21. In chronic exposures, organisms come into contact with low, continuous doses of a toxicant . 22. Some toxicants in these experiments by using chemical methods would affect the mechanisms of the assays. 23. The toxicants used in these experiments were chosen because they had a known mode of action. 24. However, the toxicant continued to break down the proton gradient, inevitably leading to mortality. 25. There is general agreement that e-cigarettes expose users to fewer toxicants than tobacco cigarettes. 26. Typically using selected organisms with ecologically relevant sensitivity to toxicants and a well-established literature background. 27. The toxicant is added to the water in order to obtain the correct concentrations to be tested. 28. Nevertheless, the specific action of the toxicant is always shown first because it requires lower concentrations. 29. Statistical analyses were used to determine significant differences in responses between toxicants with different modes of action. 30. This mechanism can include such toxicants as dichlorodiphenyltrichloroethane ( DDE ) and polychlorinated biphenyls ( PCBs ).
