Incidence of cancer in Sydney and Cape Breton County, Nova Scotia 1979-1997

Lung cancer risk and past exposure to emissions from a large steel plant

We studied the spatial distribution of cancer incidence rates around a large steel plant and its association with historical exposure. The study population was close to 600,000. The incidence data was collected for 1995–2006. From historical emission data the air pollution concentrations for polycyclic aromatic hydrocarbons (PAH) and metals were modelled. Data were analyzed using Bayesian hierarchical Poisson regression models. The standardized incidence ratio (SIR) for lung cancer was up to 40% higher than average in postcodes located in two municipalities adjacent to the industrial area. Increased incidence rates could partly be explained by differences in socioeconomic status (SES). In the highest exposure category (approximately 45,000 inhabitants) a statistically significant increased relative risk (RR) of 1.21 (1.01–1.43) was found after adjustment for SES. The elevated RRs were similar for men and women. Additional analyses in a subsample of the population with personal smoking data from a recent survey suggested that the observed association between lung cancer and plant emission, after adjustment for SES, could still be caused by residual confounding. Therefore, we cannot indisputably conclude that past emissions from the steel plant have contributed to the increased risk of lung cancer.

Identifying at-risk communities for action on cancer prevention: a case study in new brunswick (Canada) communities

Health statistics reported by large geographic area such as province, state, county or health region offer little insight into disease conditions at the community level where people live and work, where occupational and environmental exposures occur, and where industrial emissions are often concentrated. This study investigated overall patterns of cancer incidence and socioeconomic status (SES) among 14 communities in the province of New Brunswick (Canada). A multivariate ordination technique, hierarchical clustering, and permutation procedures were used to identify and test significance of community clusters and whether the overall pattern of SES was correlated with patterns of cancer among communities. Communities with significantly high or significantly low overall rates of cancers were identified, patterns that were not related to SES. The potential influence of age, small populations, diagnostic screening, smoking and environmental risk factors contributing to locally elevated cancer rates are discussed. Cancer incidence reported at smaller spatial scales provides health officials and researchers with a basis for identifying communities potentially at-risk and aids in the development of appropriate community-based risk reduction actions and cancer prevention.

Spatial mapping of lead, arsenic, iron, and polycyclic aromatic hydrocarbon soil contamination in Sydney, Nova Scotia: community impact from the coke ovens and steel plant

This paper presents spatial maps of the arsenic, lead, and polycyclic aromatic hydrocarbon (PAH) soil contamination in Sydney, Nova Scotia, Canada. The spatial maps were designed to create exposure cohorts to help understand the observed increase in health effects. To assess whether contamination can be a proxy for exposures, the following hypothesis was tested: residential soils were impacted by the coke oven and steel plant industrial complex. The spatial map showed contaminants are centered on the industrial facility, significantly correlated, and exceed Canadian health risk-based soil quality guidelines. Core samples taken at 5-cm intervals suggest a consistent deposition over time. The concentrations in Sydney significantly exceed background Sydney soil concentrations, and are significantly elevated compared with North Sydney, an adjacent industrial community. The contaminant spatial maps will also be useful for developing cohorts of exposure and guiding risk management decisions.

A method for managing re-identification risk from small geographic areas in Canada

Background

A common disclosure control practice for health datasets is to identify small geographic areas and either suppress records from these small areas or aggregate them into larger ones. A recent study provided a method for deciding when an area is too small based on the uniqueness criterion. The uniqueness criterion stipulates that an the area is no longer too small when the proportion of unique individuals on the relevant variables (the quasi-identifiers) approaches zero. However, using a uniqueness value of zero is quite a stringent threshold, and is only suitable when the risks from data disclosure are quite high. Other uniqueness thresholds that have been proposed for health data are 5% and 20%.

Methods

We estimated uniqueness for urban Forward Sortation Areas (FSAs) by using the 2001 long form Canadian census data representing 20% of the population. We then constructed two logistic regression models to predict when the uniqueness is greater than the 5% and 20% thresholds, and validated their predictive accuracy using 10-fold cross-validation. Predictor variables included the population size of the FSA and the maximum number of possible values on the quasi-identifiers (the number of equivalence classes).

