Inorganic arsenic compounds – performance measurement evaluation (ecological component)
This summary presents the ecological component of the performance measurement evaluation for inorganic arsenic compounds.
The Government of Canada first assessed inorganic arsenic compounds under the 1993 Priority Substances List 1. That assessment concluded that inorganic arsenic compounds were entering the environment in quantities or under conditions that were harmful to the environment and potentially to human health in Canada. For this reason, they were added to Schedule 1 to the Canadian Environmental Protection Act, 1999 (CEPA) in March 2000. Based on past assessment activities and the implementation of risk management actions, it was determined that inorganic arsenic compounds met the readiness criteria outlined in the Performance Measurement Evaluation Strategy for Risk Management of Toxic Substances. These criteria included the existence of risk management tools that had been in place for a sufficient period to allow impacts to be measured, as well as the availability of key performance indicator data. Consequently, inorganic arsenic compounds were selected for performance measurement evaluation.
The approach to managing the risks of inorganic arsenic compounds relied on existing measures designed to control releases of metals and other toxic substances, rather than developing arsenic-specific risk management instruments. While no objectives were previously developed specifically for arsenic, the following objectives were applied for the purposes of this evaluation, informed by existing policy frameworks and approaches used for other toxic metals:
- Risk management objective: prevent or reduce releases of inorganic arsenic compounds to the greatest extent feasible
- Environmental objective: reduce environmental concentrations of inorganic arsenic compounds to below levels thought to cause adverse effects
Inorganic arsenic compounds are naturally present in the environment as a result of processes such as volcanic eruptions and the weathering of rocks. They are also released through human activities, including metal and mineral production, coal combustion, and the historical use of arsenic in pesticides. Arsenic is persistent in the environment and can be found in air, water, soil, sediments, plants, animals, and humans.
Overall, the performance measurement evaluation found that progress has been made toward achieving both the risk management and environmental objectives. Risk management measures have generally been effective at reducing releases from the sources of concern identified in the 1993 assessment.
Industrial releases of arsenic have declined significantly since 1993, primarily due to reductions from the metal and mineral production sector. Although this sector remains the largest source of arsenic releases to the environment, releases are expected to continue declining through the continued implementation of existing risk management measures. These measures should be updated, as appropriate, to reflect advances in best environmental practices and best available technologies, and to support tracking of the implementation rate of voluntary measures.
The evaluation also identified a significant increase in on-site disposals of arsenic from the mining sector. This increase is largely attributable to arsenic contained in waste rock and mine tailings and reflects increased mining activity and/or improved reporting practices. While current disposal practices are considered appropriate, the growing volume of arsenic-containing mining waste represents an emerging concern for future environmental management. This concern is heightened when considering long-term risks following facility closures and the presence of numerous abandoned mine sites requiring remediation.
Reductions in industrial releases have contributed to declines in environmental concentrations of arsenic to below levels of concern in many areas of Canada. However, some regions, such as the Great Lakes, continue to exhibit arsenic concentrations above levels thought to cause adverse effects. Continued monitoring of arsenic levels in the environment is therefore essential to support future evaluations. Enhancing monitoring efforts to address data gaps, including through collaboration with provinces and territories, would further strengthen the evidence base. Additional research into the adverse effects of arsenic on wildlife and fish tissues is also recommended to improve the evaluation of ecological risk.
In summary, human activities continue to release inorganic arsenic compounds into the environment, resulting in concentrations that exceed levels associated with adverse effects in some areas. Further investigation is needed to determine whether additional reductions in releases are feasible and whether new or enhanced risk management actions are warranted for certain sectors and sources. Continued collaboration with the United States and domestic partners is important for managing releases from sources beyond federal jurisdiction. A follow-up performance measurement evaluation is recommended by 2035 to allow time for the implementation of any new measures, where appropriate, and for the collection of additional performance measurement and environmental data.
In addition, the evaluation found that relatively few communication materials have been published on arsenic in the environment and its associated risks. Ongoing efforts to improve public awareness and access to information are expected to enhance the public's understanding of toxic substances, their sources, and actions that can be taken to prevent pollution.
Complete details on the performance measurement evaluation for inorganic arsenic compounds can be found in the Performance Measurement Evaluation of the Ecological Component for Inorganic Arsenic Compounds.