Potassium dihydrogenorthophosphate

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:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 207 (Earthworm, Acute Toxicity Tests)

GLP compliance:

not specified

Remarks:

no data provided in literature

Analytical monitoring:

not specified

Vehicle:

no

Details on preparation and application of test substrate:

- Controls: unamended soil

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Details on test organisms:

TEST ORGANISM
- Common name: earthworm
- Source: Blades biological Ltd, Cowden, Edenbridge, Kent, UK
- Age at test initiation (mean and range, SD): no data
- Weight at test initiation (mean and range, SD): 340 +/- 3.7 mg

ACCLIMATION
- Acclimation period: no data

Study type:

laboratory study

Substrate type:

natural soil

Limit test:

no

Total exposure duration:

28 d

Test temperature:

20°C

pH:

7-7.2

Moisture:

60% water holding capacity

Details on test conditions:

TEST SYSTEM
- Test container (material, size): no data
- Amount of soil or substrate: 500 g
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 4
- No. of replicates per control: 8


SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographic location: Jetting Loam - bought
- Soil texture (if natural soil): sieved to less than 2mm

Properties are similar to the OECD standard soil.

OTHER TEST CONDITIONS
- Photoperiod: performed in dark


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : mortality


TEST CONCENTRATIONS
- Spacing factor for test concentrations: 1.8

Nominal and measured concentrations:

15,000 mg P/kg with concentrations decreasing by a factor of 1.8 downwards to 441 mg P/kg

Reference substance (positive control):

not specified

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

> 3 500 other: mg P/ kg

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality

Duration:

28 d

Dose descriptor:

LC50

Effect conc.:

> 3 500 other: mg P / kg

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality

Validity criteria fulfilled:

not specified

Conclusions:

LC50 (14 day and 28 day values) of potassium dihydrogen phosphate was found to be > 3500 mg P / kg.

Description of key information

One key study exists. Study was performed in accordance with OECD 207 and reported in the literature.

Additional information

LC50 (14 day and 28 day values) of potassium dihydrogen phosphate was found to be > 3500 mg P / kg.

In addition, potassium and phosphate ions (from the natural breakdown of potassium dihydrogenorthophosphate) are ubiquitous in the environment and are found naturally in soil, water and sediment. All are assimilated by species residing in the sediment, water or soil and are essential for maintaining a good chemical balance. Furthermore, inorganic phosphate fertilizers (containing K+, and PO4 - ions) are often added to soils to improve soil quality. Given the extensive use of inorganic phosphates as soil fertilizers and the natural occurrence of the ions in the environment it is unlikely that inorganic phosphates of this nature would have a detrimental effect on soil macroorganisms and plants and hence further toxicity studies are scientifically unjustified.