Acute toxicity of chlorobenzenes in Tetrahymena: Estimated by microcalorimetry and mechanism

The toxicity of chlorobenzenes to Tetrahymena growth metabolism was studied by microcalorimetry. The growth constant (k), peak time (T) and generation times (TG) were calculated. IC50 of chlorobenzenes was obtained through the kinetic parameters. The results suggested that the order of toxicity was 1,2,4-trichlorobenzene > o-dichlorobenzene > p-dichlorobenzene > m-dichlorobenzene > chlorobenzene. ATR-FTIR spectra revealed that amide groups and PO2− of the phospholipid phospho-diester, both in the hydrophobic end exposed to the outer layer, were the easiest to be damaged. The relationship between IC50 and chemicals structure parameters (ELUMO, EHOMO, log KOW, ∑QR, ΔQπR and ΔE), indicated that the more chlorine atoms were substituted, the greater the toxicity was. Chlorobenzenes have toxicity of non-polar narcosis. Their toxicity is proportional to their concentrations at the site of action, and caused by membrane perturbation.

► The most toxicity of chlorobenzenes to Tetrahymena was 1,2,4-trichlorobenzene.
► The cell surface was found the micro destruction by microscopy images.
► ATR-FTIR spectra were investigated the decay of functional groups.
► The simple linear regression equations were designed to study the mechanism.