resorcinol; 1,3-benzenediol

Toxicity to soil macroorganisms except arthropods

Link to relevant study record(s)

Reference

Endpoint:

toxicity to soil macroorganisms except arthropods: long-term

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Provides basic data

Guideline:

other:

Principles of method if other than guideline:

Method: other:
The study was designed to determine whether a pattern of toxicity could be discerned (a) among low molecular weight compounds with certain simple functional groups commonly found in fungal products of secondary metabolism (Turner, 1971; Moreau, 1979) and (b) between such compounds and high molecular weight humic acids and lignins.  Toxicity in this study is ascribed to substances that significantly reduce the growth rate or survival of E. foetida.

GLP compliance:

not specified

Details on preparation and application of test substrate:

The test substance was obtained/purchased from Aldrich Chemical co., Milwaukee, WI and used without further purification. Indulin AT and Reax 31 lingins were obtained from Westvaco Co., N. Charleston, SC; Marasperse from American Can Co., Rothschild, WI and Orzan A from Crown Zellerback Co,, Camas, WA. Lignin from cherry tree (Prunus serotina Ehrh.) was prepared according to Tappi (1954).

The test substance  was processed for assay by mixing 0.01, 0.1, 0.05 or 1.0 g or ml into 100 g sludge which contained 11-15% solids.  Assuming exactly 13% solids in the sludge, the substance was thus tested at concentrations of about 0, 0.1, 1.0, 4 and 8% (w/w) dry wt, including controls. Correspondingly on a dry wt basis, the humic acids and lingnins were tested at concentrations of 0, 1, 4, 8 and 16%

Test organisms (species):

Eisenia fetida

Animal group:

other: earthworm

Details on test organisms:

Stock cultures of E. foetida were maintained on horse manure or activated sludge (Neuhauser et al., 1980). Sludge and hatchlings were obtained and sludge prepared according to Hartenstein et al. (1981a).

Humic acids were prepared from anaerobic and activated sludge digests as follows. The pH of sludge, whicch contained about 2% solids w/w, was brought to pH 11 with 40% NaOH, centrifuged and the supernatant reduced to pH 2 with 6 N HCl. The resulting precipitate (humic acids) was collected by centrifugation, resuspended in alkalie, reprecipitated and resuspended twice, dialyzed exhaustively against distilled water and lyophilized.

Study type:

laboratory study

Substrate type:

artificial soil

Total exposure duration:

6 wk

Test temperature:

24 C

Details on test conditions:

About 30 g sludge (ca. 13% solids) with test substance were placed over a ca. 4 mm depth of silt loam in a 20 x 100 mm Petri dish.  Two hatchlings, each under 10 mg live, wt, were added.  The set of 25 dishes with 5 replicates of 5 concentrations was then stored at 24 ± 1°C.  Growth was checked every 2 weeks and worms were transferred to freshly prepared substance at 4 weeks.  Growth achieved at 2 or 4 weeks was determined by rinsing the worms in distilled water, blotting and weighing.  Weight at 6 weeks was evaluated by analysis of variance.  Significant differences were determined by the Neulman-Keul test (Zar, 1974).

Mortality was determined by enumeration and said to be significant if 5 or more earthworms died.

Nominal and measured concentrations:

The substance was thus tested at concentrations of about 0, 0.1, 1.0, 4 and 8% (w/w) dry wt, including controls. Correspondingly on a dry wt basis, the humic acids and lingnins were tested at concentrations of 0, 1, 4, 8 and 16%.

Reference substance (positive control):

not specified

Duration:

42 d

Dose descriptor:

LC100

Effect conc.:

ca. 40 000 mg/kg soil dw

Basis for effect:

mortality

Duration:

42 d

Dose descriptor:

LOEC

Effect conc.:

10 000 mg/kg soil dw

Basis for effect:

growth

Details on results:

The test substance did not permit the worms to grow more rapidly and achieve greater weight than was obtained in the controls.  Resorcinol caused significant mortality (100%) at 4% in sludge (w/w) dry weight.

LC100: 40000 mg/kg soil dw
LOEC (growth): 10000 mg/kg soil dw

Possibly some of the test substances were altered in the sludge in time, though no attempt was made to determine this. It is also possible that microbes in a sludge sample with a greater concentration of some energy source such as cellulose (derived from, say, toilet tissue) could degrade a test substance faster than sludge microbes in a sample with a lower level of cellulose might degrade their test substance. Repeition of several of the assays a year later yielded identical results.

Neither humic acids or lignins were toxic to E. foetida.

Validity criteria fulfilled:

not specified

Conclusions:

Resorcinol caused mortality (LC100) at 40000 mg/kg soil dw to Eisenia fetida. The LOEC for growth was 10000 mg/kg soil dw.

Description of key information

Data are available for both mortality and growth in Eisenia fetida (worm).

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for soil macroorganisms:

10 000 mg/kg soil dw

Additional information

Data are available for both mortality and growth in Eisenia fetida (worm).  Worms were exposed for a period of 6 weeks (42 days) to resorcinol concentrations ca. 0, 0.1, 1.0, 4 and 8% (w/w) dry wt, including controls.  Resorcinol showed no effect on growth rate or body weight compared to controls.  Mortality among controls was less than 2%.  Resorcinol caused significant mortality at 4% in sludge (w/w) dry weight with the LC100 = 40000 mg/kg soil dw and the LOEC = 10000 mg/kg soil dw (Hartenstein, 1982).