SETAC Globe - Environmental Quality Through Science
16 March 2017
Volume 18 Issue 3

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Brazilian Effluent Legislation: A Major Concern to Aquatic Systems Monitoring

Alexandre Arenzon, Federal University of Rio Grande do Sul, SETAC Latin America Council Member and Ecotox-Brazil Vice President

Among South American countries, Brazil is the only one to have a specific legislation about ecotoxicological effluent assessment. This legislation should be something to be proud of; however, the practical application of such legislation remains deficient and has been so from the beginning. The first time that effluent toxicity appeared in Brazilian legislation was in 1986. By that time, article 23 of the Environmental Resolution CONAMA 20/86 only declared that “the effluents cannot add to the receiving water body characteristics in disagreement with its framing under the terms of this Resolution.” The questions were: How can this condition be tested? Which analyses should be done to verify it? There was no information in the Resolution clarifying those specific issues.

Nineteen years were necessary for new legislation to appear. In 2005, the newly created CONAMA 375/2005 stated, “The effluent should not cause or present the potential to cause toxic effects to the aquatic organisms in the receiving water body, according to the toxicity criteria established by the environmental agency.” Brazil has 28 independent environmental agencies – one from each state. Thus, the challenge was that with their differences in structure, knowledge and resources, each environmental agency from Brazil had to create their own criteria for effluent toxicity. With all possibilities for discrepancy among the agencies, at least the environmental resolution CONAMA 375/2005 stated that the toxicity criteria established must be based on standardized toxicity tests using aquatic organisms and carried out in the effluent. However, they still had to establish the methods to be applied, species to use as test-organisms, frequency of the analyses and toxicity that would be tolerated.

With help from the USEPA, only one Brazilian state, Rio Grande do Sul, developed a group of stepped criteria which, after fourteen years, were expected to result in the absence of acute toxicity for three different trophic levels, absence of chronic toxicity for two different trophic levels, and absence of genotoxicity for every effluent discharged. “This is impossible!” industries shouted. And unfortunately, after ten years in force, the law was revoked. This 10-year period was enough to convince some industries that efforts were necessary to reduce the industries’ impact on the environment, but it was not enough to establish this as a new standard.

Up to 2011, six years after CONAMA 375/2005 became an environmental law, only a few states had established their own toxicity criteria. Most of those that had developed the criteria demanded acute toxicity testing for two different trophic levels as the bacteria, Vibrio fischeri, and the microcrustacean, Daphnia magna; or acute and chronic toxicity testing to the microcrustaceans, Daphnia and Ceriodaphnia. Therefore, in order to assist the majority of states that did not present any proposal to effluents toxicity monitoring, a new environmental resolution was created, CONAMA 430/2011.
According to this new environmental resolution, effluent assessment needs to be performed using species from at least two different trophic levels. Some states continue to use the test-organism species specified by themselves, while others allowed the choice to be made by the laboratory executer of the analyses or by the effluent generator, which enables the choice of the most “convenient” method or species.

To exemplify this “free choice” problem, a sample from a food industry effluent was analyzed by the Laboratory of Ecotoxicology from the Federal University of Rio Grande do Sul. All possible test-organisms used in Brazil for acute fresh water effluents assessment were considered. Four different trophic levels were analyzed using nine test-organism species: bacteria (Vibrio fischeri), algae (Desmodesmus subspicatus and Pseudokirchneriella subcapitata), microcrustacean (Daphnia similis and D. magna), and fish (7-day-old Pimephales promelas, juvenile Danio rerio, 10±2 day D. rerio and embryo D. rerio tests).

It is well known that species present distinct sensitivity to compounds. This is exactly why assessment with different trophic levels are desirable. From the nine executed acute toxicity test, four of them were not able to detect toxicity. These four negative results included three different trophic levels. The V. fischeri bacteria, the D. rerio embryos and the D. similis and D. magna microcrustacean were not sensitive to the sample. This means that depending on the chosen method, the sample can be considered nontoxic or reporting a potentially false negative result. By lack of knowledge or inappropriate infrastructure, most state’s environmental regulatory agencies present a poor critical analysis of the methods applied or even the results obtained through ecotoxicological assays.

In addition to the problems acknowledged up until this point, the ecotoxicological criteria adopted by the Resolution CONAMA 430/2011 accept some level of toxicity in effluent samples. The resolution considers the relation between the effluent flow and the receiving waterbody flow. The bigger the river, the higher the toxicity allowed. The only specification is that the amount of effluent going into the river cannot be higher than the No Observed Effect Concentration (NOEC). However, the number of sites of discharge in each river as well as the distance between them are not considered.

The perfect assessment activity does not exist, so methods and results cannot be blindly accepted. The aim of effluent’s toxicity assessment is to protect the biota of the natural aquatic ecosystem. Thus, the spreading of ecotoxicology knowledge into Brazilian environmental regulatory agencies is an eminent necessity. Not only for Brazil but all Latin America, it is about time that the academia and environmental agencies start to communicate more effectively and to elaborate ways to improve ecotoxicological assessments of aquatic systems. It is imperative to reduce the abyss between research activities and regulation.

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