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

Endpoint summary

Description of key information

Based on weight of evidence from studies on substances in the relevant carbon number range, the acute oral LD₅₀ in male and female rats is considered to be >5000 mg/kg bw.

Based on an acute inhalation toxicity study performed with Hydrocarbons, C18-C24, iso-alkanes, <2% aromatics (GS310), the acute (4-hour aerosol LC₅₀ in male and female rats is considered to be >1 – 5 mg/l. However, the observed mortalities were concluded to be due to aspiration of the test material rather than indicating systemic toxicity. 

Based on weight of evidence from studies on substances in the relevant carbon number range, the acute dermal LD₅₀ in male and female rats is considered to be >2000 mg/kg bw. 

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Reference 1

Endpoint:

acute toxicity: oral

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

1. Hypothesis for the analogue approach:
The hypothesis for the analogue approach is that the test substance GTL Base Oil Distillates (C18-C50 branched, cyclic and linear hydrocarbons – Distillates / 848301-69-9 / 482-220-0) is produced in the same Fischer-Tropsch process as GTL Gasoil which is the starting material from which the registration substance, Hydrocarbons, C18-C24, iso-alkanes, <2% aromatics (GS310), is produced by fractional distillation. The source substances contain constituents of the target substance, Hydrocarbons, C18-C24, iso-alkanes, <2% aromatics, although they cover a wider carbon number distribution. The substances therefore have qualitatively similar properties (RAAF Scenario 2 applies). See Endpoint Summary (CSR Section 5.6.3 for additional information).
2. Source and target chemical(s)
The source substance GTL Base Oil Distillates (Distillates (Fischer-Tropsch), heavy, C18-50 - branched, cyclic and linear) is composed of linear, branched and cyclic hydrocarbons of chain length C18-C50.
The source substance GTL Gasoil (C8-C26) (C8-C26 branched and linear hydrocarbons – Distillates) is the substance from which the registration substance is produced. GTL Gasoil is composed of linear, branched and cyclic hydrocarbons of chain length C8-C26
The target substance, Hydrocarbons, C18-C24, iso-alkanes, <2% aromatics, is composed of linear, branched and cyclic hydrocarbons of chain length C18-24.
3. Analogue approach justification
The constituents of the source and target substances are all hydrocarbons. Identical constituents have identical toxicity profiles. There is no evidence of toxicity in the studies on the source substance, and no evidence of toxicity in studies on hydrocarbons with shorter carbon chain length and a narrower range of carbon number, therefore there is no evidence for mixture effects or for increased toxicity with increased concentration.
It is estimated that relatively more of the source substance GTL Gasoil is absorbed orally than would be the case for the target substance, Hydrocarbons, C18-C24, isoalkanes, <2% aromatics (GS310) (48 and 34% respectively), based on the relative absorption of constituents of different carbon chain length. It is concluded that read across of data for GTL Gasoil is conservative. See the document attached to the target study record for more detailed discussion of read across of toxicity data between the two substances.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 5 000 mg/kg bw

Reference 2

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2006-10-03 to 2006-10-24

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

GLP-study according to relevant guideline. Read-across considered to be reliability 2.

Qualifier:

according to guideline

Guideline:

OECD Guideline 420 (Acute Oral Toxicity - Fixed Dose Method)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.1 bis (Acute Oral Toxicity - Fixed Dose Procedure)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test type:

fixed dose procedure

Limit test:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: At the start of the study the animals were eight to twelve weeks of age.
- Weight at study initiation: The bodyweights fell within an interval of i 20% of the initial bodyweight of the first treated animal.
- Fasting period before study: With the exception of an overnight fast immediately before dosing and for approximately three to four hours after
dosing, free access to mains drinking water and food (Certified Rat and Mouse Diet (Code SLF2) was allowed throughout the study.
- Housing: On receipt the animals were randomly allocated to cages.
- Diet (e.g. ad libitum): Overnight fast immediately before dosing and for approximately three to four hours after dosing (free access to mains
drinking water and food was allowed throughout the study).
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: At least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): The temperature was set to achieve limits of 19 to 25°C.
- Humidity (%): The relative humidity was set to achieve limits of 30 to 70%.
- Air changes (per hr): The rate of air exchange was at least fifteen changes per hour.
- Photoperiod (hrs dark / hrs light): Lighting was controlled by a time switch to give twelve hours continuous light (06:00 to 18:00) and twelve hours darkness.

Route of administration:

oral: gavage

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

VEHICLE
- Concentration in vehicle: Not applicable
- Amount of vehicle (if gavage): Not applicable
- Justification for choice of vehicle: Not applicable
- Purity: Not applicable

MAXIMUM DOSE VOLUME APPLIED:
5000 mg/kg

DOSAGE PREPARATION (if unusual):
Not applicable

CLASS METHOD (if applicable)
- Rationale for the selection of the starting dose: Not applicable

Doses:

5000 mg/kg bw

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Day 0, 7 and 14
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight,organ weights, histopathology: yes

Statistics:

No statistical procedures were applied.

Preliminary study:

Following a preliminary test in which there were no deaths at a dose level of 5000 mg/kg, an additional 4 fasted Sprague-Dawley DC rats received a dose of 5000 mg of the undiluted test material per kg body weight by gavage.

