Dr. Jake Thiessen told an Ontario legislative committee Monday that the service is part of the "customary" evolution of services that professionals provide.
He says it's a sense of entrusting to professionals things that professionals know most about, which is common in dentistry and medicine as well.
Thiessen says the current system has served people well for many years, but things could slip between the cracks.
He says it may be time to solidify the licensing standards, education requirements and experience for these companies.
Thiessen says he'll deliver his report to the Ontario government by July 12.
Health Minister Deb Matthews has said she'll make it public.
Marchese Hospital Solutions prepared the drug-and-saline mixture that was supplied to four hospitals in Ontario and one in New Brunswick.
Extra saline in the bags containing cyclophosphamide and gemcitabine effectively watered down the prescribed drug concentrations by up to 20 per cent.
Some of the 1,200 cancer patients affected were receiving the diluted drugs for as long as a year.
The drug scare revealed the lack of both federal and provincial oversight over companies that mix drugs.
Marchese fell into a jurisdictional grey area, with Health Canada and the college unable to agree on who was responsible for the facility.
Thiessen said he doesn't like the term "grey."
"I've never felt this is particularly grey — this is a personal opinion — I've felt this is part of the customary evolution of service that professionals provide," he told the committee Monday.
"Does that necessarily offer the security that we all would like? Well, perhaps not. But you know what? We can fix some of these things and hopefully embed them for future generations."
The governing Ontario Liberals brought in rules May 15 to close the gap in oversight over companies that mix drugs for hospitals.
Hospitals can only purchase drugs from accredited, licensed or otherwise approved suppliers. The Ontario College of Pharmacists will also be responsible for inspecting drug preparation facilities where pharmacists and pharmacy technicians work.
Thiessen said he supports national standards or guidelines for labelling of bags containing drugs mixed with saline to ensure that the right amount of drugs is administered.
The committee has heard that the drug mixture Marchese was producing was completely different from the one the hospitals thought they were buying.
Marchese said it prepared the drugs the way it was asked to under its contract with Medbuy, the bulk purchaser.
But the bags didn't account for extra saline that's usually in the bags, thinking they were being administered to a single patient.
The hospitals were actually extracting fluid from the bag to prepare chemotherapy treatments for different patients, unaware that the drug mixture had too much saline.