Sydney Tar Ponds
Testing and Risk Assessment Backgrounder

October 2001


Health Canada took the lead in arranging testing, in conjunction with the Nova Scotia Department of Health. The relationship between the two levels of government has not been characterized by mutual trust. The N.S. government has consistently minimized any risk to health in the few test results made public.


The human biological testing was done on a volunteer basis, with residents who wanted testing being asked to come forward. Pregnant women and children under five were offered blood and urine testing first. Of the over thirty contaminants in the area, only two (lead and arsenic) were tested. Lead and arsenic are easier to find in blood and urine than benzene or PAHs, for instance. The governments set 20 micrograms per litre of urine as a level indicating concern. Arsenic, however, is a substance for which the U.S. Environmental Protection Agency (EPA) has not established any level of exposure that poses no risk, as arsenic is a known carcinogen. Arsenic is usually not found in urine 48 hours after exposure, and for some reason (never explained) the hair testing included in Minister Rock's action plan of May 18th never took place. While hair testing is imperfect, it does allow testing for long term exposures (hair nearest the scalp showing recent exposure; hair at the ends showing exposure from some time ago, depending on length). As of the end of July, 2001, 14 people, 10 children and 4 adults out of the 247 people who volunteered had unacceptably high levels of arsenic or lead. These ranged from infants to teenagers to adults. Everyone who tested positive was re-tested. While levels of arsenic had dropped in each case, two children still had levels over the arsenic limit. Meanwhile, those who tested negative initially were not re-tested, although they could well have shown arsenic on another occasion.

While the names of those who tested high for arsenic were not released to the press, many of them approached Sierra Club. Toddlers within a few streets of the coke ovens had high levels of arsenic, others worried about whether their repeated miscarriages had been due to their arsenic exposure. In at least one case, we are convinced the child's arsenic exposure more likely came from pressure treated lumber and a parent's occupational exposure unrelated to the tar ponds and coke ovens.

Taken as a whole, the blood and urine tests were only capable of demonstrating a cause for concern. Negative results from such tests do not establish the converse: that there is no problem. There are so many other types of carcinogens and toxics which were not tested and so much of the population was not tested, that the blood and urine tests are incapable of demonstrating that there are no health problems in those who tested below the level identified for concern.


An elaborate and extensive testing program was undertaken. Over 2,000 individual samples were taken through an area reaching 20 km from the site. Most sampling was in neighbourhoods adjoining the coke ovens. Once again, testing was done on a voluntary basis. Many residents, objecting to more testing before action, rejected testing of their properties. The full results have not been released. In fact, the government/consultant team has told Sierra Club the raw data will never be released. It will be treated as confidential information belonging to the property owner.

At the suggestion of Health Canada and the consultants, Sierra Club has been seeking individual permissions from residents in support of an Access to Information request.

The only information about the test results over the summer were of "hot spots" -- samples that tested above the new short-term acute risk standard unveiled by Health Canada in July. The short-term standards compared to the CCME standards follow:


National limits*

Sydney limits**


All measures are milligrams per kilogram

*Existing federal guidelines for safe soil determined by the Canadian Council of Ministers of the Environment.

**New made-in-Sydney guidelines for 60-day exposures.

The values, created in June 2001 for the first time in Canada by federal bureaucrats, will be used to determine whether an immediate cleanup or evacuation occurs.

"Hot spot" areas that were over the new mad-for-Sydney standards were fenced in and residents were advised, on a one to one basis, how to reduce exposure (stay inside, wash hands and keep the house clean of dust.) In media statements, government representatives stressed non-coke oven sources for the contamination. Lead contamination was blamed on old pipes; arsenic or PAHs or the use of coal for home heating, or from in-fill brought to the yard.


The most controversial aspect of governmental testing this summer was what came to be known as the "made-in-Sydney" standards as presented in the table above. Sierra Club has tried to understand why these standards were developed, as it has not been done in Canada before. The approach is not uncommon in the U.S. and Health Canada and its consultant, environmental engineer Richard Lewis, applied the model developed in the US by Agency for Toxic Substances and Disease Registry (ATSDR).