Sex:

female

Dose descriptor:

LD50

Effect level:

> 5 000 mg/kg bw

Mortality:

- Mortality: no deaths

Clinical signs:

other: - Clinical observations: no signs of systemic toxicity

Gross pathology:

- Necropsy: no abnormalities

Other findings:

None

Table 1: Individual Clinical Observations and Mortality Data

Dose level	Animal	Effects noted after dosing (hours)				Effects noted during period after dosing (days)
(mg/kg)	No.	0,5	1	2	4	1	2	3	4	5	6	7	8	9	10	11	12	13	14
5000	Female 1 -0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
5000	Female 2 -0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
5000	Female 2 -1	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
5000	Female 2 -2	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
5000	Female 2 -3	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0

0- No signs of systemic toxicity

Table 2: Individual Body weights and Bodyweight changes

Dose level	Animal	Bodyweight at day (g)			Body weight gain during week (g)
(mg/kg)	No.	Day 0	Day 7	Day 14	Day 1	Day 7
5000	Female 1 -0	213	247	268	34	21
5000	Female 2 -0	190	213	216	23	3
5000	Female 2 -1	216	251	273	35	22
5000	Female 2 -2	198	236	249	36	15
5000	Female 2 -3	206	229	238	23	9

Interpretation of results:

GHS criteria not met

Remarks:

Criteria used for interpretation of results: EU

Conclusions:

The acute oral median lethal dose (LD50) of the test material in the female Sprague-Dawley CD strain rat was estimated to be greater than 5000 mg/kg bodyweight. Using the EU Globally Harmonised System (GHS), it would be ‘unclassified’. However, since the substance is composed of aliphatic
hydrocarbons and has low viscosity, it may present an aspiration hazard in humans following oral exposure. It is therefore appropriate to classify
the substance as ‘Harmful: may cause lung damage if swallowed’.

Executive summary:

'Distillates (Fischer-Tropsch), C8-26 branched and linear' was tested in an acute oral toxicity study according to the fixed dose method (OECD 420). Following a preliminary test in which there were no deaths at a dose level of 5000 mg/kg, an additional 4 fasted Sprague-Dawley DC rats received a dose of 5000 mg of the undiluted test material per kg body weight by gavage. There were no signs of toxicity, all animals showed normal gains in body weight, and there were no abnormalities on necropsy. The acute oral median lethal dose (LD₅₀) of the test material in the female Sprague-Dawley CD strain rat was estimated to be greater than 5000 mg/kg bodyweight.

Reference 3

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

The study was performed between 23 October 2006 and 13 November 2006.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Study conducted to GLP and in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not effect the quality of the relevant results. Read-across is considered to be reliability 2.

Qualifier:

according to guideline

Guideline:

OECD Guideline 420 (Acute Oral Toxicity - Fixed Dose Method)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.1 bis (Acute Oral Toxicity - Fixed Dose Procedure)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of inspection: 30/8/2005. Date of signature: 21/11/2005

Test type:

fixed dose procedure

Limit test:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: Eight to twelve weeks of age.
- Weight at study initiation: 205-225 g at Day 0.
- Fasting period before study: Overnight fast immediately before dosing and for approximately three to four hours after dosing.
- Housing: The animals were housed in groups of up to four in suspended solid-floor polypropylene cages furnished with woodflakes.
- Diet (e.g. ad libitum): Free access to food (certified rate and mouse diet) was allowed throughout the study.
- Water (e.g. ad libitum): Free access to mains drinking water was allowed throughout the study.
- Acclimation period: At least five days.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): The temperature was set to achieve limits of 19 to 25°C.
- Humidity (%): The relative humidity was set to achieve limits of 30 to 70%.
- Air changes (per hr): At least fifteen changes per hour.
- Photoperiod (hrs dark / hrs light): Lighting was controlled by a time switch to give twelve hours continuous light and twelve hours darkness.

Route of administration:

oral: gavage

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

MAXIMUM DOSE VOLUME APPLIED: 6.20 ml/kg

DOSAGE PREPARATION (if unusual):
For the purpose of the study the test material was used as supplied. The specific gravity was determined and used to calculate the appropriate dose volume for the required dose level.

Doses:

5000 mg/kg

No. of animals per sex per dose:

A total of 5 female animals at a dose level of 5000 mg/kg.

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days.
- Frequency of observations and weighing:
Clinical observations were made 1/2, 1, 2 and 4 hours after dosing and subsequently once daily for fourteen days. Morbidity and mortality checks were made twice daily.
Individual bodyweights were recorded on day (day of dosing) and on days 7 and 14.
- Necropsy of survivors performed: All animals were subjected to gross necropsy. This consisted of an external examination and opening of the abdominal and thoracic cavities. The appearance of any macroscopic abnormalities was recorded.

Preliminary study:

There was no death and no signs of systemic toxicity at 5000 mg/kg.
In the absence of toxicity at 5000 mg/kg, an additional group of 4 animals was treated at a dose level of 5000 mg/kg.

Sex:

female

Dose descriptor:

LD50

Effect level:

> 5 000 mg/kg bw

Based on:

test mat.

Mortality:

There were no deaths.

Clinical signs:

other: No signs of systemic toxicity were noted.

Gross pathology:

No abnormalities were noted at necropsy.

Interpretation of results:

GHS criteria not met

Remarks:

Criteria used for interpretation of results: EU

Conclusions:

The acute oral median lethal dose (LD50) of the test material in the female Sprague-Dawley CD strain rat was estimated to be greater than 5000 mg/kg bodyweight.

Executive summary:

Introduction.

The study was performed to assess the acute oral toxicity of the test material 'Distillates (Fischer-Tropsch), heavy C18-50 - branched, cyclic and linear' in the Sprague-Dawley CD strain rat. The method was designed to meet the requirements of the following:

• OECD Guidelines for Testing of Chemicals No 420 "Acute Oral Toxicity - Fixed Dose Method" (adopted 17 December 2001)

• Method B1 bis Acute Toxicity (Oral) of Commission Directive 2004/73/EC Method.

Method.

Following a preliminary test in which there was no death at a dose level of 5000 mg/kg, an additional four fasted female animals were given a single oral dose of undiluted test material at a dose level of 5000 mg/kg bodyweight. Clinical signs and bodyweight development were monitored during the study. All animals were subjected to gross necropsy.

Mortality.

There were no deaths.

Clinical Observations.

