September 04, 2001
Volume 37 Issue 29
| THE TROUBLE WITH TAR PONDS Medical Post staff writer Jenny Manzer visited Sydney, N.S., to talk to doctors and townspeople about the personal and professional challenges of living in the shadow of the tar ponds. Here are her reports. |
The tar ponds: a primer By Jenny Manzer The Sydney tar ponds are a tidal estuary located on the doorstep of downtown Sydney, N.S. They contain at least 700,000 tonnes of toxic sludge left over from decades of steel making, including polycyclic aromatic hydrocarbons (PAHs), benzene, lead and more than 40,000 tonnes of polychlorinated biphenyls or PCBs.
Although Sydney's toxic waste problems are strongly associated with "the tar ponds," there are a number of contaminated areas around the city, which each contribute to the carcinogenic mess.
The 60 hectare coke ovens site, minutes from downtown (where coal was baked as part of the steel manufacturing process), is believed to be contaminated well into the bedrock—to depths of up to 24 m.
On a nearby hill sits a 100-year-old municipal landfill. Leachate from the site, which contains contaminates such as PAHs and metals, flows through the coke ovens site. Watercourses carry contaminates from these areas into the tar ponds. As well, about 30 outfalls spew raw sewage through Muggah Creek and into the ponds. From there, the toxic waste can travel into Sydney's harbour.
For more than 80 years, Sydney neighbourhoods downwind of the steel plant and the coke ovens—which operated without pollution controls—were coated with airborne contaminates. The coke ovens were demolished in 1988. A handful of residents living nearby were relocated in 1999. The rest are still waiting.
What's being done about cleanup?
Following a costly—and ultimately failed—attempt to incinerate the sludge, the federal and provincial governments pledged $62 million in 1996 for remediation of the contaminated sites. They created the Joint Action Group (JAG) for Environmental Cleanup, made up of community and government representatives, to lead the study of remediation and health effects. In their most recent progress update, JAG said they now have a detailed idea of what contaminates are in the tar ponds, and are in the process of choosing a consultant to create a game plan for remediation.
What have some of the previous health studies said?
Most health studies to date have focused on Sydney's elevated rates of cancer. The multifactorial nature of the disease has made it difficult to separate out factors such as lifestyle and genetic influences, to draw a direct link between residents' health problems and environmental exposure.
A multi-year study by Dalhousie University epidemiologist Dr. Judith Guernsey, released in 1998, found the rate of cancer diagnosis was 50% higher in Sydney than the provincial average. Men in Sydney had a 70% or greater chance of developing stomach, colon, rectal and brain cancer. Women had greater chances of developing stomach, cervical and brain cancer.
A mortality study of the area released by Health Canada in 1996 showed rates of cancer were 16% higher in Cape Breton county compared to the rest of Canada.
The Health Canada team is following up with a prospective study of 200 new cases of lung, breast and colon cancer in the area, hoping to get a better picture of what factors are contributing to the elevated rates of disease. They plan to include variables such as occupation, diet, lifestyle, hormonal influences and residence.
"If you have a lung cancer difference in mortality, is it due to smoking differences or is it due to exposure to radon gas or to asbestos? You don't know that from a mortality study," said study co-author Dr. Pierre Band in an interview.
"If we find after controlling for all these factors that you still have a difference, then you're closer to attributing that difference to an environmental exposure." Dr. Band anticipates having results from the case-control study next year.
A 1999 birth outcomes study also showed rates of major congenital anomalies were higher in Sydney in comparison to Nova Scotia and the rest of Cape Breton county. The study was descriptive only, however, and could not tie the outcomes to environmental exposure.
What was the latest health testing about?
This summer, the local health authority and the province teamed up to do arsenic and lead testing in residents who live near contaminated sites. Testing was available to pregnant women and children under the age of five, and all residents living north of the coke ovens. More than 270 people were tested. Initial results showed 10 children and three adults had elevated levels of arsenic or lead.
In the spring, tests found high levels of contaminates in public properties north of the coke ovens, prompting Health Canada to begin soil testing on residential properties. As of press time, results were available for 1,300 of 1,500 samples. Ten had been found to exceed short-term exposure values for some contaminates, indicating a potential health risk to children. Some residents had parts of their yards fenced off by government officials. Others refused.
At the same time, Health Canada is also using the soil samples to determine the chronic health risk of living on a property for 70 years. Final summary reports on both these initiatives are expected to be made public later in September.
For more stories from the THE TROUBLE WITH TAR PONDS, click on the links below. Doctoring in the tar ponds of Sydney Sydney study will focus on residents' reproductive health The tar ponds: a primer Sydney's patients: a look behind the statistics Tar pond mental toll on kids huge and 'inappropriate'
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