C8-C26 branched and linear hydrocarbons – Distillates

Endpoint summary

Additional information

A logistic function QSAR model has been used to predict BCF values for the GTL Gasoil constituents (See EPSR PFA, 2014). Using the logistic function QSAR model, predicts a worst case scenario for high log K_ow constituents as it assumes a plateau at log BCF 3.3 (BCF 2000) for constituents with log K_ow >4.3 (equivalent to carbon chain length ~9).

As shown in Table 1, the logistic function QSAR model indicates that the majority of the GTL Gasoil constituents may reach the criteria for B. When the error in the QSAR is taken into account (average error in log BCF = 0.2), the logistic function QSAR model indicated that all GTL Gasoil constituents may reach the criteria for B. There are no vB constituents.

Further details are available in the attached QMRF report (PFA, 2014a) and QPRF report (PFA, 2014b), and in the Chemical Safety Report attached in Section 13.

Table 1 Predicted BCF values and assessment of bioaccumulation(B) for GTL Gasoil constituents

Carbon No	Linear/Branched	log Kow	log BCF (predicted – logistic QSAR)	BCF (predicted – logistic QSAR) (l/kg)	B/vB
8	Linear	4.3	3.3	2000	B
8	1-branched	4.2	3.2	1600	Not B
8	2-branched	4.1	3.2	1600	Not B
8	3-branched	4.1	3.2	1600	Not B
9	Linear	4.8	3.3	2000	B
9	1-branched	4.7	3.3	2000	B
9	2-branched	4.6	3.3	2000	B
9	3-branched	4.5	3.3	2000	B
10	Linear	5.3	3.3	2000	B
10	1-branched	5.2	3.3	2000	B
10	2-branched	5.1	3.3	2000	B
10	3-branched	5.0	3.3	2000	B
11	Linear	5.7	3.3	2000	B
11	1-branched	5.7	3.3	2000	B
11	2-branched	5.6	3.3	2000	B
11	3-branched	5.5	3.3	2000	B
12	Linear	6.2	3.3	2000	B
12	1-branched	6.2	3.3	2000	B
12	2-branched	6.1	3.3	2000	B
12	3-branched	6.0	3.3	2000	B
13	Linear	6.7	3.3	2000	B
13	1-branched	6.7	3.3	2000	B
13	2-branched	6.6	3.3	2000	B
13	3-branched	6.5	3.3	2000	B
14	Linear	7.2	3.3	2000	B
14	1-branched	7.1	3.3	2000	B
14	2-branched	7.1	3.3	2000	B
14	3-branched	7.0	3.3	2000	B
14	4-branched	6.9	3.3	2000	B
15	Linear	7.7	3.3	2000	B
15	1-branched	7.6	3.3	2000	B
15	2-branched	7.6	3.3	2000	B
15	3-branched	7.5	3.3	2000	B
15	4-branched	7.4	3.3	2000	B
16	Linear	8.0	3.3	2000	B
16	1-branched	8.0	3.3	2000	B
16	2-branched	8.0	3.3	2000	B
16	3-branched	8.0	3.3	2000	B
16	4-branched	7.9	3.3	2000	B
17	Linear	8.0	3.3	2000	B
17	1-branched	8.0	3.3	2000	B
17	2-branched	8.0	3.3	2000	B
17	3-branched	8.0	3.3	2000	B
17	4-branched	8.0	3.3	2000	B
18	Linear	8.0	3.3	2000	B
18	1-branched	8.0	3.3	2000	B
18	2-branched	8.0	3.3	2000	B
18	3-branched	8.0	3.3	2000	B
18	4-branched	8.0	3.3	2000	B
19	Linear	8.0	3.3	2000	B
19	1-branched	8.0	3.3	2000	B
19	2-branched	8.0	3.3	2000	B
19	3-branched	8.0	3.3	2000	B
19	4-branched	8.0	3.3	2000	B
20	Linear	8.0	3.3	2000	B
20	1-branched	8.0	3.3	2000	B
20	2-branched	8.0	3.3	2000	B
20	3-branched	8.0	3.3	2000	B
20	4-branched	8.0	3.3	2000	B
21	Linear	8.0	3.3	2000	B
21	1-branched	8.0	3.3	2000	B
21	2-branched	8.0	3.3	2000	B
21	3-branched	8.0	3.3	2000	B
21	4-branched	8.0	3.3	2000	B
22	Linear	8.0	3.3	2000	B
22	1-branched	8.0	3.3	2000	B
22	2-branched	8.0	3.3	2000	B
22	3-branched	8.0	3.3	2000	B
22	4-branched	8.0	3.3	2000	B
23	Linear	8.0	3.3	2000	B
23	1-branched	8.0	3.3	2000	B
23	2-branched	8.0	3.3	2000	B
23	3-branched	8.0	3.3	2000	B
23	4-branched	8.0	3.3	2000	B
24	Linear	8.0	3.3	2000	B
24	1-branched	8.0	3.3	2000	B
24	2-branched	8.0	3.3	2000	B
24	3-branched	8.0	3.3	2000	B
24	4-branched	8.0	3.3	2000	B
25	Linear	8.0	3.3	2000	B
25	1-branched	8.0	3.3	2000	B
25	2-branched	8.0	3.3	2000	B
25	3-branched	8.0	3.3	2000	B
25	4-branched	8.0	3.3	2000	B
26	Linear	8.0	3.3	2000	B
26	1-branched	8.0	3.3	2000	B
26	2-branched	8.0	3.3	2000	B
26	3-branched	8.0	3.3	2000	B
26	4-branched	8.0	3.3	2000	B