There were no signs of systemic toxicity.

Bodyweight.

All animals showed expected gains in bodyweight.

Necropsy.

No abnormalities were noted at necropsy.

Conclusion.

The acute oral median lethal dose (LD50) of the test material in the female Sprague-Dawley CD strain rat was estimated to be greater than 5000 mg/kg bodyweight (Globally Harmonised Classification System - Unclassified).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

5 000 mg/kg bw

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Experimental Starting Date: 10 March 2014; Experimental Completion Date: 04 August 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study has been performed according to OECD and/or EC guidelines and in compliance with GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 436 (Acute Inhalation Toxicity: Acute Toxic Class Method)

Deviations:

yes

Remarks:

The first exposure was repeated due to a high achieved concentration. Animals from Group 3 were acclimatized to the restraint tubes on the day of exposure. These deviations are considered not to affect the purpose or validity of the study.

GLP compliance:

yes (incl. QA statement)

Test type:

acute toxic class method

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

Male and female RccHan™ : WIST strain rats were supplied by Harlan Laboratories UK Ltd. On receipt the animals were randomly allocated to cages. After an acclimatization period of at least five days the animals were given a number unique within the study by ear punching and a number written on a color coded cage card. At the start of the study the animals were approximately eight to twelve weeks old and within the weight range of 200g to 350g. The females were nulliparous and non-pregnant.

The animals were housed in groups of up to three by sex in solid-floor polypropylene cages with stainless steel lids, furnished with softwood flakes and provided with environmental enrichment items: wooden chew blocks and cardboard “fun tunnels”. With the exception of the exposure period, free access to mains drinking water and food (Harlan 2014C Rodent Diet) was allowed throughout the study. The diet, drinking water, bedding and chew blocks are routinely analyzed and are considered not to contain any contaminants that could reasonably be expected to affect the purpose or integrity of the study.

The temperature and relative humidity were set to achieve limits of 19 to 25°C and 30 to 70% respectively. The rate of air exchange was at least fifteen changes per hour and the lighting was controlled by a time switch to give twelve hours continuous light (06:00 to 18:00) and twelve hours darkness. The animals were retained in this accommodation at all times except during the exposure period.

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

air

Details on inhalation exposure:

ATOMOSPHERE GENERATION:
The test item was aerosolized using a glass concentric jet nebulizer located at the top of the exposure chamber. The nebulizer was connected to a plastic syringe attached to an infusion pump, which provided a continuous supply of test item under pressure, and to a metered compressed air supply.

Compressed air was supplied by means of an oil free compressor and passed through a water trap and respiratory quality filters before it was introduced to the nebulizer.

The cylindrical exposure chamber had a volume of approximately 30 liters (dimensions: 28 cm diameter x 50 cm high). The concentration within the exposure chamber was controlled by adjusting the rate of the infusion pump. The extract from the exposure chamber passed through a ‘scrubber’ trap and was connected with a high efficiency filter to a metered exhaust system. The chamber was maintained under negative pressure.

Homogeneity of the test atmosphere within the chamber was not specifically determined during this study. Chambers of the same design have been fully validated and shown to produce evenly distributed atmospheres in the animals’ breathing zone with a wide variety of test items.

Prior to the start of the study, test item atmospheres were generated within the exposure chamber. During this characterization period test item input rates were varied to achieve the required atmospheric conditions.

EXPOSURE PROCEDURE:
On the day of exposure (Group 3) and prior to the day of exposure (Group 2) each rat was acclimatized (for approximately 2 hours) to a tapered polycarbonate restraining tube. During the exposure period, each rat was individually held in a tapered, polycarbonate restraining tube fitted onto a single tier of the exposure chamber and sealed by means of a rubber ‘O’ ring. Only the nose of each animal was exposed to the test atmosphere.

Following an appropriate equilibration period two groups, each of six rats (three males and three females), were subjected to a single exposure to the test item for a period of four hours*. Based on the expected toxicity of the test item, a target concentration of 5.0 mg/L was used for the first exposure. The second concentration was selected after consideration of the results of the first exposure.

*Previously to this another group of animals (Group 1) had been exposed to an atmosphere of the test item. However, this exposure was not suitable for the purposes of the study due to the achieved atmosphere concentration being significantly higher than the target concentration of 5mg/L.

EXPOSURE CHAMBER TEMPERATURE AND RELATIVE HUMIDITY:
The temperature and relative humidity inside the exposure chamber were measured by an electronic thermometer/humidity meter located in a vacant port in the animals’ breathing zone of the chamber and recorded every thirty minutes throughout the four-hour exposure period.

EXPOSURE CHAMBER OXYGEN CONCENTRATION:
Oxygen levels within the exposure chamber were measured by an electronic oxygen analyzer (Servomex (UK) Ltd, Crowborough, East Sussex) located in a port in the animals breathing zone during the four-hour exposure period. The test atmosphere was generated to contain at least 19% oxygen.

EXPOSURE CHAMBER ATMOSPHERE CONCENTRATION:
During the characterization phase of the study the test atmosphere was sampled twice and filter samples were then submitted for chemical analysis to determine if the original test item was similar to the composition of the airborne test item. The standard and sample solutions were analyzed by GC.

Prior to the inhalation phase of the study, the non-volatile component of the test item was determined by adding a small, known amount of test item to glass fibre filters and recording their weights. The filters were then dried in a desiccator between 20 and 21°C for approximately 24 hours and then weighed again. The difference in the two weights was taken as the volatile content of the test item and the non-volatile component was calculated as a percentage. The mean non-volatile component of the batch used during the formal exposure was found to be 99.42 % (n=10).

The test atmosphere was sampled at regular intervals during the exposure period. A weighed glass fibre filter was placed in a filter holder and temporarily sealed in a vacant port of the exposure chamber in the animals’ breathing zone. A known quantity of the exposure chamber atmosphere was drawn through the filter using a vacuum pump.

