2,6-dimethylpyridine

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

Data is from computational model developed by USEPA

Qualifier:

according to guideline

Guideline:

other: Modelling database

Principles of method if other than guideline:

Estimation 96 hrs EC50 value of test chemical on aquatic algae by EPI Suite ECOSAR version 1.11.

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

other: green algae

Test type:

static

Water media type:

freshwater

Total exposure duration:

96 h

Reference substance (positive control):

no

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

43.728 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Neutral Organics

Validity criteria fulfilled:

not specified

Conclusions:

Based on effect of test chemical on the growth rate of the test organism green algae, the 96 hrs EC50 value was estimated to be 43.72 mg/l.

Executive summary:

The toxicity of the test chemical to green algae was predicted using EPI Suite ECOSAR version 1.11. On the basis of effect of test chemical observed in a static system on the growth rate of the test organism during the 96 hr exposure duration, the median effect concentration (EC50) for the test chemical was estimated to be 43.72 mg/l. Thus, based on the EC50 value, test chemical can be considered as toxic to aquatic algae. Since the test chemical is readily biodegradable in water, test chemical was considered as non-toxic and hence, considered to be 'not classified' as per the CLP classification criteria.

Description of key information

The toxicity of the test chemical to green algae was predicted using EPI Suite ECOSAR version 1.11. On the basis of effect of test chemical observed in a static system on the growth rate of the test organism during the 96 hr exposure duration, the median effect concentration (EC50) for the test chemical was estimated to be 43.72 mg/l. Thus, based on the EC50 value, test chemical can be considered as toxic to aquatic algae. Since the test chemical is readily biodegradable in water, test chemical was considered as non-toxic and hence, considered to be 'not classified' as per the CLP classification criteria.

Key value for chemical safety assessment

EC50 for freshwater algae:

43.72 mg/L

Additional information

Predicted data of the target chemical and supporting weight of evidence studies for its read across analogue were reviewed for toxicity to aquatic algae and cyanobacteria endpoint which are summarized as below:

 

In a prediction done using EPI Suite ECOSAR version 1.11, toxicity to aquatic algae of the test chemical was predicted. On the basis of effect of test chemical observed in a static system on the growth rate of the test organism during the 96 hr exposure duration, the median effect concentration (EC50) for the test chemical was estimated to be 43.72 mg/l. Thus, based on the EC50 value, test chemical can be considered as toxic to aquatic algae. Since, the test chemical is readily biodegradable in water, chemical was considered as non-toxic and hence, considered to be ‘not classified’ as per CLP classification criteria.

 

In a supporting weight of evidence study from handbook (2009) and secondary source,algal toxicity study was carried out for 72 hrs for assessing the effect of test chemical. The study was performed following the principles of the OECD Guideline 201 (Alga, Growth Inhibition Test).Pseudokirchneriella subcapitata (CCAP no. 278/4) (green algae) was used as a test organism. Test chemical concentrations were determined analytically. Test chemical concentrations used for the study were 1, 3.2, 10, 32 and 100 mg/l (nominal conc.) and 0.689, 2.40, 7.57, 28.1 and 83.0 (geometric mean measured conc.), respectively. Test vessel was loosely plugged with non-porous cotton wool. Study was carried out at a temperature of 22.6 to 23.9°C and pH 7.9 to 9.0, respectively. The intended exposure concentrations were substantially achieved (between 77 and 94% of their nominal values) and adequately maintained during the test (between 80 and 88% of their starting concentrations).Exposure at measured levels of 2.40 mg/l and above resulted in significant reduction in both the specific growth rates and biomass values compared to control cultures (p < 0.05). Thus, the NOEC for both growth rate and biomass was 0.689 mg/l.On the basis of effect growth rate & biomass of the test organism, the 72 hr ErC50 and EbC50 value was determined to be 61.2 & 30.6 mg/l, respectively. Thus, test chemical can be considered as toxic to aquatic algae. Since, the test chemical is readily biodegradable in water, chemical was considered as non-toxic to aquatic algae at environmental relevant concentrations and hence, considered to be ‘not classified’ as per the CLP classification criteria.

 

Another toxicity to aquatic algae study was carried out for 72 hrs for assessing the effect of test chemical (authoritative database, 2020). The study was performed following the principles of the OECD Guideline 201 (Alga, Growth Inhibition Test). Study was performed under static conditions. On the basis of effect growth rate & biomass of the test organism, the 72 hrs NOEC value was determined to be 1 mg/l and on the basis of effect growth rate & biomass of the test organism, the 72 hr ErC50 and EC50 value was determined to be >32 & 5.7 mg/l, respectively. Thus, test chemical can be considered as toxic to aquatic algae. Since, the test chemical is readily biodegradable in water, chemical was considered as non-toxic to aquatic algae at environmental relevant concentrations and hence, considered to be ‘not classified’ as per the CLP classification criteria.

 

On the basis of the above results, test chemical can be considered as toxic to aquatic algae. Since the test chemical is readily biodegradable in water, chemical was considered as non-toxic to aquatic algae at environmental relevant concentrations and hence, considered to be 'not classified' as per the CLP classification criteria.