Hydrocarbons, C18-C24, iso-alkanes <2% aromatics

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

no hazard identified

Marine water

Hazard assessment conclusion:

no hazard identified

STP

Hazard assessment conclusion:

no hazard identified

Sediment (freshwater)

Hazard assessment conclusion:

no hazard identified

Sediment (marine water)

Hazard assessment conclusion:

no hazard identified

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

no hazard identified

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential to cause toxic effects if accumulated (in higher organisms) via the food chain

Additional information

Measured acute (short-term) aquatic data are available for the effects of Shell GTL Solvent GS310 (Hydrocarbons, C18-C24, isoalkanes, <2% aromatics) on toxicity to fish, Daphnia and algae. The substance shows no effects at the highest concentrations tested, prepared as WAFs.

Long-term data for fish and Daphnia are read across from GTL-derived substances in the relevant carbon number range for the registered substance. These data also show no effects that would be relevant to the registration substance at the highest concentrations tested.

Measured terrestrial data with earthworms, honeybees and higher plants are also available for the registration substance.

For the purposes of the Chemical Safety Assessment, a model composition for the substance has been assessed using the PETRORISK model (Version 7.04), which is attached in Section 13 of the IUCLID dossier.

The chronic toxicity of alkanes to fish, invertebrates (Daphnia) and algae can be predicted using the ECOSAR suite of QSARs developed by Syracuse Research Corporation. The QSARs take the form of a generic equation:

log NOEC = m log Kow + n

where m and n are constants equal to the slope and the intercept on the y axis of the regression equation and Kow is octanol-water partition coefficient of the alkane.

The constants employed in the ECOSAR QSARs for predicting the chronic toxicity of non-polar narcotics (relevant to alkanes) are shown in Table 7.14.

Table 7.14 Constants used in prediction of chronic toxicity of non-polar narcotics by ECOSAR

 

Organism	m	n
Fish	-0.851	0.606
Invertebrate	-0.747	0.196
Algae	-0.555	0.0063

 

These QSAR equations can be used in conjunction with Kow values derived using the SRC KOWWIN prediction software to predict NOEC values for alkanes.

The principle of log Kow-based cut-off values for toxic effects has been embraced by the ICCA and OECD high Production Volume (HPV) chemical programmes (e.g. UNEP, 2000). The US EPA has also accepted them in its Pollution Prevention Framework (http://www.epa.gov/oppt/p2framework/docs/casestu.htm). The ECOSAR QSAR applies a log Kow cut-off value of 8.0 beyond which chronic toxicity of neutral organics would not be expected because of limitations in bioavailability and uptake of the substance (Clements, 1996). These cut-offs are empirically derived and based on experimental test data (Personal communication Vince Nabholz, US EPA).

The previously available data on long-term toxicity to aquatic organisms with petroleum hydrocarbons has benefitted from recent studies undertaken by CONCAWE, and summarised in its report An Evaluation of the Persistence, Bioaccumulation and Toxicity of Petroleum Hydrocarbons (Concawe, 2019). The studies have tested a range of hydrocarbons with aquatic invertebrates and algae. The invertebrate studies tested substances with a carbon number range from C12 to C14 (2,2,4,6,6-pentamethylheptane and 2,6-dimethyldecane with C12 and n-octylcyclohexane for C14) with a range of log Kow; from 5.52 to 7.03. The algal studies tested substances with a carbon number range from C12 to C16 with a range of log Kow; from 5.52 to 7.49. The available results are summarised in Tables 7.15 and 7.16 Only structures that are relevant to GTL products have been retained in these tables; data for aromatic and polycyclic substances are also available.

