18.104.22.168.1. Test and control groups
1) The number of doses and replicates tested should meet the statistical requirements for determination of LD50 with 95% confidence limits (OECD, 1998b). Normally, five doses in a geometric series, with a factor not exceeding 2.2, and covering the range for the LD50, are required for the test. However, the number of doses has to be determined in relation to the slope of the toxicity curve (dose versus mortality) and with consideration taken to the statistical method which is chosen for analysis of the results.
2) A range-finding test preceding the actual toxicity test enables one to choose the appropriate doses.