Reaction mass of 4,4'-isopropylidenediphenol and phenol

Sediment toxicity

Description of key information

The lowest freshwater sediment NOEC of 22 mg/kg dw was obtained in the 28-day Lumbriculus variegatus study. The lowest marine sediment NOEC of 32 mg/kg dw was obtained in the 28-day chronic Leptocheirus plumulosus study.

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater sediment:

22 mg/kg sediment dw

EC10, LC10 or NOEC for marine water sediment:

32 mg/kg sediment dw

Additional information

The reaction mass of phenol and 4,4'-isopropylidenediphenol is manufactured and used under strictly controlled conditions, and thus there are no direct emissions to the environment. Direct or indirect exposure of the sediment compartment is unlikely to occur, thus there is no need to investigate the effects on sediment organisms.

Nevertheless, data on sediment dwelling organisms are available for 4,4'-isopropylidenediphenol (Bisphenol A), which is one of the major constituents of the multi-constituent substance. A justification for read-across is attached to Iuclid section 13.

 

Studies with Bisphenol A

A 10-day Corophium volutator mortality and sublethal effect study was performed with Bisphenol A-dosed sediment according to OSPAR (1995) guidance for the performance of sediment bioassays (Whale et al., 1999). The nominal concentrations were 0, 1, 3.2, 10, 32, 100, 320, 1000, and 3200 mg/kg dry weight. The mean measured concentrations were approximately 86% of nominal so the test concentrations were reported as the nominal dose range. The 10-day LC50 values calculated for the Bisphenol A/acetone and directly spiked tests based on bulk sediment concentrations were 46 and 40 mg/kg, respectively. The corresponding lowest 10-day EC50 values based on mortality and failure to burrow in the Bisphenol A/acetone and directly spiked tests were 31 and 36 mg/kg, respectively. When the endpoints of the toxicity tests are based on predicted interstitial water concentrations the 10-day LC50 and 10-day EC50 values are between 1.4 and 1.5 and 1.1 and 1.3 mg/L, respectively. As such, these values are similar to other acute and longer term toxicity values for other aquatic invertebrates exposed to Bisphenol A.

 

A 28-day chronic freshwater oligochaete study was performed exposing Lumbriculus variegatus to nominal Bisphenol A concentrations in artificial sediment of 2.0, 5.1, 13, 32 and 80 mg a.i./kg under static renewal conditions. The results of the analysis of sediment exposure concentrations established mean measured concentrations of 1.6, 3.9, 9.9, 22 and 57 mg a.i./kg.  At test termination (day 28), the mean number of surviving oligochaetes observed among the oligochaetes exposed to the 1.6, 3.9, 9.9, 22 and 57 mg a.i./kg treatment levels was 20, 28, 25, 24 and 15, respectively. Statistical analysis (Bonferroni’s t-Test) determined a significant reduction in the mean number of surviving oligochaetes in the 1.6 and 57 mg a.i./kg treatment levels compared to the control data (27 oligochaetes). However, due to the lack of dose-response in the higher treatment levels, the effect determined in the 1.6 mg a.i./kg treatment level was not considered to be toxicant-related. Mean biomass per replicate in the 1.6, 3.9, 11, 22 and 57 mg a.i./kg treatment levels was 37, 43, 37, 34 and 24 mg, respectively. Statistical analysis (Bonferroni’s t-Test) determined a significant difference in the 57 mg a.i./kg treatment level compared to the control data (36 mg). Based on mean measured concentrations of Bisphenol A in the sediment, the NOEC for this exposure was determined to be 22 mg a.i./kg. The Lowest-Observed-Effect Concentration (LOEC) for this exposure was determined to be 57 mg a.i./kg. Since no concentration tested resulted in ≥ 50% reduction in reproduction or biomass, the EC50 value was empirically estimated to be > 57 mg a.i./kg, the highest mean measured concentration tested. 

