More than 40 years after a Dryden, Ont. paper mill was caught dumping mercury into a river through the Grassy Narrows First Nations, area residents continue to suffer from mercury poisoning, a new report shows.

The report, to be released Monday in Toronto, outlines the long-term effects of the dumping on people who live along the Wabigoon-English River system in northwestern Ontario.

The report was written by Dr. Masazumi Harada, a Japanese mercury expert who first visited Grassy Narrows in 1975 and has returned periodically to study the effects of the pollution on locals.

His latest report finds that 59 per cent of 160 people he examined in the area have been impacted by mercury poisoning. As well, 44 per cent of people aged 21 to 41 — those born after commercial fishing ended — have been impacted.

Health Canada stopped testing for mercury in Grassy Narrows residents years ago, claiming that mercury poisoning should no longer be a problem because levels of the contaminant have fallen below its safety guidelines.

Harada has found that even residents whose mercury levels were within the Health Canada limits are still experiencing mercury-related problems.

Common neurological symptoms include unsteadiness, tremors, and sensory impairment.

"Our people are still sick from the ongoing impacts of the mercury poison that the government allowed to be dumped in our river," Grassy Narrows Chief Simon Fobister said in a statement Monday, ahead of the report's release.

Commercial fishing in the Wabigoon-English River system was outlawed in 1970 after it was discovered that the Dryden Pulp & Paper Co. dumped the effluent from mercury-laden slimicides directly into the river for more than eight years in the 1960s.

The Mercury Disability Board was established in 1986 to compensate local residents for the loss of jobs and way of life from the mercury poisoning. Benefits are meant to be paid to claimants showing symptoms of mercury poisoning.

But the Grassy Narrows First Nation says that 74 people of the people Dr. Harada diagnosed as impacted by mercury are not receiving any support from the Board.

Leaders of the Grassy Narrows First Nations are demanding that the Ontario government acknowledge mercury poisoning in Grassy Narrows and apologize. They also want to see the river cleaned.

As well, they want a permanent Grassy Narrows-run environmental health monitoring centre.

And they want the compensation offered to those affected to be retroactively indexed to inflation.