After sampling, the filter was dried, under similar conditions as those previously described, and weighed again 24 hours later. The difference in the pre and post sampling weights, divided by the volume of atmosphere sampled, was the chamber concentration in terms of non-volatile component.

Based on the results of the preliminary work, these figures were adjusted to obtain a true figure for the test item concentration in the chamber.

The nominal chamber concentration was calculated by dividing the mass of test item used by the total volume of air passed through the chamber.

The nominal concentration for each group was found to be 250 % or 227 % (Groups 2 and 3 respectively) of the actual mean achieved atmosphere concentration and shows that keeping the aerosol airborne was relatively straightforward at each target concentration.

PARTICLE SIZE DISTRIBUTION:
The particle size of the generated atmosphere inside the exposure chamber was determined three times during the exposure period using a Marple Personal Cascade Impactor. The device consisted of six impactor stages (8.9, 6.2, 3.6, 1.6, 0.93 and 0.37 µm cut points) with stainless steel collection substrates and a back up glass fiber filter, housed in an aluminum sampler. The sampler was temporarily sealed in a sampling port in the animals’ breathing zone and a suitable, known volume of exposure chamber air was drawn through it using a vacuum pump.

The collection substrates and backup filter were weighed before and after sampling and the weight of test item, collected at each stage, calculated by difference.

The mean amount for each stage was used to determine the cumulative amount below each cut-off point size. In this way, the proportion (%) of aerosol less than 8.9, 6.2, 3.6, 1.6, 0.93 and 0.37 µm cut points was calculated.

The resulting values were converted to probits and plotted against Log10 cut-point size. From this plot, the Mass Median Aerodynamic Diameter (MMAD) was determined (as the 50% point) and the geometric standard deviation was calculated. In addition the proportion (%) of aerosol less than 4 µm (considered to be the inhalable fraction) was determined.

Analytical verification of test atmosphere concentrations:

yes

Remarks:

It was considered appropriate to utilize gravimetric analysis to determine test atmosphere concentrations during the formal exposure (see exposure chamber atmosphere concentration)

Duration of exposure:

4 h

Concentrations:

Group 2:
Mean Achieved Atmosphere Concentration (mg/L): 4.98

Group 3:
Mean Achieved Atmosphere Concentration (mg/L): 1.14

No. of animals per sex per dose:

3 males and females per dose group.

Control animals:

no

Details on study design:

Observations:
Clinical signs: All animals were observed for clinical signs at hourly intervals during exposure, immediately on removal from the restraining tubes at the end of exposure, one hour after termination of exposure and subsequently once daily for up to fourteen days. Any evidence of overt toxicity was recorded at each observation.

Body Weight: Individual body weights were recorded on arrival, prior to treatment on the day of exposure and on Days 1, 3, 7 and 14.

Necropsy: At the end of the fourteen day observation period the animals were killed by intravenous overdose of sodium pentobarbitone. All animals were subjected to a full external and internal examination, and any macroscopic abnormalities were recorded. The respiratory tract was subjected to a detailed macroscopic examination for signs of irritancy or local toxicity.

Statistics:

Data evaluations included the relationship, if any, between the animals’ exposure to the test item and the incidence and severity of all abnormalities including behavioral and clinical observations, necropsy findings, body weight changes, mortality and any other toxicological effects.

Using the mortality data obtained, an estimate of the acute inhalation median lethal concentration (LC50) of the test item was made.

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 1 - 5 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Mortality:

The mortality data is summarised as follows:
Group 2:
Mean Acheived Atmosphere Concentration (mg/L): 4.98
Deaths:
Male: 2/3 (deaths on Days 1 and 2 of observation)
Female: 1/3 (death on Day 1 of observation)
Total: 3/6

Group 3:
Mean Acheived Atmosphere Concentration (mg/L): 1.14
Deaths:
Male: 0/3
Female: 1/3 (death on Day 2 of observation)
Total: 1/6

Clinical signs:

other: Signs of hunched posture and pilo-erection are commonly seen in animals for short periods on removal from the chamber following 4-hour inhalation studies. Wet fur is commonly recorded both during and for a short period after exposure. These observations a

Body weight:

Group 2 – All animals exhibited body weight losses on Day 1 post-exposure. All surviving animals exhibited body weight loses or showed no body weight gain from Days 1 to 3 post-exposure, body weight gains were noted in all surviving animals during the remainder of the recovery period.

Group 3 – All males and two female animals exhibited body weight losses on Day 1 post-exposure. Body weight gains were noted in all surviving animals during the remainder of the recovery period.

Gross pathology:

Necrospy:
Dark patches on the lungs were noted at necropsy amongst all three surviving animals from Group 2 and in one out of five surviving animals from Group 3, a further surviving female from Group 3 exhibited a dark liver at the end of the fourteen day recovery period.

The following macroscopic abnormalities were detected in the animals that died during the course of the study at necropsy:

Lungs – abnormally dark or dark patches;
Liver – dark;
Large Intestine – gaseous distension.

Due to the observations noted it is considered that the deaths noted during the study may have been mainly attributable to local toxicity.

Dark patches in the lungs and abnormally dark lungs in a proportion of animals in both treatment groups were associated with congestion at histopathological examination, and were considered to be treatment-related.

Other findings:

Histopathology:
The following treatment-related findings were present in animals surviving to terminal sacrifice:

Lungs:
- minimal to slight congestion
- minimal to slight hemorrhage
- moderate edema
- minimal to slight alveolar macrophages
- slight acute alveolar inflammation
- minimal to slight acute perivascular inflammation

Trachea:
- minimal intraepithelial inflammation

The following treatment-related findings were present in the lungs of premature decedent animals:
- slight to moderate congestion
- slight hemorrhage
- minimal to moderate edema
- minimal to slight alveolar macrophages
- minimal to slight acute alveolar inflammation
- minimal to moderate acute perivascular inflammation

There were no findings in the trachea.

