Ken Karipidis

Non-Hodgkin lymphoma and occupational radiation exposure assessed using local data

BACKGROUND Our previous investigation of occupational exposure to ionizing radiation using a Finnish job-exposure matrix (JEM) showed no association with non-Hodgkin lymphoma (NHL) in a population-based case-control study in Australia. AIMS To determine whether occupational exposure to ionizing radiation assessed using an Australian JEM is associated with NHL. METHODS We analysed 694 NHL cases, first diagnosed between 1 January 2000 and 31 August 2001 and 694 controls from south-eastern Australia, matched by age, sex and region of residence. A detailed occupational history was obtained using a lifetime calendar and a telephone interview. Exposure to radiation was assessed using the ionizing radiation component of an Australian JEM. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated from logistic regression models that included the matching variables as covariates. RESULTS The OR for workers ever exposed to ionizing radiation was 0.86 (95% CI = 0.52-1.40). Dividing the subjects into tertiles of exposure also found ORs that were close to or below the null for each exposure group. CONCLUSIONS The application of an Australian JEM did not provide evidence for an association between NHL and occupational exposure to ionizing radiation and is consistent with previous analyses.

Survey of residential power-frequency magnetic fields in Melbourne, Australia

Pooled analyses of epidemiological studies have reported an association between prolonged residential exposure to power-frequency magnetic fields of >0.4 μT and an increased risk in childhood leukaemia. In order to compare residential magnetic fields in Australia with those in other countries, a survey was conducted in 296 randomly selected homes in Melbourne. Magnetic fields were assessed by performing spot measurements throughout the house and 24-h measurements in rooms where children spend large amounts of time. Childrens exposure in Australia was generally comparable with that in other countries with average fields of 0.05-0.06 μT (95 % CI 0.05-0.06 μT). Prolonged exposure of >0.4 μT was shown in ∼2 % of the homes (95 % CI 0.2-3.6 %) mainly being due to close proximity of the house to transmission lines. Based on the results of this survey, the public health impact of a causal association between residential magnetic fields and childhood leukaemia is expected to be small.

Exposure to Radiofrequency Electromagnetic Fields From Wi-Fi in Australian Schools.

Abstract The increasing use of Wi-Fi in schools and other places has given rise to public concern that the radiofrequency (RF) electromagnetic fields from Wi-Fi have the potential to adversely affect children. The current study measured typical and peak RF levels from Wi-Fi and other sources in 23 schools in Australia. All of the RF measurements were much lower than the reference levels recommended by international guidelines for protection against established health effects. The typical and peak RF levels from Wi-Fi in locations occupied by children in the classroom were of the order of 10−4 and 10−2% of the exposure guidelines, respectively. Typical RF levels in the classroom were similar between Wi-Fi and radio but higher than other sources. In the schoolyard typical RF levels were higher for radio, TV and mobile phone base stations compared to Wi-Fi. The results of this study showed that the typical RF exposure of children from Wi-Fi at school is very low and comparable or lower to other sources in the environment.

Assessment of bias in a survey of residential magnetic fields in Melbourne, Australia

An important consideration in surveys of residential magnetic fields is whether the sample of homes measured is representative of the population. This study assessed the potential bias in a survey of magnetic fields conducted in 296 homes randomly selected from the telephone directory in Melbourne. The choice of the telephone directory as the sampling frame introduced some bias when compared with census information. There was also evident self-selection bias with residents twice as likely to participate if they lived in the vicinity of visible electrical infrastructure such as transmission lines. However, when corrected for bias the corrected magnetic fields were only slightly lower than the measurements with a percentage difference in the range of 2.8-6.0 %. These results provide confidence that the measurements in the survey were good estimates of the distribution of residential magnetic fields in Melbourne.

Is the Risk Comparison Made by the Public Between EMF and Smoking or Asbestos a Valid One

The possibility of adverse health effects from exposure to extremely low frequency (ELF) electric and magnetic fields (EMF) has caused considerable controversy in the scientific community and has received great attention in the media and among the general public with many comparing ELF EMF with tobacco smoking and asbestos. Although both smoking and asbestos are now classified by the International Agency for Research on Cancer (IARC) as Group 1 or “established” carcinogens, this was not always the case. In this paper the evidence for the carcinogenicity of ELF EMF is compared with that for smoking and asbestos using the Bradford Hill model for establishing causality between exposure and disease. Application of the model shows that present data are insufficient to demonstrate that exposure to ELF EMF poses a definite human health hazard. However, while the bulk of the evidence is weak, there are several epidemiological studies which have reported an association between prolonged exposure to magnetic fields at levels above what is normally encountered and an increased risk in childhood leukaemia. On this basis IARC has classified ELF magnetic fields as a Group 2B or “possible” carcinogen.