Where acute LC50 data were used in combination with chronic data, they were converted to chronic NOECs by dividing by an acute to chronic ratio (ACR) of 11.49. This value was adopted in the calculation of the ANZECC/ARMCANZ (2000) trigger value.Chronic EC50s were converted to chronic NOECs using their recommended divisor of 5. Where there were multiple endpoints for a species, the geometric mean was used.