Exposure Chamber Concentration:

Test atmospheres were sampled seventeen times during each exposure period and the actual concentration of the test item calculated. 

The mean values obtained for each group were:

Group Number	Atmosphere Concentration
	Mean Achieved (mg/L)	Standard Deviation	Nominal (mg/L)
2	4.98	0.17	12.4
3	1.14	0.12	2.59

The chamber flow rate was maintained at 60 L/min providing 120 air changes per hour.

 

The theoretical chamber equilibration time (T₉₉) was 3 minutes*(Silver, 1946).

*= The test atmosphere was generated for 20 minutes and 11 minutes prior to animal insertion (for Groups 2 and 3 respectively) to ensure test item concentration was being achieved.

It is noted that one sample from Group 3 was lower than 20% of the mean achieved atmosphere concentration. As the majority of samples taken during the exposure were above the target concentration of 1mg/L this deviation to the test guideline was considered not to have affected the purpose or validity of the study.

Particle Size Distribution:

The particle size analysis of the atmosphere drawn from the animals’ breathing zone, was as follows:

Group Number	Mean Achieved Atmosphere Concentration (mg/L)	Mean Mass Median Aerodynamic Diameter (µm)	Inhalable Fraction (% <4 µm)	Geometric Standard Deviation
2	4.98	3.17	60.9	2.34
3	1.14	2.45	78.1	1.88

Exposure Chamber Temperature:

Temperature maintained at 19 - 20 °C for Groups 2 and 3.

Exposure Chamber Relative Humidity:

25 - 26% Group 2 and 26 - 27% Group 3.

The relative humidity within the exposure chamber during each exposure was found to be slightly lower than the range specified in the inhalation test guidelines (30 – 70 %). The humidity probe was removed from the test chamber and was found to be working correctly. The reduced humidity may well have been due to the nature of the test item, the reduced humidity was therefore considered to be an accurate representation within the exposure chamber and is considered not to have affected the purpose or validity of this study

Exposure Chamber Oygen Concentration:

20.8 - 20.9 %.

Interpretation of results:

GHS criteria not met

Remarks:

Criteria used for interpretation of results: EU

Conclusions:

Three deaths occurred in a group of six rats exposed to a mean achieved atmosphere concentration of 4.98 mg/L, whereas, one death occurred at a mean achieved atmosphere concentration of 1.14 mg/L. It was therefore considered that the acute inhalation median lethal concentration (4 hr LC50) of Shell GTL Solvent GS310, in the RccHanTM : WIST strain rat, was in the range of >1 - 5 mg/L.

The microscopic findings observed in the lungs (alveolar and perivascular inflammation, edema, congestion and hemorrhage) were all consistent with hydrocarbon aspiration induced inflammation (i.e. a chemical pneumonitis). The substance is therefore classified as Aspiration Toxicity Category 1.

Executive summary:

Introduction:

A study was performed to assess the acute inhalation toxicity of the test item. The method used was compatible with that described in the OECD Guidelines for Testing of Chemicals (2009) No. 436 “Acute Inhalation Toxicity – Acute Toxic Class Method”.

Methods:

Two groups of six RccHan™ : WIST strain rats (three males and three females) were exposed to an aerosol atmosphere. The animals were exposed for four hours using a nose only exposure system, followed by a fourteen day observation period.

Results:

The mean achieved atmosphere concentration was as follows:

 

Group Number	Atmosphere Concentration
	Mean Achieved (mg/L)	Standard Deviation	Nominal (mg/L)
2	4.98	0.17	12.4
3	1.14	0.12	2.59

The characteristics of the achieved atmosphere were as follows:

 

Group Number	Mean Achieved Atmosphere Concentration (mg/L)	Mean Mass Median Aerodynamic Diameter (µm)	Inhalable Fraction (% <4 µm)	Geometric Standard Deviation
2	4.98	3.17	60.9	2.34
3	1.14	2.45	78.1	1.88

The mortality data were summarized as follows:

 

Group Number	Mean Achieved Atmosphere Concentration (mg/L)	Deaths
		Male	Female	Total
2	4.98	2/3	1/3	3/6
3	1.14	0/3	1/3	1/6

Clinical Observations:

Common abnormalities noted during the study included increased respiratory rate, hunched posture, pilo-erection and wet fur, occasional instances of tip-toe gait were also noted. Surviving Group 2 animals recovered to appear normal on Day 8 post-exposure. Surviving Group 3 animals recovered to appear normal from Days 6 to 7 post-exposure. 

Body Weight:

Group 2 – All animals exhibited body weight losses on Day 1 post-exposure. All surviving animals exhibited body weight loses or showed no body weight gain from Days 1 to 3 post-exposure, body weight gains were noted in all surviving animals during the remainder of the recovery period.

 

Group 3 – All males and two female animals exhibited body weight losses on Day 1 post-exposure. Body weight gains were noted in all surviving animals during the remainder of the recovery period.

Necropsy:

Dark patches on the lungs were noted at necropsy amongst all three surviving animals from Group 2 and in one out of five surviving animals from Group 3, a further surviving female from Group 3 exhibited a dark liver at the end of the fourteen day recovery period.

 

The following macroscopic abnormalities were detected in the animals that died during the course of the study at necropsy:

 

Lungs – abnormally dark or dark patches;

Liver – dark;

Large Intestine – gaseous distension.

 

Due to the observations noted it is considered that the deaths noted during the study may have been mainly attributable to local toxicity.

 

Dark patches in the lungs and abnormally dark lungs in a proportion of animals in both treatment groups were associated with congestion at histopathological examination, and were considered to be treatment-related.

