"It's just part of the process, it's part of our job, and it just happens that this check that we made had a broader impact than we certainly would have anticipated," Craig Woudsma said Tuesday.
"But definitely not a hero, no," he said.
Speaking at a meeting of the Ontario legislature's standing committee on social policy, Woudsma, 28, of Peterborough Regional Hospital and senior pharmacy assistant Judy Turner described the chance discovery that revealed cancer drugs administered to 1,200 patients in Ontario and New Brunswick were diluted.
The committee is looking into the oversight, monitoring and regulation of non-accredited pharmaceutical companies in the province.
Last Tuesday, officials from the Peterborough hospital told committee members a red flag went up when an assistant checked the labels on IV bags provided by Marchese Hospital Solutions.
It was the first day that the hospital used the new supplier. A staffer noticed a difference between Marchese's label for the chemo drug gemcitabine and the one from the previous supplier, Baxter.
Woudsma said he began to question what the final concentration per millilitre was, which led to a series of phone calls and emails among hospital staff and the Durham Regional Cancer Center and Marchese, the committee heard.
Woudsma told the committee he started to ask questions when hospital staff observed that the IV bags from Marchese Hospital Solutions required refrigeration while Baxter's didn't.
Progressive Conservative health critic Christine Elliott is concerned that experienced experts in the health-care system weren't able to catch the problem before so many patients were affected.
"We need to make sure that we have all the checks and balances necessary in the system to make sure that mistakes like this don't happen," Elliott said.
Patients at four hospitals in Ontario and one in Brunswick received IV bags of the chemotherapies cyclophosphamide and gemcitabine that were overdiluted between three and 20 per cent, according to Cancer Care Ontario.
On Monday, MPPs at the committee heard executives of Medbuy, the London,-based company that awarded the contract for intravenous chemotherapy drugs to Marchese Hospital Solutions in 2011.
Medbuy officials said Marchese pharmacists didn't account for the overfill of saline and assumed the entire bag would be given to a single patient.
Medbuy's "testimony was in stark contrast to that of Marchese, the supplier of diluted chemo drugs," NDP health critic France Gélinas said during Question Period.
"But to Ontario's patients, all they see is a lot of finger pointing, but none of the accountability, none of the oversight that they know is needed. Will the minister admit that her office stood back and did nothing while oversight of our health-care system vanished?"
Ontario's Health Minister Deb Matthews replied: "I completely reject that notion.
"We have learned that there are steps that need to be taken and that are being taken to be able to give the assurance to patients that when their doctor orders a drug, they get exactly that drug in exactly the concentration that was ordered."
Last week, Marita Zaffiro, the president of Marchese Hospital Solutions, appeared before the same committee and said it prepared pre-mixed cancer medications under the supervision of qualified pharmacists and according to the contract it was awarded by Medbuy.
MPPs have been asking hospital staffers and officials from the health ministry and pharmacy college about the regulatory grey zone surrounding Marchese Hospital Solutions' mixing services, which was not accredited by the Ontario College of Pharmacists.
Health Canada and the provinces and territories say they are working to improve oversight, including inspections of companies like Marchese Hospital Solutions that aren't federally licensed as manufacturers or provincially accredited as pharmacies, while they look for a long-term solution.