Questions are now being asked because new homes are being built where the runoff flows.

Brisbane bird vet Dr Adrian Gallagher says he believes the Marsden Road, Dakabin, scenario is a modern-day "canary in a coal mine" and has urged the Queensland government's Contaminated Land Unit and Moreton Bay Council to urgently investigate and properly cap what he believes is toxic leachate.

"I think, from a human health perspective, if we have these uncapped, or poorly capped toxic waste sites – that we are building on – I think people should know about it," Dr Gallagher said.

"I feel that the likelihood that the chemical exposure, being the initial damage that resulted in this cancer developing, is still high."

Both the Contaminated Land Unit and Moreton Bay Council insist they have no record of a dump which became the sports fields behind Dakabin State High School. Some local residents have said they are shocked to discover this.

A long-time resident of the area, Alan Williams, said he and poultry breeder Viv had previously lived at Marsden Road, Dakabin, but moved to nearby Kurwongbah abut a year ago after Viv's hens began dying in 2013.

Mr Williams said he has been told of the old Dakabin dump - and the location of the six chemical pits beside the old Dakabin dump in Marsden Road – by two original farming families.

One is the Dohles family, whose local history is recognised in the naming of Dohles Rocks Road.

George Dohles showed Mr Williams the location of the six chemical pits around Marsden Road, telling him dieldren and cyanide – used to kill rats and mice around farms – was dumped in the 1920s and 1930s.

Dieldren breaks down very slowly and can be fatal to animals and humans.

A second farming family asked their identity be kept private, but provided a statement to Fairfax Media.

"All rubbish from the farm was dumped at the tip in Marsden Road; paint, oils, chemicals, poisons," the statement reads.

"The rubbish dump was a council-controlled dump at Marsden Road; where the sports field are now. I know that chemicals and poisons were dumped in pits adjacent to this dump for the disposal of old chemicals from the local farms (bananas and pineapples).

"There has been contaminated seepage from this tip since the tip was filled in, with the sports field on Marsden Road built on top of it.

"I am sure that the seepage from this old tip would be the source of contamination of soil in the area."

How did the issue emerge?

Twenty "dark-barred Plymouth Rock" speciality  hens died, possibly after drinking water or scratching up muddy soil which oozed out after one chemical pit was unearthed at 235 Marsden Road in Dakabin in late April or early May 2013.

The block of land where the chickens fed is literally 200 metres below the North Pine sports fields behind Dakabin State High School.

North Pine sports club secretary Gavin Hamilton said Dakabin's Bob Brock Park and the nearby cricket and football ovals were built on the old dump.

He said when the sports field was resurfaced "about 10 years ago; there were car bodies and everything found in there".

"There is always seepage right at the bottom of Bob Brock Park."

Mr Hamilton said the chemicals in the liquid seeping from the ground could be linked to the deaths of the show chickens.

"If they lived in a property below Bob Brock Park, it could be," he said.

"I don't know what is coming out of there, but it is whatever is left from the tip that is leaking out."

Chermside bird vet Dr Adrian Gallagher – who treated most of the sick and dying poultry – believes there is a link between the birds' deaths and what he believes could be leftover chemicals.

Dr Gallagher wrote after inspecting the first of three chickens bought in for treatment: "One has since been diagnosed with cancer that we believe is a result of protracted exposure to an environmental toxin."

Later on November 25, 2013 he wrote: "I feel that the likelihood that the chemical exposure, being the initial damage that resulted in this cancer developing, is still high."

Alan Williams wants the leachate to be tested urgently.

"We would like this pit to be cleared and the chemicals in it to be neutralised in some way," he said.

"They are the deadliest that we have. That is why they are in the pits."

What do environmental authorities – state and local governments say?

Neither will move first to investigate a link between possible chemical leaching from where residents say there is landfill, and the deaths of the poultry. Moreton Bay Council is still unsure if actual soil and water tests were completed. Neither believes an old dump existed.

The Department of Environment and Heritage Protection

Moreton Bay Regional Council contacted EHP's Contaminated Land Unit in February 2014 about the matter, and it was found that no land in the vicinity was listed on the Environmental Management Register.

EHP is aware that the council investigated the reports at that time and did not report contamination at the suggested premises.

EHP does not hold any evidence of an 'old Dakabin tip'. Contaminated Land records do not identify a former landfill and MBRC does not have records of a former municipal landfill.

Moreton Bay Regional Council

In January 2014, Moreton Bay Regional Council received a complaint regarding alleged soil contamination issues at a property on Marsden Road, Kallangur.

Council interviewed the complainant and neighbouring residents, and inspected properties in the area for signs that might indicate possible contamination but

found nothing to indicate the site was contaminated. The complainant was unable to provide any evidence of contamination.

Council encouraged the complainant to lodge his concerns with the Department of Environment and Heritage Protection (EHP), as the agency responsible for land contamination issues.

Council understands that EHP is now reviewing this matter.