Reaction mass of 4,4'-isopropylidenediphenol and phenol

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across is based on the hypothesis that the properties of the target substance Reaction mass of phenol and 4,4’-isopropylidenediphenol can be predicted by studies conducted with the source substances phenol, 4,4’-isopropylidenediphenol (BPA), and 2-acetone, polymer with phenol, because the target substance Reaction mass of phenol and 4,4’-isopropylidenediphenol contains phenol (40-45%, typical concentration ca. 40%) and 4,4’-isopropylidenediphenol (BPA) (20-40%, typical concentration ca. 33%) as main constituents. Both constituents are data rich substances with distinct hazard properties, so that mainly data on the constituents have been applied to characterize the Reaction mass of phenol and 4,4’-isopropylidenediphenol. Since this is a common approach in mixture hazard assessment, is reasonable to apply it also to multi-constituent substances.
Additionally, some data from a structurally related substance (2-acetone, polymer with phenol) containing the same constituents/impurities at different concentrations are available, which are applied to characterize the environmental fate and ecotoxicity of the impurities present in the Reaction mass of phenol and 4,4’-isopropylidenediphenol.

This read-across hypothesis corresponds to scenario 2 - different compounds have qualitatively and quantitatively the same type of effects - of the read-across assessment framework i.e. properties of the target substance Reaction mass of phenol and 4,4’-isopropylidenediphenol are predicted to be similar to those of the source substances phenol, 4,4’-isopropylidenediphenol (BPA), and 2-acetone, polymer with phenol.

Therefore, read-across from the available studies with the source substances is considered as an appropriate adaptation to the standard information requirements of the REACH Regulation for the target substance Reaction mass of phenol and 4,4’-isopropylidenediphenol, in accordance with the provisions of Annex XI, 1.5 of the REACH Regulation.


2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
please refer to justification for read-across attached to Iuclid section 13

3. ANALOGUE APPROACH JUSTIFICATION
please refer to justification for read-across attached to Iuclid section 13

4. DATA MATRIX
please refer to justification for read-across attached to Iuclid section 13

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Duration:

24 h

Dose descriptor:

IC50

Effect conc.:

21 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of nitrification rate

Remarks on result:

other: Phenol

Duration:

16 h

Dose descriptor:

IC50

Effect conc.:

54.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: BPA

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

4 539 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks on result:

other: 2-acetone, polymer with phenol

Conclusions:

The lowest toxicity value for this endpoint was the 24-hour IC50 of 21 mg/L for phenol based on inhibition of nitrification.
In a growth inhibition study with P. fluorescens, the 16-hour IC50 was 54.5 mg/L for Bisphenol A.
2-acetone, polymer with phenol was much less toxic to microorganisms than the main constituents (3-h EC50= 4539 mg/L).
Due to the physicochemical properties of BPA, this major constituent of the reaction mass is capable of targeting aquatic and terrestrial wildlife through a different exposure route than 4,4’-isopropylidenediphenol. Therefore, to adequately characterize the hazard of the reaction mass toward ecotoxicology endpoints, the toxicity and fate of both major constituents of the reaction mass of phenol and 4,4’-isopropylidenediphenol were considered and two sets of PNECs (one for phenol one for 4,4’-isopropylidenediphenol) were derived and an assessment entity approach was applied.

Description of key information

The 24-hour IC50 for inhibition of nitrification by members of the genus Nitrosomonas was 21 mg/L phenol.  

Key value for chemical safety assessment

EC50 for microorganisms:

21 mg/L

Additional information

No experimental data are available for the target substance reaction mass of phenol and 4,4’-isopropylidenediphenol. The toxicity to fish was assessed by examination of the properties of the constituents and impurities of the multi-constituent substance. A justification for read-across is attached to Iuclid section 13.

 

Studies with Bisphenol A

The toxicity of Bisphenol A in agar to Pseudomonas putida was studied in a test similar to DIN 38412-8 (Pseudomonas Zellvermehrungshemmtest). In this study, an EC10 of >320 mg/L was reported.

The biodegradability of Bisphenol A was studied in a number of tests. One of them evaluated the inhibition of growth of the bacteria, Pseudomonas fluorescens. In this microbial inhibition test, the IC50 for the inhibition of growth of Pseudomonas by Bisphenol A was 54.5 mg/L.

 

Studies with Phenol

The toxicity of phenol for Nitrosomonas sp. was tested. The seed bacteria for the nitrifiying enrichment culture were obtained from the mixed liquor of an acitivated sludge plant treating meat-packing, rendering, and hide-curing waste-water. The reactor vessel was a 20 L glass bottle. Diffused aeration provided complete mixing and aeration. The culture was fed two times per day apporximately 1000 mg/L ammonia-nitrogen in an inorganic nutrient solution buffered by sodium bicarbonate. The inhibition of ammonium consumption was used as the criterion for toxic inhibition of Nitrosomonas. Sealed serum bottles (125 mL) were prepared with ammoniua feed and 20 mL of surcharged oxygen. Ammonia was measured at the end of the assay period using an ammonia selective elctrode. Nitrite was checked to ensure that only toxicity to Nitrosomonas and not toxicity to Nitrobacterer was controlling the rate of metabolism activity. A range of toxicant concentrations were tested. Toxicants were tested in at least two experiments. An average IC50 of 21 mg/L was calculated.

 

Studies with 2-acetone, polymer with phenol

A study was performed to assess the toxicity of Bisphenol A-Harz to bacteria. The study was conducted in accordance with ISO 8192-1986 "Activated sludge respiration inhibition" (1986). This test method is equal to OECD Guideline 209 (1984).  

The activated sludge was exposed to Bisphenol A-Harz at different concentrations. The respiration rate of each mixture was determined after aeration periods of 3 hours. Bisphenol A-Harz showed 87.3 % respiration inhibition of activated sludge at a test item concentration of 10000 mg/L.

The EC50 is 4539 mg/L (by probit analysis). The effect value related to nominal concentration, since no analytical monitoring was performed.

 

Conclusion

The lowest toxicity value for this endpoint was the 24-hour IC50 of 21 mg/L for phenol based on inhibition of nitrification. 

In a growth inhibition study with P. fluorescens, the 16-hour IC50 was 54.5 mg/L for Bisphenol A. 

2-acetone, polymer with phenol was much less toxic to microorganisms than the main constituents (3-h EC50= 4539 mg/L).

Due to the physicochemical properties of BPA, this major constituent of the reaction mass is capable of targeting aquatic and terrestrial wildlife through a different exposure route than 4,4’-isopropylidenediphenol. Therefore, to adequately characterize the hazard of the reaction mass toward ecotoxicology endpoints, the toxicity and fate of both major constituents of the reaction mass of phenol and 4,4’-isopropylidenediphenol were considered and two sets of PNECs (one for phenol one for 4,4’-isopropylidenediphenol) were derived and an assessment entity approach was applied.