Pentaerythritol, reaction product with fatty acids, C8 to 18 (even numbered) and/or branched and/or unsaturated

Biodegradation in water: screening tests

Description of key information

The study was performed according to OECD Guideline 301-B/EU method C4-C and GLP guidelines.
Degradation data on all individual components were retrieved from public and company owned sources.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Radialube 7819 was degraded significantly (50 and 58%) during the test period. However, since at least 60% biodegradation was not reached in 28 days, the criterion for ready biodegradability was not met. Thus, under the conditions of this test Radialube 7819 was not readily biodegradable. However as significant degradation was observed and the biodegradation curve is comparable to the one of the positive control substance, the substance will probably degrade rapidly in the environment.

Further strategy would include focusing on further studies for persistency. However, it should be noted that in the performed biodegradation screening study the test substance concentration was far above the maximum solubility of the substance (17.5 mg/L based on TS). This means that there was no optimal contact between the TS and microorganisms. In view of the degradation rate reached it is not advicable to do a further test on biodegradation (enhanced study) as it is highly uncertain that in this study the required threshold will pass. The enhanced study is designed to increase the contact surface of microorganisms with the substance. As this substance is mainly composed of fatty acids it is uncertain that an enhanced study can further increase the contact area.

Instead of this degradation data were searched for all invidual components (data retrieved from public sources and company owned sources):

Biodegradation data are available for all components of Radialube 7819. In the following these data will be shortly described.

Fatty acids, C14-18 and C16-18 unsatd (CAS 67701-06-8; EC 266-930-6)
In an OECD301D study with CAS 67701-06-8 (C14-18 and C16-18-unsaturated fatty acids 14-18 & 16-18 unsatd. Mixture) the test substance degraded 76% in 7 days (92% in 28 days) at 2 mg/L and 65% in 7 days at 5 mg/L. In the 5 mg/l concentration of test substance, low oxygen concentration limited the degradation results. It can be concluded that this substance is readily biodegradable.
The substance has also been registered under the REACH regulation for the 2010 deadline. A weigh-of-evidence has been applied for the endpoint biodegradation. An OECD 301B study in compliance with GLP showed that C14-18 (even numbered) and C16-18-unsatd.(even numbered) was degraded after 28 d by 81% and 70% at 10 and 20 mg/L, respectively. The 10 day-window was failed barely (59.8% degradation instead of 60%, which was almost identical to the reference substance). Beside the low water solubility another reason for this failure might have been that the test substance was added via an inert membrane filter and thus probably had reduced the bioavailability and the barely failure of the 10-day window. In another OECD301B performed in compliance with GLP concentrations of 10 and 20 mg/L showed that the degradation values were 71% and 74%, respectively at test termination (28 d). The pass criterion for ready biodegradability (60% degradation has to be reached within 10 days once exceeded 10% degradation) was barely missed. Since the sampling interval was not as small as recommended by the OECD guideline (sampling every second day, followed by sampling every fifth day) this might have led to the barely missing of the 10-day window.

The biodegradation of C14-18 (even numbered) and C16-18-unsatd.(even numbered) was investigated in marine seawater according to the BODIS-Test (comparable to OECD 306) under GLP. Unlike similar ready test in freshwater this method uses natural seawater fortified with mineral nutrients and no inoculums was added in addition to the microorganisms already present in the seawater. The overall degradation monitored by the BOD concentration was 92% over 28 days and showed an inhibition of -10% to seawater bacteria. The soluble reference substance sodium benzoate degraded by more than 60% in the first fourteen days indicating the viability of the seawater bacteria.

