Radiation literature survey

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This report, published by the United Kingdom (UK) Institution of Occupational Safety and Health, examines how health messaging to construction workers can influence their sun protection behaviour and manage their vitamin D levels. Low levels of ultraviolet (UV) are required for the body to synthesis vitamin D. The study split 94 construction workers into an intervention group and a control group for the study periods (one summer and two winter cycles). The intervention group which was provided with sun protection advice in the summer period and advice on Vitamin D supplementation vitamin D during winter. This information was delivered to the participants using text messages and a mobile phone app. The outcome of the interventions was assessed by measuring UV exposure from a wearable UV sensors and for vitamin D assays were conducted from blood samples. The authors reported that the UV exposure of the intervention group was higher than the control group, indicating the sun protection communication was not successful. The intervention was more successful for vitamin D communication indicated by the much higher percentage of participants in the intervention group with sufficient vitamin D than the control group in both of the winter study periods. The authors concluded that while the study demonstrated that text messaging and mobile phone apps were an effective way of delivering messages, they were not successful at promoting sun protection behaviours. It was recommended that a more regimented risk-based approach be explored to reduce the risk of skin cancer among outdoor construction workers.

Nudging construction workers towards better sun safety behaviour

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The authors tested the effectiveness of text messaging and mobile phone apps as a way of communicating the risk of UV exposure to outdoor workers. However, it was found that this strategy had a low impact in promoting sun protection behaviour. It was concluded that changes to this approach are required to prove its potential effectiveness. The results of this research are particularly important in Australia, considering our high solar UV environment. Reports by Safe Work Australia found that agriculture and construction workers are amongst the highest UV exposed groups in Australia (Safe Work Australia, 2016). Australia also has one of the highest rates of skin cancer. Two in three Australians will be diagnosed with skin cancer by the age of 70 and more than 2000 Australians die from skin cancer each year (Cancer Council Australia, 2019). Occupational exposure can significantly contribute to these rates with a meta-analysis by Schmitt et al 2011 finding that people who were occupationally exposed to UV had an increased risk of squamous cell carcinoma.

To protect workers from the consequences of high UV exposure, each Australian State or Territory has an occupational health and safety act that sets requirements for the protection of outdoor workers from solar UV. There is also sun protection controls that the Cancer Council Australia promote for workers that include the slip, slop, slap, and slide measures. Despite Australia’s high solar UV one in four Australians are estimated to be vitamin D deficient (Cancer Council Australia). The Cancer Council and the Endocrine Society of Australia recommend that people who may be at risk of vitamin D deficiency discuss their vitamin D requirements with their medical practitioner rather than seeking sun exposure.

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This was a cohort study investigating the risk of developing hyperthyroidism following incidental radiation exposure to the thyroid and the pituitary gland during radiation therapy for childhood (<21 years) cancer. The study included 11,608 childhood cancer patients, of which 148 self-reported to have been diagnosed with hyperthyroidism by a doctor more than 5 years after their first radiotherapy treatment. The study did not show a statistically significant increase in the risk of developing hyperthyroidism from radiotherapy exposure to the pituitary gland. However, the study did show a statistically significant increase in the risk of hyperthyroidism associated with a dose to the thyroid above 25 Gray (Gy) (relative risk 3.1; 95% confidence interval (CI) of 1.3-7.2). The authors also reported a linear dose response between radiation received by the thyroid and excess relative risk of developing hyperthyroidism per Gy of 0.06 (95% CI of 0.03-0.14). The authors concluded the results supported radiation exposure as a risk factor for hyperthyroidism. Further, the authors concluded that the results were consistent with the linear no threshold model. However, the risk was concluded to be relatively small, except at therapeutic doses.

Hyperthyroidism After Radiation Therapy for Childhood Cancer: A Report from the Childhood Cancer Survivor Study

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The study reported increased risk of developing hyperthyroidism per Gy of radiation exposure of 0.06.  However, the results demonstrated that below 25 Gy the risk of developing hyperthyroidism was not significant. The United Nations Scientific Committee on the Effects of Atomic Radiation also reports an increased relative risk of hyperthyroidism following radiation treatment for childhood cancer. The Inskip et al study overall was large, however, the findings are limited by the small number of cases of hyperthyroidism. 

The study by Inskip et al is one of many studies that have examined the data from the US/Canadian childhood cancer survivor study. These studies have examined the possible latent health effects in children after diagnoses and treatment of a range of cancers after 5 years. 
 

