The trial of two test cases against IBM, alleging that exposure to toxic chemicals caused abnormally high rates of illness and death at Big Blue, began last week. These are the first among a number of lawsuits being brought by workers and families of former workers, most of whom were employed in IBM's semiconductor and disk drive manufacturing processes.

Former IBM worker Alida Hernandez, who suffered breast cancer, began her testimony on Wednesday, with James Moore, suffering from non-Hodgkins lymphoma, due to give evidence later this week.

The question of what IBM actually knew will be the most crucial one. The individuals are seeking damages not just to compensate the harm they suffered, but also to punish IBM – known as punitive damages. To win punitive damages, Californian law requires them to prove that IBM knew that the chemicals were affecting its employees and that IBM hid that knowledge.

Pre-trial hearings have already dealt a blow to this argument. An IBM database of employee death records has been ruled inadmissible, after IBM lawyers argued that it was solely for the purpose of dealing with death benefits, according to a report on CNet News.com.

IBM has denied the claims, maintaining that it had done everything it could to provide a safe environment for its workers. It has also argued that the workers' diseases are amongst the most common forms of cancer and were not linked to the time spent working for IBM.

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