Octanoic acid (CAS 124-07-2; EC 204-677-5)
It can be concluded that octanoic acid (CAS 124-07-2) is readily biodegradable based on the following data. Octanoic acid reached 43, 53, 64 and 63% of its theoretical BOD after 2,5,10, and 30 days, respectively using a domestic sewage inoculum and an octanoic acid concn of 3.0 ppm. 100% decreases in initial octanoic acid concns of 0.5 mg/l and 4.3 mg/l were observed after 21 days incubation in aerobic mixed bacterial cultures obtained from trench leachate at low-level radioactive waste disposal sites in Maxey Flats, KY and West Valley, NY, respectively. Octanoic acid reached 60% of its theoretical oxygen demand after 5 days using a sewage seed. After a lag period of 2.2 days, octanoic acid present at a concn of 10,000 ppm, reached 60, 66, and 68% of its theoretical BOD after 5, 10, and 20 days, respectively using a sewage seed. Use of an adapted sewage seed reduced the lag period to 1.6 days, after which octanoic acid reached 60, 69, and 70% of its theoretical BOD after 5, 10, and 20 days, respectively. In Warburg respirometer tests using an activated sludge seed, octanoic acid, present at a concn of 500 ppm, reached 9.8, 20.4, and 32.8% of its theoretical oxygen demand after 6, 12, and 24 hours incubation, respectively. After 24 hours incubation, octanoic acid, present at a concn of 500 ppm, reached 5 and 59% of its theoretical oxygen demand using activated sludge inoculum from two different municipal sources. In a Warburg test using an activated sludge inoculum acclimated to phenol, octanoic acid, present at a concn of 500 ppm, reached 20% of its theoretical BOD after 12 hours. Two bacterial soil isolants were able to utilize caprylate as a growth substrate. A total organic carbon removal ratio of 97% was observed for octanoic acid using a non-acclimated activated sludge and an initial octanoic acid concn of 100 mg total organic carbon/l.

Decanoic acid (CAS 334-48-5; EC 206-376-4)
Based on the available dataset decanoic acid seems not to fulfill the criteria to be listed as readily degradable. However, based on the following and strong analogy to octanoic acid it can be concluded that decanoic acid will probably breakdown rapidly in the environment.
The 5 day BOD of decanoic acid, concn 100 ppm, was determined to be 8.52 mmol/mmol decanoic acid using acclimated mixed microbial cultures in a mineral salt medium. Decanoic acid, present at 10,000 ppm, reached 45 to 53% and 46 to 54% of its theoretical BOD in 5 and 20 days, respectively, using a sewage inoculum. Decanoic acid, present at 10,000 ppm, reached 13, 45, and 46% of its theoretical BOD in 5, 10, and 20 days, respectively, using a sewage inoculum. In a similar study, decanoic acid, present at 10,000 ppm, reached 49, 53, and 54% of its theoretical BOD in 5, 10, and 20 days, respectively, using an acclimated sewage inoculum. Decanoic acid, present at unknown concn, reached 9% of its theoretical BOD in 5 days using a sewage inoculum. Using the Warburg test method, decanoic acid, present at 500 ppm, reached 29 to 42% of its theoretical BOD in 1 day, using an activated sludge inoculum with a microbial population of 2,500 mg/L corrected for endogenous respiration. Biodegradation of 100 ppm decanoic acid using the cultivation method was 100% in river water and 100% in sea water after 3 days. The theoretical oxygen demand for 500 mg/L decanoic acid was determined to be 10.9%, 18.9%, and 23.4% after 6, 12, and 24 hours of exposure to activated sludge solids at 2,500 mg/L in the Warburg respirometer. An aerobic biodegradation screening study of decanoic acid, based on BOD measurements, using a sewage inoculum and an unknown decanoic acid concn, indicated 23% of its theoretical BOD over a period of 20 days. The biodegradation of 100 mg/L decanoic acid by non-acclimated activated sludge over an unspecified time period was determined to have 100% total organic carbon removal.

2-Ethylhexanoic acid (CAS 149-57-5; EC 205-743-6)
This substance is registered under the REACH Regulation for the 2010 deadline and available data show that the substance is readily degradable.
In a study performed according to OECD 301E (non-GLP) with a test concentration of 20 mg/L based on DOC 99% degradation based on DOC removal was seen after 28 days.

Pentaerythritol (CAS 115-77-5; EC 204-104-9)
This substance is registered under the REACH Regulation for the 2010 deadline and available data show that the substance is readily degradable.
In a study performed according to OECD 310 (non-GLP) with a test concentration of 10 mg/L based on DOC 83.7% degradation based on CO2 evolution was seen after 28 days. Pentaerythritol is readily biodegradable with inoculum concentration at least 10^5 viable cells per litre. The recommended inoculum concentration for ready biodegradability is in the range of 10^4 to 10^8 cells per litre. When given at least 0.05% vol/vol of secondary effluent (~ 3 x 10^ 5 viable cells/litre), within the recommended range, pentaerythritol will biodegrade by >70% after 27 days and with 5.0% vol/vol secondary effluent, the biodegradation is up to 86% after 27 days, indicating that pentaerythritol is readily biodegradable. From the results of the study it is clear that after an initial lag period (of around 10 days) biodegradation of the test substance occurred rapidly and within the 10 day window from day 10 to day 20. During this time biodegradation rates progressed well beyond the 80% level. As such the substance meets the classification criteria for ready biodegradability.