1.5 Acute Toxicity and Ammonia
At each session, participants were presented with the following information on acute toxicity and ammonia:
Acute Toxicity Requirements
Non-acutely toxic discharge limit and monitoring requirements for acute toxicity would apply to medium, large and very large wastewater systems
- not applicable to very small and small wastewater systems
Additional requirements for acute toxicity test failures
- Submission of an “Action Plan” within 60 days
- Specified timelines to identify (within 1 year) and implement corrective actions (within 2 years)
Acute Toxicity and Ammonia
For medium, large and very large wastewater systems
- If ammonia is the cause of acute toxicity test failure, then receiving environment considerations such as chronic toxicity would determine if reduction of ammonia in the effluent would be required
- Specific requirements for acute toxicity, chronic toxicity, mixing zone would be included as appropriate
- If the ammonia concentration does not exceed the chronic toxicity at the edge of the defined mixing zone, no further effluent ammonia reduction would be specified
Participants were asked the following questions, which they discussed in plenary or in small groups:
“What are your initial reactions to”:
- The approach to acute toxicity and ammonia that applies to medium, large and very large systems?
Feedback from Participants and Written Submissions
Aboriginal Peoples and their Organizations
Many participants were satisfied with the approach to acute lethality, however participants from the west coast sessions held an opposing view - that the proposed timelines for addressing acutely toxic effluents are too long and do not allow for the proper protection of fish that they rely upon. Participants from several regions also expressed concerns over the applicability of the rainbow trout bioassay as the measure of acute toxicity. The opinion given was that there should be consideration for using local species to determine the environmental effects of the discharges, as well as using alternatives to the standard bioassay, such as using caged bivalves (mussels).
A written submission and participants from northern regions expressed concerns regarding the suggested requirement for initial acute lethality testing of wastewater systems in the north. It was noted that testing can only be conducted by certified testing facilities, within 48 hours after a sample has been collected. Participants pointed out that some communities are further than 48 hours transit away from the nearest testing facility, and therefore could not feasibly achieve this requirement. The written submission provided broader comments, outlining the difficulties in effectively transporting samples long distances prior to analysis. This submission recommended that: "From a First Nations perspective, there will be a need for clear guidance about the use and application of toxicity testing – including realistic advice about the limitations of the testing procedure as well as about the interpretation of results. It would be good to take a careful look at the use of effluent toxicity testing in other sectors” (discharging to surface water).
Another written submission noted that temperature has an influence on the toxicity of ammonia, and that in the arctic the lower temperature would reduce ammonia toxicity. The submission recommended that temperature should also be factored into calculations when determining an approach to ammonia acute toxicity.
Another opinion from a written submission asserted that some First Nations communities will likely be placed in the medium size category due to factors related to industrial input and increasing populations. The submission recommended that before deciding which size categories must conduct acute lethality testing, that the CCME Strategy and EC Framework take into account the capability of the community’s wastewater treatment plant to meet effluent requirements and the knowledge and ability of First Nation plant operators to undertake the testing. The submission recommended funding should be provided to conduct the testing.
Municipalities and Organizations
There was general support for acute toxicity testing across the country with only one submission suggesting that the requirement be dropped from the regulations at this time, until further research and evaluation of the proposed method (LC50) is carried out. The appropriateness of the test method for acute toxicity was questioned by others for similar reasons expressed by the aboriginal communities, with several participants proposing that alternative tests or adjusted LC50’s be used. Further detail on the pH adjusted LC50 was requested.
Some Quebec participants suggested that no chronic toxicity (i.e. no-carcinogenicity) should be a requirement for very large facilities, such as exists in the USA, and that alternative acute toxicity tests should be allowed (i.e. Microtox).
The timelines for meeting the acute toxicity requirements was discussed at all sessions with issues raised ranging from concern that a two year timeframe may be insufficient to establish a cause and find a solution (that the timelines should be more flexible), to stating that two years is too long a period of time and that facilities should be required to be non-acutely lethal. Others indicated that the identification of the toxic pollutants causing the lethality can be very complex and require more time.
One municipality suggested that intermittent singular toxicity failures should be treated as statistical outliers and not trigger a toxicity reduction evaluation and response.
There was a sense of confusion on the part of several participants regarding the overall management proposal for acute toxicity as it relates to ammonia and how chronic toxicity and mixing zones tie into this. It was suggested that in the consideration of chronic effects due to ammonia, that the fresh water and marine environments have significant differences which need to be considered. It was also stated at several sessions that the ambiguity of mixing zones needed to be addressed, with a clear definition being required.
Federal Departments and Agencies
A written submission requested that the EC Framework clarify the procedure a facility would need to follow in the case of failure of a non-regulated acute toxicity test e.g. the facility is not required to test for acute toxicity but does so for due diligence purposes. Clarification was also sought on what enforcement action would be taken on such a situation.
There was considerable discussion with respect to mixing zones. One recommendation made was that persistent and non-persistent pollutants should be differentiated and that a mixing zone should only be used for non-persistent pollutants such as ammonia. It was expressed in a written submission that a consistent procedure would be required under the proposed regulation to calculate the size of mixing zone based on risk and should include a discharge regime that considers tidal factors, seasonal variations and flow rates. Another submission indicated that the mixing zone plays an important role in evaluating risks to the receiving environment, and that sampling should be undertaken in the mixing zone for all parameters.
The appropriateness of the using the Acute Toxicity test for rainbow trout was questioned, for reasons similar to those raised by consultation session participants in the above streams. It was recommended that Environment
Canada and Department of Fisheries and Oceans should consider further research and re-evaluate the RM13 standard test for acute toxicity as it applies to Northern communities.
One comment recommended that Environment Canada consider incorporating certain biomarkers into wastewater effluent toxicity testing, as a means of better evaluating the protection of aquatic organisms. In a written submission it was noted that,” Given the many contaminants present in wastewater effluent, much more than simple acute and chronic testing of fish will be required to ensure the protection of the aquatic environment, as recent scientific literature has confirmed that MWWE are often more harmful to primary producers and invertebrates than to fish. Also recall that MWWE often have much more subtle effects (associated with long-term risk to aquatic populations) than mere general toxicity. Adverse effects related to immunotoxicity, reprotoxicity (or endocrine disruption), genotoxicity, neurotoxicity, oxidative stress, etc. must be taken into account in the federal regulations, as recent research has shown that all of these effects are associated with MWWE”.
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