Information Sheet for Former Conwed Workers

Minnesota Department of Health

September 1993

HOW WERE WORKERS EXPOSED TO ASBESTOS AT CONWED?

Asbestos was used at the Conwed Corporation (Wood Conversion Company) plant in Cloquet, Minnesota, in making ceiling tiles and other products from 1958 through 1974.  Mixing, sawing, grinding, and other processes used in making these products created asbestos-containing dusts that were inhaled by many workers.  This is how most workers were exposed to asbestos.

WERE ANY WORKERS EXPOSED TO ASBESTOS BEFORE OR AFTER 1958-1974?

Asbestos was used at the Cloquet plant in the manufacturing process during the years 1958-1974, and this is when the greatest number of workers were exposed.  It is possible, however, that some workers were exposed to asbestos outside this time period.  For example,  workers involved with maintenance and repair of equipment that had asbestos insulation, such as steam pipes and boilers, may have been exposed to asbestos before or after this time period.  

WHICH WORKERS HAD THE MOST EXPOSURE TO ASBESTOS?

We do not have information on actual levels of asbestos in the plant air.  Asbestos dust levels probably varied at different locations and at different times.  Overall, people who worked in the following departments probably had more exposure to asbestos than other workers:

  • Nuwood Board Mill

  • Nuwood Finishing

  • Nuwood Shipping

  • Balsam Wool Pulp Mill

  • Lo Tone

  • Maintenance and Repairs

People who worked in the dustiest jobs for the longest periods of time would have had the most exposure to asbestos.

HOW MANY WORKERS WERE EXPOSED?

Anyone who worked at Conwed's Cloquet plant at any time during the years 1958-1974 may have been exposed to asbestos-containing dusts.  Company records and other sources of information show that nearly 6,000 workers were employed for some period of time during those years.   The  Minnesota Department of Health has been working for several years to identify and locate all former Conwed workers employed during those years.  

WHAT TYPES OF ASBESTOS WERE USED?

Several types of asbestos from different suppliers were used at different times at Conwed during the 1958-1974 time period.   Although all types of asbestos can cause asbestosis and lung cancer, the risk of mesothelioma may depend on the type of asbestos.  Conwed has not provided the State with information about the types and amounts of asbestos used during different years.

COULD FAMILY MEMBERS ALSO HAVE BEEN EXPOSED?

Most workers wore their work clothes home or took them home for washing.  Asbestos-containing dusts could have been carried into the home on the workers' clothing, shoes, or hair.   Any exposure to family members in the home would be small compared to exposures in the plant.   The risk of disease from these household exposures would be very small. 

HOW MANY FORMER CONWED WORKERS HAVE DEVELOPED ASBESTOS-RELATED DISEASES?

We do not know how many former Conwed workers have developed or will develop cancer or other lung diseases because of their asbestos exposure. The effects of asbestos do not occur until many years after a person was first exposed.

In 1988, medical exams were given to about 1,100 former Conwed workers and 450 spouses. These exams showed that about 30 percent of the workers had lung abnormalities that may have been caused by asbestos exposure.  As expected, those who had the most exposure were the most likely to have lung abnormalities.  Very few spouses of workers had lung abnormalities, showing that exposures were probably very low.

WHAT ABOUT CANCERS?

There is no accurate count of how many former Conwed workers have had cancers.  We do know that several workers have had mesothelioma.  This is a rare cancer of the lining of the chest or abdomen that can develop many years (20-40 years or more) after first being exposed to asbestos. Asbestos exposure is the only known cause of mesothelioma.  Some workers have had lung cancer.  Because there are other causes of lung cancer - mainly smoking - some cases of lung cancer would be expected to occur among any large group of workers.

In general, the risk of asbestos diseases is highest for those who had the most exposure and for those whose exposure took place more than 20 years ago.  The type of asbestos and industry involved may also affect the risk of disease.  In other industries that manufactured asbestos products, typically two to three times as many workers have died of lung cancer as would normally be expected.   This means that about two out of every ten deaths were due to lung cancer.  The proportion of deaths due to mesothelioma has been much smaller.

Evidence from other studies of asbestos workers suggests that spouses or other household members of highly-exposed asbestos workers do not have excessive rates of lung cancer or asbestosis.  However, some studies have found cases of mesothelioma among family members of asbestos workers. 

It is important to know about these special health risks from asbestos, but it is also important not to ignore the many other common health risks faced by all Americans such as heart disease, other cancers, diabetes, and strokes.

CAN I REDUCE MY RISKS OF ASBESTOS DISEASES?

There is presently no known way to reverse or undo the effects of past asbestos exposure, although studies are in progress to determine if lung cancer rates can actually be reduced among former asbestos workers. There are, however, several things that you can do to reduce your risks of developing or dying from asbestos-related diseases:

(1) You should stop smoking.  Smoking and asbestos exposure are both known to increase your chances of developing lung cancer. Together, they result in a very high risk of lung cancer.  There is evidence that asbestos workers can reduce their risk of lung cancer if they stop smoking.  This would also benefit your health in many other very important ways, such as reducing your risk of a heart attack and lung infections.

(2)  You should tell your doctor about your possible asbestos exposure.  You also should contact your doctor if you have any of the symptoms listed in the enclosed brochure Asbestos Exposure: What It Means, What To Do.  Your doctor can advise you if any routine or specialized exams are needed.

WHERE CAN I GET MORE INFORMATION ON THE MEDICAL STUDY OF CONWED WORKERS?

You can call the Minnesota Department of Health at 612-676-5216 or write to:

Conwed Notification Program
Chronic Disease & Environmental Epidemiology
Minnesota Department of Health
717 Delaware St. S.E.
Minneapolis, MN 55414.

Other places to write or call for information about asbestos exposure are listed in the brochure Asbestos Exposure: What It Means, What To Do. General information about cancer can be obtained by calling the American Cancer Society at 1-800-ACS-2345.

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Updated Thursday, 28-Jun-2012 15:08:28 CDT