Incidence of Malignant Mesothelioma

chest xrayMesothelioma is a rare and usually fatal cancer of the lining of the chest (pleura) or abdomen (peritoneum).  The great majority of cases are attributable to asbestos exposure in the workplace, although some cases have been associated with environmental exposures.  In contrast to lung cancer -- another cancer that can be caused by asbestos -- mesothelioma is not associated with smoking. While many occupations have had potential exposure to asbestos and are an increased risk of mesothelioma, occupations categorized as high risk include plumbers, pipefitters, steamfitters, electricians, shipyard workers, railroad workers, and construction workers. 

Mesothelioma has a long latency period, typically occurring 20 to 50 years after asbestos exposure (see figure below).  The median age at diagnosis in Minnesota is 72 for both males and females, while the age range is from 26 to 97.  Mesothelioma rates in Minnesota are over four-fold higher in males than females, reflecting differences in past employment in industries and occupations with asbestos exposure. Family members of asbestos-exposed workers may be exposed through clothing or footwear contaminated with asbestos fibers. 

Minnesota Issues

Taconite pellets from iron ore mining and processing, ready for shipment to steel mills.Concerns about mesothelioma risk in Minnesota have primarily focused on several industries and communities in northeastern (NE) Minnesota.  A two-fold excess of mesothelioma among males in that region (seven-county “Arrowhead” region) was identified in a 1997 analysis of cancer rates and trends. Two of the NE counties are among the highest 25 counties in the U.S. for mesothelioma mortality rates for 2000-2009. Carlton County ranks 3rd highest with an age-adjusted annual rate of 55.1 deaths per million (age 15 and above) population while St. Louis County ranks 21st with a rate of 25.1 deaths per million (age 15 and above). The U.S. average during that period was 11.1 mesothelioma deaths per million (age 15 and above). Subsequent analyses and record-linkage studies using existing employee records identified mesothelioma cases among employees of two large NE industries: the Minnesota taconite (iron ore) mining industry and a ceiling-tile manufacturing plant (Conwed) in Carlton County that used asbestos from 1958 to 1974 as a component of the tiles. Mesothelioma cases among taconite miners had not been previously documented prior to the 2003 MDH report. Those studies and reports can be found on the Reports page under Respiratory Disease at this web site.  State-funded studies of mesothelioma and other health outcomes among Minnesota taconite miners have been underway since 2008 by the University of Minnesota School of Public Health and final results were announced in December 2014. Information about that investigation can be found at the Minnesota Taconite Workers Health Study page. The most recent analysis conducted in January 2015 identified additional mesothelioma cases among taconite miners and former Conwed ceiling tile workers, bringing the total known cases to 101 among 69,000 miners and 39 among 5,200 Conwed Workers (MDH News Release, February 17, 2015).

Mesothelioma Rates and Trends

This indicator is based on data from the Minnesota Cancer Surveillance System (MCSS) at the Minnesota Department of Health (MDH).  The MCSS is a state-cancer registry that collects information on all newly-diagnosed cancers (cancer incidence) among state residents. All cases between the years 2000 and 2010 residing in the state of Minnesota were counted for the indicator. Additional years of data from MCSS are also shown when examining longer term trends. For comparison, data from three additional sources are shown: national mortality data for mesothelioma, state mortality data, and cancer incidence data from 13 other cancer registries in the U.S. that have been part of the U.S. SEER program since 1992 or earlier.

U.S. Annual Asbestos Consumption 1910-2012 and Mesothelioma Incidence Rates, Males and Females, All Races, 1975-2011 From Nine U.S. Cancer Registries (NCI SEER Program)

This figure shows the tonnage of asbestos used annual between 1910 and 2012 in the United States with the incidence of mesothelioma among males and females between 1975 and 2011 overlayed to demonstrate the delay in disease development after exposure.

Numbers and Age-Adjusted Rates of Mesothelioma Deaths, Minnesota vs U.S., Males and Females 1999-2012 (ages 15 and greater)

Year MN Deaths MN Rate per 100,000 U.S. Deaths US Rate per 100,000
1999 61 1.67 2,481 1.15
2000 59 1.56 2,530 1.15
2001 45 1.18 2,508 1.14
2002 49 1.27 2,573 1.15
2003 72 1.81 2,625 1.16
2004 59 1.49 2,657 1.14
2005 56 1.37 2,701 1.15
2006 70 1.73 2,588 1.08
2007 43 1.02 2,606 1.08
2008 58 1.36 2,709 1.08
2009 72 1.66 2,753 1.07
2010 52 1.21 2,744 1.07
2011 71 1.57 2,832 1.09
2012 74 1.61 2,874 1.07
Data Source: Centers for Disease Control and Prevention Wonder

Mesothelioma Mortality Rates, Minnesota vs U.S., Males and Females 1999-2012

(age 15 and greater)

Rates of mesothelioma in Minnesota and the United States, data in table above

Number of Newly-Diagnosed Mesothelioma Cases in Minnesota, 2000-2012

Year Total Males Females
2000 72 58 14
2001 47 40 7
2002 66 52 14
2003 70 53 17
2004 66 48 18
2005 65 49 16
2006 65 42 23
2007 58 47 11
2008 74 61 13
2009 50 38 12
2010 77 57 20
2011 88 61 27
2012 65 51 14

Annual Number of Incident Mesothelioma Cases in Minnesota, 2000-2012

Annual number of mesothelioma cases in Minnesota between 1988 and 2012

Annual Number of Incident Mesothelioma Cases in Minnesota by Gender, 1988-2012

Number of Mesothelioma cases by gender between 1988 and 2012

Annual Incidence Rate of Mesothelioma in Minnesota and the United States by Gender, 1992-2011

Rate of Mesothelioma cases by gender for MN and the United States between 1992 and 2012

Annual Age-Adjusted Incidence Rates of Mesothelioma among Males by Region, 1992-2012

age adjusted rate of mesothelioma cases for Males in Minnesota, the United States, and the NorthEast region of Minnesota from 1992 to 2012 in three year intervals

Number of Fatal Occupational Injuries Compared to the Number of Mesothelioma Cases, 1991-2012

Number of fatal occupational injuries compared to number of mesothelioma cases annually in Minnesota


A comparison of the number of fatal occupational injuries compared to the number of new mesothelioma cases in Minnesota over the past 20 years demonstrates that the number of individuals newly diagnosed with mesothelioma is very similar to the number of fatal occupational injuries that occur in a year.

Trends

Trend analysis reveals that between the years 2000 to 2009 the incidence rate of malignant mesothelioma in Minnesota has neither increased nor declined.  Despite the dramatic decline in asbestos use in the U.S since the early 1970s (down from 800,000 metric tons in 1973 to 1,100 tons in 2012) and implementation of more protective occupational health standards, asbestos remains present in millions of homes, offices, and industries and represents an ongoing potential exposure hazard to both workers and the public.  The continued tracking of this disease will be necessary to ensure that prevention measures have been successful and to identify any emerging hazards or at risk populations.

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Updated Wednesday, March 18, 2015 at 01:37PM