Estimating the toxicity of the weak base carbendazim to the earthworm (Eisenia fetida) using in situ pore water concentrations in different soils

► The toxicity of the weak base carbendazim to earthworm depends on soil type. ► In situ pore water concentration can estimate the toxicity of carbendazim in soils. ► The ionization results in the underestimation of carbendazim toxicity. ► Concentration in bulk pore water is lower than in pore water where earthworm lives.