DuPont Co. officials have discovered evidence of a possible "cancer cluster" among workers at the company's Washington Works plant near Parkersburg, government records show.

The company has told federal regulators there may be a fivefold increase in certain cancers among Washington Works employees, compared to other DuPont plants.

DuPont officials say they do not know the cause - or whether the issue could be related to the toxic chemical C8 - but promised a full review of the matter.

A. Michael Kaplan, DuPont's director of regulator affairs and occupational health, filed reports about the cancers with the U.S. Environmental Protection Agency in November and December of 2006, and an updated report in December 2007.

The findings have never been announced publicly and it is not clear what information about the reports DuPont shared with its employees.

Kaplan refused to speak with a reporter about the reports he filed with EPA, and a DuPont media spokeswoman issued only a brief prepared statement when asked about the matter last week.

"DuPont Health Services is conducting a study of a possible cluster of carcinoid tumors at DuPont Washington Works," company spokeswoman Robin Ollis said in the statement. "It is important to note that the true incidence of this tumor type is unclear."

The statement quoted plant manager Bill Hopkins saying, "While we have not determined if there is any association with workplace exposure, we take this matter seriously. We have already begun a follow-up study and will continue to communicate this information to our employees and to regulatory agencies."

DuPont Co. officials have discovered evidence of a possible "cancer cluster" among workers at the company's Washington Works plant near Parkersburg, government records show.

The company has told federal regulators there may be a fivefold increase in certain cancers among Washington Works employees, compared to other DuPont plants.

DuPont officials say they do not know the cause - or whether the issue could be related to the toxic chemical C8 - but promised a full review of the matter.

A. Michael Kaplan, DuPont's director of regulator affairs and occupational health, filed reports about the cancers with the U.S. Environmental Protection Agency in November and December of 2006, and an updated report in December 2007.

The findings have never been announced publicly and it is not clear what information about the reports DuPont shared with its employees.

Kaplan refused to speak with a reporter about the reports he filed with EPA, and a DuPont media spokeswoman issued only a brief prepared statement when asked about the matter last week.

"DuPont Health Services is conducting a study of a possible cluster of carcinoid tumors at DuPont Washington Works," company spokeswoman Robin Ollis said in the statement. "It is important to note that the true incidence of this tumor type is unclear."

The statement quoted plant manager Bill Hopkins saying, "While we have not determined if there is any association with workplace exposure, we take this matter seriously. We have already begun a follow-up study and will continue to communicate this information to our employees and to regulatory agencies."

In its reports to EPA, DuPont described carcinoid tumors as "rare, slow-growing tumors that tend to occur in the respiratory and the digestive systems, particularly the appendix and the small intestine."

Initially, DuPont told EPA that it had found 16 confirmed cases of such tumors among U.S. active workers at DuPont plants. Based on that figure, DuPont said it "did not find any significant increased association between carcinoid tumor incidence rate and occupational assignment."

But after that report, DuPont said it "became aware" of three additional cases occurring among its workers.

Among the total of 19 cases, DuPont said that six of them were current or former employees of the Washington Works plant.

"Initial evidence suggests that most plants within the company do not have an excessive incidence rate of carcinoid tumors," Kaplan said in a Dec. 6, 2007, letter to EPA.

"However, six cases of this rare tumor type among approximately 5,000 workers at the Washington Works Plant introduces the possibility of a cancer cluster due to the number of cases and the fact that four diagnoses have been made in the last three years," Kaplan wrote. "A cancer cluster investigation is being planned for further analyses."

To contact staff writer Ken Ward Jr., use e-mail or call 348-1702.