Potential ecotoxic effects probe

Based on case studies, many countries have tried to develop similar indices where a number of toxicological parameters are integrated with the aim of quickly measuring the potential danger of the samples, particularly industrial effluents. The potential ecotoxic effects probe (PEEP) is one of the best known. It was developed in Canada as part of the St. Lawrence River Action Plan and was used to rank the impact of 50 industrial effluents discharged daily into the St. Lawrence River (Costan elal.. 1993). 

The following four bioassays are used to derive the PEEP index  

To apply the PEEP index, the effluent sample is first evaluated using all four bioassays. After biodegradation, the sample is tested using three of the four toxicity tests the Ceriodaphnia test is excluded. 

Results of all bioassays are reported as TOEC values, so a value can be entered into the PEEP index even if no inhibitory concentration (IC) or median effective concentration (EC50) was determined. The TOECs are converted to toxic units. The PEEP is calculated as the sum of the toxic units, including both before and after biodegradation, according to the following formula  

The four tests produce a total of six end-points, because the Ceriodaphnia and SOS Chromotest each have two end-points. Without Ceriodaphnia there are four end-points after biodegradation, so the value of N is 10. The PEEP formula sums the toxic units from each end-point and divides by N to derive an average toxic unit for the effluent. This is multiplied by n to account for the breadth of toxic response and by the discharge volume to compute the total hourly number of toxic units entering the river or receiving water. The result is expressed as a logarithm (adding 1 in the formula merely ensures that the log is computable). This produces a scale of results that would normally fall between 0 and 10. 

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Environment Canada recently developed an evaluation system based on effluent toxicity testing, capable of ranking the environmental hazards of industrial effluents [185]. This so-called Potential Ecotoxic Effects Probe (PEEP) incorporates the results of a variety of small-scale toxicity tests into one relative toxicity index to prioritize effluents for sanitation. In the index no allowance has been made for in-stream dilution, therefore the acmal risk for environmental effects is not modeled. The tests performed on each effluent are the following bacterial assay [V.fisheri (P. phosphoreum), Microtox], microalgal assay S. capricornutum) crustacean assay (C. dubiay, and bacterial genotoxicity test E. coli, SOS-test). 

Costan, G. Bermingham, N. Blaise, C. Ferard, J.F. Potential Ecotoxic Effects Probe (PEEP) a novel index to assess and compare the toxic potential of industrial effluents. Environ. Toxic. Water Quality 1993, 8 (1). 

EFFLUENT ASSESSMENT WITH THE PEEP (POTENTIAL ECOTOXIC EFFECTS PROBE)... 

PEEP index Potential Ecotoxic Effects Probe index Purpose... 

The proposed hazard assessment scheme (HAS) used in Colombia is a ranking system where toxicity data obtained from the application of a test battery enables one to determine the degree of toxicity of liquid samples on a relative basis. Test battery results are then integrated into the Potential Ecotoxic Effects Probe (PEEP) index formula developed by Environment Canada for the comparison of wastewaters (Costan et al., 1993). This index can be applied to evaluate the potential toxicity of industrial and municipal wastewaters, and to assess the effectiveness of toxicity abatement measures for effluents. This procedure is easy to apply and can be used with different batteries of tests (see Chapter 1 of this volume). 

Blaise, C. and J.F. Ferard. 2005. Effluent assessment with the PEEP (potential ecotoxic effects probe) index. In C. Blaise and J.F. Ferard. (eds), Small-scale Freshwater Toxicity Investigations, Vol. 2, pp. 69-87. New York Springer. 

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