Phosphoric acid, 2-ethylhexyl ester

Sediment toxicity

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

sediment toxicity: short-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

19 to 29 January 1996

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The test was conducted in accordance to GLP guidelines and a standard testing guideline.

Guideline:

other: Based on a draft of the Paris Commission Guideline "MAFF/ERT Harmonised Protocol. A Sediment Bioassay Using an Amphipod Corophium spn (PARCOM, 1994)

GLP compliance:

yes

Analytical monitoring:

no

Details on sediment and application:

Test sediment was collected locally from the same site that the test organisms were obtained. Test sediment was sieved (500 μm) in the laboratory using reference sea water to remove indigenous Corophium volutator or potential predator organisms and to adjust interstitial salinity to that of the reference sea water. The sieved sediment was kept at 12-14 °G in 30 L covered plastic containers until use. The wet to dry weight ratio of the sediment was determined by drying a sample in a tared crucible at 60 °C for 24 hours and reweighing after cooling to room temperature in a dessicator. Actual test concentrations in mg/kg dry sediment/weight were determined from the wet to dry weight ratio.The behaviour of the test substance in sea water was examined according guidelines in the OSPAR HOCNF 1995; Annex 2. A mixture of 1 g of the test substance in 1 litre of reference sea water was shaken vigorously, upending for 10 reversals of the contents. This was allowed to stand for 4 hours and then examined. The test substance exhibited behaviour category 4, that is floating and settled liquids or solids were observed. This determined the method of application of the test substance which is detailed below:The appropriate weight of test substance was added to a tared 2 L polypropylene bottle containing between 550 and 700 g wet sediment. A minimum quantity of clean sea water was then added to give a free-flowing slurry. Bottles containing sediment were then placed horizontally on an orbital shaker and shaken for approx. 3 hours at 150 rpm. After a final shaking by hand, small aliquots of the spiked sediment samples were equally allocated to each replicate test vessel in turn to minimise bias in chemical content or particle-size distribution. Test vessels were 1 L tall borosilicate glass beakers. Beakers were then left overnight to allow the sediment to settle.

Test organisms (species):

Corophium volutator

Details on test organisms:

Corophium volutator were collected locally. Animals were sieved from the sediment on site and kept in 40 L glass tanks of ambient sea water together with detrital material for transport to the laboratory. Animals were acclimated to the test temperature (15 ± 2 °C).

Study type:

laboratory study

Test type:

static

Water media type:

saltwater

Type of sediment:

natural sediment

Limit test:

no

Duration:

10 d

Exposure phase:

total exposure duration

Test temperature:

15.7 to 16.4°C

pH:

Control: 7.72 to 7.86Lowest test concentration (45 mg/kg): 7.73 to 7.83Highest test concentration (45235 mg/kg): 3.92 (10 days) to 6.0 (Time 0)

Dissolved oxygen:

91 to 97%. A value of 78% was recorded for one of the replicate vessels of the highest test concentrationat Time 0. This was clearly an anomalous recording as the lowest reading for all other test concentration/time combination were =>91%

Salinity:

36.5 to 40.3 mS/cm

Nominal and measured concentrations:

Nominal: 45, 156, 454, 1483, 4586, 14587, 45235 mg/kg dry weight

Details on test conditions:

750 mL of seawter was added to the test containers which contained 100 mL of sediment. A plastic cover had been placed over the sediment in order to avoid disturbance of it. The test vessels were left to allow any resuspended sediment to settle. When the sediment had resettled, the sea water was aerated carefully, avoiding resuspension of the sediment. The test vessels were aerated for 12-24 hours before the test commenced. Corophium volutator were sorted and transferred to 100 mL glass beakers containing reference sea water. 10 test animals were added per beaker. Sea water volume was adjusted to 50 mL in each beaker. The test was initiated by randomly placing the groups of Corophium volutator in the test vessels. Two replicate vessels per treatment were set up for each concentration of the test item. Three replicates were prepared for the untreated control.The level of water In each test vessel was marked at the start of the test (Day 0). Water quality (pH, temperature, dissolved 02) were recorded at the start of the test, after 24 hours, and at least twice during the test period, including day 10. Salinity was measured at the start and. end ofthe test only (during the test seawater levels were topped up to the mark with distilled water if necessary).After 10 days the test was terminated by gently stirring up the sediment in each test vessel to form a slurry. The slurry was then sieved (500 μm) to remove the test animals. The number of Corophium volutator alive and dead was recorded. Death was defined as the absence of movement after gentle stimulation with forceps.

Reference substance (positive control):

no

Duration:

10 d

Dose descriptor:

LC50

Effect conc.:

1 907 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: 95% CL: 911 to 3439 mg/kg dry weight

Details on results:

See Table 1.

Table 1. Mortality of Corophium volutator after 10 days exposure to sediment treated with OFLP 95/1820

Test concentration (mg/kg dry weight)	Number of animals per treament	Number of animals allive at test end	10 -day mortality (%)
45	22	17	23
156	22	16	27
454	22	13	41
1483	22	16	27
4586	22	0	100
14587	22	0	100
45235	22	0	100
0 (control)	33	24	27

Validity criteria fulfilled:

yes

Conclusions:

The 10-day LC50 for Corophium volutator after exposure to OFLP 95/1820 was determined to be 1908 mg/kg dry weight sediment. The 95% confidence limits were 911 to 3439 mg/kg dry weight sediment.

Executive summary:

Corophium volutator were exposed to OFLP 95/1820 in a natural marine sediment fopr a period of 10 days. The 10-day LC50 was determined to be 1908 mg/kg dry weight sediment. The 95% confidence limits were 911 to 3439 mg/kg dry weight sediment.