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This was a review investigating the risk of exposure to artificial tanning devices (sunbeds) and the risk of melanoma. The review included an analysis of three cohort studies, multiple case-control studies and various meta-analyses. The authors reported that the cohort studies display consistent results of increased risk of melanoma associated with sunbed use. The authors further stated that the meta-analyses, which included all published studies until 2012, demonstrate an increased risk of melanoma associated with sunbed use. The largest of these meta-analyses, which included 27 studies between 2006 and 2012 found a pooled relative risk (RR) of 1.20 (95% confidence interval (CI) of 1.08-1.34). This risk was reported to be higher when exposure took place at younger age (RR = 1.59; 95% CI 1.36–1.85). The authors concluded that there is overwhelming evidence that ultra-violet radiation (UVR) from artificial sources is carcinogenic. They recommend that there should be efforts to strengthen regulations for the use of sunbed. 

Epidemiological evidence of carcinogenicity of sunbed use and of efficacy of preventive measures

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This review outlined the epidemiological evidence for an association between solariums and melanoma. The evidence presented supports Australia’s nation-wide policy to ban all commercial solaria. Sunbeds emit both UV-A and UV-B radiation, both of which are listed as carcinogens by the World Health Organization (WHO). Exposure to both types of UVR in a tanning bed increases the risk of developing skin cancer. An Australian study that examined the use of tanning beds, prior to the Australian ban, found that they contribute to 43 melanoma-related deaths and 2572 new cases of squamous cell carcinoma per year in Australia (Gordon et al, 2008). Although solariums have been banned in Australia since 2016 in commercial settings, there are no restrictions for personal use and Australians travelling overseas may still seek tanning services abroad. ARPANSA’s advice is to avoid using artificial tanning services and equipment due to the association with skin cancer.

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This was a French cohort study investigating a possible relationship between maternal exposure to extremely low frequency magnetic fields (ELF MF) and the risk of moderate preterm birth or small size for gestational age at birth. The cohort included 18,329 infants born in 2011 from 33 weeks of gestation. The study examined the cumulative ELF MF exposure of the mothers both at home and at work. Exposure to participants was categorised at work by a job exposure matrix (JEM) and at home by previous measurements. The study reported no statistically significant association at any cumulative exposure level. The authors concluded that there was no evidence of an association between cumulative ELF MF exposure and moderate preterm birth or a baby being small for their gestational age at birth. 

Maternal cumulative exposure to extremely low frequency electromagnetic fields and pregnancy outcomes in the Elfe cohort

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A similar UK cohort study (de Vocht et al 2014) examined residential proximity to magnetic fields and the association with low birth weight and preterm birth. This study included 140356 births. The authors reported no statistically significant changes in either birth weight or rates of preterm birth associated with magnetic fields. A 2015 review by the Scientific Committee on Emerging and Newly Identified Health Risks concluded there is no evidence that fetal exposure to ELF magnetic fields is associated with adverse developmental outcomes. 

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This was a cohort study that examined the association between health symptoms and perceived and actual modelled environmental exposure of the participants. The environmental exposures included in the study were radiofrequency electromagnetic fields (RF EMF), noise and air pollution. The study originally in 2012 had 14,829 participants, however, in the 2015 follow-up only 7905 people responded. Perceived exposure was assessed using questionnaires in which participants self-assessed the extent to which they believed they were exposed to RF EMF on a scale of 1 to 6. The participants also completed questionnaires to assess their non-specific symptoms, sleep disturbances and respiratory symptoms, respectively. Lastly, the RF EMF exposure at each participant’s residence was modelled as either high (above 0.050 mW/m2) or low (below 0.050 mW/m2). The study found that the modelled RF EMF was not associated with any health symptoms. However, the perceived RF EMF exposure was associated with higher health symptoms in all categories. The authors suggest that when examining environmental exposure symptoms it is important to examine the perception of exposure to avoid bias when attributing health effects.

Modeled and perceived RF-EMF, noise and air pollution and symptoms in a population cohort. Is perception key in predicting sympt

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A study by Baliatsas et al 2015 had similar results, finding no significant association between modelled RF EMF and non-specific symptoms or sleep quality. This study also concluded that perceived exposure was associated with the examined outcomes. At levels below the Australian standard, there is no established scientific evidence to support adverse health effects from RF EMF.

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This was an exposure study analysing ultraviolet radiation (UVR) measurement data collected in Germany from nine monitoring stations over ten years. The authors used the measurement data to explore the potential for receiving UV doses that would lead to erythema (sunburn) for fair skin (Fitzpatrick skin type II) people on days where the ultraviolet index (UVI) had a median value of 2 or less. Current UV protection advice given by the World Health Organisation (WHO) states that no protection is needed when the UVI is under 3. The authors reported that on days with UVIs of 1 or 2, sunburn could occur in a matter of hours around solar noon in summer and was also possible in winter over a longer exposure period.

