Relative Toxicities of Chemicals to the Earthworm Eisenia Foetida

Abstract

In the present study, 90 chemicals were tested against Eisenia foetida for the purpose of using this organism as the marker species to indicate the relative toxicities of chemicals to earthworms and other soil invertebrates. The worms were exposed to deposits of the chemicals on filter paper for 48 hand the mortality was recorded; concentrations were expressed in pgkm'. Based on the resulting LC,, values, the chemicals were classified as supertoxic (< 1.0 pglcm'), extremely toxic (1-10 pg/cm ' 1, very toxic (10-100 pg/cm2), moderately toxic (IOO-I,OOO pg/cm2) or relatively nontoxic (> 1,000 pg/cm2). Of the chemicals tested (pesticides, solvents, metals, drugs, carcinogens, etc.), only carbofuran and eserine salicylate, both carbamates, were supertoxic. The remaining chemicals were distributed about equally among the other toxicity categories. The most surprising results were that the phenolic hydrolytic products of parathion, carbaryl, 2,4-D and 2,4,S-T were as toxic, or more toxic, than the parent material, with all of these compounds falling within the extremely toxic and very toxic classifications. Several chemicals, considered only moderately or relatively nontoxic to mammals, were extremely or very toxic to earthworms; among these compounds were carbaryl, malathion, cypermethrin and benomyl. The results of this study further demonstrate the unpredictability of chemical toxicity to different animal species, a fact which complicates the assessment of environmental risk to one or more species basedon data attained with another.

Ecotoxicity studies of the levulinate ester series

“…foetida (Roberts and Dorough 1984). Interestingly, this study also revealed that Eisenia was unexpectedly tolerant to many solvents and fuels, even at very high concentrations (i.e., cyclohexane, dichloromethane or methanol).…”

“…However, some fungicides are known to show the opposite trend (non-toxic for mammals and extremely toxic to fish and earthworms). Many other examples exist that demonstrate little to no correlation between non-target species, and consequently, interspecies extrapolations of chemical hazard from one animal species to another based on toxicity data are not easy to make (Roberts and Dorough 1984). We find that the mechanisms of action for levulinate toxicity are both exposure-and species-dependent.…”

“…Interestingly, this study also revealed that Eisenia was unexpectedly tolerant to many solvents and fuels, even at very high concentrations (i.e., cyclohexane, dichloromethane or methanol). However, other solvents such as acetone or benzene were moderately toxic while benzaldehyde and dimethylacetamide were very toxic (Roberts and Dorough 1984). 14 According to the classification presented in this study, LA and BL can be considered as non-toxic, while ML is moderately toxic (Roberts and Dorough 1984).…”

“…However, other solvents such as acetone or benzene were moderately toxic while benzaldehyde and dimethylacetamide were very toxic (Roberts and Dorough 1984). 14 According to the classification presented in this study, LA and BL can be considered as non-toxic, while ML is moderately toxic (Roberts and Dorough 1984). Considering the differences in toxicity shown by very similar compounds it is difficult for us to correlate the structure and properties of the chemicals tested (i.e., the levulinate series) and their effect in Eisenia.…”

Artificial Soil Test of Phorate on Eisenia fetida

“…Brown [11] has stated that OP compounds intended for soil use have little lasting effect on earthworm population but some can cause heavy initial kills; while Bennuor [12] pointed out that formothion-an organophosphate is found toxic to Aporrectodea caliginosa causing moderate reduction in numbers and body mass. Bharati and Subba Rao [13] The toxicity of the OP compounds to earthworms is mainly through their ability to inhibit the acetylcholine esterase (AchE) -an enzyme responsible for the synthesis of the neurotransmitter, Acetylcholine which is found in the synaptic regions of the nervous system [17,18] and the role of neurotransmitter is considered as a vital process for usual functioning of the entire nervous system [19][20][21]. The chloropyrifos -an organophosphate compound have toxic effect on the earthworm, Aporrectodea caliginosa causing mortality on high dose [22,23].…”