A Cell survival of Chlamydomonas reinhardtii (black circle) and Saccharomyces cerevisiae (black square) after the treatment with PbCl2 concentrations in the range of 0.45–3.6 mM for 2 hours B cell survival of Chlamydomonas reinhardtii after the treatment with PbCl2 concentrations in the range of 0.03–0.22 mM for 2 hours C three doses of lethality were calculated. Results are from at least three experiments with independently grown cell cultures and presented as mean ± SEM. Asterisks represent statistical significance (ns P > 0.05; *** P < 0.001). Where no error bars are evident, they are equal to or smaller than the values.