In late 2004, Duke Health Raleigh and Durham Regional Hospitals accidentally used the fluid to wash surgical instruments.
Patients claim the mix-up led to their on-going health problems and at least one family claims the mistake caused their loved one's death.
Now, Duke is being accused of manipulating studies done following the incident.
One allegation is that half of the instruments Duke gave to RTI International to analyze for possible contamination were washed outside the likely exposure time.
The suit also claims Duke had asked RTI not to report how much zinc it had discovered.
Another allegation is a Pharmalink study, which was set to monitor the affected patients' health for two years, was presented to the public as independent.
The lawsuit claims a Duke doctor authored some of it and ordered which patients should be included or deleted from the study.
It also states that while patients were given an opportunity to submit their own medical records, have a non-Duke physician submit their records on their behalf, or call into a Pharmalink hotline to make a report of potential exposure --no records were obtained from any of the sources for inclusion into the registry database.
E-mails in the lawsuit allegedly show Duke calculated the actual time of exposure to a 21-day period, yet included patients beyond the time frame to "dilute" the study results.
In a separate part of the case, Duke is accused of not getting in touch with patients who likely weren't exposed.
Meanwhile, Duke is counter-suing one patient. It claims some of the patients suing the healthcare provider were never exposed to the elevator fluid. Duke is also suing those patients to recoup the costs of their legal fees.
By Monday afternoon, six patients were dismissed from the suit --one voluntary and five others by the judge, who ruled they were not exposed.
Attorneys representing Duke say the patients who have been dismissed should have to pay Duke some of the fees associated with the case.
"These people weren't exposed," Duke attorney Mark Anderson said. "You have no basis to sue us, but they did anyway."
Attorneys representing those patients say Duke never told their clients they hadn't been exposed, until they filed suit.
"Those costs are unfair and they are wrong," patients' attorney Henry Temple said.
The patients' attorneys argue that for five years they had every reason to believe they had been exposed --receiving letters from Duke explaining the incident and learning from Duke that they were part of a long-term study tracking the effects of the possible exposure.
Duke has maintained that the possible exposure was limited and the risk was minimal.