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| Last Review/Updated: July 8, 2002 |
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NRBS - HomeTable of Contents |
Northern River Basins Study Final Report
3.0 Major Findings
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Introduction General Health Contaminants in Fish Mercury Dioxins and Furans Toxaphene Relevant Documents |
When compared to other countries, the northern river basins environment has not generally placed residents at great risk to their health. However, research within the Traditional Knowledge Component reveal that a substantial proportion of the local people are concerned about the subtle link between the state of their environment and diseases such as cancer, diabetes, heart problems, diarrhea, asthma, and other health problems in their communities.
According to a 1988 Environment Canada study, the Canadian public considered the environment to be first and foremost a human health issue, although concern for plant and animal life was also very high. A majority believed that pollution was affecting their family's health and more than 90 per cent believed that a number of environmental hazards were causing serious health problems. The respondents were particularly concerned about chemicals in water and air, and about protecting drinking water supplies.
The preoccupation with environmental health issues has not changed over the past decade. As with other Canadians, northern river basins residents now realize that health and environmental quality are inseparable. The top health-related environmental issues that were repeatedly raised during the Study's community gatherings, surveys, scientific forums and individual discussions include water and air pollution, contaminants and drinking water quality. In its simplest form, the recurring questions "Can we eat the fish?", "Can we drink the water?", "Can we breathe the air?", "Can we use the land?" prompted the Study Board to establish the Human Health Committee to champion our understanding of health and the environment.
One of the committee's major tasks was to identify environmental issues and human health concerns and ensure that they are thoroughly examined. Another task was to initiate a study of health status in the Alberta portion of the Study area. Recognizing the importance of the human health concerns, the Minister of Health launched the Northern River Basins Human Health Monitoring Program on October 28, 1994. The results from this two-year, $300 000 companion study are expected by late 1996.
The first phase of the monitoring program will seek answers in three major areas represented by environmental stressors, human exposure, and health status. In the first area, that of environmental factors, the study will attempt to review chemical, physical and biological agents from a human health perspective. These will be prioritized based on their relative importance. In the second area, that of human exposure, the scientists will assess potential pathways of exposure such as drinking water, consuming fish and breathing the air. Third, disease rates will be analyzed to identify linkages, if any, between the health status of the population and environmental determinants.
| Figure 3.13.1 | Economy and Health Status (Selected WHO Member Countries, 1991-1993) |
| Figure 3.13.2 | Study Area Life Expectancy: An Historical Perspective |
| Figure 3.13.3 | Study Area Life Expectancy: Regional Differences (1990-92) |
| Figure 3.13.4 | Major Causes of Premature Deaths in Alberta (1992) |
| Figure 3.13.5 | Infant Mortality Rates in Northern Alberta: Regional Differences (1993-1994) |
| Figure 3.13.6 | Low Birth Weight in Northern Alberta: Regional Differences (1993-1994) |
| Figure 3.13.7 | Perceived Health Status: Comparison of Selected Northern Communities and Alberta |
Economic development has dramatically improved the quality of people's drinking water, nutrition, housing, clothing and general sanitation. As shown in Figure 3.13.1, a strong relationship exists between economy and health. People in developed countries experience a longer life span than those who live in less developed nations. Over the past 70 years, development contributed to the significant increase in the life expectancy of all Albertans (Figure 3.13.2). Today, there are small differences in the regional life expectancies. People living in northern Alberta have a slightly shorter life expectancy than those living in central and southern Alberta (Figure 3.13.3).
Although life expectancy is steadily increasing, accidents, cancer, suicide, heart disease, stroke and respiratory disease remain the major causes of premature death in Alberta. Loss of life at an early age is reflected by the potential years of life lost (Figure 3.13.4). Many of the concerns raised by northern river basins residents are also found on this list. Not all major causes of death have close links with the environment, but some do. In particular, certain types of cancer are known to be partially linked to environmental factors. Lifestyle choices such as drinking and smoking, along with genetic influences are among other important contributing factors in the causes of death.