The authors pointed to some limitations in the exposure and dose assessments within the study. These included comparing human exposure to the horizontally oriented flat design of the UV detectors, assigning the dose needed for sunburn to fair skin people without taking account variations within this group and not allowing for higher resistance to erythema caused by previous exposure. However, the largest uncertainty was around human exposure caused by individual behaviour in regard to aspects like clothing, shade and indoor activities. 

Erythemal UV Radiation on Days with Low UV Index Values—an Analysis of Data from the German Solar UV Monitoring Network over a T

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The large dataset analysed in this study was a key strength in being able to categorise UV exposure over a long period of time and account for seasonal variability. Despite some of the limitations described by the authors, the study showed that, at least theoretically, sunburn could occur when the UVI is below 3 during extended periods outdoors. Although the WHO and leading radiation bodies such as ARPANSA apply the UVI model to communicate risk for solar UV protection, Cancer Council Australia has recently recommended that the application of sunscreen should be part of everyone’s daily routine if the UVI is above 3 or for extended periods outdoors at lower UVIs.

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This was a meta-analysis investigating the possible relationship between childhood leukaemia and living near power lines. The study included 4879 cases and 4835 controls. Exposure to power lines was assessed by assessing magnetic field strength and residential distance to power lines. Homes that were determined to be close enough to power lines and of sufficient voltage to have elevated magnetic fields had measurements taken. Additionally, all residences close to power lines over 100 kV had their exposure modelled and calculated. All other residences were considered to be exposed to a magnetic field of less than 0.1 µT. The study found that there was no statistically significant increased risk of childhood leukaemia associated with living within 50 meters of a power line (odds ratio (OR) of 1.44 with a 95% confidence interval (CI) of 0.63 - 3.29) or being exposed to a magnetic field above 0.4 µT (OR of 1.24 with a 95% CI of 0.50 – 3.05). However, when the authors examined participants who lived within 50 meters of 200 kV power lines and had a magnetic field above 0.4 µT, there was an increased risk of childhood leukaemia (OR of 4.06 with a 95% CI of 1.16 – 14.3). The authors concluded that their results suggest magnetic field exposure is not causally related to childhood leukaemia. They further suggest that there could be an unidentified explanation for the possible link between power lines and childhood leukaemia. 
 

Childhood leukemia risk in the California Power Line Study: Magnetic fields versus distance from power lines

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A similar study by Draper et al 2005 also found an association between distance to power lines and a small increased risk of childhood leukaemia. However, Draper et al did not calculate or measure the magnetic field exposure of the included participants. When the Crespi et al study examined exposure to magnetic fields, it was found that elevated exposure alone was not associated with childhood leukaemia. Both authors conclude that their results did not casually link magnetic field exposure to childhood leukaemia. 

The major positive result in the Crespi et al study was limited by a small sample size, as there was only 13 cases and 3 controls who lived within 50 meters from a power line and were exposed to magnetic fields greater than 0.4 µT. The epidemiological and laboratory evidence for an association between childhood leukaemia and magnetic field exposure has been reported as weak and it is not known how magnetic field exposure could cause childhood leukaemia (WHO, 2007).
 

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This was a case-control study in Iran, investigating a possible link between high voltage power lines and female infertility. The study included 462 women with infertility and 471 match controls with no history of infertility. The exposure to the participants was assessed by residential distance to high voltage power lines. The authors reported statistically significant associations between female infertility and high voltage power lines at distances of less than 500 meters (odds ratio (OR) of 4.14 with a 95% confidence interval (CI) of 2.61-6.57) and between 500-1000 meters (OR of 1.61 with a 95% CI of 1.05-2.47). When the results were adjusted for confounders, the association was no longer significant at distances between 500 and 1000 meters (OR of 1.53 with a 95% CI of 0.99 to 2.37). Based on the association at distances of less than 500 metres, the authors concluded that the current safety guidelines for exposure to electric and magnetic fields (EMF) are inadequate to protect people from the hazardous effects of these fields.

Exposure to Electromagnetic Fields of High Voltage Overhead Power Lines and Female Infertility.

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The study suggested that exposure to EMF from high voltage power lines is associated with female infertility. However, the exposure assessment was based on residential distance to high voltage power lines, not by EMF strength. This association was reported when homes were less than 500 meters from power lines. However, at distances over 50 meters, the EMF from high voltage power lines is indistinguishable from typical background levels in the home (Karipidis, 2014). This indicates that exposure to EMF is unlikely to be the cause of the reported association.

