DETERMINATION OF TOXICITY OF PLANT-GROWTH REGULATORS IN SELECTED AQUATIC ORGANISMS DAPHNIA-MAGNA AND TUBIFEX TUBIFEX

An aquatic ecological risk assessment is presented including the aquat ic effects and exposure assessment of five plant growth regulators: be ta-indolylacetic acid (IAA), 2,4-di-chlorophenoxyacetic acid (2,4-D), 2-methyl-4-chloro-phenoxyacetic acid (MCPA), 1-naphthylacetic acid (NA A) and N-6-(delta(2)-isopentenyl)adenosine (IPA) on D. magna and T. tu bifex. The tests were done under laboratory conditions and survival la te was the only biological end-point checked. The hazard of plant grow th regulators to non-target aquatic organisms was evaluated as LC5 and LC50 values (concentration causing 5 or 50% mortality, respectively) for the given aquatic test organisms. On the basis of LC50 values rank toxicity orders were established. These rank orders were NAA > IAA > IPA > 2,4-D greater than or equal to MCPA for T. tubifex and NAA = IAA greater than or equal to IPA > MCPA greater than or equal to 2,4-D fo r D. magna. The 96 h LC50 values in both species were very similar for IPA, MCPA and 2,4-D. T. tubifex worms were more sensitive to IAA and NAA than D. magna.