Fatty acids, tall-oil, reaction products with boric acid (H3BO3) and diethanolamine

Endpoint summary

Description of key information

Biodegraadation

The test item cannot be declared readily biodegradable but was determined to be rapidly degradable. At the end of the 35-day test period in the key study, the activated sludge inoculum was active, degrading the reference substance 94.1 % and, as a UVCB, the test item may be considered rapidly biodegradable since the pass level of 60% of ThIC was achieved within 28 days (OECD 310).

 

Adsorption/desorption

The absorption coefficient of the test item has been determined to be > 4.27 E+05 (Log Koc≥5.63). The test substance has low mobility in soil.

Additional information

Biodegradation

Key study

In the key Headspace Test conducted in accordance with OECD Guideline 310, inoculated test medium was dosed with a known amount of test substance as the nominal sole source of organic carbon and sealed. CO2 evolution from the ultimate aerobic biodegradation of the test substance is determined by measuring the inorganic carbon (IC) produced in the test bottles over that produced in the blank control bottles. The amount of IC produced by the test substance (corrected for that evolved by the controls and the amount added by basification, where applicable) is expressed as a percentage of the theoretical amount of IC (ThIC) that could have been produced if complete biodegradation of the test substance occurred. The test contained a control group, a reference group and a treatment group. Each group contained twenty-seven replicate test chambers. The control chambers were used to measure the background IC production of the inoculum medium and were not dosed with a carbon source. The reference chambers were dosed with 1-octanol, a substance known to be biodegradable, at a nominal concentration of 20 mg C/L. The treatment group test chambers were used to evaluate the test item at a nominal concentration of approximately 20 mg C/L.

The results at the end of the 35-day test period indicated that the activated sludge inoculum was active, degrading the reference substance 94.1 %. The average cumulative percent biodegradation for the test item was 73.1 %.

The test item may not be considered readily biodegradable under aerobic conditions since biodegradation ≥ 60 % ThIC was not achieved within a 10-day window of reaching 10 % ThIC. However, as a UVCB, the test item may be considered rapidly biodegradable since the pass level of 60 % of ThIC was achieved within 28 days.

Supporting study

The supporting study was conducted according to the procedures outlined in the protocol "Ready biodegradability by the carbon dioxide evolution test method". The protocol was based on the procedures specified in the OECD guideline for testing of chemicals, Methods 301B, and EEC Method C.4-C.

The viability of the inoculum and validity of the test were supported by the results of the reference substance, sodium benzoate, from which 99.3% of theretical CO2 was evolved. An average percent biodegradation of greater than 60% was achieved within 7 days, thereby fulfilling the criteria for a valid test by reaching the pass level by day 14. The average cumulative percent of theoretical carbon dioxide produced by the test substance at 10 mg C/L was 57.0%.

Evidence of ready biodegradability in a carbon dioxide evolution test is 60 % TCO2 within the 28-d test period. In addition, the pass value must be reached within 10 days of achieving 10 % TCO2. The test item may not be considered readily biodegradable under the conditions tested since the pass level of 60 % TCO2 was not achieved. However since tests of ready biodegradability provide limited opportunity for biodegradation to occur, a negative result does not mean that the test substance will not be biodegraded under relevant environmental conditions.

Abiotic degradation; Hydrolysis

The study does not need to be conducted because the substance is highly insoluble in water. The experimentally determined water solubility was < 4.93 mg/L at 20 °C (OECD 105 and EU Method A.6). However, the final result was considered to be higher than the actual water solubility of the test item and the calculated value given by WSKOW v1.41 (2000, US EPA) was 4.3E-16 mg/L based on structural information.

Bioaccumulation

An experimental investigation does not need to be conducted if the substance has a low potential for bioaccumulation. The experimentally derived Log Pow value for the substance has been identified as > 9.4, with extrapolation to a Log Pow value of 11.7. A QSAR calculation of Log Pow gave the estimated value of Log Pow as 16.6. ECHA Guidance on Information Requirements and Chemical Safety Assessment Chapter R11: PBT assessment (Version 3.0; June 2017) states that the aquatic BCF of a substance is probably lower than 2000 L/kg if the calculated log Kow is higher than 10. A study is therefore considered scientifically unjustified with regard to the low bioaccumulative potential of the substance.

Transport and distribution

Adsorption/desorption

The absorption coefficient of the test item has been determined to be > 4.27 x 10E+05 (Log Koc ≥ 5.63). The test substance has low mobility in soil.

 

Henry's Law Constant

The value of Henry’s constant (25 °C) was calculated as 0.041 Pa/m3/mol (EUSES 2.1.2).

 

Distribution modelling

The substance is predicted to partition mainly to soil (33.1 %) and sediment (64.1 %).