Hop, Humulus lupulus, ext., isomerized, potassium salt

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

48 hours

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Justification for type of information:

The study performed on hop extract is relevant for iso-alpha acids, since iso-alpha acids are derived from hop extract.
A further study has been planned for iso-alpha acids and will be entered as an update.

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch 160025

Analytical monitoring:

yes

Vehicle:

no

Details on test solutions:

Media was stirred for 22 hours and 15 minutes and settled for 4 hours. After settling the first 100ml (approximately) of aqueous phase was removed (avoiding all settled and floating material) and discarded. The remaining aqueous phase provided sufficient volumes for water quality
measurements and testing.

Test organisms (species):

Daphnia magna

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

pH:

7.08 - 7.57

Dissolved oxygen:

6.17 - 7.31 mg/l

Nominal and measured concentrations:

Loading rates 0.1, 1.0, 10 and 100mg/l from stock solutions (WAF) used in preliminary study
Loading rates 1.0, 1.8, 3.2, 5.8 and 10.4mg/l were used in the main study

Reference substance (positive control):

yes

Remarks:

1.4 mg/l potassium dichromate in a separate GLP study

Key result

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

ca. 2.242 mg/L

Nominal / measured:

nominal

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 5.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

mobility

In range finder, 1 mg/l loading lead to no effect, but at 10 mg/l and 100 mg/l, there was 100% immobilisation

In main study, 2.42 or lower concentrations gave no adverse effects

A concentration of 5.8 mg/l resulted in 30% (6/20) immobilisation

A concentration of 10 mg/l resulted in 0% immobilisation (possibly due to partition effects from undissolved material)

Validity criteria fulfilled:

yes

Conclusions:

The 24-hour EC50 and 48-hour EC50 of HOP EXTRACT to Daphnia magna were >2.24mg/l and >2.24mg/l respectively (both determined by Linear Interpolation).
The 0 to 24-hour NOEC and LOEC were 2.242mg/l and >2.24mg/l respectively
The 0 to 48-hour NOEC and LOEC were 2.242mg/l and >2.24mg/l respectively
The Daphnia were examined at 24-hours and 48-hours for abnormal behaviour during the determination of immobility. All Daphnia appeared normal with no signs of abnormality
No test concentration immobilised 100% Daphnia and the highest concentration where no immobilisation occurred was 2.242mg/l.

Executive summary:

The study performed on hop extract is relevant for iso-alpha acids, since iso-alpha acids are derived from hop extract. A further study has been planned for iso-alpha acids and will be entered as an update.

Higher treatment levels up to 10 mg/l were also tested, but at higher concentrations, there was a lower rate of immobilisation, perhaps due to partitioning of biologically active components into undissolved oils.

The water solubility has been hard to determine due to the multiple components in the substance; the biological effects seen in this study indicate that there is dissolved material present

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

48 hours

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch DB EXP 9

Analytical monitoring:

yes

Vehicle:

yes

Remarks:

Dilution water

Details on test solutions:

Information provided by the Sponsor indicated that Potassium salt of Iso-alpha acids partially
dissolves in aqueous alkaline solutions. Iso-alpha acids (70.96% w/w) dissolve up to 40.3g/litre in
water with the other constituents remaining undissolved. The sample was therefore tested as
insoluble.
Both the preliminary range finding test and the definitive test were prepared by the direct addition
of measured amounts of test substance to dilution water and stirred.

Each test concentration was stirred for 22 hours and 25 minutes and settled for 4 hours and 5
minutes. After settling the first 100ml (approximately) of aqueous phase was removed (avoiding
all settled and floating material) and discarded. The remaining aqueous phase provided sufficient
volumes for water quality measurements and testing. The only practicable method to prepare the
0.1 and 1mg/l test concentrations was by dilution (addition of 2.5 and 25ml of the 10mg/l
preparation to 250ml of dilution water respectively).

The test concentrations for the definitive test were prepared as follows;
Nominal concentration (mg/l): 100
Total volume of dilution water (ml): 1000
Nominal weight of sample (g): 0.1000

The test concentration was stirred for 24 hours and settled for 4 hours and 10 minutes. After
settling the first 100ml (approximately) of aqueous phase was removed (avoiding all settled and
floating material) and discarded. The remaining aqueous phase provided sufficient volumes for
water quality measurements and testing.

Test organisms (species):

Daphnia magna

Test type:

static

Water media type:

freshwater

Total exposure duration:

48 h

Test temperature:

20.1 - 21.0 oC

pH:

6.96 - 7.12

Dissolved oxygen:

6.80 - 8.60 mg/l

Nominal and measured concentrations:

A preliminary (range-finding) test was conducted at
concentrations of 0 (control), 0.1, 1, 10 and 100mg/l.
The duration of the preliminary test was 48 ± 1 hours.
There was a single replicate at each concentration.
NB: All concentrations of the test substance are reported as nominal
as received and are expressed as loading rates, following
preparation of water accommodated fractions (WAF’s).

Definitive test:
Number of replicates: Four replicates at each concentration.
Test Concentrations (mg/l):
Mean measured concentrations (mg/l):
0 (control) and 100mg/l
0 (control) and 57.286mg/l

Reference substance (positive control):

yes

Remarks:

1.4 mg/l potassium dichromate in a separate GLP study

Key result

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

ca. 57.286 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr. (dissolved fraction)

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 57.286 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr. (dissolved fraction)

Basis for effect:

mobility

Data from the preliminary test identified the 48-hour

EC50 as being >100mg/l.

The definitive test conducted from 19 to 21 June 2018 was performed according to the OECD

202 2004 guideline and met all validity criteria.

The 57.286mg/l (mean measured) test concentration did not immobilise any of the twenty Daphnia

after 48-hours.

Validity criteria fulfilled:

yes

Conclusions:

The definitive test conducted from 19 to 21 June 2018 was performed according to the OECD
202 2004 guideline and met all validity criteria.
The 24-hour EC50 and 48-hour EC50 of Potassium salt of Iso-alpha acids to Daphnia magna were
>57.286mg/l and >57.286mg/l respectively (both determined by direct observation). Graphical
representations of the 24-hour and 48-hour EC50 values are given in Graphs 1 and 2 respectively.
The 0 to 24-hour NOEC and LOEC were 57.286mg/l and >57.286mg/l respectively (both
determined by direct observation).
The 0 to 48-hour NOEC and LOEC were 57.286mg/l and >57.286mg/l respectively (both
determined by direct observation).
The Daphnia were examined at 24-hours and 48-hours for abnormal behaviour during the
determination of immobility. All Daphnia appeared normal with no signs of abnormality (see section
3.2).
The 57.286mg/l (mean measured) test concentration did not immobilise any of the twenty Daphnia
after 48-hours.
None (0%) of the twenty control Daphnia maintained in dilution water were immobilised and none
were trapped in the meniscus during the study. This fulfills the control validity criteria of the study
as the percentage of immobilisation did not exceed 10%, confirming that the test organisms were of
suitable “health” for use in the study.

Executive summary:

EC50 (48h): >57.286 mg/L

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

57.286 mg/L

Additional information

Number for CSR. Results from endpoint show that the EC50 for 24 or 48 h was >57.286 mg/l.