Results

All model parameters were significant and the models had very high prediction accuracy, with specificity above 0.9, and sensitivity at 0.87 and 0.74 for the 5% and 20% threshold models respectively. The application of the models was illustrated with an analysis of the Ontario newborn registry and an emergency department dataset. At the higher thresholds considerably fewer records compared to the 0% threshold would be considered to be in small areas and therefore undergo disclosure control actions. We have also included concrete guidance for data custodians in deciding which one of the three uniqueness thresholds to use (0%, 5%, 20%), depending on the mitigating controls that the data recipients have in place, the potential invasion of privacy if the data is disclosed, and the motives and capacity of the data recipient to re-identify the data.

Conclusion

The models we developed can be used to manage the re-identification risk from small geographic areas. Being able to choose among three possible thresholds, a data custodian can adjust the definition of "small geographic area" to the nature of the data and recipient.

Integron gene cassettes and degradation of compounds associated with industrial waste: the case of the Sydney tar ponds

Integrons are genetic platforms that accelerate lateral gene transfer (LGT) among bacteria. They were first detected on plasmids bearing single and multiple drug resistance determinants in human pathogens, and it is abundantly clear that integrons have played a major role in the evolution of this public health menace. Similar genetic elements can be found in nonpathogenic environmental bacteria and in metagenomic environmental DNA samples, and it is reasonable to suppose that integrons have facilitated microbial adaptation through LGT in niches outside infectious disease wards. Here we show that a heavily impacted estuary, exposed for almost a century to products of coal and steel industries, has developed a rich and unique cassette metagenome, containing genes likely to aid in the catabolism of compounds associated with industrial waste found there. In addition, we report that the most abundant cassette recovered in this study is one that encodes a putative LysR protein. This autoregulatory transcriptional regulator is known to activate transcription of linked target genes or unlinked regulons encoding diverse functions including chlorocatechol and dichlorophenol catabolism. Finally, only class 1 integrase genes were amplified in this study despite using different primer sets, and it may be that the cassettes present in the Tar Ponds will prove to be associated with class 1 integrase genes. Nevertheless, our cassette library provides a snapshot of a complex evolutionary process involving integron-meditated LGT likely to be important in natural bioremediation.

Development of local knowledge of environmental contamination in Sydney, Nova Scotia: environmental health practice from an environmental justice perspective

In Sydney, Nova Scotia, from 1901 through 1988 a coke and steel factory operated with no pollution controls, depositing over a million tons of particulate matter and releasing several thousands of tons of coal tar into the estuary. Previously we documented the presence of lead, arsenic and PAHs, in soil above Canadian guidelines, and in house dust in the communities surrounding the site [Lambert, TW, Lane, S. Lead, arsenic, and polycyclic aromatic hydrocarbons in soil and house dust in the communities surrounding the Sydney, Nova Scotia, tar ponds. Environ Health Perspect 2004; 112:35-41.]. In this paper we further the research by documenting and developing community knowledge with a study of resident's observations and experiences of the industrial contamination. We conducted two surveys, a quantitative door-to-door survey and qualitative dust interview, designed to complement each other and bring together the observations and experiences in the different communities to develop the local knowledge. The combined methodology uses techniques from both social and physical science, and was developed with the cooperation of community members. The research supports the proposition that local knowledge adds contextual meaning that complements the physical measurement of environmental contaminants, in order to understand the complex environment in which people live, and the multiple exposure pathways through which they can be affected. Residents in all three communities provided vivid observations and detailed experiences of the industrial pollution in their community and homes. The local knowledge is consistent with our physical data and review of the historical scientific research in Sydney, and supports the inference that the community was adversely impacted by the coke and steel facility. From a justice perspective, the three communities should be equally considered for remediation as part of the 'tar pond remediation policy' rather than the current policy of including only a few streets and houses.

Morbidity and mortality rates in a NOVA SCOTIA First Nations Community, 1996-1999

BACKGROUND

Despite an abundance of data and analysis of First Nations morbidity and mortality rates, accurate data have not been available to serve the First Nations community in Eastern Canada.

METHODS

Data for Eskasoni, the largest Mi'kmaq community, were obtained for 1996 through 1999 and Cape Breton and Nova Scotia were used as regional and provincial reference populations respectively. Age-adjusted relative risks (AARR) were calculated for overall mortality and disease-specific hospital admissions.

