Synopsis
Aluminum sulfate can enter the Canadian environment from natural sources in restricted geological environments; however, since aluminum is present in most rocks, dominantly in aluminosilicate minerals, which weather and slowly release aluminum to the surface environment, releases of aluminum from aluminum sulfate cannot be distinguished from other natural aluminum releases. During their use in water treatment, aluminum salts react rapidly, producing dissolved and solid forms of aluminum, and some are released to Canadian surface waters. The amount of anthropogenic aluminum released is small compared with natural aluminum releases. Concentrations of aluminum are highest in wastewaters released by drinking water treatment plants (DWTPs). However, direct releases of process waters from DWTPs are regulated by many provincial authorities, and these releases typically occur in circumneutral water, where aluminum’s solubility is minimal. Disposal of sludge produced by DWTPs on land through landfarming practices is a source of aluminum to the terrestrial environment. However, the presence of dissolved organic matter and inorganic chelating agents will lower the amount of bioavailable aluminum in both the terrestrial and aquatic environments.
Extensive recent data on total aluminum concentrations in Canadian surface water are available, but few data exist on levels in areas close to sites where releases occur. The situation for sediment and soil is similar, in that data exist for the Canadian environment in general, but not for areas where releases occur. A large number of environmental toxicity data are available for acidified environments, but relatively few exist for circumneutral environments similar to those where most releases occur. Based on the highest measured and estimated aluminum levels present in both aquatic and terrestrial environments in Canada that receive direct inputs of aluminum from the use of aluminum salts, and on the Estimated No-Effects Values derived from experimental data for aquatic and terrestrial biota, it is in general unlikely that organisms are exposed to harmful levels of aluminum resulting from the use of aluminum salts in Canada.
Aluminum chloride, aluminum nitrate and aluminum sulfate do not deplete stratospheric ozone, contribute to the formation of ozone in the troposphere or influence climate change. The general population of Canada is exposed to aluminum primarily by ingestion from food, soil and drinking water. Available data on aluminum levels in these media are primarily for total aluminum rather than for dissolved, monomeric or other fractions. Foods with the highest concentrations of aluminum include those with aluminum-containing food additives (e.g., cakes and muffins) and foods that have naturally elevated levels of aluminum (e.g., raisins, shellfish, cucumbers). Since aluminum is naturally present in rocks and soil, exposure can occur through inadvertent ingestion of soil on food, from the hands, etc. Aluminum is present in drinking water from natural sources and from the use of aluminum-based coagulants in DWTPs to remove organic compounds, microorganisms and particulate matter. Airborne dust particles containing aluminum can be inhaled from indoor and ambient air. Those who use cosmetics can be dermally 2 exposed to aluminum-containing active ingredients, and those who use aluminum-containing medications (e.g., antacids and buffered aspirins) can ingest significant quantities of aluminum. Generally, the bioavailability of aluminum via inhalation, ingestion and dermal exposure appears to be relatively low — in the range of tenths of a percent to a few percent.
Building on previous initiatives by Health Canada, the weight of evidence for potentially critical neurological effects of aluminum has been considered, primarily as a basis for delineation of previously developed research plans. While the evidence of an association between exposure to aluminum and Alzheimer’s disease is weak, it cannot be dismissed completely in view of the consistency of some results with several lines of circumstantial evidence. In view of the potentially significant public health implications if the association were causal, this area is considered a priority for research. Specifically investigation of the biological plausibility in appropriate animal models is recommended.
Extensive recent data on total aluminum concentrations in Canadian surface water are available, but few data exist on levels in areas close to sites where releases occur. The situation for sediment and soil is similar, in that data exist for the Canadian environment in general, but not for areas where releases occur. A large number of environmental toxicity data are available for acidified environments, but relatively few exist for circumneutral environments similar to those where most releases occur. Based on the highest measured and estimated aluminum levels present in both aquatic and terrestrial environments in Canada that receive direct inputs of aluminum from the use of aluminum salts, and on the Estimated No-Effects Values derived from experimental data for aquatic and terrestrial biota, it is in general unlikely that organisms are exposed to harmful levels of aluminum resulting from the use of aluminum salts in Canada.
Aluminum chloride, aluminum nitrate and aluminum sulfate do not deplete stratospheric ozone, contribute to the formation of ozone in the troposphere or influence climate change. The general population of Canada is exposed to aluminum primarily by ingestion from food, soil and drinking water. Available data on aluminum levels in these media are primarily for total aluminum rather than for dissolved, monomeric or other fractions. Foods with the highest concentrations of aluminum include those with aluminum-containing food additives (e.g., cakes and muffins) and foods that have naturally elevated levels of aluminum (e.g., raisins, shellfish, cucumbers). Since aluminum is naturally present in rocks and soil, exposure can occur through inadvertent ingestion of soil on food, from the hands, etc. Aluminum is present in drinking water from natural sources and from the use of aluminum-based coagulants in DWTPs to remove organic compounds, microorganisms and particulate matter. Airborne dust particles containing aluminum can be inhaled from indoor and ambient air. Those who use cosmetics can be dermally 2 exposed to aluminum-containing active ingredients, and those who use aluminum-containing medications (e.g., antacids and buffered aspirins) can ingest significant quantities of aluminum. Generally, the bioavailability of aluminum via inhalation, ingestion and dermal exposure appears to be relatively low — in the range of tenths of a percent to a few percent.
Building on previous initiatives by Health Canada, the weight of evidence for potentially critical neurological effects of aluminum has been considered, primarily as a basis for delineation of previously developed research plans. While the evidence of an association between exposure to aluminum and Alzheimer’s disease is weak, it cannot be dismissed completely in view of the consistency of some results with several lines of circumstantial evidence. In view of the potentially significant public health implications if the association were causal, this area is considered a priority for research. Specifically investigation of the biological plausibility in appropriate animal models is recommended.
Keyword : PRIORITY SUBSTANCES, ALUMINUM CHLORIDE, ALUMINUM NITRATE AND ALUMINUM SULFATE
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