06-02-2016, 02:13 PM
Some quotes from the published study:
"In these communities, geothermal water has been used for domestic and greenhouse heating, laundry, bathing, showering, and washing, in spas and swimming pools."
"The causes are unknown for the higher HRs (Hazard Ratio) of many cancer sites in the present study, which are related to length of cumulative residence in the study areas. In reflection on this, it is difficult to explain the risk for the different cancer sites by a single component of the ground gas emission in the geothermal area, or traces of chemicals in the geothermal water. When considering the classification of human carcinogens according to the International Agency for Research on Cancer [45], two carcinogens in particular i.e. As and Rn come to mind, as these have been mentioned in previous studies on cancer risk among populations in geothermal areas. A recent mortality study in an old volcanic area provided evidence of association of low dose (below 10 ppb) As in drinking water and cancer risk [46], and in a case-control study a positive association between BCC and a low dose exposure to As was found [47]. The concentrations of As in geothermal well water used for bathing in the geothermal heating area range from 11 to 116 ppb [48], and should be contrasted to < 0.3 ppb in water used for bathing in the cold reference area [49, 50]. According to a recent nation-wide survey of indoor Rn concentration in Iceland, a mean of 13 Bq/m3 is among the lowest in the world [51]. Nevertheless the amount of Rn in the geothermal water in the geothermal heating area (9 Bq/l) (used for bathing) [10] is approximately four times the amount of Rn in water used for bathing in the cold reference area (approximately 1.5 Bq/l) [49, 50]. The role of these differences in concentrations is unknown; bearing in mind that dermal exposure may in this situation be of greater importance than exposure through inhalation or ingestion."
In this study, as in all studies, the devil is in the details. Intensity of exposure (to what), duration of exposure, and mode of exposure are all important considerations. If these folks are drinking well water having as much as ten times the EPA permitted arsenic levels in drinking water, then a higher incidence of cancer is not too surprising (neither would be other effects of excess exposure to As). As noted, too, dermal exposure to high levels of arsenic are also related to higher incidences of cancer.
It would have been interesting to see how the indoor radon/radon daughter product levels compared between the geothermaly heated and non-geothermaly heated homes; if the geothermal water used for heating was venting its dissolved gases indoors (which would be occurring in any event for hot water uses of washing/bathing, laundry, and other indoor domestic uses) then you would have an ideal situation (with a tightly constructed home with low air exchange rates) for exposure to radon daughter products which are associated with increased lung cancer. (although not widely recognized outside the field, radon itself isn't the lung cancer threat, it is the radon daughter products that can be inhaled and stick to the lung tissue where they continue to decay and irradiate the underlying tissue. Hence, lung cancer threat is a two step process - access of radon to indoor air, and a long enough residency for significant amounts to convert to radon daughters...).
As long as you are not secretly piping PGV's reinjection water into your house for heating/washing/drinking, then the relevance of these findings to Leilani estates and other communities around PGV, are pretty tenuous.
If you want to read the publication from which the above quotes were drawn, this is the link that I used:
http://journals.plos.org/plosone/article...ne.0155922
"In these communities, geothermal water has been used for domestic and greenhouse heating, laundry, bathing, showering, and washing, in spas and swimming pools."
"The causes are unknown for the higher HRs (Hazard Ratio) of many cancer sites in the present study, which are related to length of cumulative residence in the study areas. In reflection on this, it is difficult to explain the risk for the different cancer sites by a single component of the ground gas emission in the geothermal area, or traces of chemicals in the geothermal water. When considering the classification of human carcinogens according to the International Agency for Research on Cancer [45], two carcinogens in particular i.e. As and Rn come to mind, as these have been mentioned in previous studies on cancer risk among populations in geothermal areas. A recent mortality study in an old volcanic area provided evidence of association of low dose (below 10 ppb) As in drinking water and cancer risk [46], and in a case-control study a positive association between BCC and a low dose exposure to As was found [47]. The concentrations of As in geothermal well water used for bathing in the geothermal heating area range from 11 to 116 ppb [48], and should be contrasted to < 0.3 ppb in water used for bathing in the cold reference area [49, 50]. According to a recent nation-wide survey of indoor Rn concentration in Iceland, a mean of 13 Bq/m3 is among the lowest in the world [51]. Nevertheless the amount of Rn in the geothermal water in the geothermal heating area (9 Bq/l) (used for bathing) [10] is approximately four times the amount of Rn in water used for bathing in the cold reference area (approximately 1.5 Bq/l) [49, 50]. The role of these differences in concentrations is unknown; bearing in mind that dermal exposure may in this situation be of greater importance than exposure through inhalation or ingestion."
In this study, as in all studies, the devil is in the details. Intensity of exposure (to what), duration of exposure, and mode of exposure are all important considerations. If these folks are drinking well water having as much as ten times the EPA permitted arsenic levels in drinking water, then a higher incidence of cancer is not too surprising (neither would be other effects of excess exposure to As). As noted, too, dermal exposure to high levels of arsenic are also related to higher incidences of cancer.
It would have been interesting to see how the indoor radon/radon daughter product levels compared between the geothermaly heated and non-geothermaly heated homes; if the geothermal water used for heating was venting its dissolved gases indoors (which would be occurring in any event for hot water uses of washing/bathing, laundry, and other indoor domestic uses) then you would have an ideal situation (with a tightly constructed home with low air exchange rates) for exposure to radon daughter products which are associated with increased lung cancer. (although not widely recognized outside the field, radon itself isn't the lung cancer threat, it is the radon daughter products that can be inhaled and stick to the lung tissue where they continue to decay and irradiate the underlying tissue. Hence, lung cancer threat is a two step process - access of radon to indoor air, and a long enough residency for significant amounts to convert to radon daughters...).
As long as you are not secretly piping PGV's reinjection water into your house for heating/washing/drinking, then the relevance of these findings to Leilani estates and other communities around PGV, are pretty tenuous.
If you want to read the publication from which the above quotes were drawn, this is the link that I used:
http://journals.plos.org/plosone/article...ne.0155922