April 16, 2012
Further review of Fridley area cancer data shows overall cancers rate is 7.6 percent, not 10 percent, above state average
Lung cancer rate remains major concern at 30 percent higher; 49 percent among women
The rate at which all types of cancers occur in the Fridley area, compared to the rest of the state, is 2.4 percentage points lower than officials originally thought, based on a more comprehensive analysis of data by the Minnesota Department of Health (MDH). The area’s lung cancer rate remained high.
The department first looked at data on cancers in the Fridley area several weeks ago after receiving a request from a Fridley resident who was concerned about an apparent excess of cancers in the community. That initial look at the data indicated that the number of all cancers was about 10 percent higher than the rest of the state, or what would be expected for a population the size of Fridley. But a closer, more thorough analysis of the data reveals that the rate is more accurately 7.6 percent above expected, according to John Soler, MDH cancer epidemiologist.
For the period 2000-2009, the number of observed cancers in the community was 1,529 and the expected number is 1,421. Previously, those numbers were 1,537and 1,402 respectively. Several factors account for the changes in the numbers, Soler said:
- The number of expected cases went up because the statewide average increased after completion of a data review found more statewide cases for 2009.
- The number of observed cancers went down slightly as Soler used corrected addresses for cases, making sure those who were counted actually lived in the seven census tracts of Fridley.
It’s not unusual to find communities that have a rate of cancer five to 10 percent above expected and as many that are five to 10 percent below expected, especially when one of the main cancer types is well above or below average rates, Soler said.
Fridley’s elevated overall cancer rate appears to be due largely to its high lung cancer rate, Soler said. It was the highest of any type of cancer at 30 percent above expected; the rate is 49 percent higher for women alone. The next highest rates for any type of cancer were bladder at 17 percent and leukemias at 17 percent, however these are based on smaller numbers.
“While we don’t have data to tell us exactly what is causing lung cancer in the community, we do know that the primary cause of lung cancer in the United States is smoking,” Soler said. “We also know that Anoka County’s smoking rate is relatively high.” According to a 2010 metropolitan area adult survey, Anoka’s smoking rate is 23.3 percent, the highest of any of the six counties in the survey, Anoka, Carver, Dakota, Ramsey, Scott and Washington. The next highest was Ramsey County at 15.7 percent. Minnesota’s overall smoking rate is 16.1 percent.
“We don’t know whether all those who had lung cancer in Fridley were smokers, but we can infer that smoking plays an important role in the elevated lung cancer rates in the community,” Soler said. Smoking has also been linked with other forms of cancer, such as bladder and some leukemias.
Fridley’s elevated lung cancer rate is similar to that of Anoka County as a whole. For the period 2004-2008, MCSS data shows a 15 percent higher incidence for men and a 27 percent higher incidence for women. Historically, Anoka County has had higher rates of lung cancer. For the period 1988-1993, lung cancer was nine percent higher in males, 39 percent higher in females.
“Past smoking history is the only known risk factor that could be driving such large excesses of lung cancer,” Soler said. “While other things, such as radon and occupational exposures, do cause lung cancer, their relative contribution to overall lung cancer rates is considerably less than smoking, which drives the rates of any community.”
Trying to attribute cancers in any community to possible environmental exposures is very difficult, Soler said, because of the extreme mobility of the U.S. population and the fact that most adult cancers take many years, even decades, to develop. Fridley is no exception, according to U.S. Census Bureau data. Many Fridley residents have lived there less than five years. Nevertheless, because of concerns people have expressed, MDH reviewed data on possible sources of environmental exposure.
Some in the community have pointed to several Superfund sites in the Fridley area as possible sources of exposure to contaminated water, soil or air. However, environmental specialists from MDH and the Minnesota Pollution Control Agency (MPCA) say there is no evidence to suggest that people are being exposed to anything in the environment that could lead to elevated cancer risk.
Regular monitoring of Fridley’s drinking water system has found no evidence of contaminants exceeding levels of health concern. “In the treated water that comes out of everyone’s tap, detections of trichloroethylene (TCE) have been well under the limit set by the Environmental Protection Agency,” said Karla Peterson, a supervisor with MDH’s Drinking Water Protection program. “These limits, or Maximum Contaminant Levels (MCLs), are very protective of health. Even if they were exceeded for a short time, that likely would not result in a health effect, as the limits are based on long-term exposure.”
Detections of contaminants in drinking water are reported every year by Fridley in the water quality report it sends to its residents. Although MDH has sometimes found trace levels of TCE, the city has never exceeded the standard set by the EPA.
Similarly, routine monitoring required and overseen by the U.S. Environmental Protection Agency and the MPCA at the federal and state Superfund sites in Fridley indicate there are no known human health exposures from contaminated soils, vapor and groundwater.
The MPCA says Fridley’s air quality is similar to that of other suburbs near the I-494/I-694 loop, and slightly better than that in the core parts of Minneapolis and St. Paul. In addition, the MPCA has not seen air pollutant levels above a federal or state standard at either of its air monitors closest to Fridley.
Naturally-occurring radon is the second leading cause of lung cancer in the U.S. Data from homeowners who have tested their homes for radon also does not suggest anything unusual occurring in the Fridley area, according to MDH indoor air specialists. Of the 1,100 tests on record with MDH, only 280 exceeded four pCi/L (picocuries per liter), the level of health concern. That is well below the metro average of 48 percent above four pCi/L. However, there could be homes that have not been tested that have high levels of radon that pose health risks, said Josh Miller, radon specialist with MDH.
It’s understandable that people in the Fridley area can identify many fellow residents who have or had cancer, Soler said. “Cancer is actually more common than people often assume. Nearly 50 percent of Minnesotans will be diagnosed with cancer, given current rates and medical practice,” he said. It’s also true that as we get older, we are more likely to know many contemporaries who have cancer.
The good news is that there are things people can do to lower their cancer risk, such as:
- Abstaining from smoking or other tobacco use.
- Eating a proper diet and getting adequate exercise.
- Getting screened for cancer based on your doctor’s advice.
- Getting vaccinated for viruses leading to cancer (such as HPV).
- Getting your home tested for radon and taking steps to reduce radon levels if necessary.
- Protecting yourself from excessive sun exposure.
MN Cancer Surveillance System