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This study was a systematic review and meta-analysis of 12 previously published articles that investigated the risk of melanoma and keratinocyte cancers (KC) in airline pilots and cabin crew. The studies included in the analysis consisted of both retrospective and prospective cohort studies and provided data on both the incidence of these cancers and the resulting mortality as established by death registries, death certificates and physician records. The authors reported that, based on the available evidence, airline pilots and cabin crew had approximately twice the risk of developing melanoma and other skin cancers when compared to the general population. For melanoma incidence the pooled Standardised Incidence Ratio (SIR) was 2.03 (95% Confidence Interval (CI) 1.71-2.40) for airline pilots and 2.12 (95% CI 1.71-2.62) for cabin crew. This was similar for KC in pilots (SIR: 1.86 (95% CI 1.54-2.25) and cabin crew (SIR: 1.97 (95% CI 1.25-2.96). Further, airline pilots were about twice as likely to die from melanoma pooled Standardised Mortality Ratio (SMR) of 1.99 (95% CI 1.17-3.40). This higher mortality rate was not observed in cabin crew. The exposure agents considered as possible explanations for the higher than normal risk factors were occupational ultraviolet radiation (UVR) exposure and cosmic ionising radiation. 

The authors assessed that both pilots and cabin crew were not occupationally exposed to UVR as it was not detectable in the cabin of modern airliners and pilots were exposed to no higher than levels encountered on the ground during their flights. However, the study was not able to take into account recreational UVR exposure. Both pilots and cabin crew are recognised as being the highest exposed occupations to ionising radiation from cosmic rays and in this study this was assessed by measures including duration of employment, type of licence and cumulative flight hours.  Exposure to cosmic radiation, recreational UVR exposure and disruptions in circadian rhythm due to crossing time zones on long haul flights were considered to be potential explanations for the higher risk factors of melanoma and KC within pilots and cabin crew. 

Do airline pilots and cabin crew have raised risks of melanoma and other skin cancers? Systematic review and meta-analysis.

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This review included studies of airline crews where the data was collected mostly between the 1970s to the 1990s, with some data covering the period from 1947. Therefore, the evidence is outdated and the relevance to modern air travel is uncertain. However, the reported higher risk to airline crew of developing skin cancer is a useful indicator for the direction of further research. This research currently includes dose assessments of exposure to cosmic radiation. Further, the recreational solar UVR exposure of airline crew may need to be investigated.
 

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This was a meta-analysis of three cohort studies which investigated the risk of lung cancer mortality to workers exposed to low-level radon in uranium mines. The cohort studies included were from the Czech Republic, France and Canada collectively covering exposure periods from 1953 to 1999. Exposure to workers was assessed by both the concentration of radon in the air and by the length of employment in months. This was then used to derive an exposure unit of working level month (WLM). The study was limited to workers who had received less than 100 WLM in order to investigate low-level effects. The study found was an increased excess relative risk (ERR) risk in lung cancer mortality among workers per WLM of 0.022 (95% confidence interval (CI) of 0.013-0.034). However, the authors report that this risk was no longer statistically significant at an exposure of less than 10 WLM. The authors suggest the higher exposures are compatible with a linear non-threshold model and lower exposures are not. However, the authors state that no conclusion can be made at the low exposures due to the low statistical power.

Low radon exposures and lung cancer risk: joint analysis of the Czech, French, and Beaverlodge cohorts of uranium miners

Low radon exposures and lung cancer risk: joint analysis of the Czech, French, and Beaverlodge cohorts of uranium miners

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This study demonstrates the difficulty of evaluating the risk of lung cancer mortality from low-level exposures to radon. The authors reported that at low radon exposure of less than 10 WLM the risk of lung cancer mortality was no longer significant. A working level month within a uranium mine is approximately equivalent to 10 mSv of dose (ARPANSA, 2019). However, the data by Lane et al showed that this extends further and that at less than 19 WLM there is not a statistically significantly increased risk of lung cancer mortality (1.41 relative risk with a 95% CI of 0.90–2.25). In Australia, RPS C-1 2016 sets out the requirements for the protection of occupationally exposed persons in uranium mines. A number of studies have demonstrated the additional risk of lung cancer from radon exposure is small relative to the risk from tobacco smoking (ICRP, 2010). The best way of reducing the total lung cancer risk, as well as the lung cancer risk from exposure to radon, is to avoid tobacco smoking.