OBJECTIVES: The aim of this study is to assess the toxicity of PAX-18 in different developmental stages of common carp (Cyprinus carpio). The preparation PAX-18, with its active ingredient polyaluminium chloride (9% of Al), is a coagulation agent that is used mainly to precipitate phosphates, to prevent surface water eutrophication and incidences of cyanobacteria. It is applied to the water environment and thus could present a potential risk to fish.
DESIGN: The toxicity tests were performed on common carp according to OECD (203, 210) methodologies. The acute toxic effect was evaluated for juveniles and the early development stage effect was observed in embryo-larval toxicity tests. The results of the toxicity tests (the number of dead individuals at particular test concentrations) were subjected to a probit analysis using an EKO-TOX 5.2 programme to determine the LC50 values of PAX-18.
RESULTS: Acute toxicity value expressed as 96hLC50 was 753.1 +/- 24.3 mg.l-1 (67.8 mg.l-1 Al). Effect on early development stage expressed as the no observed effect concentration was 10 mg.l-1 (0.9 mg.l-1 Al), the lowest observed effect concentration was 50 mg.l-1 (4.5 mg.l-1 Al). No significant effects of the preparation PAX-18 in concentrations of 50 mg.l-1 of PAX-18 and lower were found on hatching, length and weight parameters, morphology and histopathology.
CONCLUSION: The lethal concentration of PAX-18 found in acute toxicity tests on common carp was 7-14 times higher than the concentration which is usually applied to water (5-10 mg.l-1 Al). Moreover, fish in eutrophicated water sources are exposed to PAX-18 concentrations corresponding with the lowest observed effect concentration only for a short time, therefore the effect on them can be considered as minimal.