Use of TETRA personal radios and sickness absence in the Airwave Health Monitoring Study of the British police forces.

BACKGROUND: Terrestrial Trunked Radio (TETRA) is used for radiocommunications among the British police forces. OBJECTIVES: To investigate association of personal radio use and sickness absence among police officers and staff from the Airwave Health Monitoring Study. METHODS: Participant-level sickness absence records for 26 forces were linked with personal radio use for 32,102 participants. We used multivariable logistic regression to analyse TETRA usage in year prior to enrolment and sickness absence (lasting more than 7 or 28 consecutive days) in the following year and a zero-inflated negative binomial model for analyses of number of sickness absence episodes of any duration ('spells') over the same period. In secondary analyses, we looked at an extended period of observation among a sub-cohort with linked data over time, using Cox proportional hazards regression. RESULTS: Median personal radio use (year prior to enrolment) was 29.7 min per month (interquartile range 7.5, 64.7) among users. In the year following enrolment there were 25,655 sickness absence spells among 15,248 participants. There were similar risks of sickness absence lasting more than seven days among users and non-users, although among users risk was higher with greater use, odds ratio = 1.04 (95% confidence interval [CI] 1.02 to 1.06) per doubling of radio use. There was no association for sickness absence of more than 28 days. For sickness absence spells, risk was lower among users than non-users (incidence rate ratio = 0.91; 95% CI 0.75 to 1.11), again with higher risk among users for greater radio use. There was no association between radio use and sickness absence in secondary analyses. DISCUSSION: There were similar or lower risks of sickness absence in TETRA radio users compared with non-users. Among users, the higher risk of sickness absence with greater radio use may reflect working pattern differences among police personnel rather than effects of radiofrequency exposure.

Personal radio use and cancer risks among 48,518 British police officers and staff from the Airwave Health Monitoring Study.

BACKGROUND: Radiofrequency electromagnetic fields (RF-EMF) from mobile phones have been classified as potentially carcinogenic. No study has investigated use of Terrestrial Trunked Radio (TETRA), a source of RF-EMF with wide occupational use, and cancer risks. METHODS: We investigated association of monthly personal radio use and risk of cancer using Cox proportional hazards regression among 48,518 police officers and staff of the Airwave Health Monitoring Study in Great Britain. RESULTS: During median follow-up of 5.9 years, 716 incident cancer cases were identified. Among users, the median of the average monthly duration of use in the year prior to enrolment was 30.5 min (inter-quartile range 8.1, 68.1). Overall, there was no association between personal radio use and risk of all cancers (hazard ratio [HR] = 0.98, 95% confidence interval [CI]: 0.93, 1.03). For head and neck cancers HR = 0.72 (95% CI: 0.30, 1.70) among personal radio users vs non-users, and among users it was 1.06 (95% CI: 0.91, 1.23) per doubling of minutes of personal radio use. CONCLUSIONS: With the limited follow-up to date, we found no evidence of association of personal radio use with cancer risk. Continued follow-up of the cohort is warranted.

Estimation of TETRA radio use in the Airwave Health Monitoring Study of the British police forces.

BACKGROUND: The Airwave Health Monitoring Study aims to investigate the possible long-term health effects of Terrestrial Trunked Radio (TETRA) use among the police forces in Great Britain. Here, we investigate whether objective data from the network operator could be used to correct for misreporting in self-reported data and expand the radio usage availability in our cohort. METHODS: We estimated average monthly usage of personal radio in the 12 months prior to enrolment from a missing value imputation model and evaluated its performance against objective and self-reported data. Factors associated with TETRA radio usage variables were investigated using Chi-square tests and analysis of variance. RESULTS: The imputed data were better correlated with objective than self-reported usage (Spearman correlation coefficient = 0.72 vs. 0. 52 and kappa 0.56 [95% confidence interval 0.55, 0.56] vs. 0.46 [0.45, 0.47]), although the imputation model tended to under-estimate use for higher users. Participants with higher personal radio usage were more likely to be younger, men vs. women and officer vs. staff. The median average monthly usage level for the entire cohort was estimated to be 29.3 min (95% CI: [7.2, 66.6]). CONCLUSION: The availability of objective personal radio records for a large proportion of users allowed us to develop a robust imputation model and hence obtain personal radio usage estimates for ~50,000 participants. This substantially reduced exposure misclassification compared to using self-reported data and will allow us to carry out analyses of TETRA usage for the entire cohort in future work.

Validation of objective records and misreporting of personal radio use in a cohort of British Police forces (the Airwave Health Monitoring Study).

BACKGROUND: Terrestrial Trunked Radio (TETRA) is a digital communication system progressively adopted by Police Forces in Great Britain since 2001. In 2000, the UK Independent Expert Group on Mobile Phones suggested that exposure to TETRA-like signal modulation might have adverse effects on health. The Airwave Health Monitoring Study was established to investigate possible long-term effects of TETRA use on health. This requires estimation of TETRA use among Police Force employees participating in the study. METHODS: We investigated TETRA usage among 42,112 Police officers and staff. An algorithm was created to link each personal radio user to his/her objective radio usage records for the 26,035 participants with available data. We linked 16,577 personal radio users to their objective radio usage records and compared self-reported usage with data from the TETRA operator for those individuals. RESULTS: For weekly usage, the correlation between self-reported and operator-derived personal radio usage was r=0.69 for number and r=0.59 for the duration of calls. Compared with objective data, participants under-reported the number of calls and over-reported the duration of calls by a factor of around 4 and 1.6 respectively. Correlations were lower and bias higher when looking at daily usage. CONCLUSION: Where both objective and self-reported information were available, our study showed substantial misreporting in self-reported TETRA usage. Successful linkage of large numbers of TETRA users to objective data on their personal radios will allow objective assessment of TETRA radio usage for these participants and development of algorithms to correct bias in self-reported data for the remainder.