Histopathology:

The following treatment-related findings were present in animals surviving to terminal sacrifice:

 

Lungs:

-          minimal to slight congestion

-          minimal to slight hemorrhage

-          moderate edema

-          minimal to slight alveolar macrophages

-          slight acute alveolar inflammation

-          minimal to slight acute perivascular inflammation

Trachea:

-          minimal intraepithelial inflammation

The following treatment-related findings were present in the lungs of premature decedent animals:

-          slight to moderate congestion

-          slight hemorrhage

-          minimal to moderate edema

-          minimal to slight alveolar macrophages

-          minimal to slight acute alveolar inflammation

-          minimal to moderate acute perivascular inflammation

 

There were no findings in the trachea.

Conclusion:

Three deaths occurred in a group of six rats exposed to a mean achieved atmosphere concentration of 4.98 mg/L, whereas, one death occurred at a mean achieved atmosphere concentration of 1.14 mg/L. It was therefore considered that the acute inhalation median lethal concentration (4 hr LC₅₀) of Shell GTL Solvent GS310, in the RccHan: WIST strain rat, was in the range of >1 - 5 mg/L.

The microscopic findings observed in the lungs (alveolar and perivascular inflammation, edema, congestion and hemorrhage) were all consistent with hydrocarbon aspiration induced inflammation (i.e. a chemical pneumonitis).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Acute toxicity: via dermal route

Link to relevant study records

Reference

Reference 1

Endpoint:

acute toxicity: dermal

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Hypothesis for the analogue approach:
The hypothesis for the analogue approach is that the test substance GTL Base Oil Distillates (C18-C50 branched, cyclic and linear hydrocarbons – Distillates / 848301-69-9 / 482-220-0) is produced in the same Fischer-Tropsch process as the test substance GTL Gasoil which is the starting material from which the registration substance is produced by fractional distillation. The source substances contain constituents of the target substance, Hydrocarbons, C18-C24, iso-alkanes, <2% aromatics (GS310), although they cover a wider carbon number distribution. The substances therefore have qualitatively similar properties (RAAF Scenario 2 applies).
2. Source and target chemical(s)
The source substance GTL Base Oil Distillates (Distillates (Fischer-Tropsch), heavy, C18-50 - branched, cyclic and linear) is composed of linear, branched and cyclic hydrocarbons of chain length C18-C50.
The source substance GTL Gasoil (C8-C26) (C8-C26 branched and linear hydrocarbons – Distillates) is composed of linear, branched and cyclic hydrocarbons of chain length C8-C26.
The target substance, Hydrocarbons, C18-C24, iso-alkanes, <2% aromatics (GS310), is composed of linear, branched and cyclic hydrocarbons of chain length C18-24.
3. Analogue approach justification
The constituents of the source and target substances are all hydrocarbons. Identical constituents have identical toxicity profiles. There is no evidence of toxicity in the studies on the source substance, and no evidence of toxicity in studies on hydrocarbons with shorter carbon chain length and a narrower range of carbon number, therefore there is no evidence for mixture effects or for increased toxicity with increased concentration.
The source substance GTL Gasoil (C8-C26) has low dermal penetration with the increasing carbon chain length contained in the constituents. The constituents of the target substance, Hydrocarbons, C18-C24, isoalkanes, <2% aromatics (GS310) have carbon numbers predominantly ≥ C18, these carbon chain lengths indicate that most of the applied material will remain in the stratum corneum with negligible systemic exposure. It is concluded that because of the low penetration of the alkanes contained in GS310, it will be of low acute dermal toxicity and its effects will be lower or similar (but not greater) than those observed with GTL Gasoil. See the document attached to the target study record for more detailed discussion of read-across of toxicity data between the two substances. See the document attached to the target study record for more detailed discussion of read across of toxicity data between the two substances.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Reference 2

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2014-01-08 to 2014-01-22

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study was conducted according to an appropriate OECD test guideline, and in compliance with GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Version / remarks:

1987

Deviations:

no

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

other: Wistar: (RccHan; WIST)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories Ltd, UK
- Age at study initiation: 8-12 weeks
- Weight at study initiation: 200 g
- Fasting period before study:
- Housing: housed individually during the exposure period; in groups of 5 by sex for the rest of the study period; housed in polypropylene cages
- Diet: 2014C Teklad Global Rodents diet, ad libitum
- Water: drinking water ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-25 °C
- Humidity (%): 30-70 %
- Air changes (per hr): 15 per hour
- Photoperiod (hrs dark / hrs light): 12/12

Type of coverage:

semiocclusive

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

TEST SITE
- Area of exposure: back and flanks
- % coverage: 10 % of the total body surface area
- Type of wrap if used: surgical gauze

REMOVAL OF TEST SUBSTANCE
- Washing (if done): After the 24-hout exposure period the area was wiped with cotton wool moistened with arachis oil BP
- Time after start of exposure: 24 hours

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 2000 mg/kg
- Constant volume or concentration used: yes; 2.48 mL/kg

Duration of exposure:

24 hours

Doses:

2000 mg/kg

No. of animals per sex per dose:

5 males and 5 females

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Animals were examined at 30 min, 1, 2, and 4 hours post-application, and every day for the 14 day study period. Body weights were recorded prior to the treatment and at days 7 and 14.
- Necropsy of survivors performed: yes; at the end of the study the animals were killed by cervical dislocation; external examination and opening of the abdominal and thoracic cavities were performed at necropsy
- Other examinations performed: behavioural and clinical observations, gross lesions, body weight changes, mortality and any other toxicological effects were noted during the 14 day study period. The test sites were examined for evidence of primary irritation and scored.

Statistics:

No statistics were used in the study.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

No mortalities occured.

Clinical signs:

other: No signs of systemic toxicity were observed.

Gross pathology:

No abnormalities were noted at necropsy.

Other findings:

Slight desquamation was observed in 3 females on days 4, 5 and 6 of the 14-day study period.

