The former clinical chief of pathology at Eastern Health concluded his testimony Tuesday at the Cameron Inquiry, saying burn-out is the reason he is on sick leave from the health authority, whose pathology labs are being investigated for generating hundreds of faulty test results.

Donald Cook said he simply burned-out from working 10-hour days and weekends, and he could no longer concentrate on his tasks.

"It's important for a pathologist to focus intentionally on that slide and nothing else," Cook said of his work. "But when you have issues surrounding the inquiry, issues surrounding your pathology shortages, and it was not unusual to have 10 to 15 interruptions per day," he said.

The Cameron Inquiry is investigating why hundreds of breast cancer patients received erroneous hormone receptor test results from the labs at Eastern Health. The tests are used to help determine whether a breast cancer patient can benefit from the antihormonal therapy Tamoxifen.

The inquiry has been hearing testimony since March.

Cook said he took leave from his job as chief pathologist at St. Clare's Mercy Hospital in St. John's in May for his own health and because he felt he could no longer do his work to the standard of public safely.

'Three months later, we buried him'

Cook told the inquiry about how in 1988 he discovered on the job that his father had cancer.

He was working in a lab when two doctors entered and requested the emergency reading of a slide that contained a tissue sample. When he looked at the slide, he saw his father's name written in the corner.

"The name was that of Eric Thomas Cook — my father. That's how I discovered Dad had cancer," Cook said. "Three months later, we buried him."

Cook said he hopes the inquiry, headed by Justice Margaret Cameron, will lead to a better health care system in Newfoundland and Labrador, adding that he's already seen improvements at the lab since the mistakes were discovered in 2005.

Cook said he doesn't know when he'll return to work.

Eastern Health is the largest integrated health network in Newfoundland and Labrador, serving a regional population of more than 290,000 and employing more than 12,000 people in eastern Newfoundland. It oversees more than 80 hospitals, health-care centres, long-term care facilities and community care sites.