# RF-026 — Long-term, low-level microwave irradiation of rats

Why this matters
An older, long-running rat experiment found more animals with malignant tumours when different cancer types were combined. No single tumour site or overall tumour total increased significantly. Its value is historical evidence for a fresh look at the underlying pathology, without calling it another confirmation of the heart-tumour finding.

Id: RF-026

Author: Chou et al.

Full Authors: C.-K. Chou; A. W. Guy; L. L. Kunz; R. B. Johnson; J. J. Crowley; J. H. Krupp

Year: 1992

Title: Long-term, low-level microwave irradiation of rats

Journal: Bioelectromagnetics

Citation: Chou CK, Guy AW, Kunz LL, Johnson RB, Crowley JJ, Krupp JH. Long-term, low-level microwave irradiation of rats. Bioelectromagnetics. 1992;13(6):469-496. doi:10.1002/bem.2250130605.

Doi: 10.1002/bem.2250130605

Pmid: 1482413

Topic: Tumours

Verification Group: Original text reviewed

Record Role: Original text reviewed

Featured: False

Exposure: 2450 MHz pulsed microwaves: 800 pulses/s, 10 µs width, 8 Hz square-wave modulation; whole-body SAR approximately 0.4 to 0.15 W/kg as animals grew; 21.5 h/day, 7 days/week, 25 months from 8 weeks of age. Individual circularly polarised waveguides.

Design: 100 male Sprague-Dawley rats exposed, 100 sham; 10/group interim sacrifice at 13 months; 200 animals examined pathologically.

Finding: Primary malignant lesions in 18/100 exposed vs 5/100 sham. Age-stratified Mantel-Haenszel OR 4.27, p=.006; death-time surrogate analysis p=.006. No significant specific tumour-site increase or all-neoplasms increase; longevity comparable.

Boundary: Pooling across histologically different organs/tumours and numerous endpoints limits inference; one intensity/one sex; authors considered biological meaning uncertain. SAR declines with growth. Not a demonstrated schwannoma replication.

Related: University of Washington/USAF programme. Guy et al. 1985, USAFSAM-TR-85-64, Volume 9/AD-A159512, and component reports describe the same animals; count once.

Protection Question: How much weight can the pooled malignant-lesion increase carry when single-site and overall-neoplasm results were not significant? It remains relevant chronic-pathology history, with uncertainty about biological meaning.

Access: Original 28-page published article reviewed, including Tables 2-4, survival and discussion; 1985 USAF summary checked as same programme.

Locator: pp 469-470 abstract; p 478 exposure; pp 487-488 survival/pathology; p 490 Table 2; p 491 statistics; p 492 Table 4; pp 493-494 interpretation/funding.

Notice: Scite metadata/publisher and targeted DOI-notice search 2026-10-20: no correction/retraction/concern located.

Funding: USAF School of Aerospace Medicine contracts F33615-78-C0631 and F33615-80-C-0612; partial NCI grant CA33752. No modern conflict declaration located.

Conflicts: Not established from retrieved material.

Source Url: https://doi.org/10.1002/bem.2250130605

Retrieval Links: https://doi.org/10.1002/bem.2250130605 | https://pubmed.ncbi.nlm.nih.gov/1482413/ | https://www.stralskyddsstiftelsen.se/wp-content/uploads/2018/09/Chou-CK-et-al.-Long-term-MW-rad-of-Rats-1992.pdf | https://www.rfsafe.com/wp-content/uploads/2025/02/Effects-of-Long-Term-Low-Level-Radiofrequency-Radiation-Exposure-on-Rats.-Volume-9.-Summary_.pdf

Verification Date: 2026-10-20