The logic behind developing these standards was that, as no results were to be released from the testing until the numbers had been fed through a chronic health risk assessment, leading to a recommendation about moving people, only those tests revealing an immediate risk required being shared with residents. Health Canada had promised that an announcement would be made by August 31st, so from July 1 what was needed was a 60-day risk assessment. A short-term risk assessment makes more sense when one is confronted by a sudden, accidental exposure. If there is a spill of arsenic contaminated material, one wants to know the immediate risk to residents.

In Sydney, of course, the arsenic exposure was been chronic for decades, so a calculation of 60-day risk, in the absence of any estimate of existing exposure is flawed. Nevertheless, the model used did not consider any past exposure that might have made the residents more susceptible to any more exposures.

Both Health Canada and Richard Lewis did a 60-day assessment. Neither risk assessment was peer reviewed, nor were they publicly available. Sierra Club has obtained both and finds the following serious deficiencies:

  • For arsenic, the assessment done by Lewis uses a toxic dose level from a poisoning incident in Japan in the 1950s involving adults. The dose level used by Health Canada was ten times the chronic effects dose. To be protective of human health, particularly to children, The Sierra Club of Canada believes that the short-term dose used for the case of arsenic should have been ten times the chronic (cancer causing) now proposed in the US ATSDR latest profile on the toxicology of arsenic. That dose would have been between 6 to 16 times LESS than the dose used by Lewis or Health Canada;

  • The arsenic dose exposure levels used in both Lewis and Health Canada models for toddler exposure was not made safer by the normal procedure of applying a safely factor for converting the acceptable exposure dose from an adult to a child.

  • The dose level for arsenic used by Lewis was for a toxic effect in adults. That toxic dose was deemed to be acceptable in Sydney for a 60 day exposure. From that acceptable dose, an exposure model was worked backward to determine how much arsenic would have to be in the soil for a child weighing 13 kg to receive the critical dose while eating dirt (the weight of the child and the amount of dirt ingested in play activities are variables set by ATSDR to be plugged into the model;)

  • Lewis and Health Canada ran the model on children of different weights and different soil ingestion rates. If Health Canada had used a child of the same weight as Lewis for its calculations the amount of arsenic in soil for the short-term standard would have been 20% lower (650 vs. 813 to 825 mg of arsenic per kg of soil.) Typically the weight of a less than five year old child is deemed by Health Canada, in its exposure handbook, at 13 kg for the purpose of the exposure modelling. But in the Sydney case, Health Canada used a child weight of 16.5 kgs, thus obtaining a number closer to Lewis'.

Any manipulation of the assumptions in this model, or building in a safety factor, can credibly lead to levels of soil arsenic concentrations far below the 813 mg/kg level chosen. We have asked our consultant Daniel Green to run the same models with elements from the Health Canada and Lewis assumptions slightly altered. Sierra Club will release these risk assessment results once they have been peer reviewed.

The importance of the determination of acceptable levels of contamination is huge. It has a direct bearing on how many families should be moved.

The cavalier manner in which the acute short-term risk assessment was conducted leaves us very concerned about the soon-to-be-released chronic, long-term risk assessment.


Over the summer, as noted, there was very little information shared with the public. No public meetings were held sponsored by the government. The only session to offer information was an Open House on August 1, 2001. It was falsely reported that at that session a protest got out of hand leading to arrests. In fact, prominent activist Bruno Marcochio was invited into the Open House by Health Canada's public relations officer. As Mr. Marcochio asked questions of one consultant, the same public relations officer became concerned and phoned for the police to arrest him. There was no protest, nor were voices raised, nor was the consultant in question threatened in any way. When the police put Mr. Marcochio under arrest, a melee ensued in which two other people were arrested. John Steele, a former steelworker, was pepper sprayed at point blank range while lying on the ground. His wife who rushed to check on him was grabbed from behind in a choke-hold and wrestled to the ground. Criminal charges have been laid against all three.