Potassium hydrogencarbonate

Toxicity to soil macroorganisms except arthropods

Link to relevant study record(s)

Reference

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Justification for type of information:

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across hypothesis is based on transformation of the target and source substances to common compounds (scenario 1 of the Read-Across Assessment Framework (RAAF), ECHA, March 2017 - transformation to common compounds). The target substance potassium hydrogencarbonate as well as the source substance potassium chloride dissociate in aqueous media to potassium and the respective anion.

For further details, please refer to the Justification for Read-Across attached in Iuclid Chapter 13.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Please refer to the Justification for Read-Across attached in Iuclid Chapter 13.

3. ANALOGUE APPROACH JUSTIFICATION
Please refer to the Justification for Read-Across attached in Iuclid Chapter 13.

4. DATA MATRIX
Please refer to the Justification for Read-Across attached in Iuclid Chapter 13.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 207 (Earthworm, Acute Toxicity Tests)

Analytical monitoring:

no

Vehicle:

not specified

Details on preparation and application of test substrate:

- Method of mixing into soil (if used): Soil was placed in 1L- Mason-type glass jars. The test substance was first dissolved in water or acetonitrile at a defined concentration before being spiked into the soil. The acetonitrile was evaporated overnight in a chemical hood, and then the soil was rehydrated to 75% of its water holdung capacity /WHC) before the beginning ofthe experiment. WHC measurements were done in triplicate and achieved by adding 15 mL of water to approximately 10g of soil in a Whatman No. 1 filter paper-lined funnel placed onto an Erlenmeyer flask and allowing the ewater to drain out. To avoid evaporation the glassware and the soil were covered with a sheet of aluminium foil. Then, a small quantity of wet soil, approximately 10 g, was taken and dried for 24 hours at 103 ± 2°C.

- Controls: yes
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): acetonitrile, not clear if vehicle was used for KCl
- Concentration of vehicle in test medium (stock solution and final test solution): not reported
- Evaporation of vehicle before use: yes

Test organisms (species):

Eisenia sp.

Animal group:

annelids

Details on test organisms:

TEST ORGANISM
- Common name: Earthworm (Eisenia andrei)
- Source: Carolina Supply Co. (Burlington, NC); laboratory culture
- Age at test initiation (mean and range, SD): Adult: animals had a well-developed clitellum
- Weight at test initiation (mean and range, SD): 300 - 600 mg wet weight


ACCLIMATION
- Acclimation period:yes
- Acclimation conditions (same as test or not): yes

Study type:

laboratory study

Substrate type:

other: Two soils were used: artificial OECD soil

Total exposure duration:

14 d

Post exposure observation period:

no

Test temperature:

20 ± 1°C

pH:

artificial OECD soil: 6.0 ± 0.5

Moisture:

artificial OECD soil: 70 - 80% humidity

Nominal and measured concentrations:

0, 3260, 4238, 5869, 7825, 10433 mg/kg dry soil

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

5 595 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: CV (95%): 5338.4 - 5863.9 mg/kg soil dw

Duration:

7 d

Dose descriptor:

LC50

Effect conc.:

5 725.1 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: CV (95%): 5455.5 - 6008.1 mg/kg soil dw

Dose descriptor:

NOEC

Effect conc.:

4 238 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Dose descriptor:

LOEC

Effect conc.:

5 869 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

- Mortality at end of exposure period: see table 1
- Total mass of adults at beginning of test: not reported
- Changes in body weigth of live adults (% of initial weight) at end of exposure period: see table 1
- Morphological abnormalities: not reported
- Behavioural abnormalities: not reported
- Other biological observations:no

The CV (chronic value, geometric mean of NOEC and LOEC) was determined for 4987.3 mg/kg soil dw.

Reported statistics and error estimates:

The toxicity endpoints LC50, NOEC, LOEC and CV were calculated using the ToxCalc program (Version 5.0; Tidepool Scientific Software, McKinleyville, CA). Statistical methods for point estimates included Maximum Likelihood Regression (Finney, 1971 a,b), Spearman -Karber methods (Hamilton et al., 1971 a,b) , the linear interpolation of bootstrapping (Norberg-King, 1993), and the nonlinear interpolation with bootstrapping (US EPA, 1989b). Other statistical methods for LOEC/NOEC included a parametric hypothesis test (e.g. Dunnett's Multiple Comparison Test, Williams Multiple Comparison test) and nonparametric hypothesis test (e.g. Steel's Many-One Rank tests, Wilcoxon's, Two-Sample Test).

Table 1: Acute Effects of KCl-Spiked OECD Artificial soil on Eisenia andrei

Nominal concentration (mg/kg dry soil)	pH (initial/final)	Mortality (%) after 7 days	Mortality (%) after 14 days	Weight changes after 14 days (mg)^a)	Weight changes after 14 days % (w/w)^b)
0	6.87/6.90	0	0	-22 ± 14	4.3 ± 2.5
3260	6.72/6.33	0	0	-28 ± 28	5.4 ± 5.0
4238	6.79/6.41	0	0	-55 ± 37	10.6 ± 6.9
5869	6.82/6.71	55*	62.5*	-136 ± 43	27.5 ± 8.3
7825	6.71/6.91	100*	100*	NA	NA
10433	6.69/6.66	100*	100*	NA	NA

 

*Significant mortality compared to controls

NA: not applicable

^a)based on wet matter

^b)compared to initial mean weight

Validity criteria fulfilled:

not specified

Conclusions:

In a 14 d acute toxicity study with earthworms (Eisenia andrei) the LC 50 of KCl in artificial OECD soil was determined to be 5595 mg/kg soil dw (CV (95%): 5338.4 - 5863.9 mg/kg soil dw). The NOEC was 4238 mg/kg soil dw, the LOEC was 5869 mg/kg soil dw.
This result indicates very low toxicity of Potassium to earthworm.

Description of key information

 Potassium hydrogencarbonate is not expected to have an intrinsic toxic activity to soil macro-organisms except arthropods.

Additional information

In accordance with REACH Annex 9.4.1, column 2, and Annex X, 9.4.4. short and long-term toxicity testing on invertebrates is only required, if the chemical safety assessment according to Annex I indicates the need to investigate further the effects on terrestric organisms. Potassium and carbonate are essential for almost all living organisms including terrestrial invertebrates and natural components in their habitats. Therefore, potassium hydrogencarbonate is not expected to have a intrinsic toxic activity to terrestrial organisms.

These results are underlined by the test of the read across substance potassium chloride, that indicates very low toxicity of potassium to earthworms (Eisenia andrei). In a 14 d acute toxicity study with earthworms (Eisenia andrei) the LC50 of KCl in artificial OECD soil was determined to be 5595 mg/kg soil dw (CV (95%): 5338.4 - 5863.9 mg/kg soil dw). The NOEC was 4238 mg/kg soil dw, the LOEC was 5869 mg/kg soil dw.