The absence of a distinct dose-dependent curve and the induction of less than 50% mortality in
almost all the above organisms may be suggestive of an unstable leachate with reduced toxicity
probably due to the various attenuation processes acting on the leachate. In all cases, except in
the bioassays involving Culex pipiens, mortality in controls were below 10%. 96hr LC50 in Culex
pipiens was 20% leachate dilution (Figure 6) while LC50 values for all the other organisms were
indeterminate. The results of bioassays using the larvae of Culex pipiens showed a preference of
these organisms for the leachate. Lower percentage mortalities were observed at higher dilutions
of the leachate, compared to the control (Table 6; Figure 6). This may not be unconnected with
the preference of this particular species for a contaminated rather than an uncontaminated
environment as toxicity reduced with increasing concentrations of the leachate. This was also
supported by the results of pupal emergence which further indicate the preference of this species
for a contaminated environment.