Cellular telephone use and time trends for brain, head and neck tumours.

AIM: The objective of this study was to determine whether incidence rates of head and neck malignancies in New Zealand have varied since the introduction of cellular telephones in 1987. In particular, we sought to compare trends in tumour rates in anatomical sites that receive high, medium and low levels of cellular telephone radiation (based on dosimetry data). METHODS: We investigated whether trends in tumour incidence rates in New Zealand have varied since the introduction of cellular telephones in 1987. The exposure measure used was the proportion of cellular telephone subscribers within the national population, calculated using the number of subscribers over the study period. RESULTS: The graphs for high, medium and low exposure sites did not display any significant changes in trend patterns for either gender over the years 1986 to 1998. CONCLUSIONS: Incidence rates for malignancies arising in the head and neck, including those sites that hypothetically receive the highest levels of radio frequency radiation during cellular telephone use, have not changed materially since the introduction of cellular telephones to New Zealand. However, ecological studies of this nature are limited in many ways and a stronger study design is clearly needed to establish more exactly any elevation in risk.