Wireless phone use by young New Zealanders: Health and policy implications
Over the last decade the use of cellphones has increased dramatically among the young adolescent population. In New Zealand, most children of this age also use a cordless phone. With the rapid proliferation in children‘s use of these devices, there has been increasing concern about whether children are more vulnerable than adults to possible adverse outcomes if such effects do result from wireless phone radiofrequency exposure. This is the first study of young New Zealanders‘ wireless phone habits, focusing particularly on the extent of use, and the relationship of that use with well-being. Two studies were undertaken: a census of schools with Year 7 and 8 classes in the Wellington Region of New Zealand to ascertain what rules were in place regarding cellphones at school, and a cross-sectional survey of students from the same region, using a representative sample of 373 students aged 10.3-13.7years. Both studies were conducted by the author independently from any research group. The primary research appears in Part II. Chapter 5 presents wireless phone user-habits. The large majority of young adolescents were already using cellphones and cordless phones regularly in 2009, although use was generally light or moderate. A small group (5%) was using both phone types extensively (≥ 30 minutes cordless daily plus ≥ 10 cellphone calls weekly); almost a quarter used a cordless phone ≥ 30 minutes daily, and 6% reported, on average, 1¼ hours or more use daily. This extent of use over 4 or more years has been associated in several major studies with an increased risk of glioma. Both the MoRPhEUS data and this study‘s data (Appendix 1 and Chapter 5) showed that use of the two phone types is positively correlated, increasing the comparative and actual radiofrequency exposure in heavy users. Cellphone use during school was compared with school expectations, discussed in chapter 6, showing there was a considerably greater level of illicit use than that of which principals were aware. This use was adjacent to the lower abdomen, and a brief review of relevant fertility literature suggested that cellphone use, or even carriage, in that position may impair sperm quality and duration of use like this appeared consistent with reduced fertility. A novel observation is explored in chapter 7. The mental process in recalling the extent of cellphone use was not linear. It parallels that found in many types of magnitude estimation, using a logarithmic mental number line. This carried implications for epidemiology methods that use recall data, particularly the need to record the geometric rather than arithmetic mean when a range of estimated use is provided. Not doing so put almost 5% of participants in an incorrect category when estimated use was split into tertiles. Recall estimation has a large variance. Chapter 8 presents a Bayesian method of reducing estimation bias in recall data. It should be applicable for use by studies that conform to the method‘s requirements. Chapter 9 presents the results of logistic regression analysis of the participants‘ reported well-being with respect to their wireless phone use. A dose-response relationship with frequent headaches confirmed findings elsewhere. Tinnitus and tiredness results suggested that responses were different depending upon phone type. This is the first study to explore and demonstrate different well-being responses according to cordless phone frequency or modulation. There was a strong association between being woken by the cellphone in the night and being tired at school. This research carries implications for young people‘s wireless phone use, including the advisability of limiting daily use to no more than 15 minutes daily. The relevance of researchers considering cellphone exposures, compared to that of cordless phones, is questioned. Further research on bio-sensitive frequencies, modulations and exposures is needed. An important recommendation is for the inclusion of education about wireless technology in schools and school communities and for child-health practitioners.