 

Table 7.15 Chronic Daphnia toxicity data for aliphatic hydrocarbons

Carbon number	Test substance	Slow-Stir Water Solubility (µg/l)	Mean Measured Exposure (µg/l)	Chronic Daphnia toxicity observed?	KOWWIN	Ecosar predicted chronic value Daphnia (µg/l)	Reference for measured data
12	2,2,4,6,6-pentamethylheptane	23	13	Yes	5.94	10	SafePharm, 2004b
12	2,6-dimethyldecane	11	10	No	6.09	8	EMBSI, 2007d
13	2,6-dimethylundecane	2.7	2	No	6.58	4	EMBSI, 2006f
13	2,6-dimethylundecane	2.7	3	No	6.58	4	EMBSI, 2007d
14	n-octylcyclohexane	1.4	3	No	7.03	2	EMBSI, 2006f

Table 7.16 Chronic algal toxicity for aliphatic hydrocarbons

Carbon number	Test substance	Slow-Stir Water Solubility (µg/l)	Mean Measured Exposure (µg/l)	Chronic Algal toxicity observed?	KOWWIN	Ecosar predicted chronic value algae (µg/l)	Reference
12	2,2,4,6,6-pentamethylheptane	23	6	No	5.94	90	SafePharm, 2004a
12	2,2,4,6,6-pentamethylheptane	23	146	Yes	5.94	90	Tolls and van Dijk, 2002
12	2,6-dimethyldecane	11	19	Yes	6.09	70	EMBSI, 2009c
13	n-heptylcylohexane	6.2	64	Yes	6.54	44	EMBSI, 2006e
13	2,6- dimethylundecane	2.7	16	No	6.58	40	EMBSI, 2006d
14	n-octylcyclohexane	1.4	9	No	7.03	25	EMBSI, 2006d
13	2,6,10-trimethyldodecane	0.3	23	No	7.49	15	EMBSI, 2006c

The new data indicate that in tests conducted at the maximum achievable concentration in test medium, no chronic effects are observed in Daphnia magna for substances with log Kow at or above 6.09 (KOWWIN predicted value), while for algae, chronic effects were not observed at or above log Kow = 6.58.

Table 7.17 shows predicted ECOSAR (v1.00) chronic values for some representative hydrocarbons in the relevant log Kow range. These indicate that fish is the most sensitive species, although by only a small margin. No new measured fish data are available, so it is not possible to determine the cut-off value for chronic fish toxicity. A reasonable approach is to therefore assume that the overall long-term ecotoxicity cut-off is equivalent to the value determined for algae, log Kow = 6.58.

Table 7.17 ECOSAR v1.00 predicted NOEC values for representative linear aliphatic hydrocarbons

Carbon number	Substance	Molecular weight	log Kow(KOWWIN)	NOEC fish (µg/l)	NOEC Daphnia (µg/l)	NOEC algae (µg/l)
8	n-octane	114.224	4.27	1.07E+02	1.16E+02	4.96E+02
9	n-nonane	128.25	4.76	4.62E+01	5.61E+01	2.98E+02
10	n-decane	142.276	5.25	1.96E+01	2.68E+01	1.77E+02
11	n-undecane	156.302	5.74	8.25E+00	1.27E+01	1.04E+02
12	n-dodecane	170.328	6.23	3.44E+00	5.95E+00	6.05E+01
13	n-tridecane	184.354	6.73	1.40E+00	2.72E+00	3.46E+01
14	n-tetradecane	198.38	7.22	5.77E-01	1.26E+00	1.99E+01

 

Table 7.18 shows the calculated log Kow values for relevant constituents of the GTL products, and Table 7.19 summarises the toxicity assessment in relation to the PBT criteria in Annex XIII of the REACH Regulation.

It can be seen that constituents up to C13 have predicted log Kow below the cut-off for chronic toxicity, but all constituents at C14 and above, and therefore all constituents of Hydrocarbons, C18-C24, isoalkanes <2% aromatics, are predicted to be non-toxic to aquatic organisms. Using the ECOSAR equation for neutral organics, some constituents in the range C11-C13 meet the criteria for “T”. The explanation for lack of effects at high C number is a combination of decreasing water solubility (poor bioavailability) and low rate of uptake.

