Radiation literature survey

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This study, by Smith-Roe et al, is part of the National Toxicology Program’s (NTP) investigation of the effects radio waves, also called radiofrequency electromagnetic fields, have on rats and mice. This study examined possible genotoxic effects on a separate sample of rats and mice that were exposed for a shorter time period as part of the NTP study. The animals were exposed to radio waves at certain frequencies used by mobile phone networks (CDMA or GSM) for 9 hours a day at levels of up to 10 watts per kilogram (W/kg) over a period of up to 19 weeks. The study specifically reported on DNA damage within the tissues of the animals examined. The authors reported a statistically significant increase in levels of DNA damage in the frontal cortex of male rats and mice and in the hippocampus of male rats. Only the CDMA-modulated exposed rats had statistically significant levels of DNA damage for both tissue regions. Further, the study concluded there was variable levels of DNA damage observed. Overall, for female rats and mice, the study did not report any consistent statistically significant results.

Evaluation of the genotoxicity of cell phone radiofrequency radiation in male and female rats and mice following subchronic exposure.

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In 2018, the NTP released their final reports, which investigated whether exposure to radio waves causes any health effects, including cancer, in rats and mice. An assessment of the results from the NTP study reports in their entirety have previously been provided by ARPANSA and the International Commission on Non-ionizing Radiation Protection (ICNIRP). 

The study by Smith-Roe et al reports certain genotoxic effects related to radio waves at very high exposure levels, however the effects were inconsistent across rats and mice, males and females, and type of radio wave exposure (GSM or CDMA). There is no explanation for these variations in the results across species, gender and type of radio waves. 

It is possible that that the reported effects occurred due to the high exposure levels. It is known that exposure to sufficiently high level radio waves can heat biological tissue and potentially cause tissue damage. It is also possible that the reported effects occurred due to chance. This is because the study conducted a number of different tests and, statistically, a positive result is always possible with multiple tests. This is often called the multiple comparisons or multiple testing problem.

In Australia, the safety standard for radio waves developed by ARPANSA sets mobile phone limits at 0.08W/kg for whole body and 2 W/kg for localised exposure. Most mobile phones produce exposures well below the limit. This makes it difficult to relate the high radio wave exposures of the animals in this study to the much lower exposure when people are using mobile phones. There have been many proposals for how radio waves, below the current exposure limits, could induce DNA damage in cells, however, there remains no proven mechanism for this effect or consistent results to confirm that it occurs. Overall, the study by Smith-Roe et al does not demonstrate consistent DNA damage across species, genders, or for types of radio waves and this could indicate that there is no common mechanism causing DNA damage (Fedak, 2015). 

ARPANSA‘s safety standard is based on scientific research that shows the levels at which harmful effects occur and it sets limits, based on international guidelines, well below these harmful levels to provide a high level of protection to the public. Overall, the limitations in the results by Smith-Roe et al do not provide sufficient evidence to justify a change in the current safety limits for radio wave exposures set within the standard. 
 

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This is a measurement study of radiofrequency (RF) electromagnetic field (EMF) exposure around small cell base station sites. With the proliferation of new mobile technology to meet increased demand, small cells play an important role in high density urban areas. The paper reported that measurements were conducted at 295 positions around 98 small cell sites in South Africa, the Netherlands and Italy. The measured exposure levels were then compared with exposure guidelines set by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the results of other EMF surveys. The maximum EMF exposure recorded was less than 4% of the ICNIRP general public limit. These results were in agreement with other surveys.

Measurement of EMF exposure around small cell base station sites

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ARPANSA has conducted similar measurements around macro mobile phone base stations and published the results on the ARPANSA website. In 2017, ARPANSA published a study assessing the RF EMF exposure level due to Wi-Fi in Australian schools. Exposure levels from other RF sources such as mobile phone base stations, radio, and TV broadcasts were also measured. Overall, the exposure levels from all RF sources measured were much lower than the public exposure limits in the Australian RF standard.

This exposure study by Wyk et al. is one of few studies that have been performed around small cell base station sites. These sites are predominantly deployed inside shopping centres, on street lamp posts, bus stops etc. which improves capacity and coverage. As the small cell sites are widely visible and closer to sensitive areas, there has been increased concern from the general public regarding the EMF exposure from these sites, which this study has attempted to address. Small cell sites, which transmit less power have also been proposed as a possible replacement for macro base stations in future 5G network infrastructure, which will require a high base station density. Overall, the paper reported that the measured exposure levels were much lower than the Australian and international general public exposure limits.

Finally, it is noted that an internationally approved measurement protocol was used in this study and the measurements were conducted during the busiest time of the day while steps were taken to minimise interference to the measurement instruments.
 

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This was a cohort study investigating the incidence of cancer among 83,284 UK electricity generation and transmission workers from 1973 to 2015. Electricity generation and transmission workers are often exposed to higher than normal levels of extremely low frequency (ELF) electric and magnetic fields (EMF) The study found statistically significant increases in the occurrence of mesothelioma and skin cancer and a statistically significant decrease in the occurrence of lung cancer. The author indicated that the increase in mesothelioma and skin cancer in the cohort could be explained by the past use of asbestos in the industry and the prevalence of outdoor work, respectively. Further, the author speculated that the reduction in lung cancer was due to a decrease of smokers in the industry; however, there was no smoking data collected from the cohort. The author concluded that the results support the need for protection of workers from asbestos and solar UV exposure. Further, the author states that the results suggest that the current protections for EMF exposure are adequate.  

