Reaction mass of butyl diphenyl phosphate and dibutyl phenyl phosphate and tributyl phosphate

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study carried out according to old guidelines and under GLP, study is well documented and scientifically acceptable.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: Standard Methods for Examination of Water and Wastewater

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Methods of Acute Toxicity Tests with Fish, Macroinvertebrates and Amphibians

Deviations:

no

Principles of method if other than guideline:

the test was conducted to see the influence of DBPP in a chronic exposure experiment on 4 different endpoint: growth, survival, reproduction and percentage of gravid female

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

grab samples followed by extraction with dichloromethane

Vehicle:

yes

Details on test solutions:

Test solution were prepared with dimethylformamine as a vehicle.

Test organisms (species):

Daphnia magna

Details on test organisms:

The water fleas were cultured at the EG&G Bionomics laboratory where the exposure took place.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Post exposure observation period:

not applicable

Hardness:

175 +/- 15 mg/L as CaCO3

Test temperature:

22°C

pH:

8.1 +/- 0.2

Dissolved oxygen:

8.6 - 9.0 mg/L

Salinity:

no data

Nominal and measured concentrations:

nominal concentrations: 0 (control), 0.012, 0.025, 0.050, 0.10, 0.20
Measured concentrations: 0 (control), 0.014, 0.028, 0.055, 0.092, 0.25

Details on test conditions:

no data

Reference substance (positive control):

no

Duration:

21 d

Dose descriptor:

EC10

Effect conc.:

0.106 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: survival

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

> 0.25 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

> 0.25 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

> 0.25 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: percentage of gravid females

Details on results:

The Maximum Threshold Concentration test was designed to determine what the minimum concentration of a substance is without causing negative effects on different toxicological endpoints. The only endpoint that was affected by DBPP was mortality (!). Length, reproduction and gravid females was not statistically different in any of the tested concentrations compared to the controls.

Results with reference substance (positive control):

not applicable

Reported statistics and error estimates:

Significant differences (p=0.05) between the controls and the test concentrations were determined, using the Dunnets procedure. An EC10 for survival was derived using the DEBTox model.

Validity criteria fulfilled:

yes

Conclusions:

The Maximum Threshold Concentration test was designed to determine what the minimum concentration of a substance is without causing negative effects on a number of toxicological endpoints. The only endpoint that was affected by DBPP in this study was mortality. Length and reproduction were not statistically different at 21 days in any of the tested concentrations compared to the controls. The percentage of gravid females at day 7 was also not affected by DBPP.

Executive summary:

In a study carried out according to Standard Methods for Examination of Water and Wastewater (American Public Health Association, 1976) and Methods of Acute Toxicity Tests with Fish, Macroinvertebrates and Amphibians (US EPA 660 -3 -75 -009, 1975) the Maximum Threshold Concentration for Daphnia magna exposed to DBPP in a 21 day lifecycle study was determined. The MTC is considered to be the concentration that an organism can be exposed to without any negative effects. The endpoints studied were mortality (day 7,14 and 21), total length (day 7 and 21), number of offspring (day 9, 12, 13, 14, 15, 16, 19, 20, 21) and percentage of gravid females at day 7.

Mortality was the only endpoint which was significantly affected by the exposure after 21 days of exposure. Total length at 7 days was slightly less in the highest concentration compared to the controls, but at 21 days there was no statistical difference (p=0.05) between the different treatments and the controls for any of the sublethal endpoints. However a significant nr of the young daphnids died due to exposure to DBPP in the highest concentration (0.25 mg/L). None of the endpoints, including mortality, was affected in any of the concentrations up to 0.092 mg/L. Therefore the study concluded that sublethal endpoints do not give an accurate representation of the chronic effects of DBPP. Based on these results, a 21 day EC10 value for survival of 0.106 mg/L was derived (based on measured concentrations) using DEBTox.

Description of key information

A long-term (21-day) study with Daphnia magna was carried out in 1980 (Altshul et al., 1980) to find the Maximum Tolerable Concentration (MTC) of DBPP for Daphnia magna. The study was carried out according to then existing guidelines and can be regarded as a well-performed study (K2). There were no effects on any of the sublethal endpoints evaluated. Based on the effects on survival (21-days), an EC10 of 0.106 mg/L was determined.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.106 mg/L