cause cancer independently. What this means for you: while this study found no cancer-promoting effects in the liver, it doesn't address whether long-term exposure might initiate cancer in other organs or through different mechanisms. The science on RF radiation and cancer remains complex, with studies showing mixed results depending on the organ system, exposure duration, and biological endpoints examined.

Exposure Details

SAR
7.2-6.6, 2.0-1.7, 0.80-0.58 W/kg
Source/Device
929.2-MHz
Exposure Duration
90 min a day, 5 days a week, over 6 weeks

Exposure Context

This study used 7.2-6.6, 2.0-1.7, 0.80-0.58 W/kg for SAR (device absorption):

Building Biology guidelines are practitioner-based limits from real-world assessments. BioInitiative Report recommendations are based on peer-reviewed science. Check Your Exposure to compare your own measurements.

Where This Falls on the Concern Scale

Study Exposure Level in ContextStudy Exposure Level in ContextThis study: 7.2-6.6, 2.0-1.7, 0.80-0.58 W/kgExtreme Concern - 0.1 W/kgFCC Limit - 1.6 W/kgEffects observed in the Extreme Concern range (Building Biology)FCC limit is 3 times higher than this level
A logarithmic frequency spectrum from 10 Hz to 100 GHz showing where this study's 929.2 MHz exposure sits relative to common EMF sources.Where This Frequency Sits on the EMF SpectrumELFVLFLF / MFHF / VHFUHFSHFmm10 Hz100 GHzThis study: 929.2 MHzPower lines50/60 Hz5G mm28 GHzLogarithmic scale

Study Details

The possible cancer promotion potential of local exposure to a pulse modulated 929.2 MHz electromagnetic near-field on chemically-initiated rat liver carcinogenesis was investigated employing a medium-term bioassay.

A 929.2-MHz electromagnetic near-field of time division multiple access (TDMA) signal for PDC (Perso...

The numbers (no./cm2) of GST-P positive foci were 4.61 +/- 1.77, 5.21 +/- 1.92 (P < 0.05, versus con...

There were no significant differences between the exposed and sham-exposed groups. These findings clearly indicated that local body exposure to a 929.2-MHz field, modulated in a PDC waveform, has no significant effect on rat liver carcinogenesis under the experimental conditions employed.

Cite This Study
Imaida K, Taki M, Yamaguchi T, Ito T, Watanabe S, Wake K, Aimoto A, Kamimura Y, Ito N, Shirai T (1998). Lack of promoting effects of the electromagnetic near-field used for cellular phones (929.2 MHz) on rat liver carcinogenesis in a medium-term liver bioassay. Carcinogenesis 19(2):311-314, 1998.
Show BibTeX
@article{k_1998_lack_of_promoting_effects_3100,
  author = {Imaida K and Taki M and Yamaguchi T and Ito T and Watanabe S and Wake K and Aimoto A and Kamimura Y and Ito N and Shirai T},
  title = {Lack of promoting effects of the electromagnetic near-field used for cellular phones (929.2 MHz) on rat liver carcinogenesis in a medium-term liver bioassay.},
  year = {1998},
  
  url = {https://pubmed.ncbi.nlm.nih.gov/9498282/},
}
PubMed: 9498282

Cited By (70 papers)

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Quick Questions About This Study

No, a 1998 Japanese study found that 929.2 MHz cell phone radiation does not promote liver cancer development in rats. Researchers exposed rats to high levels (up to 7.2 W/kg SAR) for 90 minutes daily over 6 weeks and found no difference in pre-cancerous liver lesions compared to unexposed animals.
No, 90 minutes of daily exposure to 929.2 MHz cell phone radiation did not accelerate liver tumor development in rats. The 1998 study used relatively high radiation levels and found no significant differences in GST-P positive foci (pre-cancerous markers) between exposed and control groups after 6 weeks.
Based on a 1998 rat study, 7.2 W/kg SAR from 929.2 MHz cell phone radiation showed no harmful effects on liver health. Despite using SAR levels much higher than typical phone use, researchers found no increase in pre-cancerous liver lesions after 6 weeks of daily exposure.
No, PDC-modulated 929.2 MHz radiation had no significant effect on liver carcinogenesis in rats according to a 1998 Japanese study. Researchers found no differences in the number or area of GST-P positive foci (cancer markers) between radiation-exposed and unexposed rat groups.
The 1998 Japanese liver cancer study tested SAR levels up to 7.2 W/kg using 929.2 MHz cell phone radiation. These levels are significantly higher than typical phone use, yet researchers found no promotion of liver cancer development in rats during the 6-week exposure period.