Table 7.18 KOWWIN calculated log K_owvalues for constituents in the range C6 to C26

	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26
No. of branches
0	3.29	3.78	4.27	4.76	5.25	5.74	6.23	6.73	7.22	7.71	8.2	8.69	>8	>8	>8	>8	>8	>8	>8	>8	>8
1	3.22	3.71	4.2	4.69	5.18	5.67	6.16	6.65	7.14	7.63	8.13	8.62	>8	>8	>8	>8	>8	>8	>8	>8	>8
2	3.14	3.63	4.12	4.61	5.11	5.6	6.09	6.58	7.07	7.56	8.05	8.54	>8	>8	>8	>8	>8	>8	>8	>8	>8
3			4.05	4.54	5.03	5.52	6.01	6.51	7.00	7.49	7.98	8.47	>8	>8	>8	>8	>8	>8	>8	>8	>8
4									6.92	7.41	7.91	8.4	>8	>8	>8	>8	>8	>8	>8	>8	>8
Nominal cyclopentane structure (linear)			4.08	4.58	5.07	5.56	6.05	6.54	7.03	7.52	>8	>8	>8	>8	>8	>8	>8	>8	>8	>8	>8
Nominal cyclopentane structure (branched)			4.01	4.5	4.99	5.48	5.98	6.47	6.96	7.45	7.94	>8	>8	>8	>8	>8	>8	>8	>8	>8	>8
Nominal cyclohexane structure (linear)			4.08	4.58	5.07	5.56	6.05	6.54	7.03	7.52	>8.0	>8	>8	>8	>8	>8	>8	>8	>8	>8	>8
Nominal cyclohexane structure (branched)				4.5	4.99	5.48	5.98	6.47	6.96	7.45	7.94	>8	>8	>8	>8	>8	>8	>8	>8	>8	>8

 

Below chronic toxicity cutoff

Table 7.19 Predicted NOEC values (µg/l) and T assessment*

Some measured data e.g. for C13 may not agree with the prediction but for consistency predicted data are presented unamended.

	6	7	8	9	10	11	12	13	14	15	≥16
No. of branches
0	5.53E+02	2.46E+02	1.07E+02	4.62E+01	1.96E+01	8.25E+00	3.44E+00	1.40E+00	>WS	>WS	>WS
1	6.34E+02	2.82E+02	1.23E+02	5.30E+01	2.25E+01	9.47E+00	3.95E+00	1.64E+00	>WS	>WS	>WS
2	7.42E+02	3.30E+02	1.44E+02	6.20E+01	2.58E+01	1.09E+01	4.53E+00	1.88E+00	>WS	>WS	>WS
3			1.65E+02	7.11E+01	3.02E+01	1.27E+01	5.30E+00	2.15E+00	>WS	>WS	>WS
4									>WS	>WS	>WS
Nominal cyclopentane structure (linear)			1.53E+02	6.47E+01	2.75E+01	1.16E+01	4.84E+00	2.01E+00	>WS	>WS	>WS
Nominal cyclopentane structure (branched)			1.76E+02	7.57E+01	3.22E+01	1.36E+01	5.55E+00	2.30E+00	>WS	>WS	>WS
Nominal cyclohexane structure (linear)			1.53E+02	6.47E+01	2.75E+01	1.16E+01	4.84E+00	2.01E+00	>WS	>WS	>WS
Nominal cyclohexane structure (branched)				7.57E+01	3.22E+01	1.36E+01	5.55E+00	2.30E+00	>WS	>WS	>WS

*T if NOEC ≤0.01 mg/l (1.00E+01 µg/l)

>WS indicates predicted NOEC value exceeds water solubility of consituent

Candidate T

Reference

Concawe, 2019. An Evaluation of the Persistence, Bioaccumulation and Toxicity of Petroleum Hydrocarbons (Revision 2).

Conclusion on classification

Hydrocarbons, C18-C24, isoalkanes, <2% aromatics should not be classified in the EU for acute or chronic toxicity according to Regulation (EC) No. 1272/2008 (as amended) on the basis of measured short-term and read-across long-term ecotoxicity data as reported in Section 6.1.