Reference 2

Endpoint:

sediment toxicity: short-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

9 to 21 January 2002

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The test was conducted according to an ineternationally recognised guideline and in accordance with the principles of GLP.

Guideline:

other: Based on a draft of the Paris Commission Guideline "MAFF/ERT Harmonised Protocol. A Sediment Bioassay Using an Amphipod Corophium spn (PARCOM, 1994) and supplementary information from the PARCOM Ring Test Workshop in 1993 (PARCOM, 1993).

GLP compliance:

yes

Analytical monitoring:

no

Details on sediment and application:

The sediment was collected from the same inter-tidal area as the test organisms. At the laboratory the sediment was sieved through a 500 μm sieve in a closed system using natural seawater. The characteristics of the sediment were as follows: Organic content of between 0.5 and 4%Silt/clay fraction (< 63μm) of between 5 and 20%.A median grain size of 90 to 125 μm.A wet weight to dry weight ratio of between 1.3 and 1.5.

Test organisms (species):

Corophium volutator

Details on test organisms:

Corophium volutator were collected from Buvik in South Tr0ndelag an area of inter-tidal mud/sand free of significant contamination. The test animals were sieved from the sediment 12 days before the initiation of the test and held in an aquarium at test conditions for acclimatisation. Mortality during acclimatisation was 0%.

Study type:

laboratory study

Test type:

static

Water media type:

saltwater

Type of sediment:

natural sediment

Limit test:

no

Duration:

10 d

Exposure phase:

total exposure duration

Test temperature:

12.5 to 13.8°C

pH:

7.8 to 8.1

Dissolved oxygen:

93 to 98% of saturation

Salinity:

3.3 to 3.6%

Nominal and measured concentrations:

Nominal wet weight concentrations were: 50, 250, 875, 3000 and 10000 mg/kg wet weight of sediment

Details on test conditions:

The sediment was thoroughly homogenised immediately prior to use. Three 20 g samples of the homogenised sediment were taken to determine the wet to dry weight ratio of the sediment. The samples were oven dried at 100 °C to a constant weight. 5 nominal concentrations (per unit wet weight) of spiked sediment were prepared as follows:Approximately 450-500 g of wet sediment was placed in a 2 litre polypropylene container, one container per concentration and one for the control;Insoluble test substances were mixed with a small amount dried sediments before added to the wet sediment;A spatula was used initially to disperse the test substance throughout the sediment in the container and sufficient clean seawater was then added to create free flowing slurry;The containers were then placed horizontally on a shaking table (-100 revolutions per min.) for a minimum of 3 hours.The containers were removed from the shaking table and shaken vigorously by hand for one minute immediately before the contents were dispensed to the appropriate replicate 1 litre tall-form glass test vessels. The contents were dispensed in small aliquots to each replicate (5 reps per control and 3 for each test substance concentration) in turn to ensure an even chemical and particle size distribution. The sediment was left to settle in the test vessels overnight or for a minimum of 3 hours. Within 24 hours of the sediment being introduced to the test vessel, natural seawater was carefully added to each vessel to bring the total volume up to 900 mL. Once the sediment had settled the vessels was aerated for 12 hours prior to the initiation of the test.10 Corophium were randomly added to each of the test vessels, thus initialising the test. Aeration of the test vessels was resumed. The test was conducted under constant dim illumination. The behaviour of the Corophium was monitored throughout the test and the water quality (pH, DO and temperature) in the vessels was monitored three times during the 10 days of the test. A constant water level (900 mL) was maintained in the test vessels by topping up with distilled water.Salinity was monitored immediately prior to the initiation of the test and the 10'th day when the test was terminated.On the 10'th day the test was terminated by sieving the content of each beaker through a 500 μm sieve and counting the number of live and dead Corophium in each vessel. Missing animals were presumed to be dead and counted as such.

Reference substance (positive control):

no

Duration:

10 d

Dose descriptor:

LC50

Effect conc.:

345.5 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: 95% CL: 237.4 to 486.7

Duration:

10 d

Dose descriptor:

NOEC

Effect conc.:

51 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

See Table 1 for mortality data for each treatment group.

Table 1. 10 day % mortality for each treatment

Test concentration (mg/kg dry weight	0	51	254	870	3010	10047
Mortality (%)	4	3.3	10	100	100	100

Validity criteria fulfilled:

yes

Conclusions:

The ten day LC50-value for the test substance SERVO RM 93700 was found to be 345.5 mg/kg of (dry weight) sediment. Confidence range was 237.4-486.7 mg/kg of (dry weight) sediment. The NOEC value was 51.0 mg/kg of (dry weight) sediment

Executive summary:

A test was conducted with SERVO RM 93700 using the sediment dweller Corophium volutator. The ten day LC50-value for the test substance SERVO RM 93700 was found to be 345.5 mg/kg of (dry weight) sediment. Confidence range was 237.4-486.7 mg/kg of (dry weight) sediment. The NOEC value was 51.0 mg/kg of (dry weight) sediment The test met all validity requirements with regard to control mortality. In this test, the control parameters temperature, DO, pH and salinity were within the recommended ranges.

Description of key information

10d LC50 = 345.5 mg/kg dw, 10d NOEC = 51 mg/kg dw; Furst (2002); PARCOM (1994)
10d LC50 = 1,908 mg/kg dw; Torp, U.M.F (1996); PARCOM (1994)

Key value for chemical safety assessment

EC50 or LC50 for marine water sediment:

345.5 mg/kg sediment dw

EC10, LC10 or NOEC for marine water sediment:

51 mg/kg sediment dw

Additional information

Two key studies were presented for the sediment toxicity endpoint, both marine studies on the sediment dwelling amphipod Corophium volutator. Based on the results of Furst (2002) the 10d EC₅₀ = 345.5 mg/kg dw and the NOEC = 51 mg/kg dw.