The NTP studies found that high exposure to RFR (900 MHz) used by cell phones was associated with:
Clear evidence of tumors in the hearts of male rats. The tumors were malignant schwannomas.
Some evidence of tumors in the brains of male rats. The tumors were malignant gliomas.
Some evidence of tumors in the adrenal glands of male rats. The tumors were benign, malignant, or complex combined pheochromocytoma.
It was unclear if tumors observed in the studies were associated with exposure to RFR in female rats (900 MHz) and male and female mice (1900MHz).
The results are based on NTP’s four categories of evidence that a substance may cause cancer: clear evidence (highest), some evidence, equivocal evidence, no evidence (lowest).