Death in the first year of life or infant mortality is a population health indicator. Infant mortality is related to prenatal care, the mother's health, access to health care and congenital conditions or diseases. Slight regional differences may result both from the small number of infant deaths and the small number of babies born. The infant mortality in the seven northern Alberta health regions is illustrated in Figure 3.13.5.
Birth weight is a health indicator of newborn babies. Low birth weight babies are more likely to have health problems, developmental delays, learning and behavioral differences. The proportion of low birth weight babies in the seven northern Alberta health regions is illustrated in Figure 3.13.6.
In a recent Alberta survey on health, people were asked to rate their health status compared with others of their age. The Traditional Knowledge Component also conducted a survey in selected northern communities, asking respondents to rate their health on a scale of one to five. A comparison between the two studies shows that approximately the same proportion of respondents rated their health as being "excellent" (Figure 3.13.7). However, a larger proportion of the northern residents reported their health "somewhat poor" (fair) and "poor." Such regional differences in self-reported health status may result from a combination of health determinants including the economic and social environment, physical environment, personal health practices, individual capacity and coping skills, and health services.
Safe food and drinking water supplies are essential to protect human health. While food and drinking water sustain us, they are usually the major route for contaminants to enter our bodies. People are exposed to contaminants mainly through contaminated food, such as fish, meats, poultry, eggs, milk and dairy products. The presence of contaminants in the food chain is a concern for many local people in the Study area who rely extensively on traditional foods for subsistence.
During the Study, over 3 000 fish representing 25 species were submitted for various chemical analyses by the NRBS scientists. Most of the analyses (91 per cent) were for six species: burbot, mountain whitefish, longnose sucker, northern pike, walleye and goldeye.
Computerized databases required by an in-depth human health risk assessment are currently being developed. While an extensive review of contaminants in fish is not yet complete, a preliminary assessment of these data indicates that mercury and methylmercury, 2,3,7,8-TCDD and 2,3,7,8-TCDF, and toxaphene should be reviewed from a human health perspective. Other contaminants such as PCBs, chlorinated phenolics and radionuclides were generally at low levels, within the human health consumption guidelines.
People are exposed to mercury largely through the food chain (e.g., by consuming mercury-contaminated fish). Organic mercury (methylmercury) is more toxic than the inorganic (metallic mercury). When methylmercury is ingested, it rapidly enters the bloodstream and is distributed throughout the body. Certain organs, particularly the liver and kidneys, accumulate more of it than others. Mercury is slowly accumulated in the brain where in sufficiently high doses it affects the brain's sensory, visual, auditory and coordinating functions. A developing fetus may be affected in many ways; possible effects include retarded physical growth and coordination, and cerebral palsy as well as delayed development of intellect and behaviour.
A few initial observations on mercury with relevance for human health are:
Existing fish consumption restrictions in the Study area extend to walleye in the mainstem Athabasca River. From a health perspective, it is generally recommended that a balance be found between traditional foods, which can provide an excellent source of protein in the form of fish, and the potential danger to health due to mercury. Certain types of fish with generally lower levels of mercury, such as suckers and whitefish, may be favoured over those with high levels, such as walleye, pike, goldeye and burbot. Pregnant women and children under the age of 15 should not consume mercury-contaminated fish.
The observed mercury levels along the rivers, fish movements, fish type and the dietary patterns of the local people are important factors to be considered in the development of new, health-based fish consumption advisories. Considering the significant geographic variation of mercury in fish and the types of contaminated fish, the applicability of the current health advisories and the geographic boundaries as well as the fish species should be re-evaluated and adjusted based on the new information generated by the NRBS.
Wastewater from pulp and paper mills contains many potentially hazardous chemicals. While dioxins and furans can originate from natural sources such as forest fires, most are released in the environment by pulp and paper mills that use chlorine bleaching, combustion sources such as incinerators, burning wood and motor vehicles. They have been classified as "toxic" to health and the environment under the Canadian Environmental Protection Act.
