There is a connection between cancer and lengthy habitation in municipalities that use geothermal water. This is revealed a new study conducted by Aðalbjörg Kristbjörnsdóttir, a doctoral student in public health sciences at the University of Iceland; Thor Aspelund, a professor at the Faculty of Medicine, and Vilhjálmur Rafnsson, professor emeritus at the Faculty of Medicine. An article on the study has been published in the science journal PLOS One.
Aðalbjörg and Vilhjálmur have been studying the connection between cancer rates and habitation near active volcanic and geothermal areas where all kinds of chemicals are released from the earth or from hot springs, such as carbonic acid, hydrogen sulphide, hydrogen, radon, sulphuric acid, and hydrogen fluoride. Other significant chemicals include arsenic, lead, and mercury. International research scientists have conducted similar studies and considered whether there is a cancer risk involved in living in geothermal and volcanic areas.
The aim of the study discussed in PLOS One was to examine whether lengthy residence in geothermal areas, whose inhabitants have used geothermal water to heat their houses, wash their clothes and bathe, was connected to cancer risk. Possible confounding factors were evaluated or eliminated with various known research methods.
The main results of the study were that there is an increased risk of cancer in geothermal areas compared with the populations in warm and cold reference areas. This was the case for most cancers; such as for pancreatic cancer, breast cancer, prostate cancer, kidney cancer, lymphoid and haematopoietic tissue, non-Hodgkin´s lymphoma, and basal cell carcinoma of the skin.
Furthermore, the cancer rates were higher in the geothermal area when the length of residences was factored into the comparison. Cancer rates were also connected to the stages of the geothermal and volcanic activity in the areas in that the more activity and older heating utility, the more the risk.
The cohort obtained from the census in 1981 was followed to the end of 2013. Personal identifiers were used to record linkage with nation-wide emigration, death, and cancer registries. The exposed population, defined by community codes, was located on young bedrock and had utilised geothermal water supply systems since 1972. Two reference populations were located by community codes on older bedrock or had not utilised geothermal water supply systems for as long a period as had the exposed population.
The populations in the area of the capital, Reykjavik, and the adjacent Reykjanes area were not included in the study in order to avoid bias due to capital effect.
Researchers do not know the cause of this high cancer rate. It is now more urgent than before to investigate the chemical and physical content of the geothermal water and of the ambient air of the areas to detect recognized or new carcinogens. If carcinogens are found, or other causal factors, it is important to take preventive measures.
Aðalbjög, Thor and Vilhjálmur's article can be accessed on PLOS One: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0155922#sec012.