Commiphora myrrha, ext.

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016-04-25 to 2018-XX-XX

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

none

Analytical monitoring:

yes

Remarks:

unspecific

Details on sampling:

- Sample storage conditions before analysis: Refrigeration (+2°C to +8°C); store in closed container.

Vehicle:

no

Details on test solutions:

The study was carried out using WAFs (Water Accommodated Fractions). The WAFs were prepared under closed conditions and by slow-stirring.
After 22 hours of gentle stirring in the dark at room temperature, the WAFs were allowed to stand for at least 1 hour before use. The first 100 mL were discarded via the drain port. Then the WAFs were filtered and added into test flasks containing a fixed amount of inoculum (5.103 cells.mL-1 per vessel) that were immediately sealed after filling with a minimum of headspace. At the start of the test, the solution was observed to be clear and colourless.

Test organisms (species):

Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)

Details on test organisms:

Algae stock cultures were started by inoculating growth medium (= test water) with algal cells from a pure culture on agar. The suspensions were continuously aerated and exposed to light in a climate room at a temperature of 23 ± 2°C.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Remarks on exposure duration:

none

Post exposure observation period:

n.a.

Test temperature:

23 ± 2°C

pH:

7.76 to 9.45

Dissolved oxygen:

>60% of saturation

Salinity:

n.a.

Conductivity:

n.a.

Nominal and measured concentrations:

nominal: 1, 3, 10, 31, 99 and 313 mg.L-1

Details on test conditions:

100 mL, all-glass closed flasks with ground glass stopper, completely filled with test solution with minimum headspace.
Each test vessel was uniquely identified with study code, replicate number, date of experimentation and treatment group.
72hr
static

Reference substance (positive control):

yes

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

60.371 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

growth rate

Details on results:

95% conf. limits = 27.425 – 178.292mg/L

Results with reference substance (positive control):

KA17-002, the 72h-EC50 was 1.457 mg.L-1 for the parameter growth rate.

Reported statistics and error estimates:

Probit analysis by Toxrat.

TheE_rL_x and E_yL_x were as follows:

Parameter	Growth rate (mg.L^-1)	Yield (mg.L^-1)
72-hour EL10	1.529	n.d.
95% conf. limits	0.055 – 5.310	n.d.
72-hour EL20	5.401	n.d.
95% conf. limits	0.603 – 13.626	n.d.
72-hour EL50	60.371	0.760
95% conf. limits	27.425 – 178.292	0.135 – 1.785

n.d.: not determined due to mathematical reasons or inappropriate data

Validity criteria fulfilled:

yes

Conclusions:

Under the experimental conditions and based on nominal loading rates of test item, the 72-hour EL50 for the parameters growth rate is 60.371mg/L.

Executive summary:

A study was performed to assess the test item Essential oil of Commiphora myrrha for its ability to generate toxic effects on the unicellular algal species Pseudokirchneriella subcapitata. The followed method was designed to be compliant with OECD Guideline for Testing of Chemicals No. 201, "Freshwater Alga and Cyanobacteria, Growth Inhibition Test", referenced as Method C.3 of Commission Regulation No. 440/2008 amended by Commission Regulation (EU) 2016/266 and with the “Guidance document on aquatic toxicity testing of difficult substances and mixtures” (OECD No. 23).

 

Following a preliminary range-finding test, algal cells were exposed to Water Accommodated Fractions (WAFs) of the test item over a range of nominal loading values of 1, 3, 10, 31, 99 and  313 mg.L^-1 and to a control. The inhibition of growth in comparison to control cultures was determined over a test period of 72 hours, and thus over several algal generations. Concentration of dissolved organic material in the controls and the WAFs was checked by analysis of Total Organic Carbon (TOC) at the startand the end of the test.

The analytical results of this test showed that WAF concentrations were overall stable between the start and the end of the test, within or close to the ± 20% of the initial TOC concentrations values.

After 72 hours of exposure, E_rL_x and E_yL_x values were as follows:

Parameter	Growth rate (mg.L^-1)	Yield (mg.L^-1)
72-hour EL10	1.529	n.d.
95% conf. limits	0.055 – 5.310	n.d.
72-hour EL20	5.401	n.d.
95% conf. limits	0.603 – 13.626	n.d.
72-hour EL50	60.371	0.760
95% conf. limits	27.425 – 178.292	0.135 – 1.785

n.d.: not determined due to mathematical reasons or inappropriate data

Statistical analyses were performed by the computer program ToxRat

The toxic effect of the test item Essential oil ofCommiphora myrrhato the unicellular algal speciesPseudokirchneriella subcapitatawas investigated in a closed static test usingWater Accommodated Fractions. Under the experimental conditions andbased on nominal loading rates,the 72-hour EL₅₀for the parameters growth rate and yield were determined to be 60.371 mg.L^-1and 0.760 mg.L^-1, respectively. The 72-hour EL₁₀for growth rate was 1.529 mg L^-1.

Description of key information

The toxic effect of the registered substance to the unicellular algal species Pseudokirchneriella subcapitata was investigated in a closed static test using Water Accommodated Fractions. Under the experimental conditions and based on nominal loading rates, the 72-hour EL₅₀ for the parameters growth rate and yield were determined to be 60.371 mg.L^-1 and 0.760 mg.L^-1, respectively. The 72-hour EL₁₀ for growth rate was 1.529 mg L^-1.

Key value for chemical safety assessment

EC50 for freshwater algae:

60.371 mg/L

EC10 or NOEC for freshwater algae:

1.529 mg/L

Additional information

For that endpoint, an experimental GLP study with the registered substance was available.

This study was performed to assess the test item for its ability to generate toxic effects in the unicellular algal species Pseudokirchneriella subcapitata. The method followed was designed to be compliant with OECD Guideline for Testing of Chemicals No. 201, "Freshwater Alga and Cyanobacteria, Growth Inhibition Test", referenced as Method C.3 of Commission Regulation No. 440/2008 amended byCommission Regulation (EU) 2016/266 and with the “Guidance document on aquatic toxicity testing of difficult substances and mixtures” (OECD No. 23).

In this 72 hour acute toxicity study, the cultures of P. subcapitata were exposed to test item at nominal concentrations 1, 3, 10, 31, 99 and 313 mg.L-1 under static conditions in accordance with the OECD 201. WAF preparation was performed to prepare the sample. The EL50 values based on growth rate was at 60.371 mg/L. 

 

All the validity criteria were fulfilled. This toxicity study is classified as acceptable and satisfies the guideline requirements for OECD 201 toxicity study.

 

Results Synopsis

Test Organism: P. subcapitata

Test Type: static

72hr EL₅₀:  60.371.mg/L              

Endpoint(s) Effected: growth rate inhibition