Much of the health concern about dioxins and furans stems from the result of animal toxicity tests. Animals exposed to 2,3,7,8-TCDD, the most toxic of the dioxins and furans, experienced weight loss, skin disorders, impaired liver function, and impaired reproduction including birth defects and cancer. It is difficult to assess the human health effects of dioxins and furans. It does appear, however, that effects on humans are much more limited than those on animals. The human health effects most consistently observed in occupational exposure settings are chloracne and other skin problems, as well as effects on the liver, immune system and behaviour.
People are exposed to dioxins and furans mainly through contaminated food, such as fish, meats, poultry, eggs, milk and dairy products. Air, soil, water and consumer products are minimal contributors to exposure.
Some general observations on dioxins and furans with relevance for human health are:
Existing fish consumption restrictions for dioxins and furans extend to the upper reaches of the Peace and Athabasca River basins. Bull trout, burbot and mountain whitefish are affected in the Athabasca (upstream of Whitecourt, Iron Point and Fort Assiniboine), Berland, Wildhay and McLeod Rivers. Burbot and mountain whitefish are contaminated in the Wapiti, Cutbank, Kakwa, Smoky, Little Smoky and Simonette Rivers. From a health perspective, the current advisory recommends that only the fillet portions should be eaten; organs such as liver should be discarded. In the Athabasca River drainage, mountain whitefish should be limited to one meal per week. In the Peace River drainage, mountain whitefish should not be eaten at all.
Considering the decreasing trends of dioxins and furans in fish and their geographic variation, the applicability of the existing health advisories and the geographic boundaries should be re-evaluated and adjusted based on the newly available information.
Toxaphene is an organochlorine insecticide. This group of compounds also includes DDT, chlordane and lindane. Because of their particular structure, the organochlorines do not break down easily and therefore remain in the environment for a long time. As a result they have the tendency to accumulate in the food chain, potentially resulting in health risks in humans.
A total of 571 tissue samples were analyzed for toxaphene using a detection limit of 0.05 ppm or 0.01 ppm. Among the samples analyzed using the higher detection limit, 95 per cent of the samples were below the detection limit. Only five per cent of the tissue samples were above the limit. All of the walleye, goldeye and lake whitefish tissue samples were below 0.05 ppm. Burbot, mountain whitefish and pike accounted for all the positive samples. When using the 0.01 ppm detection limit, approximately 16 per cent of the samples were above the detection limit. Mountain whitefish accounted for most of the positive samples followed by the longnose sucker and burbot.
There are currently no fish consumption restrictions for toxaphene in Alberta, but the Government of the Northwest Territories health authorities have issued a cautionary note regarding burbot liver taken from the Slave River.
NRBS Synthesis Reports
Gabos, S. 1996. A Review of Population Health Status in Northern Alberta. Northern River Basins Study Synthesis Report No. 6.
Flett, L., Bill, L., Crozier, J. and D. Surrendi. 1996. A Report of Wisdom Synthesized from the Traditional Knowledge Component Studies. Northern River Basins Study Synthesis Report No. 12.
Other Relevant Documents
Alberta Health. 1995. Results of a Public Survey on Health and the Health System in Alberta. Edmonton, Alberta.
Environment Canada. 1988. Public Opinion and the Environment. Ottawa, Ontario.
Health and Welfare Canada. 1991. Pulp and Paper Mill Effluent: Issues. Health Protection Branch. Ottawa, Ontario.
Health and Welfare Canada. 1990. Mercury, Fish and You. Mercury Questions and Answers. Medical Services Branch. Ottawa, Ontario.
Hum, L.C. and R. Semenciw. 1991. Mortality Patterns in Canada, 1988. Chronic Diseases in Canada.
Wheatley, B. and S. Paradis. 1995. Exposure of Canadian Aboriginal peoples to methylmercury. Water, Air and Soil Pollution. 80: 3-11.
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