Phosphorus tribromide

Endpoint summary

Description of key information

Short-term toxicity to fish

In Acute aquatic toxicity tests on fathead minnows(Pimephales promelas)Fathead minnows (10 per group) were exposed to 0.0, 6.25, 12.5, 25.0, 50.0 or 100.0 mg/L PBr3 in fresh water (88 mg/L hardness as CaC03) at 22 ±2 °C. The static tests were performed in replicate and the results were pooled. The 96-hour LC50 value for fathead minnow was 71 mg/L (50 -100 mg/L confidence limit) and the no observed effect concentration (NOEC) was 25 mg/L.

Based on the lethal concentration (LC50) value the Phosphorus tribromide was considered to be toxic to fish and can be considered to be classified in aquatic chronic 3 category a per the CLP regulations.

Short term toxicity to aquatic invertebrates

Short term toxicity to aquatic invertebrates was performed from HSDB,2016 and NTRL report, 1997 for phosphorus tribromide at different concentrations as 0.0, 6.25, 12.5, 25.0, 50.0 or 100.0 mg/L. Experiment performed in static condition in fresh water for 48 hrs. Mortality was observed and effective concentration was determined to be 22.6 mg/L (18.2 - 27.9 mg/L confidence limit). Therefore, the endpoint for the Phosphorus tribromide (7789-60-8) for short term toxicity to aquatic invertebrates was determined to be NOEC and EC50 value at 6.25 mg/l and 22.6 mg/l concentration. Based on the value, the Phosphorus tribromide was considered to be toxic to aquatic invertebrates and can be considered to be classified in aquatic chronic 3 category a per the CLP regulations.

Toxicity to aquatic algae and cyanobacteria

Based on the prediction done using the EPI Suite ECOSAR version 1.10, the short term toxicity on green algae was predicted for test substance phosphorus(3 +) tribromide (CAS:7789 -60 -8). On the basis of effects observed in a static freshwater system, the effect concentration EC50 value for the substance is estimated to be 60.376 mg/l for green algae for 96 hr duration. Based on this value, it can be concluded that the test chemical phosphorus(3 +) tribromide can be considered as toxic to green algae at environmentally relevant concentrations and can be considered to be classified in aquatic chronic category 3 as per the CLP classification criteria.

Although the data from all trophic levels above suggests the classification of the substance in Aquatic chronic category 3, the substance has been classified according to the as per the Annex VI of the CLP regulation

Additional information

Short-term toxicity to fish

Two studies including experimental data from reliable data source of short term fish toxicity endpoint for Phosphorus tribromide (7789-60-8) with relevant read across chemical which is structurally similar to target were summarized as follows:

First study from NTRL report, Human Effectiveness Directorate Deployment and Sustainment Division Operational Toxicology Branch, UNITED STATES AIR FORCE RESEARCH LABORATORY, 1997 and HSDB authorative database suggest Acute aquatic toxicity tests on fathead minnows (Pimephales promelas)Fathead minnows (10 per group) were exposed to 0.0, 6.25, 12.5, 25.0, 50.0 or 100.0 mg/L PBr3 in fresh water (88 mg/L hardness as CaC03) at 22 ±2 °C. The static tests were performed in replicate and the results were pooled. The 96-hour LC50 value for fathead minnow was 71 mg/L (50 -100 mg/L confidence limit) and the no observed effect concentration (NOEC) was 25 mg/L.

Based on the lethal concentration (LC50) value the Phosphorus tribromide was considered to be toxic to fish and can be considered to be classified in aquatic chronic 3 category a per the CLP regulations.

Above aquatic classification of target chemical supported by read across chemical Phosphorus trichloride (Cas no. 7719-12-2) study from authorative database (HSDB by US EPA; 2017) which indicate in short term fish toxicity the lethal concentration (LC100) was observed to be 65 mg/l in fish species sturgeon (Acipenser), carp (Cyprinus carpio), perch (Percidae), Esox lucius (northern pike), and Leuciscus leuciscus (dace).The mentioned lethal concentration indicate that the test substance Phosphorus trichloride toxic to fish.

Based on the both studies concluded that the test chemical Phosphorus tribromide (7789-60-8) toxic to fish for short exposure period.

Short term toxicity to aquatic invertebrates

Short term toxicity to aquatic invertebrates was summaries with one experimental study , one prediction for Phosphorus tribromide (7789-60-8) and one experimental study with read across.

