Cancer Incidence in Dakota and Washington Counties
1988 to 2002 & 2003 to 2012
In response to concerns about cancer and the presence of perfluorochemicals (PFCs) in drinking water supplies in the eastern Metro area communities, the Minnesota Department of Health (MDH) has twice examined cancer incidence in Dakota County and Washington County.
MDH released the first report in 2007, which was followed by an updated report in 2015. While community cancer rates have a high degree of statistical uncertainty and must be interpreted cautiously, these reports can be useful to address public concerns over cancer rates in a county or a community by providing a complete and accurate profile of cancer occurrence.
Recent concerns arising from media coverage of the State of Minnesota lawsuit against 3M, prompted MDH to re-examine and expand on the two previous reports of cancer incidence in Washington and Dakota Counties, and eight communities within those counties.
The cancer experience of Dakota and Washington County residents is not unusual compared with the State of Minnesota as a whole. For many cancer types, the number of cancers occurring in the two counties did not differ from the numbers expected.
MDH staff evaluated the two counties separately, across two time periods – 1988 to 2002 and 2003 to 2012. The analysis covered 24 cancer types in males – all cancers combined and 23 specific types, and 26 cancer types in females – all cancers combined and 24 specific types.
Out of the 200 analyses of county cancer rates compared to statewide rates, 173 of the comparisons showed no differences in the rates. County cancer incidence was lower than the statewide rates in 15 analyses and higher than statewide rates in 12 analyses.
The reports also examined cancer incidence for eight communities within the region that had known or potential drinking water contamination. Due to the very small numbers, cancer rates could only be examined for the more common types of cancer. For all eight communities combined, the rate of only one of the 14 types of cancer differed from rates in the Metro area communities overall. That cancer was lower than the Metro area rate.
While these analyses are instructive, the department only examined data for two potential health outcomes: birth outcomes and cancer. MDH has not collected public health data on other types of potential health effects reported in the scientific literature, such as liver and kidney effects, thyroid disease, or immune system changes. While MDH’s water guidance values protect against all of these effects, data on their occurrence in people are not available.
Cancer in Minnesota
Cancers are much more common than most people realize. In Minnesota each year, there are roughly 26,000 new cancer cases. That means about one out of two Minnesotans will be diagnosed with a potentially serious cancer during his or her lifetime.
Cancer is not just one disease, it's more than 100 different diseases. Each cancer has its own traits, progression, risk factors or causes, treatment, and chances of survival. Cancer risk depends greatly on age, lifestyle – smoking, alcohol use, obesity, what you eat or don't eat, amount of exercise, getting too much sun – and on family history of cancer.
Some environmental factors represent a small fraction of cancer risk, including pollution, secondhand smoke, exposure to chemicals at work and radon gas in our homes and workplaces. Even though environmental exposures to contaminants are a smaller contributor to overall cancer risk, we can reduce that risk. MDH supports steps to identify and reduce or eliminate exposures where possible.
Efforts to reduce or eliminate exposures
MDH is responsible for ensuring safe drinking water for all Minnesotans. One way MDH does this is through regular testing of public water supplies for contaminants. MDH also works with the Minnesota Pollution Control Agency (MPCA) to investigate situations where groundwater contaminants may affect private wells.
In addition, MDH develops health-based guidance for drinking water contaminants. The guidance can be in the form of Health-Based Values (HBVs) or Health Risk Limits (HRLs). Visit the MDH webpage for information about Guidance Values and Standards for Contaminants in Drinking Water.
From 2008 to 2014, MDH led a biomonitoring study that tracked blood levels of PFCs in people who live in the East Metro.
The biomonitoring study results show that:
- PFC blood levels are going down in long-term residents who were exposed to PFCs in drinking water before the 2006 public health intervention. That intervention, including installing filtration systems for polluted public and private wells, reduced PFCs in drinking water to below health-based limits.
- PFC levels in newer residents – who moved to Oakdale after the intervention – are similar to levels seen elsewhere in the U.S.
For more information, see East Metro PFC Biomonitoring Follow-up Project
MDH cancer data and surveillance
The Minnesota Cancer Reporting System (MCRS) is Minnesota’s statewide, population-based cancer registry. MCRS systematically collects demographic, diagnostic and treatment information on all Minnesota residents with newly diagnosed cancers.
Annual incidence data for 20 common cancer types are available on MDH’s Public Health Data Access Portal.
Minnesota Cancer Reporting System
- Monitors the occurrence of cancer in Minnesota and describe the risks of developing cancer
- Informs health professionals and educate citizens regarding specific cancer risks
- Answers the public's questions and concerns about cancer
- Promotes cancer research
- Guides decisions about how to target cancer control resources