Cancer incidence in UK electricity generation and transmission workers, 1973–2015

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There have been numerous previous studies that have investigated whether occupational exposure to ELF EMF causes cancer and especially breast cancer. In 2007, the World Health Organisation (WHO) reviewed in detail the risk of cancer from occupational exposure to ELF EMF. The review concluded no established evidence between occupational ELF EMF exposure and breast cancer or other cancers. This conclusion from WHO is in agreement with outcomes from the UK electricity generation and transmission workers cohort with Sorahan stating that of the 11 papers that have been previously published on this cohort no convincing links between magnetic fields and the examined health outcomes have been found. Two Australian studies by Karipidis et al (2007a and 2007b) reported no increased risk of glioma or non-Hodgkin lymphoma from workers exposed to ELF EMF. 

The current study by Sorahan also showed the importance of protecting workers from the harmful effects of the sun. Australia 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. 

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The International Agency for Research on Cancer (IARC) is part of the World Health Organization (WHO) and is responsible for assessing and classifying agents for their potential to cause cancer in humans. Initially, IARC was formed to classify the carcinogenicity of chemicals; however, the scope has since broadened to other agents including complex mixtures, physical agents (which includes radiation), biological organisms, pharmaceuticals, and other exposures. Expert working groups are set up to examine and classify the cancer risk of the agents being assessed. A preamble outlines the requirements of the identification, assessment and classification process. The preamble describes how a working group should gather and assess the evidence of carcinogenicity of the agent being considered and the role of the participants. Further, the preamble is also designed to promote transparency surrounding the evaluation process so the scientific community and the public can understand the decision of the working group.

The first part of the preamble characterises the exposure to the agent including descriptions of the physical quantities of the agent and the exposure scenarios in the environment. This part also includes a discussion of current regulations and a critical review of the exposure assessment in key epidemiological studies. There are three major categories used to examine the evidence of carcinogenicity. These categories include:

• carcinogenicity in humans
• carcinogenicity in experimental animals
• mechanistic evidence

A working group aims to thoroughly research and evaluate the available evidence of cancer risk from an agent within these categories.  

The final section of the preamble is an overall evaluation that discusses the evidence assessed and places the agent in set risk categories. The risk categories currently include:

• Group 1 - the agent is carcinogenic to humans
• Group 2A -the agent is probably carcinogenic to humans
• Group 2B - the agent is possibly carcinogenic to humans 
• Group 3 -the agent is not classifiable as to its carcinogenicity to humans

Recently IARC have updated the preamble for classifying carcinogenicity (IARC, 2019). The evaluation process in the reviewed 2019 IARC preamble has some key changes to its last revision in 2006 (IARC, 2006). One key change to the preamble is a strengthening of the evaluation process to make it more prescribed, for example, assessing the quality of the studies has been broken into seven well-described parts. This refining of the assessment methodology should increase the consistency and transparency of the evaluation process. Another key change is the addition of a table by Smith et al, 2016 describing key characteristics of an established carcinogen that can be used to help evaluate the mechanistic evidence. A small change was the removal of the group 4 classification, which was used to classify an agent as probably not carcinogenic to humans. This implies that IARC classifications now only include agents that have been confirmed as carcinogenic or display varying degrees of evidence and are still being assessed.

IARC has to date classified the carcinogenicity of over a thousand agents. The identification of an agent as carcinogenic may have a significant impact on society or the processes that result in exposure to the agent. Further, IARC’s classification does not include an assessment of exposure levels. Consequently, there is no consideration of dose or exposure level to which an agent begins to be carcinogenic. Therefore, the assessment is limited to whether the agent is or is not carcinogenic. This means that, with the appropriate control mechanisms, exposure to an agent may be possible with minimal risk of harm.

In 2013, IARC examined the evidence of carcinogenesis from radiofrequency electromagnetic fields. The results of the assessment were published in the IARC monograph “Non-ionising Radiation Part 2: radiofrequency electromagnetic fields Volume 102”. The overall evaluation found that radiofrequency electromagnetic fields are possibly carcinogenic to humans (Group 2B). This decision was based on limited evidence from epidemiological studies, which showed an increased risk of brain tumours among heavy mobile phone users. IARC noted at the time of the decision that the occupational and environmental exposures provided inadequate evidence of a cancer risk.

Periodically an IARC advisory group meet to make recommendations for what agents should be evaluated or re-examined for their carcinogenicity. In March 2019, recommendations for evaluations to be conducted in the 2020-2024 period were published in the Lancet Oncology journal. The list of recommendations included a re-assessment of radiofrequency electromagnetic fields (IARC, 2019). The rational for this re-evaluation was stated by IARC to be new bioassay and mechanistic evidence.

IARC Monographs Preamble

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ARPANSA fully supports the work of IARC and the revision of its preamble as it increases the transparency of the scientific evaluation process.

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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.