Short term toxicity to aquatic invertebrates was performed from HSDB,2016 and NTRL report, 1997 for phosphorus tribromide at different concentrations as 0.0, 6.25, 12.5, 25.0, 50.0 or 100.0 mg/L. Experiment performed in static condition in fresh water for 48 hrs. Mortality was observed and effective concentration was determined to be 22.6 mg/L (18.2 - 27.9 mg/L confidence limit). Therefore, the endpoint for the Phosphorus tribromide (7789-60-8) for short term toxicity to aquatic invertebrates was determined to be NOEC and EC50 value at 6.25 mg/l and 22.6 mg/l concentration. Based on the value, the Phosphorus tribromide was considered to be toxic to aquatic invertebrates and can be considered to be classified in aquatic chronic 3 category a per the CLP regulations.

Using the EPI suite, ECOSAR version 1.1, the LC 50 value for short term toxicity to aquatic invertebrates was predicted. On the basis of this program, the LC 50 value for short term toxicity to aquatic invertebrates was predicted to be72.88mg/l for Phosphorus tribromide (7789-60-8) in 48 hrs. Based on the value, the Phosphorus tribromide was considered to be toxic to aquatic invertebrates and can be considered to be classified in aquatic chronic 3 category a per the CLP regulations.

Study on read across Phosphorus trichloride (7719-12-2) from SIDS Assessment Report, 2004 in Daphnia magna for 48 hrs at different six concentrations along with control. The test was performed without feeding to Daphnia magna. 10 neonates were taken for each concentration at 18-20 degree C temperature. pH and oxygen values measured at the end of the test. After the experiment, the EC 50 value for Phosphorus trichloride (7719-12-2) was determined to be 35.4 mg/l.

Based on the above data for the target and functionally related read across chemicals, it can be considered the substance was considered to be toxic to aquatic invertebrates and can be classified in aquatic chronic 3 as per the CLP regulations.

Toxicity to aquatic algae and cyanobacteria

Various predicted data for the target chemical phosphorus tribromide (CAS No. 7789-60-8) and weight of evidence study for its read across substance were reviewed to summarize the following information:

 

Short term toxicity on aquatic algae and cyanobacteria of target chemical phosphorus tribromide (CAS No. 7789-60-8) is predicted using the using the EPI Suite ECOSAR version 1.10 (EPI Suite, 2017).On the basis of effects observed in a static freshwater system, the effect concentration EC50 value for the substance is estimated to be 60.376 mg/l for green algae for 96 hr duration.

 

In a weight of evidence study from secondary source (OECD SIDS, 2004) of the read across chemical Phosphorus trichloride (CAS no. 7719 -12 -2), short term toxicity to Scenedesmus subspicatus study was carried out for 72 hrs. The study was performed according to OECD Guideline 201 (Alga, Growth Inhibition Test) and EC Directive 92/69 C3, respectively. The study was based on the effects of the read across compound Phosphorus trichloride (CAS no. 7719 -12 -2) on Scenedesmus subspicatus (green algae) in a static fresh water system at a temperature of 21 – 25°C with light intensity of 60 -120 μE/m²/s, respectively. Scenedesmus subspicatus was used as a test organism. Initial cell density of the test organism was 10 × 10(4)cells/ml. Test chemical conc. used for the study were 3.13, 6.25, 12.5, 25, 50 and 100 mg/l (nominal concentrations), respectively. Experimental design consists of 6 test concentrations plus 1 control, 3 replicates per concentration, 6 replicates per control, highest test concentration without algae. 300 ml Erlenmeyer flasks with stoppers was used as a test vessels. pH is measured at the beginning of the test and at 72 h. Cell densities measured at 24 h intervals using a microcell counter. Inhibition of algal population measured as reduction in biomass growth (index b) and population density growth rate (index r), relative to control cultures under identical conditions. The 72 h-EC50 values are calculated or read from the concentration/percentage response curve. After 72 hours of exposure to Phosphorus trichloride, the NOEC and LOEC values was determined to be12.5 and 25 mg/l based on biomass and population density growth rate, the 72 hrs EC10 and EC50 value was determined to be 24.89 and 33.41 mg/l based on population density growth rate and on the basis of biomass, the 72 hr EC10 and EC50 value was determined to be 21.30 and 30.24 mg/l, respectively.

Thus, based on the overall reported results for target chemical phosphorus tribromide (EPI suite, 2017) and for its read across substance (from secondary source), it can be concluded that the test substance phosphorus tribromide can be considered as toxic to aquatic environment and can be considered to be classified in aquatic chronic category 3 as per the CLP classification criteria.

Final classification:

Although the data from all trophic levels above suggests the classification of the substance in Aquatic chronic category 3, the substance has been classified according to the as per the Annex VI of the CLP regulation