RESULTS

Eskasoni's mortality AARR was greater than 1.0 in 3 of the 4 years studied, although the data may understate Eskasoni's mortality rates. Eskasoni's total admission AARRs were significantly greater than the two reference populations. Neoplasm admission rates were generally lower, while circulatory disease admission AARRs were significantly higher. A rise in diabetic admission rates was noted with the AARR reaching statistical significance in the final years of the study. Respiratory disease was the leading cause of hospitalization with significantly greater rates of admission than regional or provincial rates. Pneumonia and influenza accounted for more than one half of respiratory admissions. Infectious disease admissions were more prevalent in Eskasoni while rates of liver disease were generally low.

CONCLUSION

Results suggest that members of the largest Mi'kmaq band are at greater risk for a number of disease categories and health promotion should be targeted toward respiratory ailments, circulatory disease and diabetic management. Further analysis, however, remains an important priority.

Morbidity and mortality rates in a NOVA SCOTIA First Nations Community, 1996-1999

BACKGROUND

Despite an abundance of data and analysis of First Nations morbidity and mortality rates, accurate data have not been available to serve the First Nations community in Eastern Canada.

METHODS

Data for Eskasoni, the largest Mi'kmaq community, were obtained for 1996 through 1999 and Cape Breton and Nova Scotia were used as regional and provincial reference populations respectively. Age-adjusted relative risks (AARR) were calculated for overall mortality and disease-specific hospital admissions.

RESULTS

Eskasoni's mortality AARR was greater than 1.0 in 3 of the 4 years studied, although the data may understate Eskasoni's mortality rates. Eskasoni's total admission AARRs were significantly greater than the two reference populations. Neoplasm admission rates were generally lower, while circulatory disease admission AARRs were significantly higher. A rise in diabetic admission rates was noted with the AARR reaching statistical significance in the final years of the study. Respiratory disease was the leading cause of hospitalization with significantly greater rates of admission than regional or provincial rates. Pneumonia and influenza accounted for more than one half of respiratory admissions. Infectious disease admissions were more prevalent in Eskasoni while rates of liver disease were generally low.

CONCLUSION

Results suggest that members of the largest Mi'kmaq band are at greater risk for a number of disease categories and health promotion should be targeted toward respiratory ailments, circulatory disease and diabetic management. Further analysis, however, remains an important priority.

Lead, arsenic, and polycyclic aromatic hydrocarbons in soil and house dust in the communities surrounding the Sydney, Nova Scotia, tar ponds

This study evaluated lead, arsenic, and polycyclic aromatic hydrocarbon (PAH) contamination in the residential communities adjacent to the Sydney, Nova Scotia, tar ponds, the area considered Canada's worst contaminated site. The tar pond remediation policy has been limited to the site and some residential properties. We compared background concentrations in 91 soil samples taken 5-20 km from the coke oven site with those in soil samples from the three communities surrounding the tar ponds: Whitney Pier, Ashby, and North End. These surrounding communities were statistically different from background regarding arsenic, lead, and PAHs. Twenty percent of the background soil samples and 95% of the tar pond soil samples were above the Canadian health-risk-based soil guidelines for arsenic (12 ppm), and 5% of the background samples and 80% of the tar pond soil samples were above the Canadian guidelines for lead (140 ppm). Regarding dust lead and arsenic loading, the results provide no evidence that Whitney Pier is significantly different than Ashby and North End. Children in these communities are predicted to have a 1-15% chance of blood lead > 10 microg/dL. The results suggest that lead and arsenic found in the homes originate outside. The lead content of paint in the homes was not evaluated, but consideration of painted wood at the doorway did not confound the results of the study. The results indicate that the residential environment has been adversely affected by PAHs, lead, and arsenic and should be considered for remediation.

Congenital anomalies and other birth outcomes among infants born to women living near a hazardous waste site in Sydney, Nova Scotia

Using data from the Nova Scotia Atlee Perinatal Database, rates of adverse birth outcomes were compared among residents of Sydney, Nova Scotia and residents of Cape Breton County, Nova Scotia (excluding Sydney) with birth outcomes among residents of the rest of Nova Scotia. There was a small but statistically significant increase in the rate of major congenital anomalies in Sydney (2.8%) compared to the rest of Nova Scotia (2.3%) (adjusted RR = 1.25, 95% CI = 1.04-1.51). Rates of anomaly sub-groups were consistently elevated in Sydney compared to the rest of Nova Scotia, but most were not statistically significant. For the most part, the increased rates of congenital anomalies observed among residents of Sydney were not evident in the neighbouring community. Since Sydney and the rest of Cape Breton County share a similar risk factor and socio-demographic profile, other factors likely explain the increased rates observed in Sydney.