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Environmental fate & pathways

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The phototransformation of AAPB consisting of C8-, C10-, C12- , C14- , C16-, and C18-fatty acids was calculated using EPIWIN v3.11, AOPWIN v1.91. Based on a OH radical concentration of 500000 molecules/cm³ (24 h-day, average hydroxyl concentration) and the estimated atmospheric reaction rate constants (C8: 42.769 x 10E-12 cm³/molecule x s; C10: 45.595 x 10E-12 cm³/molecule x s; C12: 48.420 x 10E-12 cm³/molecule x s; C14: 51.247 x 10E-12 cm³/molecule x s; C16: 54.073 x 10E-12 cm³/molecule x s, and C18: 56.899 x 10E-12 cm³/molecule x s) half-lives ranging from 6.8 h (C18 derivate) to 9 h (C8 derivate) were calculated. The results indicate theoretically a rapid photodegradation (t1/2<10 h) of the components (C8 -C18 derivates) of AAPB. Due to the ionic character of the compound and the low vapor pressure, however, the occurrence of gaseous AAPB in air is expected to be negligible and therefore this degradation pathway is only of minor importance.



In accordance with column 2 of REACH Annex VIII, the hydrolysis test does not have to be conducted because AAPB is readily biodegradable. It is shown that biodegradation is the primary route of degradation in the environment.

In addition limited information is available from an EPIWIN calculation. However, there are no details whether the calculation model is validated for the substance under investigation, therefore reliability is not assignable. The stability (hydrolysis) of Coco AAPB was calculated using EPIWIN, HYDROWIN v1.67. Hydrolysis is not to be expected under environmental conditions: the calculated hydrolysis half-life time (t1/2) for Coco AAPB consisting of C8 -C18 fatty acids was found to be > 1 year.



AAPBs are readily biodegradable, biodegradable under anaerobic conditions and under different environmental conditions (water, seawater, sewage treatment plants).


Experimental results from several guideline studies (e. g. OECD 301 A, 301 B, 301 D, 301 E) on the aerobic biodegradation of Coco AAPB, C12 AAPB and C8 -18 AAPB are available. Based on the results, Coco AAPB, C12 AAPB, and C8 -18 AAPB can be regarded as readily biodegradable. The inherent biodegradability of C12-18 AAPB was proven in a Zahn-Wellens Test. Based on these results, the AAPBs can be regarded as readily biodegradable.

The anaerobic biodegradability of Coco AAPB and C8-18 AAPB was investigated in studies conducted similar to OECD guideline 311. Based on the results of these studies, the AAPBs are considered to be biodegradable under anaerobic condition.


The ultimate biodegradation was proven and a mean elimination of 99 % was calculated. Therefore further investigation on biodegradation in soil does not need to be conducted in accordance with REACH Regulation Annex IX,

A justification for read-across is given in the respective IUCLID sections.



Meylan et al. (1999) collected measured BCF (sources: AQUIRE, CITI, HSDB and EFDB), log Kow (sources: MEDCHEM 'star list', Sangster's LOGKOW DATABANK or sources referenced in the EFDB or KOWWIN estimates), and pKa values for ionizing substances (sources: SRC's PHYSPROP database, compilation of Perrin and Serjeant and Dempsey and reference handbooks such as Handbook of Organic Chemistry, the Handbook of Chemistry and Physics and other sources cited in the EFDB or calculated using pKalc 3.1 software or SPARC. The database of 694 compounds with recommended BCF values contained 84 compounds defined as ionic, including carboxylic acids, sulfonic acids, and quaternary ammonium compounds. Based on the correlation of measured log BCF values and log Kow, log BCF values were deduced. The results were used to develop the computer program BCFWIN. Therefore, BCFWIN v2.15 was used to calculate the BCF values for the C8-C18 derivates of AAPB. The calculation yielded values in the range between 3 (C8 fatty acid derivate) and 71 (C10 – C18 and C18 unsaturated fatty acid derivates). Based on the calculated BCFs a low potential for bioaccumulation is to be expected for AAPBs. Measured BCFs are not available.


Transport and distribution


A weight of evidence approach was used for evaluation, as the experimental determined values are used as training structure for the ACD calculated values.

In a screening study conducted according to OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC)) the log Koc values of C12 and C14 AAPB were determined. Based on a corrected dead time value, the log Koc of C12 and C14 AAPB were determined to be 2.5 (Koc: ca. 320; C12 derivate) and 3.5 (Koc: ca. 3200; C14 derivate), respectively. Based on these results and taking into account the classification scheme of Blume and Ahlsdorf (1993) a medium (C12 derivate) and high sorption (C14 derivate) onto soil organic matter is to be expected.

Based on the Koc value determined by measurement, C12 AAPB was used as training structure for the ACD software and Kow values were calculated for C8, C10, C14, C16 and C18 AAPB (for this calculation to the IUCLID the following justification documents are attached: QSAR prediction report format (QPRF) and QSAR model reporting format (QMRF)). The soil sorption coefficient of AAPB containing C8-, C10-, C12-, C14-, C16-, and C18 fatty acids was calculated using the guideline conform EUSES algorithm for non hydrophobics. The calculation yielded Koc values of 89.3 (C8 derivate), 303 (C10 derivate), 726 (C12 derivate), 4870 (C14 derivate), 16500 (C16 derivate), and 56000 (C18 derivate). According to the classification scheme of Blume & Ahlsdorf (1993), a low (C8 derivate), medium (C10 derivate), high (C12 and C14 derivates), and very high (C16 and C18 derivates) sorption onto soil organic matter is to be expected.

As reported in HERA (2007), the Koc values for AAPB containing C8-, C10-, C12-, C14-, C16-, and C18 fatty acids were calculated using EPIWIN v3.11, PCKOCWIN v1.67. The calculation yielded Koc values of 264.7 (C8 derivate), 900.5 (C10 derivate), 3063 (C12 derivate), 10420 (C14 derivate), 35450 (C16 derivate), and 120600 (C18 derivate). According to the classification scheme of Litz (1990) these values indicate a low to very high sorption potential to the organic matter of soils and sediments depending on the chain length.

Based on the experimental determined Koc values of C12 and C14 AAPB, the Koc values calculated with EPIWIN seem to overestimate soil sorption. The values calculated with ACD/EUSES (reasoned in separate documents (QPRF, QMRF attached to IUCLID)) Koc and Kow values were used for further calculations (environmental exposure and risk assessment).



Due to the ionic structure of AAPB and a corresponding negligible vapour pressure volatilisation of AAPBs is negligible and therefore relevant concentration of the substance in the atmospheric compartment is not expected.


Distribution modelling

Mackay Level I distribution was not calculated. For exposure modelling higher tier calculation models were used (EUSES resp. ECETOC TRA resp. EasyTRA). Based on the available data, it can be assumed that AAPBs will not volatilize from aqueous solution. According to the results of adsorption/desorption experiments, AAPBs can be found in the environment in the aqueour phase and adsorbed by soil and sediments. Due to ready biodegradability resp. metabolization, a relevant distribution to biota is not expected.