Interpretation of results:

GHS criteria not met

Remarks:

Criteria used for interpretation of results: EU

Conclusions:

Based on the available information from the key acute dermal toxicity study for GTL Base Oil Distillates (Distillates (Fischer-Tropsch), heavy, C18-50-branched, cyclic and linear), an LD50 value was concluded to be > 2000 mg/kg bw. The study was conducted according to OECD TG 402, and in compliance with GLP.

Executive summary:

An acute dermal toxicity study for GTL Base Oil Distillates (Distillates (Fischer-Tropsch), heavy, C18-50-branched, cyclic and linear)

was performed to assess the acute dermal toxicity in rat.

A single dose of 2000 mg/kg bw of undiluted test material was applied onto the skin of 5 male and 5 female rats. The test item was held in contact with the skin under semi-occluded dressing for 24 hours. Observations for clinical signs of toxicity were performed at 30 min, 1, 2, and 4 hours post-application and every day for the 14 day study period. Body weights were recorded prior to the treatment and at days 7 and 14. At the end of the study the tested animals were killed by cervical dislocation. External examination and opening of the abdominal and thoracic cavities were performed at necropsy. Behavioural and clinical observations, gross lesions, body weight changes, mortality and any other toxicological effects were noted during the 14 day study period. The test sites were examined for evidence of primary irritation and scored.

No mortalities occured at during the 14 -day study period. There were no signs of systemic toxicity. All females showed no body loss or gain in body weight during the first week and expected gain in body weight in the second week. The males showed expected gain in body weight during the 14 day study period. No abnormalities were noted at necropsy.

The LD₅₀ value for GTL Base Oil Distillates (Distillates (Fischer-Tropsch), heavy, C18-50-branched, cyclic and linear)

was concluded to be > 2000 mg/kg bw. The study was conducted according to OECD TG 402, and in compliance with GLP.

Reference 3

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Qualifier:

according to guideline

Guideline:

EU Method B.3 (Acute Toxicity (Dermal))

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan laboratories, UK
- Age at study initiation: 8-12 weeks
- Weight at study initiation: minimum 200 g
- Fasting period before study:
- Housing: solid floor polypropylene cages, furnished with woodflakes
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: minimum 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-25
- Humidity (%): 30-70
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

Type of coverage:

semiocclusive

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

TEST SITE
- Area of exposure: not defined
- % coverage: ca. 10%
- Type of wrap if used: surgical gauze, semi-occluded with a piece of self-adhesive bandage

REMOVAL OF TEST SUBSTANCE
- Washing (if done): the skin was wiped with cotton wool, moistened with arachis oil BP
- Time after start of exposure: 24 hours

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 2.62 mL/kg
- Concentration (if solution): undiluted
- Constant volume or concentration used: yes

Duration of exposure:

24 hours

Doses:

2000 mg/kg bw

No. of animals per sex per dose:

5/sex

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: the animals were observed for deaths and overt signs of toxicity at 0.5, 1, 2, and 4 hours after dosing. Individual body weights were recorded prior to application of the test item on day 0, 7 and 14.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight, organ weights, histopathology, other: The test sites were examined for evidence of primary irritation and scored. The appearance of any macroscopic abnormalities were recorded at necropsy, no tissues were retained.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

There were no deaths.

Clinical signs:

other: There were no signs of systemic toxicity.

Gross pathology:

No abnormalities were noted at necropsy.

Other findings:

Very slight erythema and crust formation and/or small superficial scattered scabs were noted at the test sites of four females. There were no signs of dermal irritation noted at the test sites of the remaining animals.

Interpretation of results:

GHS criteria not met

Conclusions:

An LD50 value of >2000 mg/kg bw is reported in a reliable study conducted according to an OECD test guideline and in compliance with GLP.

Executive summary:

The acute dermal toxicity study is a reliable test performed with Distillates (Fischer-Tropsch), C8-26 – branched and linear, in accordance with OECD 402 and in compliance with GLP. 2000 mg/kg bw of test substance was applied to five male and five female Wistar rats for a twenty-four hour exposure period under semiocclusive conditions. The animals were observed for deaths or overt signs of toxicity, and the test sites were observed for primary irritation for fourteen days before sacrifice and necroscopy. No deaths occurred and no signs of overt toxicity were observed. There were no abnormalities noted at necroscopy. Very slight erythema and crust formation and/or small superficial scattered scabs were noted at the test sites of four females. There were no signs of dermal irritation noted at the test sites of the remaining animals.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Additional information

An acute inhalation toxicity study has been performed with Hydrocarbons, C18-C24, iso-alkanes, <2% aromatics (GS310); no oral or dermal toxicity studies are available. However, Hydrocarbons, C18-C24, iso-alkanes, <2% aromatics has a carbon range covered by the carbon ranges of the analogue substances GTL Gasoil and GTL Base Oil Distillates for which reliable oral and dermal toxicity data are available. Therefore read across from the available studies with these substances is justified.

Oral

GTL Gasoil (C8-C26) was tested in an acute oral toxicity study according to the fixed dose method (OECD 420). Following a preliminary test in which there were no deaths at a dose level of 5000 mg/kg, an additional 4 fasted Sprague-Dawley rats received a dose of 5000 mg of the undiluted test material per kg body weight by gavage. There were no signs of toxicity, all animals showed normal gains in body weight, and there were no abnormalities on necropsy (SafePharm 2006).

GTL Base Oil Distillates (C18-C50) was tested in an acute oral toxicity study according to the fixed dose method (OECD 420). Following a preliminary test in which there were no deaths at a dose level of 5000 mg/kg, an additional four fasted Sprague-Dawley DC rats received a dose of 5000 mg of the undiluted test material per kg body weight by gavage. There were no signs of toxicity, all animals showed normal gains in body weight, and there were no abnormalities on necropsy (SafePharm, 2007). The acute oral LD₅₀ was therefore >5000 mg/kg bw.

