m-phenylenediamine

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Remarks:

The study was scored K2 because it was not possible to calculate and evaluate growth rates on a section by section basis since cell counts were only performed at 0 and 72 hours.

Qualifier:

equivalent or similar to guideline

Guideline:

other: APHA, 1985; US-EPA, 1977; ASTM, 1985

Deviations:

yes

Remarks:

Initial cell density was a factor of 10 below standard guideline recommendations.

GLP compliance:

yes

Analytical monitoring:

yes

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Source (laboratory, culture collection): Culture Collection of Algae, University of Texas, Austin (USA)
- Age of inoculum (at test initiation): 7 days

ACCLIMATION
- Acclimation period: 7 days maintained under test conditions
- Culturing media and conditions (same as test or not): Culturing conditions similar to test conditions

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Test temperature:

20 ± 2 °C

Nominal and measured concentrations:

Nominal: 0, 0.1, 0.5, 1.0, 5.0, 10.0 mg/L
Measured (day 0): Not detected, 0.08, 0.43, 0.84, 5.43, 9.88 mg/L
Measured (day 4): Not detected, 0.06, 0.30, 0.99, 4.73, 9.72 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type: Closed.
- Material, size, headspace, fill volume: 250 mL glass Erlenmeyer flasks covered with inverted 150 mL beakers, and filled with 100 mL test solution
- Initial cells density: 1000 cells/mL
- Control end cells density: 57667 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

GROWTH MEDIUM
- Standard medium used: No; Bristol's medium was used instead
- Detailed composition if non-standard medium was used:
NaNO3: 25 mg/L
CaCl2: 2.5 mg/L
MgSO4.7H2O: 7.5 mg/L
K2HPO4: 7.5 mg/L
KH2PO4: 17.5 mg/L
NaCl2: 2.5 mg/L
FeCl3: 0.5 mg/L


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Bristol's medium, autoclaved (108 kPa ar 121°C) 48 hours prior to use

OTHER TEST CONDITIONS
- Sterile test conditions: Yes
- Photoperiod: Constant illumination
- Light intensity and quality: Cool-white fluorescent light, 400 foot candles


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Cell density at end of the test
- Determination of cell concentrations: [counting chamber; electronic particle counter; fluorimeter; spectrophotometer; colorimeter]: Dual haemocytometer counts

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

0.915 mg/L

Nominal / measured:

meas. (arithm. mean)

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

2.93 mg/L

Nominal / measured:

meas. (arithm. mean)

Basis for effect:

biomass

Remarks on result:

other: 0.439 to 5.42 (95% Confidence Interval)

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

2.87 mg/L

Nominal / measured:

meas. (arithm. mean)

Basis for effect:

biomass

Remarks:

yield

Remarks on result:

other: 0.366 to 5.38 (95% Confidence Interval)

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

5.63 mg/L

Nominal / measured:

meas. (arithm. mean)

Basis for effect:

growth rate

Remarks on result:

other: 4.01 to 7.25 (95% Confidence Interval)

Reported statistics and error estimates:

The initial nominal 96-hr EC50 was derived by graphical interpolation on semilogarithmic paper and no NOEC was reported.

Subsequent evaluations were made using SAS Software Version 8.2 (1999). SAS Institute, Cary, North Carolina.
The data for cell count, cell count yield, and growth rate based on cell count were determined to be normally distributed (Shapiro-Wilk test) with equal variances (Levene’s test). No outliers, as determined by the Tukey outlier rule, were found in the data for cell count and cell count yield. Outliers were found in the data for growth rate based on cell count. Since the data were normally distributed with equal variances, outliers were not considered. Therefore, the Jonckheere-Terpstra trend test was used to determine the LOEC and NOEC values. The 96-hour EbC50, EyC50, and ErC50 values (and 95% confidence intervals) for cell count, cell count yield, and growth rate were obtained by the OECD Model 2 inverse regression model.

96 hr Results for Initial and Subsequent Analysis of Study Data

Endpoint	Effect Conc. (mg/L)	Nominal / Measured	Basis for effect	Remarks (e.g. 95% CL)
NOEC	0.915	meas. (mean)	growth rate based on cell density
LOEC	5.8	meas. (mean)
EbC50	2.93	meas. (mean)	cell density	0.439 to 5.42 (95% Confidence Interval)
EyC50	2.87	meas. (mean)	cell density yield	0.366 to 5.38 (95% Confidence Interval)
ErC50	5.63	meas. (mean)	growth rate based on cell density	4.01 to 7.25 (95% Confidence Interval)
NOEC	1	nominal
LOEC	5	nominal
EC50	3.05	nominal	cell density	0.527 to 5.57 (95% Confidence Interval)
EC50	2.87	nominal	growth rate	Initial analysis of the data based on nominal concentration.

Validity criteria fulfilled:

yes

Conclusions:

Initial analysis of the nominal test concentration data determined a 96-hour EC50 of 2.87 mg/L. Subsequent evaluation of the data resulted in 96-hour NOEC and LOEC values based on mean, measured concentrations of 0.915 mg/L and 5.80 mg/L, respectively. The 96-hour EbC50, EyC50, and ErC50 values (and 95% confidence intervals) based on mean, measured concentrations were 2.93 mg/L (0.439 mg/L to 5.42 mg/L), 2.87 mg/L (0.366 mg/L to 5.38 mg/L), and 5.63 mg/L (4.01 mg/L to 7.25 mg/L), respectively.

Executive summary:

The test substance was evaluated for static acute toxicity to the freshwater algae, Selenastrum capricornutum during a 96-hour exposure period. Initial analysis of the nominal test concentration data determined a 96-hour EC50 of 2.87 mg/L. Subsequent evaluation of the data resulted in 96-hour NOEC and LOEC values based on mean, measured concentrations of 0.915 mg/L and 5.80 mg/L, respectively. The 96-hour EbC50, EyC50, and ErC50 values (and 95% confidence intervals) based on mean, measured concentrations for cell count, cell count yield, and growth rate were 2.93 mg/L (0.439 mg/L to 5.42 mg/L), 2.87 mg/L (0.366 mg/L to 5.38 mg/L), and 5.63 mg/L (4.01 mg/L to 7.25 mg/L), respectively.

Key value for chemical safety assessment

EC50 for freshwater algae:

2.87 mg/L

EC10 or NOEC for freshwater algae:

0.915 mg/L