Fifty years after a Dryden pulp mill dumped its effluent into a northern Ontario watershed, mercury continues to rise in some lakes, according to a study commissioned by the provincial government and the Grassy Narrows First Nation.

The report released Monday also reveals how little is known about the environmental and health consequences of the mercury that flowed freely into the English-Wabigoon water system between 1962 and 1970.

The research review of human and ecological health in Grassy Narrows was conducted by fresh water scientist Patricia Sellers. It takes a wide-ranging look at all published research into the contamination and mercury poisoning of people at Grassy Narrows.

"We have bits and pieces, small amounts of data here and there throughout the years of the human health in Grassy Narrows and various health issues and an assessment of initiatives to address those health issues," Sellers said. "But there hasn't been anything very comprehensive."

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Fish remains a staple in the diet for the people of Grassy Narrows, despite the contamination. A new report says information about how much is safe to eat must be better communicated and supports put in place for people who can't afford any other food. (CBC)

People in Grassy Narrows continue to suffer the effects of mercury poisoning, exhibiting symptoms such as loss of motor function, tingling and weakness in limbs, difficulty speaking and swallowing. 

"We know little about the effects of low-dose exposure [to mercury] over the long-term," Sellers wrote in the report.

Residents believe developmental delays and physical abnormalities in children are also related to the contamination, but Sellers says no studies have been conducted in Grassy Narrows on the effects of pre-natal exposure to mercury.

Surface contamination rising

Mercury levels in sediment in Clay Lake and parts of the Wabigoon River are twice the Canadian threshold for remediation and are on the rise in other area lakes where the people of Grassy Narrows continue to catch and eat fish, the report says.

"Staggering levels of mercury" are buried deep in the sediment at Clay Lake, which acts as a sort of settling pond for the contaminants, Sellers said. But sites downstream of the lake show a trend of increasing surface sediment.

Three recommendations for remediation of the river system were proposed 30 years ago and ignored, Sellers said, meaning only "natural recovery" has been underway since 1970.

"Earlier predictions that natural recovery alone would mean sustained levels [of mercury] in fish for decades have been realized," Sellers said.

The report's 40 recommendations include:

  • Conduct comprehensive health and diet surveys at Grassy Narrows to see the effects of eating fish on health, including the impact on child development and aging-related neurodegenerative diseases. (The most recent Health Canada studies are 20 years old.)
  • A comprehensive discussion about remediation of the Wabigoon River that includes Grassy Narrows First Nation.
  • Examine the effects of logging on the mercury load in the area and investigate whether any effluent continues to flow into the river from the Dryden mill.
  • Review and evaluate existing guidelines for fish consumption and ensure they are communicated to community members in a culturally appropriate way.
  • Long-term monitoring of the mercury levels in all lakes that are popular among Grassy Narrows families for subsistence fishing.
  • Establish a community-based research station to co-ordinate all 40 recommendations in the report.