Santicizer 2148

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:

1990-02-07 to 1990-02-09

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OTS 797.1300 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)

Deviations:

not specified

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source: Monsanto (ABC reference No. TS-3761)
- Purity test: >95%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Stored at room temperature

Analytical monitoring:

no

Details on sampling:

The water quality parameters of temperature, dissolved oxygen and pH were measured in the control and all test levels at 0- and 48-hours of testing.

Vehicle:

no

Details on test solutions:

Method of application: A half-litre proportional diluter system described by Mount and Brungs, utilising a Hamilton Micro Lab 420 syringe dispenser, was used for the intermittent introduction of dilution water and XP-2563 into the test chambers. The system contained 7 sets of 4 replicate 1-L test chambers designated as control, solvent control, and levels 1-5. Flow-splitting chambers were utilised to thoroughly mix and divide each test concentration for delivery to the test chambers. To minimise turbulence, the influent water was introduced into the test chambers via 14-gauge hypodermic needles.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia Magna
- Strain/clone: ABC Labs in-house culture
- Age at study initiation (mean and range, SD): <24 hours
- Stage and instar at study initiation: 1st instar
- Feeding during test : Daphnids were fed a suspension of algae (Selenastrum capricornutum) supplimented with a suspension of trout chow and yeast.

ACCLIMATION
- Acclimation period: From birth
- Acclimation conditions (same as test or not): Same as test

Test type:

flow-through

Water media type:

other: mix of Reverse osmosis water and ABC Well water

Limit test:

no

Total exposure duration:

48 h

Hardness:

160-180 mg/L

Test temperature:

20°C

pH:

8.0

Dissolved oxygen:

0 hours 8.1 mg/L control, 7.8-8.1 mg/L in solvent control/dose groups
48 hours- 8.3-8.4 mg/L

Nominal and measured concentrations:

Nominal: Control; solvent control; 0.12; .24; 0.5; 1.0; 2.0 mg/L
Measured: Control; Solvent control; 0.063; 0.23; 0.37; 1.1; 2.0 mg/L

Details on test conditions:

Test system

A half-litre proportional diluter system described by Mount and Brungs, utilising a Hamilton Micro Lab 420 syringe dispenser, was used for the intermittent introduction of dilution water and XP-2563 into the test chambers. The system contained 7 sets of 4 replicate 1-L test chambers designated as control, solvent control, and levels 1-5. Flow-splitting chambers were utilised to thoroughly mix and divide each test concentration for delivery to the test chambers. To minimise turbulence, the influent water was introduced into the test chambers via 14-gauge hypodermic needles. 1-L glass beakers with notched drains covered with 50-mesh stainless steel screen to prevent daphnid escapes were used as test chambers. The test chambers were labelled A-D and had 5 daphnids each placed in them. The dilution water used was a blend of reverse osmosis water and ABC well water, and was delivered to each test chamber at an average rate of 3.6 ml/chamber/minute, which was sufficient to replace the 1-L volume ~5.1x in 24 hours. The test chambers were immersed in a water bath held at 20°C.

- No. of organisms per vessel: 5 daphnia per replicate, 20 per concentration used overall
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Loading factorL ~1 daphnid for 200 m. of solution

OTHER TEST CONDITIONS
- Photoperiod: 16-hour daylight 8-hour darkness, including 30 min transition period.
- Light intensity: historically 50-70 footcandles intensity from fluorescent light bulbs

RANGE-FINDING STUDY
- Test concentrations: 0.3; 1.0; 3.0 mg/L
- Results used to determine the conditions for the definitive study: Immobility observed at 1.0 and 3.0 mg/L

Reference substance (positive control):

no

Key result

Duration:

4 h

Dose descriptor:

EC50

Effect conc.:

> 2 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 2 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

0.52 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

0.063 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

4-, 24-, and 48-hour EC50 values for XP-2563 were >2.0, >2.0, and 0.52 mg/L respectively. All results were based on the mean measured concentrations of 0.063, 0.23, 0.37, 1.1, and 2.0 mg/L. The NOEC based on lack of immobility and other abnormal effects was 0.063 mg/L and the dose-response slope was 1.5 after 48 hours. 1 immobile daphnid in the solvent control and 0.063 mg/L was considered aberrant and not a compound-related effect.

Reported statistics and error estimates:

The EC50 statistic and its 95% confidence limit was calculated by a computerised EC50/LC50 program using the binomial, the moving average, and the probit tests, data permitting.
3 different methods of analyzing the data were used due to no one method of analysis being appropriate for all possible sets of data that may be obtained.

Table 1

Test Compound	48-hour EC50 (95% confidence intervals) (mg/L)	48-hour no-effect concentration (mg/L)
XP-2563	0.52 (0.34 and 0.85)	0.063

 

Table 2. Acute Flow-through toxicity of XP-2563 to Daphnia Magna

Parameter	4 hours	24 hours	48 hours
EC50 (mg/L)	>2.0	>2.0	0.52
95% Confidence limits (mg/L)	Could not be determined	Could not be determined	0.32 and 0.85
Statistical method used	Bionomial	Bionomial	Moving average

Bioassay conducted at 20°C

The 48-hour no-effect concentration was 0.063 mg/L which is based on the lack of immobility and other abnormal effects. The single immobile daphnid observed in this concentration was considered aberrant

The 48-hour dose response slope = 1.5

 

Table 3. Individual immobility and behavioural observations during the acute toxicity test of XP-2563 to Daphnia magna

