1989? Adjust for technology. Those old analog phones had an output power of over 3 watts. Modern phones are generally less than a watt.
But even then, every major study of the issue I’ve ever seen said there is no strong correlation between cell phone use and cancer, much less actual causation. Probably the main reason is that cell phones produce non-ionizing radiation, the kind that doesn’t cause cancer. It’s like a microwave (it’s in the same frequency range), it may warm things up, but it’s not going to give them cancer.
Perhaps when switched off :-)
Check the IPhone specs. When talking in low reception area it's 3W microwave blasting one inch from the brain. If there is one, that is.