The ESR report noted there were indications from the results that the ingestion of poppy seeds in a food product could explain the positive result for morphine.
But that has come too late for the 54-year-old who is uncertain about what action he can now take to get his job back and clear his name.
"It seems I'm guilty until I can prove my innocence. I didn't think this was going to be too difficult to sort out and hoped common sense would prevail."
He said he couldn't appeal the decision and he was yet to meet his employers SPI. Mr Corkill said he would do another drug test and would be keen to get back to work as soon as possible as he was suffering financially.
The Northern Advocate contacted SPI but the manager was not available for comment until next week.
"I fully support workplace drug testing but the methods in use leave a large section of society vulnerable," Mr Corkill said.
Poppy seeds resulting in positive drug tests is not uncommon. Dr Paul Fitzmaurice, of The Drug Detection Agency, said while poppy seeds themselves did not contain morphine the seed surface could become contaminated with opiates from the poppy plant.
"If you eat the seeds, it's not uncommon that could produce a positive morphine result. If there was a declaration someone has eaten poppy seeds, the lab would test on that basis," Dr Fitzmaurice said.
"It's not an every-day occurrence but certainly poppy seed ingestion is a well-described event (for not negative results)."
On the back of the Freya's Lower Carb 5 seed bread, it shows the ingredients include a seed mix which contains sunflower seeds, brown linseed, golden linseed, poppy seeds and psyllium seeds. A Goodman Fielder spokesman was not aware of this incident but would be more than happy to discuss it with Mr Corkill.
"As stated in the ingredient list on packaging, this bread does contain poppy seeds, as do many other food products. Typically, our Freya's Lower Carb 5 Seed bread product contains on average 1.2 grams of poppy seeds per slice," the spokesman said.
"Many foods contain poppy seeds and we are not in a position to provide any guidance on whether the level of poppy seed content in our Freya's Lower Carb 5 Seed bread would result in a positive opiate screening test, particularly as this would depend on the thresholds adopted by the particular screening programme."
Positive poppy seeds
- They are the seeds of the opium poppy, the very same plant that has fuelled much of the world's heroin drug trade.
- Thus poppy seeds contain minute amounts of the opium alkaloids morphine and codeine.
- Drug tests look for small amounts of residual morphine in urine as an indicator of recent heroin use. It's easy to see the similarities between the two chemical structures.
- Poppy seeds are banned in Saudi Arabia. Some types are also banned in Singapore.