Mean measured test conc. (mg/L)	Replicate	Number placed in test vessel	4-hours		24-hours		48-hours
			Cumm. Immob.	Obs.	Cumm. Immob.	Obs.	Cumm. Immob.	Obs.
Control	A	5	0	-	0	-		-
	B	5	0	-	0	-		-
	C	5	0	-	0	-		-
	D	5	0	-	0	-		-
Solvent Control	A	5	0	-	1	4 N	1	4 N
	B	5	0	-	0	-		-
	C	5	0	-	0	-		-
	D	5	0	-	0	-		-
0.063	A	5	0	-	1	4 N	1	4 N
	B	5	0	-	0	-		-
	C	5	0	-	0	-		-
	D	5	0	-	0	-		-
0.23	A	5	0	-	0	-	3	2 OB
	B	5	0	-	0	-	3	2 OB
	C	5	0	-	0	-	0	3 OB; 2 N
	D	5	0	-	0	-	2	2 OB; 1 N
0.37	A	5	0	-	0	-	3	2 OB
	B	5	0	-	0	-	2	2 OB; 1N
	C	5	0	-	0	-	2	3 OB
	D	5	0	-	0	-	2	2 OB; 1 N
1.1	A	5	0	-	0	-	3	2 OB
	B	5	0	-	0	-	2	3 OB
	C	5	0	-	0	-	2	2 OB
	D	5	0	-	0	-	3	2 OB
2.0	A	5	0	-	0	-	4	1 OB
	B	5	0	-	0	-	5	-
	C	5	0	-	0	-	4	1 OB
	D	5	0	-	0	-	4	1 OB

Unless otherwise indicated the test water was clear and free of participate and all daphnids were normal in appearance in behaviour. The following abbreviations were used for observations: OB = On the bottom, N = Normal

 

Immobility not considered to be a compound related effect

 

One daphnid missing: thought to have escaped since it was present at 0 and 4-hours.

 

Table 4. Percent immobile and water quality measurements during the acute flow-through toxicity test of XP-2563 with Daphnia magna

 

Nominal conc. (mg/L)	Percent immobile			Water Quality
				0 hours			48 hours
	4-hrs	24-hrs	48-hrs	Temp.* (°C)	D.O†(mg/L)	pH‡	Temp. (°C)	D.O (mg/L)	pH
Control	0	0		21	8.1	8.0	20	8.3	8.1
Solvent Control	0	5	5	21	7.8	8.0	20	8.4	8.1
0.063	0	5	5	21	7.8	8.0	20	8.3	8.1
0.23	0	0	40	21	7.9	8.0	20	8.3	8.1
0.37	0	0	45	21	7.9	8.0	20	8.3	8.1
1.1	0	0	53	21	7.8	8.0	20	8.4	8.1
2.0	0	0	85	21	8.1	8.0	20	8.4	8.1

*= Temperatures measured with mercury thermometer

†= Dissolved oxygen concentrations measured with dissolved oxygen probe (YSI model 54 arc)

‡= pH measured with pH probe (Beckman model 39831) used with Corning model 140 pH and mV meter.

Note: Dissolved oxygen saturation at the test temperatures of 20 and 21°C are 8.7 and 8.5 mg/L, corrected for altitudinal pressure of ABC laboratories. The temperature listed here is measured directly on the water sample used for water chemistry. These values are not taken from the diluter observations.

Conclusions:

The 48-hour EC50 was 0.52 mg/L (95% confidence intervals of 0.34 and 0.85 mg/L). The 48-hour no effect concentration was 0.063 mg/L.

Executive summary:

The definitive flow-through acute toxicity of XP-2563 to Daphnia magna was conducted from February 7 1990 to February 9 1990. The study was conducted at the following nominal concentrations: 0.12, 0.50, 1.0, and 2.0 mg/L. 20 1^st-instar daphnids were exposed to each of the test concentrations and control.

Water samples were collected at 0- and 48-hours from the control and test levels and were returned 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: 0.063, 0.23, 0.37, 1.1 and 2.0 mL/L. All results are based on the mean measured values. Water quality parameters of temperature, dissolved oxygen, and pH were measured at 0- and 48-hours and were determined to be within acceptable limits. The overall ranges for these parameters were: daily diluter-temperature observations = 20-21°C, pH = 8.0 – 8.1, and dissolved oxygen = 7.8 – 8.4 mg/L.

The 48-hour EC₅₀ was 0.52 mg/L (95% confidence intervals of 0.34 and 0.85 mg/L). The 48-hour no effect concentration was 0.063 mg/L.

Description of key information

The 48-hour EC₅₀ of XP-2563 in Daphnia magna was determined to be 0.52 mg/L (95% confidence intervals of 0.34 and 0.85 mg/L) while the 48-hour no effect concentration was 0.063 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.52 mg/L

Additional information

A definitive flow-through acute toxicity of XP-2563 to Daphnia magna was conducted (Analytical Bio-chemistry Laboratories Inc., 1990b). The study was conducted at the following nominal concentrations: 0.12, 0.50, 1.0, and 2.0 mg/L. 20 1^st-instar daphnids were exposed to each of the test concentrations and control.

Water samples were collected at 0- and 48-hours from the control and test levels and were returned 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: 0.063, 0.23, 0.37, 1.1 and 2.0 mL/L. All results are based on the mean measured values. Water quality parameters of temperature, dissolved oxygen, and pH were measured at 0- and 48-hours and were determined to be within acceptable limits. The overall ranges for these parameters were: daily diluter-temperature observations = 20-21°C, pH = 8.0 – 8.1, and dissolved oxygen = 7.8 – 8.4 mg/L.