Jim Holmes, head of the London Professional Firefighters Association, told the London Free Press at least 10 firefighters had nosebleeds that recurred for weeks and many felt sick for days after fighting the May 29 fire at the farm.

Medical tests were ordered last week and are taking place this week, Holmes said.

"It's because we were there so long and there were a lot of different chemicals -- herbicides, pesticides, fungicides -- involved," he said.

He said the firefighters wore regulation protective gear such as masks and self-contained breathing equipment during the eight hours it took to douse the blaze. The area was blanketed with heavy smoke for hours during and after the fire, the report said.