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Great Lakes Article:

Quinte West - Medical Officer of Health talks about dioxins in humans
By Kate Everson
Published on on November 21, 2005

Dr. RIchard Schabas, medical officer of health for the Hastings and Prince Edward Counties Health Unit, talked about the impact of human absorption of dioxins and furans such as those reported recently at the mouth of the Trent River. He spoke to the board at the Trenton Health Unit on November 18.

He said the six cores of dioxins found in 2004 at the mouth of the Trent River have been studied in terms of their relation to human health. The dioxins are fat soluble and if ingested could cause skin rash or liver inflammation, affecting the immune system, reproductive and endocrine systems. They could also lead to a certain type of cancer called soft tissue sarcoma. The routes dioxins could take into the human body are through ingesting, inhaling or transdermal (through the skin).

He said 90 per cent of human dioxin exposure is from diet sources, including milk, meat and fish. It is present in the fat of animals. There are also some occupational exposures.

“There are dioxins everywhere,” he said. “The average Canadian gets one quarter the tolerable level of exposure every month.” He said dioxins are present in sediment, the Great Lakes, agricultural soil and soil cleanups from residential or industrial contaminants.

“Lake Ontario has a substantial level of dioxins,” he said. “Up to 75 per cent has 183 picograms. [The tolerable level is 70] .”

Dr. Schabas showed a map of where the dioxins had been discovered at the mouth of the Trent River. “There are many plausible sources up the river,” he added.

He said the routes the dioxins could take to affect human exposure are the key health question. “It is not normally found in drinking water,” he said. “Dioxins are not water soluble.”

He added the Ministry of the Environment has tested the drinking water from Trenton to Deseronto which all draw from the Bay of Quinte, and no dioxins were found. “This was never identified as a problem” he said.
However, dioxins have been identified in fish which have been monitored. Whitefish and large chinook salmon were the worst, and recommendations for consumption of all fish are included in a guidebook.

Dr. Schabas said there is a limited potential for exposure to those swimming in the water. “The surface does not have a high level of dioxins,” he said. “There is low skin absorption.”

Sandra Carter noted that there is a popular swim hole in the area where dioxins were discovered. However, Dr. Schabas said the levels were not high enough to consider that a plausible route to affect human health.
Gordon Fox asked if the dioxins stayed in the fat of fish. Dr. Schabas said the type and size of fish are specific as to the danger. “Don’t eat that kind or size of fish,” he said. “It is very specific.”

Gordon Fox asked if the chemicals would eventually break down in the body. Dr. Schabas said they do break down, but very slowly. “They will be there for a long time,” he said.

Dr. Schabas said the significant levels of dioxins found in sediments at the mouth of the Trent are the highest in Lake Ontario. “This is a significant environmental concern,” he said. “However, there is no preliminary evidence of a plausible route of dangerous human exposure. Transdermal absorption is very low. Yet we have to keep an open mind.”
Dr. Schabas said the Ministry of the Environment continues to analyze sediment samples recovered in 2005 and has taken the study further north to several locations in the mouth of the river.

“They will advise us when there is a health hazard,” he said. “The committee continues to meet. There may be more light shed on this by next spring.”

Bob Dolan asked if there were any studies done on the Moira River for contaminants like arsenic. Dr. Schabas said arsenic is more dangerous but he had no research available. Dolan said, “I am concerned about it coming down the river.”

Gordon Fox asked, “Could it lay there harmlessly as long as it is not disturbed? Or, if it is left, will it break down and be tolerable?”

Dr. Schabas said all chemicals break down but the question is how long. Aquatic plant life absorb some and fish may eat some of the material. “Is it better to dredge it up?” he asked. “That is beyond my expertise.”
Wayne Drake asked about the cause of the dioxins found at the mouth of the Trent River. “I grew up in that area,” he said. “The supermarket was once a coal yard. The whole yard up to the water plant was a dump. We didn’t pay any attention then.” He said there was also a coal plant across the river.

Sandra Carter added, “Ships came in and unloaded there.” She said a service club used to put cars on the ice every winter and let them sink.
Dr. Schabas said sediments up to 10 centimetres don’t exceed the limits but out in the bay they were more. “This needs to be taken seriously,” he said.

He added, “I don’t have the expertise about any conclusions.”
Ron Hamilton said he was relieved there is no threat to the drinking water. Peter Briscoe questioned if there was anything to worry about. Dr. Schabas replied, “I would never say that.”

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