Potentially incriminating information has emerged that International Business Machines (IBM) knowingly exposed employees to dangerous concentrations of cancer-causing chemicals. A number of cases involving 250 IBM workers from California, New York and Minnesota allege that the company was aware of the danger and did nothing to protect its workers.

Seven compact discs containing IBM’s highly confidential “corporate mortality file” database were inadvertently included with public documents for delivery to the plaintiffs’ attorneys last month. The CDs held a comprehensive list of more than 30,000 IBM employee deaths, tracked by work location and cause, between 1969 and 2000.

A medical expert who reviewed the discs asserts they contain crucial evidence that the company knowingly endangered workers over a period of decades. IBM employees died of certain cancers at higher rates and younger ages than the general population, and the higher cancer death rates are especially striking for workers in manufacturing jobs at certain unspecified locations.

“By 1975, IBM must have known their manufacturing employees had significantly increased death rates due to cancer and must have known that through the next two decades,’’ declared Richard Clapp, the Boston University epidemiologist who studied the corporate mortality file. According to Clapp, the data suggests that IBM workers were much more likely to die from cancers of the breast, blood and lymph system than were members of the general population. His study concluded, “IBM employees have suffered much more than their expected share of cancer.’’

The process of producing silicon chips had continuously exposed them to chemicals that are known carcinogens. IBM maintains there is no scientific evidence tying cancer among its employees to these practices in the workplace.

The workers represented by lawsuits may be only a small portion of those who have been harmed by such chemical processes, which continue to be widely applied in computer manufacturing. Moreover, the migration of production facilities overseas may have spread the danger to workers in other parts of the world.

“Not-so-clean rooms”

The “clean rooms” in which chips are produced have been carefully designed to protect the fragile silicon wafers from contaminants. Each layer of silicon molecules is exposed to highly toxic chemicals to achieve an ever-greater precision in etching and layering. Workers wear “bunny suits” to prevent even a hair, or speck of dust, from fatally damaging the chips, and air is filtered to eliminate any particles that could damage them. However, the chemical byproducts of the process of micro-engineering, which do not pose a hazard to the chips, are permitted to circulate freely throughout the work environment.

Dozens of chemicals such as arsenic, cadmium, lead, benzene and hydrochloric acid have been used in electronics manufacturing. Arsenic has been found to cause liver, kidney, lung, bladder and skin cancers, according to the National Institutes of Health. Benzene has been linked to leukemia, and cadmium to lung damage, bone defects and cancer.

Attorneys for IBM argue that there has been little evidence to conclusively link the chemicals in their factories to cancer in humans and that there has been no long-term research into this question. If fact, it is the semiconductor manufacturers themselves who have repeatedly impeded comprehensive studies of the health complaints of their workers.

An attempt several years ago by the California Department of Health Services and the Environmental Protection Agency was blocked when the semiconductor industry refused to cooperate in tracking cancers, birth defects and other health problems in employees.

For computer makers, the ramifications of the current lawsuits are far-reaching. If IBM is convicted of wrongdoing with regard to workplace safety, many other manufacturers may not be far behind.

The first case, involving four former employees at a factory in San Jose, Calif., and their survivors, has been set for trial in Santa Clara County Superior Court to begin October 14.