 

A 28-day chronic estuarine amphipod study was performed exposing Leptocheirus plumulosus to nominal Bisphenol A concentrations in natural marine sediment of 2.6, 6.4, 16, 40 and 100 mg a.i./kg under static renewal conditions. The results of the analysis of sediment exposure concentrations established mean measured concentrations ranging from 75 to 81% of nominal concentrations and defined the treatment levels tested as 2.0, 5.0, 12, 32 and 78 mg a.i./kg.  At test termination (test day 28), survival observed among amphipods in the 2.0, 5.0, 12, 32 and 78 mg a.i./kg treatment levels was 82, 88, 87, 81 and 2%, respectively. Statistical analysis (Dunnett’s Test) demonstrated a significant difference in survival among amphipods exposed to the 78 mg a.i./kg treatment level compared to the survival of the control (88%). Subsequently, data from the 78 mg a.i./kg treatment level was excluded from further statistical analysis for determination of NOEC and LOEC due to the significant effect observed for survival. Based on mean measured sediment concentrations, the Lowest-Observed-Effect Concentration (LOEC) and No-Observed-Effect Concentration (NOEC) for amphipod survival were determined to be 78 and 32 mg a.i./kg, respectively. The 28-day LC50 value for survival was determined to be 63 mg a.i./kg, with 95% confidence intervals of 55 to 70 mg a.i./kg. Growth observed among amphipods in the 2.0, 5.0, 12,and 32 a.i./kg treatment levels averaged 1.40, 1.81, 1.40 and 1.22 mg dry weight per amphipod, respectively. Statistical analysis (Dunnett’s Test) determined no significant difference in growth among amphipods exposed to treatment levels ≤ 32 mg a.i./kg compared to the control (1.76 mg dry weight per amphipod). The LOEC and NOEC for amphipod growth were determined to be >32 and 32 mg a.i./kg, respectively. The 28‑day EC50 value for growth was determined to be 60 mg a.i./kg, with 95% confidence intervals of 31 to 75 mg a.i./kg. Reproduction among amphipods exposed to the2.0, 5.0, 12 and 32mg a.i./kg treatment levels averaged 7, 9, 7 and 5 offspring per amphipod, respectively. Statistical analysis (Dunnett’s Test) determined no significant difference in reproduction among amphipods exposed to treatment levels ≤ 32 mg a.i./kg compared to the control (6 offspring per amphipod). The LOEC and NOEC for amphipod reproduction were determined to be >32 and 32 mg a.i./kg, respectively. The 28‑day EC50 value for reproduction was determined to be 38 mg a.i./kg, with 95% confidence intervals of 11 to 52 mg a.i./kg.

 

A 42-day chronic amphipod study was performed exposing Hyallela azteca to nominal Bisphenol A concentrations of 0.19, 0.38, 0.75, 1.5, and 3.0 mg/L under flow-through conditions. The results of the analysis of exposure solutions established mean measured time-weighted average concentrations ranging from 58-73% of nominal, defined as 0.12, 0.22, 0.49, 1.1 and 2.2 mg/L, respectively. At 42 days, the mean percent survival was 0% in the 2.2 mg/l treatment. Survival of 75, 83, 78, 72, and 77% was observed among amphipods exposed to the 0.12, 0.22, 0.49, 1.1 mg/L and controls, respectively. Survival was only statistically reduced in the 2.2 mg/L dose group. Amphipod reproduction was 12, 9.4, 13, 11 and 8.5 offspring per female in the controls, 0.12, 0.22, 0.49 and 1.1 mg/l dose groups, respectively. No significant difference was observed with respect to growth. Based on the results of this study, the 42-day LC50 value was determined by moving average analysis to be 0.78 mg/l, with 95% confidence intervals of 0.68 to 0.90 mg/l. Based on mean measured concentrations and amphipod reproduction, the LOEC was determined to be 1.1 mg/L. The NOEC was determined to be 0.49 mg/L.

 

 

Conclusion

The lowest freshwater sediment NOEC of 22 mg/kg dw was obtained in the 28-day Lumbriculus variegatus study. The lowest marine sediment NOEC of 32 mg/kg dw was obtained in the 28-day chronic Leptocheirus plumulosus study.

 

Due to the physicochemical properties of Phenol, 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. PNECs for the sediment compartment of phenol are derived using the equilibrium partitioning method in the absence of experimental data.