Santicizer 2148

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:

1990-02-05 to 1990-02-09

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: US EPA-TSCA, 40 CFR, Part 797 Guideline 797.1300

GLP compliance:

yes

Specific details on test material used for the study:

Purity >95%

Analytical monitoring:

no

Vehicle:

not specified

Test organisms (species):

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

Details on test organisms:

Supplier batch #1648

Test type:

static

Water media type:

other: Autoclaved Reverse-osmosis water

Limit test:

no

Total exposure duration:

96 h

Test temperature:

24°C

pH:

0 hours: 7.3, 96 hours: 8.1-8.6

Nominal and measured concentrations:

Measured concentrations: Control; solvent control; 0.093; 0.15; 0.26; 0.64; 1.1

Details on test conditions:

Algal cell counts accomplished utilising a hemacytometer and an Olympus Model CHA microscope

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

> 1.1 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

cell number

Details on results:

The multiple means test indicated no significant inhibition effect (p<0.05) on growth for any of the test concentrations of XP-2563 to Selenastrum capricornutum as compared to the controls after 96-hours. Based on the results, the 95 hour EC50 values based on cell counts were estimated to be >1.1 mg/L

Reported statistics and error estimates:

Initial cell counts of control and solvent control flasks result in an actual mean count of 9.4 x 10^3 cells/ml
Logarithmic phase growth confirmed at 96 hours with a mean count of 2.8 x 10^6 cells/ml in the controls, a 298-fold increase from the initial 9.4 x 10^3 cells/ml.
Growth data was subjected to a 1-way analysis of variance (ANOVA) and multiple means test (Dunnett's test). The multiple means test indicated no significant inhibition effect (p<0.05) on growth for any of the test concentrations of XP-2563 to Selenastrum capricornutum as compared to the controls after 96-hours.

Table 1. Environmental chamber data for the 96-hour static acute algal toxicity study of XP-2563 to Selenastrum capricornutum Printz

 

Date	PAR*	Light Reading		Temperature (°C)	Oscillation rate (RPM’s)‡
		LUX**	Ft-c†
2-05-90	49	4083	379	24	100
2-06-90	50	4167	387	24	100
2-07-90	49	4083	379	25	100
2-08-90	52	4333	403	24	100
2-09-90	52	4333	403	24	100

* = Photosynthetically active radiation (μmols-1m-2), -measured with a LI-COR Model LI-185B Quantum/Radiometer/Photometer and LI-COR Model LI-190SB Quantum Sensor (Serial #Q 7517).

** = LUX = Light reading (PAR) / 12 (correction factor for fluorescent lighting) x 1000

† = Footcandles (ft-c_ = LUX x (0.0929)

‡ = Taken directly from the gauge on the environmental chamber.

 

Table 2. Measured Cell Counts for Selenastrum capriconutum Printz during the exposure to XP-2563

Mean measured concentrations (mg/L)	Mean cell counts (3 flasks) cells/ml/10^4
	0 hr	24 hr*	48 hr*	72 hr*	96 hr*
Control	0.93	3.6	15	85	250
Solvent Control	0.96	4.0	21	100	310
0.093		2.8	17	94	310
0.15		3.2	18	90	310
0.26		3.1	16	87	320
0.64		3.3	17	94	350
1.1		3.2	16	77	260

*= Denotes no significant (p<0.05) inhibition effect from control was identified using transformed (square root) cell counts by Dunnets’ Test. Therefore, the EC50 was estimated to be >2.0 mg/L and the no-effect level was 2.0 mg/L

 

Table 3. Temperature and pH measurements during the exposure of Selenastrum capricornutum Printz to XP-2563

Mean Measured Concentrations (mg/L)	0-hour		96-hours
	Parent solutions		Rep. A
	Temp (°C)	pH	Temp (°C)	pH
Control	24	7.2	24	8.2
Solvent Control	24	7.3	24	8.6
0.093	24	7.3	24	8.6
1.15	24	7.3	24	8.1
0.26	24	7.3	24	8.5
0.64	24	7.3	24	8.5
1.1	24	7.3	24	8.4

Temperature measured using Mercury thermometer

pH measured ising Corning 140 pH/mV Meter and Beckman 39831 Electrode

Validity criteria fulfilled:

yes

Conclusions:

The result of the 96-hour static algal toxicity study using Selenastrum capricornutum Printz for compound XP-2563 is an estimated 96-hour EC50 (95% C.I) of >1.1 mg/L. The no effect concentration of the compound was estimated to be 1.1 mg/L since no effects were observed in any of the test concentrations after 96-hours.

Executive summary:

The acute toxicity of XP-2563 to Selenastrum capricornutum Printz was assessed using the methods outlined in ABC Protocol #8004-PMN. Nominal concentrations for the definitive study were a geometric series of 0.13, 0.25, 0.50, 1.0 and 2.0 mg/L. Temperature and light intensity were monitored throughout the test and were within acceptable limits. Samples were collected from the control and test levels and sent to Monsanto Company for analysis. Analysis was conducted using Monsanto Method #MSL-9864, ES-90-M-1. The mean measured values of XP-2563 were: 0.093, 0.15, 0.26, 0.64, and 1.1 mg/L. All results were based on the mean measured values.

 

The result of the 96-hour static algal toxicity study using Selenastrum capricornutum Printz for compound XP-2563 is an estimated 96-hour EC50 (95% C.I) of >1.1 mg/L. The no effect concentration of the compound was estimated to be 1.1 mg/L since no effects were observed in any of the test concentrations after 96 hours.

Description of key information

The 96 hour EC50 for XP-2563 in Selenastrum capricornutum Printz is estimated to be >1.1 mg/L. The no effect concentration of the compound was estimated to be 1.1 mg/L since no effects were observed in any of the test concentrations after 96 hours.

Key value for chemical safety assessment

EC50 for freshwater algae:

1.1 mg/L

EC10 or NOEC for freshwater algae:

1.1 mg/L

Additional information

The acute toxicity of XP-2563 to Selenastrum capricornutum Printz was assessed using the methods outlined in ABC Protocol #8004-PMN. Nominal concentrations for the definitive study were a geometric series of 0.13, 0.25, 0.50, 1.0 and 2.0 mg/L. Temperature and light intensity were monitored throughout the test and were within acceptable limits. Samples were collected from the control and test levels and sent to Monsanto Company for analysis. Analysis was conducted using Monsanto Method #MSL-9864, ES-90-M-1. The mean measured values of XP-2563 were: 0.093, 0.15, 0.26, 0.64, and 1.1 mg/L. All results were based on the mean measured values.

 

The result of the 96-hour static algal toxicity study using Selenastrum capricornutum Printz for compound XP-2563 is an estimated 96-hour EC50 (95% C.I) of >1.1 mg/L. The no effect concentration of the compound was estimated to be 1.1 mg/L since no effects were observed in any of the test concentrations after 96 hours.