α-Bitter acids, hop, hydrogenated, isomerized

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

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 tetra acids, since hop extract may contain significant levels of these related hop extracts.
A further study has been planned for beta 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 tetrahydroiso-alpha acids, since tetrahydroiso-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

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

5.8 mg/L

Additional information

Number for CSR. Results from endpoint show that the EC50 for 24 or 48 h was >5.8 mg/l.

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