Ontario Health Minister Deb Matthews says she doesn't know how many companies provide services like Marchese Hospital Solutions, which supplied diluted cancer drugs to five hospitals.
But she says it's part of the investigation into the province's cancer drug supply, which includes Health Canada and other groups involved in the system.
Matthews says all 77 hospitals that offer chemotherapy in Ontario have confirmed that they don't have watered down chemotherapy drugs.
She says only four Ontario hospitals received diluted drugs from Marchese and have since gotten rid of their supply.
NDP critic France Gelinas say it's disturbing that the Ministry of Health doesn't know how many other companies like Marchese are operating in the province.
Marchese Hospital Solutions fell into a jurisdictional grey area, with Health Canada and the Ontario College of Pharmacists unable to agree on who was responsible for the facility.
Health Canada regulates and inspects drug manufacturers, while the college is responsible for pharmacists in Ontario, including those who may have been working independently for the company. Hospitals are responsible for the purchase and security of their drugs.
But Marchese Hospital Solutions wasn't considered to be a pharmacy or a drug manufacturer.
More than 1,200 cancer patients in Ontario and New Brunswick received the diluted drugs.
Too much saline was added to the bags containing cyclophosphamide and gemcitabine, in effect watering down the prescribed drug concentrations by up to 20 per cent.
Marchese has said its products weren't defective, and suggested that the problem wasn't how the drugs were prepared but how they were administered at the hospitals.
Michael Hurley, president of the Ontario Council of Hospital Unions, asked the Ontario government to act decisively on outsourcing failures.
Hurley called for an end to the "culture of complacency that envelops the provincial government and allows it to brush aside major, systemic medical errors as though a blithe apology and a political out were all that is required," he said in a statement today.