Why look at public drinking water system monitoring data (other than it is part of Division of Water’s routine job)?
Answer: A series of scientific papers have been published, noting that cancer in the Appalachian Region of the country is due to coal mining and that the source of people’s exposure is their drinking water. Specifically, cancer is the result of the presence of arsenic and chromium in their drinking water. This cause-effect contention has been picked-up by regional groups such as the Appalachian Community Cancer Network Annual Reports and of course the news media.
We compiled monitoring data from the 519 facilities statewide for the years 2000-2012 (January 2000 to January 2012). This included information on from very small facilities (6 people) to large facilities such as Louisville (730,000+) and on the commercial bottled water facilities (such as High Bridge Spring Water). Results on levels of arsenic, chromium, antimony, barium, beryllium, cadmium, mercury, selenium and thallium from some 3,081 samples were evaluated. Arsenic and chromium are the only two carcinogens in the group. These nine metals are the pollutants for which national standards are available, maximum contaminant levels (MCLs), determining safe levels in drinking water.
The results of our evaluation produced unambiguous conclusions. Since all of the arsenic and chromium samples were below the safe level from all facilities statewide and in fact were below the analytical detection limit for arsenic and chromium, the conclusion is clear. Arsenic and chromium in public drinking water in the state, including Appalachian Kentucky, did not contribute to the cancer incidence during the twelve years. Since the seven non-carcinogenic metals monitored were also below their respective MCLs, other health effects that could result from drinking water exposures to those pollutants also were not indicated.
Why did we look only at the twelve years from 2000-2012?
Answer: The monitoring and reporting from some of the drinking water facilities prior to 2000 were inconsistent with regards to the MCLs. Rather than providing the actual analytical results they may have just indicated whether they had an MCL violation or not, after 2000 they provided the actual monitoring results. We stopped compiling the monitoring data at the end of 2011 and began evaluating it at that time. Since cancer was the primary concern, we looked to the reported information for Kentucky. In 2000, the Kentucky Cancer Registry (KCR) was selected as one of four expansion registries to become part of the National Cancer Institute’s Surveillance Epidemiology and End Results (SEER) program. The SEER registries are considered to be among the most accurate and complete population-based cancer registries in the world. Funding from the SEER program allowed KCR to further expand its quality control of activities and gather complete follow-up information.
Why look at cancer incidence and mortality in the regions of Kentucky?
Answer: One of the statements made and repeated from those scientific papers was that cancer incidence and mortality was greater in the coal producing regions of Kentucky (Eastern Coal Field, Western Coal Field) than other regions of Kentucky, such as the Bluegrass. It was further noted that this was related to environmental exposures of residents in these coal mining regions that other residents in other regions did not receive.
We pulled the cancer incidence and cancer mortality data from the Kentucky Cancer Registry for the years that were available between 2000 and 2012, namely the 10 years from 2000 to 2009. The data was grouped by counties within the regions (Eastern Coal Fields, Western Coal Fields, Bluegrass, Mississippi Plateau [Pennyrile], and Jackson Purchase). Some of the counties had portions that were in two regions and were put in the region that included most of the county.
The results of the regional grouping were compared and the cancer incidence rate, over the ten years, was not significantly different among the five regions. Environmental exposures were not significantly greater in the coal mining regions as compared to the non-coal mining regions, or at least to a level that was resulting in a greater cancer incidence. The cancer mortality rate was significantly higher in the Eastern Coal Field region and significantly lower in the Jackson Purchase region counties than the other regions. We did not speculate as to why the mortality rate was higher or lower. Cancer is known to have a latency period before it shows-up. It sometimes takes years of exposure before someone gets cancer, so the incidence rate and mortality rate may reflect twenty years or more of exposure.
Why did we consider coal production and cancer incidence and mortality rate?
Answer: One of the conclusions noted in the studies on coal mining and cancer was that the greater the amount of coal mining activity in an area the greater the risk of developing cancer. Since we did not see a difference in cancer incidence between coal mining and non-coal mining areas across Kentucky, we further considered if greater coal production equated to greater risk within the coal producing regions. The cancer incidence and mortality in the counties that produced the most coal over the ten years for which cancer info was collected were compared to the counties that had the lowest coal production.
The results of comparing the highest coal producing to the lowest coal producing counties indicated no significant difference in cancer incidence or mortality. High coal production did not appear to be a predictor of cancer incidence rate nor mortality rate.
This study was by no means designed to answer all the questions about cancer incidence and mortality nor as to why Kentucky has been reported to have some of the highest cancer rates of any of the states, and to why the Appalachian region states in general have higher cancer rates. We do believe, and the monitoring data support that belief, that the drinking water available to most of our citizens (95%+ on public drinking water systems) is safe to drink, and it is free from carcinogenic levels of arsenic and chromium.
Click on this link to read KY DOW Study Reveals Metals Not Detected in Public Drinking Water; No Correlation to Cancer Incidents in KY.