As described in the attached endpoint study record (See EPSR Williams, 2011), it is not feasible to undertake an OECD 305 study on whole substance.

In addition, based on OECD 307 (Aerobic and Anaerobic Transformation in Soil) studies (refer to Section 5.2.3), it is not possible to identify any constituents of GTL Gasoil as P or vP, and thus warranting further investigation for their bioaccumulation potential either in a fish bioconcentration or dietary study.

Furthermore, as discussed above, it can be demonstrated by QSAR that none of the constituents of GTL Gasoil meets the criteria for vB, and bioconcentration factors can be adequately predicted.

The available information is adequate for the purposes of both PBT/vPvB assessment and environmental exposure assessment.

In keeping with the requirement of REACH to minimise in vivo testing on vertebrates, it is therefore inappropriate to conduct a fish bioconcentration or dietary study on the grounds of animal welfare.

Some further information is available regarding bioaccumulation, from a solid phase micro extraction (SPME) study (See EPSR Harris, 2013). SPME is a biomimetic extraction system that tries to mimic the way organisms extract chemicals from water.

A biomimetic extraction technique using SPME in conjunction with gas chromatography (GC) was employed to assess the level of water soluble hydrocarbons and hence the potential toxicity of water accommodated fractions (WAFs) for a range of GTL products. In addition, the toxicity of WAFs was also monitored using an in-vitro Microtox^TMassay, a biosensor-based measurement system based on Vibro Fischeri bacteria. In this study the majority of GTL samples (including the registration substance GTL Gasoil, CAS 848301-67-7) analysed using SPME-GC indicated a low total peak area for soluble hydrocarbons (on average less than 12 000) and hence toxicity, with no detectable toxicity using the Microtox^TM assay. The low total peak area for soluble hydrocarbons for these substances is indicative of a low potential to bioaccumulate.

The related C8 -16 ("GTL Kerosine") and C4 -10 ("GTL Naphtha") samples, consisting of shorter chain hydrocarbons, produced a more soluble hydrocarbon fraction, and GTL Naphtha resulted in a moderate level of toxicity detected with the Microtox^TM assay. The level of toxicity seen with the GTL Naphtha is, however, considerably less than that seen with the crude oil gasoline.