Proxan-sodium

Toxicity to soil microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to soil microorganisms

Type of information:

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

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Considered suitable for read-across

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 216 (Soil Microorganisms: Nitrogen Transformation Test)

Deviations:

yes

Remarks:

The content of sand in the soil used in the test was 46%. The temperature increased to 23°C during incubation.

GLP compliance:

yes (incl. QA statement)

Remarks:

10/2013/DPL

Total exposure duration:

28 d

Test temperature:

19 – 23°C

Moisture:

soil moisture content: 42.1 – 51.9% of the maximum water holding capacity

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

553.9 mg/kg soil dw

Basis for effect:

nitrate formation rate

Duration:

28 d

Dose descriptor:

EC25

Effect conc.:

126 mg/kg soil dw

Basis for effect:

nitrate formation rate

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

< 125 mg/kg soil dw

Basis for effect:

nitrate formation rate

Validity criteria fulfilled:

yes

Remarks:

The coefficients of variation (CV) in the control group were 1.5 and 2.3 % on days 0 and 28 of incubation, respectively. According to the Guideline, the variation between replicate control samples should be less than * 15%.

Conclusions:

The test item at the concentrations ranging from 125 to 2000 mg/kg dry weight of soil statistically significantly inhibited the process of nitrogen transformation to nitrate.The concentration of the test item causing a 50% inhibition of nitrogen transformation to nitrate (EC50) is 553.9 mg/kg dry weight of soil.The concentration of the test item causing a 25% inhibition of nitrogen transformation to nitrate (EC25) is 126.0 mg/kg dry weight of soil.The concentration of the test item causing a 10% inhibition of nitrogen transformation to nitrate (EC10) is <125.0 mg/kg dry weight of soil.

Executive summary:

On day 0 of incubation, there were statistically significant differences in the quantities of nitrate formed during the test between the treated and the control soils. The concentrations of nitrate in the soil treated with the test item at the concentrations of 125, 250, and 1000 mg/kg dry weight of soil was statistically significantly lower than in the control.

The concentration of nitrate in the soil treated with the test item at the concentration of 500 mg/kg dry weight of soil was statistically significantly higher than in the control. The concentration of nitrate in the soil treated with the test item at the concentration of 2000 mg/kg dry weight of soil did not differ statistically significantly from the control.

 

On day 28 of incubation, statistically significant differences in the quantities of nitrate formed during the test between the treated and the control soils were noticed. The concentrations of nitrate in the soil treated with the test item at the concentrations ranging from 125 to 2000 mg/kg dry weight of soil were statistically significantly lower than in the control.

 

The concentration of the test item causing a 50% inhibition of nitrogen transformation to nitrate (EC₅₀) is 553.9 mg/kg dry weight of soil.

The concentration of the test item causing a 25% inhibition of nitrogen transformation to nitrate (EC₂₅) is 126.0 mg/kg dry weight of soil.

The concentration of the test item causing a 10% inhibition of nitrogen transformation to nitrate (EC₁₀) is <125 mg/kg dry weight of soil.

 

Description of key information

The test item at the concentrations ranging from 125 to 2000 mg/kg dry weight of soil statistically significantly inhibited the process of nitrogen transformation to nitrate.
The concentration of the test item causing a 50% inhibition of nitrogen transformation to nitrate (EC50) is 553.9 mg/kg dry weight of soil.
The concentration of the test item causing a 25% inhibition of nitrogen transformation to nitrate (EC25) is 126.0 mg/kg dry weight of soil.
The concentration of the test item causing a 10% inhibition of nitrogen transformation to nitrate (EC10) is <125.0 mg/kg dry weight of soil.

Key value for chemical safety assessment

Long-term EC10 or NOEC for soil microorganisms:

125 mg/kg soil dw

Additional information

Antimicrobial activity of xanthates was evident from median inhibitory limit on amonia oxidation in Nitrosomonas of 12 ppm(Bremner J. M. and Yeomans J. C., 1986, Biol. Fertil. Soils 173-179)

Potassium ethyl xanthate(CAS# 140-89-6) is a nitrification microbial inhibitor and was observed to inhibit soil denitrification at concentration about 50 ppm (US EPA, Washington DC, Full Public Report, Sodium Ethyl Xanthate, Priority Existing Chemical No.5, Canberra, May 1995).

 

Sodium ethyl(CAS# 140-90-9):The test item at the concentrations ranging from 125 to 2000 mg/kg dry weight of soil statistically significantly inhibited the process of nitrogen transformation to nitrate.

The concentration of the test item causing a 50% inhibition of nitrogen transformation to nitrate (EC₅₀) is 553.9 mg/kg dry weight of soil.

The concentration of the test item causing a 25%inhibition of nitrogen transformation to nitrate(EC₂₅) is 126.0 mg/kg dry weight of soil.

The concentration of the test item causing a 10%inhibition of nitrogen transformation to nitrate(EC₁₀) is <125.0 mg/kg dry weight of soil.(Anna Arendarczyk, Institute of Industrial Organic Chemistry Branch Pszczyna, Department of Ecotoxicology,43-200 Pszczyna Poland)

Sodium ethyl(CAS# 140-90-9) or sodium isopropyl xanthates(CAS# 140-93-2) depending on concentration inhibit or activate mushroom tyrosinase (enzyme). The thiol compounds can act as inhibitors of tyrosinase due to their ability to chelate Cu⁺². Tyrosinase also known as polyphenol oxidase, is a copper containing mixed - function oxidase widly distributed in microorganisms, animals and plants. The investigated xanthates act as activators at concentration about 11.5µM but as inhibitors at 20 - 50 µM(Saboury A. A., et all, J. Chinese Chem. Soc. 2008,55,937-942)

The inhibitory effect of n-alkyl xanthates on mushroom tyrosinase depend on alkyl chain length. Shorter alkyl radical gives a more potent inhibitor(Saboury A. A., et all, 2007, Acta Biochimica Polonica 54, 183-192)

Toxicity of Carbon disulfide(CAS# 75-15-0) to soil dwelling microorganisms:

Test conditions: natural soil, 

Endpoint: inhibition

Result: NOEC: 15 kg of CS₂per 100 m².

(UCLID Dataset, Carbon disulfide, 2000 European Chemicals Bureau)

Carbon disulfide (CAS# 75-15-0) is a soil disinfectant and toxic to bacteria(EPA, 1986, Health and environmental effects profile for carbon disulfide, EPA/600/X-86/155,129).