Proposed Adoption of the Interim Canadian Water Quality Guideline for Sulfolane as an Interim Provincial Water Quality Objective

This notice was originally posted in the old Environmental Registry under number PA05E0005.

Description of policy

The Interim Canadian Water Quality Guideline (iCWQG) for the Protection of Aquatic Life for sulfolane was approved for publication by the Environmental Protection and Planning Committee (EPPC) in June 2005 and will be published by the Canadian Council of Ministers of the Environment (CCME) in the fall of 2005. Available information on the physical-chemical properties, aquatic toxicity, and environmental persistence were considered in the development of the guideline.

Sulfolane has been identified as a chemical of environmental concern due to its toxicity and widespread industrial use. Sulfolane is widely used for gas treatment processes including: sour gas sweetening, hydrogen selenide removal from gasification of coal, shale or tarsands; olefin removal from alkanes; nitrogen, helium and argon removal from natural gas; atmospheric CO₂ removal in nuclear submarines; ammonia and H₂S removal from waste streams; and H₂S , hydrogen chloride (HCl), nitrous oxide (NO₂), and CO₂ removal from various streams. Sulfolane is used as a polymer solvent and it is also used in electronic/electrical applications. The worldwide production of sulfolane is estimated at between 18 000 and 36 000 tons per year.

Sulfolane is poorly adsorbed to soil and has a high aqueous solubility and low volatility. It is also highly mobile in the subsurface. Studies have shown that the biodegradation of sulfolane is unlikely to be significant without the addition of phosphorus. Sulfolane has been shown to accumulate in plants in contaminated wetlands. Estimates of the acute toxicity of sulfolane to freshwater fish range from 1000-1264 milligrams per litre, and for invertebrates range from 40-3274 milligrams per litre. There were no chronic studies available in the literature for freshwater fish. Lowest Observable Effect Concentrations (LOECs) represent the lowest concentration used in an experiment where there was a statistically different result compared to the control study (e.g. no chemical used). The 7-day LOEC for invertebrates ranged from 500-1000 milligrams per litre. The 72 hour LOEC for algae was 723 milligrams per litre. The species most sensitive to sulfolane was an invertebrate, Ceriodaphnia dubia.

There is no current Provincial Water Quality Objective for sulfolane. The CWQG for sulfolane is derived from toxicity data according to the CCME water quality guideline development protocol which is consistent with Ontario's Water Quality Objective Development Process. The proposed Interim Provincial Water Quality Objective (iPWQO) for sulfolane is 50 mg/L. It was developed by choosing the lowest measurable chronic study and applying a 10-fold safety factor.

Provincial Water Quality Objectives (PWQOs) and Interim Provincial Water Quality Objectives (iPWQO) are maximum desirable concentrations of chemicals which ensure that surface waters are satisfactory for aquatic life and recreation. They are developed with a margin of safety to protect the most sensitive aquatic life-stage of an organism for an indefinite exposure. Technical feasibility and economics are not considered during the standard development, but are considered on a case-by-case basis in the Ministry's approval process for individual discharges. Most objectives are adopted or developed in partnership through the national Canadian Water Quality Guideline Task Group which reports to the Canadian Council of Ministers of the Environment (CCME), however, PWQOs may be developed by Ontario Ministry of the Environment if there is a provincial need.

Contaminants that impair the aquatic environment are an important environmental concern. Provincial Water Quality Objectives are used to assist in managing these contaminants. The policies and procedures which govern their uses are contained in the booklet -Water Management (1994) - which deals with all aspects of Ontario's water management policy. PWQOs are used to:

1. classify receiving waters for water management purposes
2. assess contaminant discharges to the aquatic environment
3. derive water quality-based effluent limits which may be included in Certificates of Approval which are issued to regulate effluent discharges. PWQOs are not the only consideration in controlling discharges.

Purpose of policy

The Ministry is proposing to add a surface water quality standard for sulfolane through adoption of the proposed Canadian Council of Ministers of the Environment (CCME) Canadian Water Quality Guidelines. This notice seeks comments on the proposed adoption. Comments received will be evaluated and considered in finalizing the iPWQO.