Toxicity, bioaccumulation and metabolism of pesticides in the earthworm

Abstract

The toxic effects of pesticides on earthworms, one of the most important bioindicators in the terrestrial environment, are closely related to their body burden determined by uptake, metabolism and excretion processes. Not only the passive diffusion via the outer skin from a dissolved fraction of pesticide but also the ingestion of contaminated soil and food governs the uptake process, with each contribution controlled by either the hydrophobicity of the pesticide or the soil organic matter. Although the available information is limited, earthworms are likely to metabolize pesticides via hydrolysis and oxidation (Phase I) followed by conjugation (Phase II), and low bioaccumulation is observed as a result for most pesticides. The acute toxicity in the soil exposure can be partly explained by the dissolved fraction of pesticide in pore water, but the contribution of dietary uptake and metabolism should be further studied to correctly evaluate pesticide toxicity.

Untargeted metabolomics reveals transformation pathways and metabolic response of the earthworm Perionyx excavatus after exposure to triphenyl phosphate

“…The calculated BCFs of TPHP in soil-earthworm ecosystem are much smaller than the theoretical BCF of 113.3. This can be ascribed to TPHP degradation in soil, high hydrophobicity of TPHP which results in low concentration in pore water 32 , and metabolism of TPHP by the earthworms, which might be accelerated by gut microflora and ingested soil microflora. Quantitative data on the fate of TPHP in different matrices in the soil-earthworm ecosystem might be obtained in the future using isotope-labeled TPHP.…”

“…Common enzymes in earthworms responsible for xenobiotic metabolism include cytochrome P450, carboxylesterases and glutathione-S-transferases (GST) 32 . For TPHP, oxidative hydroxylation is likely catalyzed by cytochrome P450, while hydrolysis may be catalyzed by phosphotriesterase.…”

Theoretical and organic chemical approaches to environmental behavior and metabolism of pesticides

“…The log K ow value of a pesticide is also useful to estimate its bioconcentration factor (BCF) in fish, 9) but less correlation was reported in mollusks, algae, crustacean, and insects, probably due to the different physiologies even within each species. 9,10) Furthermore, either the BCF in frogs 11) or acute toxicity in earthworms 12) is well correlated with the log K ow for pesticides and industrial chemicals. Therefore, the experimental methods to measure log K ow have been standardized by the OECD (shake-flask, OECD 107; slow-stirring, OECD 123; HPLC, OECD 117), and among many theoretical estimation methods of log K ow , the fragment constant approach represented by ClogP 13) has succeeded in estimating the value with reliable precision.…”

Effects of Owinema Bio-Preparation on Vermicomposting in Earthworm Ecological Boxes

“…Chemical plant protection is, on the one hand, beneficial due to rapid reduction of unwanted organisms, but on the other hand, due to a relatively low selectivity of measures, it contributes to biological imbalance in the environment. Soil organisms show various strategies of survival under chemical stress conditions [10][11][12][13]. The effect of insecticides on soil organisms is complex, and it depends on numerous abiotic factors and complex synergistic and antagonistic reactions [14].…”