Pyrithione zinc

Toxicity to soil microorganisms

Administrative data

Endpoint:

toxicity to soil microorganisms

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study according to OECD and EU guidelines

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Report date:

2015

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 216 (Soil Microorganisms: Nitrogen Transformation Test)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.21 (Soil Microorganisms: Nitrogen Transformation Test)

GLP compliance:

yes (incl. QA statement)

Remarks:

Toxi-Coop ZRT.

Test material

Test material information

Constituent 1

Reference substance name:

Pyrithione zinc

EC Number:

236-671-3

EC Name:

Pyrithione zinc

Cas Number:

13463-41-7

Molecular formula:

C10H8N2O2S2Zn

IUPAC Name:

Bis [1-hydroxy-2(1H)-pyridinethionato-O,S](T-4)-zinc

Details on test material:

- Name of test material: Zinc pyrithione

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Not applicable.

Sampling and analysis

Analytical monitoring:

not required

Details on sampling:

Not applicable.

Test substrate

Vehicle:

yes

Details on preparation and application of test substrate:

The test item was applied using fine quartz sand (particle size: more than 40 % 0.2-0.8 mm) as carrier. For an optimum distribution of the test item in the soil, a ratio of 10 g of sand per kilogram of soil (dry weight) was used. A homogeneous distribution of the test item in the artificial soil was obtained by thorough mixing.

Study design

Total exposure duration:

28 d

Test conditions

Test temperature:

20 ± 2 °C

Moisture:

40 % to 60 % of the maximum water holding capacity (WHC) of the soil with a range of ± 5 % during the test

Details on test conditions:

TEST SYSTEM
- Testing facility: TOXI-COOP ZRT.
- Test container (type, material, size): Erlenmeyer glass flasks of 250 cm3
- Amount of soil: 20 g dry soil weight
- No. of replicates per concentration: 6
- No. of replicates per vehicle control: 6

SOIL INCUBATION
- Method: series of individual subsamples

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographical reference of sampling site (latitude, longitude): Hungary (GPSX: 45º51’36”; GPSY: 17º58’03”)
- History of site: The site chosen for soil collection was used as arable land until 2010 with cereals as the last culture grown.
- Vegetation cover: In the year 2011, it was planted with 3-year old oak plants and used as a forest since then.
- Treatments with pesticides or fertilizers: The area had not been treated with crop protection products, organic or mineral fertilizer for at least 3 years before sampling.
- Accidental contamination: None
- Other: None
- Depth of sampling: 25 cm
- Soil texture
- % sand: 59.30
- % silt: 25.50
- % clay: 15.30
- Soil taxonomic classification: Sandy loam
- Soil classification system: USDA classification system
- pH (in water): 5.65
- Initial nitrate concentration for nitrogen transformation test (mg nitrate/kg dry weight): 63.0 mg/100 g
- Maximum water holding capacity (in % dry weigth): 18.9 g/100 g soil dw
- Cation exchange capacity (mmol/kg): 130.4 mmol/kg
- Pretreatment of soil: None
- Storage (condition, duration): The soil was stored in refrigerator for 24 days and pre-incubated under test conditions for 10 days in the dark under aerobic conditions.
- Initial microbial biomass as % of total organic C: 9.42

DETAILS OF PREINCUBATION OF SOIL (if any): None

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :

VEHICLE CONTROL PERFORMED: yes

RANGE-FINDING STUDY
- Test concentrations: 0.1 - 1000 mg/kg soil dw
- Results used to determine the conditions for the definitive study: yes

Nominal and measured concentrations:

Not applicable.

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

10.24 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

nitrate formation rate

Effect concentrations 2

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

10.35 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

nitrate formation rate

Remarks on result:

other: 7.12 – 15.06

Effect concentrations 3

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

89.68 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

nitrate formation rate

Remarks on result:

other: 73.77 –109.02

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

The coefficient of variation in nitrate content between replicate control samples was less than ± 15% at each observation time, i.e. 6.3 % on day 0 and 3.6 % on day 28. Therefore, the study is considered to be valid.

Conclusions:

In a laboratory study with the test item effects on nitrogen transformation processes in soil were determined: EC10 = 10.35 mg/kg dw (95 % confidence intervals: 7.12 – 15.06 mg/kg dw); EC50 = 89.68 mg/kg dw (95 % confidence intervals: 73.77 –109.02 mg/kg dw). The overall NOEC was determined to be 10.24 mg/kg dw while the overall LOEC was determined to be 25.6 mg/kg dw.
The information contained within this robust summary document comes from studies which are in the ownership of Lonza Ltd. and which are protected in several regions globally. This information may not be used for any purpose other than in support of the Chemical safety Report submitted by Lonza Ltd. under Regulation EC 1907/2006.