Correlations between three methods for determining the toxicity of chemicals to earthworms

Abstract

Three different laboratory methods for determining the toxicity of chemicals to earthworms were tested with a variety of pesticides and other chemicals. These methods, proposed by the EEC (Determination of Ecotoxicity of Chemicals), were: the Contact Filter Paper Test, in which the skin contact toxicity is tested by placing the organisms on treated filter paper; the Artificial Soil Test, in which the toxicity by skin and gut uptake is determined by adding the earthworms to an artificial soil made of sand, clay mineral and peat; and the Artisol Test, in which the toxicity by skin and gut uptake is determined by placing the worms in an artificial substrate consisting of silica, water and glass balls. (In the Artisol Test, the earthworms ingest the silica paste as they do soil.) With several chemicals, the Artificial Soil Test was conducted as described in an early guideline of the BBA. This test is similar to that proposed by the EEC. Results from the Contact Filter Paper Test were poorly correlated to those obtained by the other two methods (correlation to the Artificial Soil Test, r=0.55; correlation to the Artisol Test, r=0.48). In contrast, there was a high correlation between the Artificial Soil Test and the Artisol Test (r=0.91). This indicated that the mode of uptake of the chemicals (skin uptake and/or gut uptake) may be the same. As the Artisol Test seems to be readily handled and standardised, it could be useful for obtaining reproducible data on the ecotoxicity of chemicals to earthworms.

Toxicity, bioaccumulation and metabolism of pesticides in the earthworm

“…[33][34][35] For several earthworm species, the acute LC 50 values obtained by this test are poorly correlated with those from the 14-day artificial soil test. 36,37) The relatively decreased toxicity in the latter test was observed for pyrethroids and some other pesticides, 34,35) possibly due to lower bioavailability by tight adsorption to the substrate, faster degradation therein or more metabolic detoxification in the earthworm via dietary uptake. Metabolic transformation generally decreases a pesticide's toxicity, but the formation of more toxic metabolites should be noted, for example the oxon of an organophosphorus pesticide and the phenol of a phenoxy herbicide.…”

“…61) Therefore, log K ow is a useful descriptor for analyzing the acute toxicity of pesticides. The 48-hr LC 50 values (µg/cm 2 ) from the paper contact tests using E. fetida for 86 pesticides and seven phenol derivatives [33][34][35][36][37]40) were first analyzed against log K ow (U.S. EPA EPI-Suite; http://www.epa.gov/opptintr/exposure/pubs/episuite. htm).…”

Exposure Assessment to Persistent Organic Pollutants in Wildlife: The Case Study of Coatzacoalcos, Veracruz, Mexico

“…It is complicated to make a comparison between crab species because they have different etiology and habitants, however, because most crab species are detritivores, we consider them as a good option to do studies related to POPs exposure. There are several studies on earthworms with ecotoxicological background mainly focused on effects at population levels (lethality), at both laboratory controlled conditions (Heimbach, 1984;Ma & Bodt, 1993;Kula, 1995, Morrison et al, 2000 as in field ones (Thompson, 1970;Tomlin, 1981;Edwards & Brown, 1982;Haque & Ebing, 1983;Potter et al, 1994;Espinosa-Reyes et al, 2010), however, there are a few studies where exposure to POPs are evaluated, Jones and Hart (1998) revised works related to exposure of different earthworms species to various pesticides-Benomyl, Carbaryl, Carbendazim, Carbofuran, Chlordane, Methiocarb, Parathion, Pentachlorophenol, Phorate, Propoxur, Thiophanateme-. These same authors mentioned that earthworms of the Eisenia type are the most resistent to the pesticides previou s l y m e n t i o n e d .…”

Toxicity Assessment of Buprofezin, Lufenuron, and Triflumuron to the EarthwormAporrectodea caliginosa

“…Earthworms used in this study belonged to species commonly found in Egypt (Aporrectodea caliginosa). Individual worms were collected from dunghills around Alexandria Governorate and reared in artificial soil in large plastic containers (38 × 60 × 10 cm) covered with muslin cloth to reduce water evaporation, as described by Heimbach [24]. The worms were maintained in this artificial soil at 23 ± 2 ∘ C for one month before the experiments.…”

“…Procedures used were based on those described by Heimbach [24]. Buprofezin and triflumuron were tested at 50, 100, 150, 200, and 300 mg active ingredient, a.i/kg artificial soil, while lufenuron was tested at 0.5, 1, 5, 10, and 25 mg/kg soil because it caused 100% mortality at concentration of 50 mg/kg soil.…”