The International Agency for Research on Cancer (IARC) at the World Health Organization (WHO) categorized radiofrequency (RF) as a possible human carcinogen, Group 2B in 2011. Studies have shown that during use of the handheld wireless phone, the thyroid gland is a target organ. The incidence of thyroid cancer has been increasing in many countries, particularly in the 21st century. A study using the Swedish Cancer Register found that the incidence of thyroid cancer increased statistically significantly in women, with an average annual percentage change (AAPC) of +2.13% during 1970-2017, and +9.65% during 2010-2017. In men, the AAPC increased by +1.49% during 1970-2017, with the highest increase found during 2001-2017 with APC +5.26%. Similar results were found in all Nordic countries, with APC +5.83% in women and +5.48% in men from 2005 to 2016 based on NORDCAN. The increasing incidence was similar for tumors less than 4 cm and tumors greater than 4 cm, indicating that the increase cannot be explained by overdiagnosis. These results are in agreement with recent studies that have shown an increased thyroid cancer risk associated with the use of mobile phones. It is postulated that RF radiation is a causative factor for the increasing thyroid cancer incidence.
Two studies suggest that non-ionizing electromagnetic radiation (NIER) at mobile phone frequency may have a potential carcinogenic effect on human thyroid cells. The first study found that exposure to NIER for 3 hours led to an increased proliferation of thyrocytes in a cell viability assay, and this result was confirmed by immunohistochemistry with antibodies against Ki67. The second study used a diathermy model on laboratory rats and found that radiation exposure at 2.45 GHz led to changes in thyroid morphology and expression of heat shock proteins (HSP-90) in the thyroid gland. However, another study found that different evaluated RFE exposure conditions had no potential carcinogenic effect on thyroid cells. They found that proliferation and cellular DNA integrity, two major players in cancer development and progression, were not affected in their conditions. Moreover, common biomarkers that are usually associated with environmental stress also remained unchanged after RFE irradiation. Additional research is needed to fully understand the potential effects of non-ionizing electromagnetic radiation on the thyroid gland.
Cancer risk in firefighters may be caused by exposure to radiofrequency radiation
The study by Milham suggests that some of the increased cancer risk in firefighters may be caused by exposure to radiofrequency radiation (RFR) from mobile two-way radio communications devices and firehouse and fire vehicle radio transmitters. The study argues that this is consistent with the increased risk of certain cancers in workers exposed to electromagnetic fields and RFR, and suggests that the precautionary principle should be applied to reduce the risk of cancer in firefighters.
Another study found that mobile phone use in healthy individuals can cause alterations in the levels of thyroid-stimulating hormone (TSH) and thyroid hormones. The study found that the TSH level increased significantly in the group of participants who used mobile phones for 30 minutes, and suggests that mobile phone use may cause thyroid dysfunction. However, it is important to note that this study had a small sample size and further research is needed to confirm these findings and to understand the potential effects of mobile phone use on the thyroid gland.
In conclusion, it is important for firefighters to be aware of the potential negative effects of cell phone radiation on their thyroid health. Studies have shown a correlation between radiation exposure and thyroid dysfunction among cell phone users, as well as an increased risk of a certain sub-type of thyroid cancer called microcarcinoma in individuals who have used cell phones for prolonged periods of time.