The acute oral toxicity of GS310 is expected to be similar or lower but not greater than that of GTL Gasoil because of the expected lower intestinal absorption of the constituents in GS310 compared to that GTL Gasoil following oral dosing. This extrapolation is justified on the following basis.

Experimentally, the absorption of a wide range of hydrocarbons, including individual linear, branched and cyclic alkanes, was investigated in the rat following oral administration at various doses, ranging from 50 to 530 mg/kg body weight (Albro & Fishbein, 1970).

The absorption of hydrocarbons from the gastro-intestinal tract was found to be inversely proportional to the carbon number according to the following equation (correlation coefficient 0.995; p < 0.001):

Percentage absorbed = 115.9 – (3.94 × number of carbon atoms)

There was no statistically significant difference in the percentage absorbed for different isomers (branched or cyclic) compared to their n-aliphatic isomers (p > 0.9). An almost constant percentage was absorbed between doses of 60 and 320 mg/kg body weight but at higher doses (up to 530 mg/kg body weight) a gradual decrease to approximately 70% of the maximum was found. This experimentally found equation predicts that hydrocarbons with carbon numbers greater than 30 are not absorbed to a significant extent. For the carbon numbers found in GTL Gasoil and GS310 the following predictions indicate an inverse relationship between carbon number and amount retained. For example, C10 shows an effective absorption of 77%, which drops to 37% by doubling the carbon chain length to C20 (Table 5.4).

Based on the estimated absorption for each carbon number and compositional information (approximated) of GTL Gasoil and GS310 the relative absorption for each carbon number can be estimated (Table 5.4). The relative absorption is the amount of the hydrocarbon absorbed (by carbon number) based on its individually calculated absorption and composition (% concentration) in the GTL substance (carbon# relative abs. = carbon# estimated abs. * carbon# conc. /100). From the relative absorption it is estimated that relatively more GTL Gasoil is absorbed than GS310 (48 vs 34% respectively). Therefore, for an oral dose of 5000 mg/kg bw of GT Gasoil, the effective dose would be about 2500 mg/kg bw whereas that of GS310 would be 1500 mg/kg bw. It is therefore reasonable to assume that acute oral data of GT Gasoil represents a “worse-case” estimation for GS310.

It is concluded that, based on the estimated hydrocarbon absorption, the acute oral toxicity of GS310 would be similar or lower but not greater than that of GT Gasoil of LD50 > 5000 mg/kg bodyweight.

Table 5.4 Estimated relative oral absorption for carbon numbers based on their approximate composition (concentration) in GTL Gasoil or GS310

Carbon number	Estimated absorption %	GTL Gasoil		GS310 *
		composition (%)	relative absorption (%)	composition (%)	relative absorption (%)
8	84	1	0.1
9	80	1	0.4
10	77	2	1.4
11	73	3	2.4
12	69	5	3.5
13	65	7	4.3
14	61	9	5.3
15	57	9	5.3
16	53	9	4.9	1	0.5
17	49	10	4.7	4	2
18	45	8	3.8	10	4.5
19	41	8	3.2	15	6.2
20	37	7	2.7	16	5.9
21	33	6	2.1	16	5.3
22	29	6	1.7	14	4.1
23	25	4	1.1	10	2.5
24	21	3	0.6	7	1.5
25	17	2	0.3	4	0.7
26	13	1	0.1	3	0.4
Total		100	48	100	34

 

Inhalation 

An acute inhalation study has been performed with Hydrocarbons, C18-C24, isoalkanes, <2% aromatics in accordance with OECD Test Guideline 436 (Acute Toxic Class Method) and GLP (Harlan, 2014). Two groups of six rats (three male, three female), were exposed for four hours to an aerosol atmosphere of the test substance (nose only) at mean measured test concentrations of 1.14 and 4.98 mg/l, followed by a 14-day observation period. 2/3 males and 1/3 females died following exposure to 4.98 mg/l, whereas no males and 1/3 females died at 1.14 mg/l. Common abnormalities noted during the study included increased respiratory rate, hunched posture, pilo-erection and wet fur; occasional instances of tip-toe gait were also noted. Surviving high dose animals recovered to appear normal on Day 8 post-exposure. Surviving low dose animals recovered to appear normal from Days 6 to 7 post-exposure.

In the high dose group, all animals exhibited body weight losses on Day 1 post-exposure. All surviving animals exhibited body weight losses or showed no body weight gain from Days 1 to 3 post-exposure, body weight gains were noted in all surviving animals during the remainder of the recovery period. In the low dose group, all males and two female animals exhibited body weight losses on Day 1 post-exposure. Body weight gains were noted in all surviving animals during the remainder of the recovery period.

Dark patches on the lungs were noted at necropsy amongst all three surviving animals from the high dose group and in one out of five surviving animals from the low dose group. A further surviving female from the low dose group exhibited a dark liver at the end of the fourteen-day recovery period. Necropsy findings in animals that died during the course of the study included abnormally dark or dark patches on the lungs, dark livers and gaseous distension in the large intestine. Due to the observations noted, the study author considered that the deaths noted during the study may have been mainly attributable to local toxicity. Dark patches in the lungs and abnormally dark lungs in a proportion of animals in both treatment groups were associated with congestion at histopathological examination, and were considered to be treatment-related.

Additional histopathological examinations were performed on the lungs and trachea of all animals. Findings in the lungs animals that survived to the end of the study period were minimal to slight congestion, minimal to slight haemorrhage, moderate oedema, minimal to slight alveolar macrophages, slight acute alveolar inflammation and minimal to slight acute perivascular inflammation. Findings in the trachea were limited to minimal intraepithelial inflammation. Examinations in animals that died during the study revealed effects on the lungs, namely slight to moderate congestion, slight haemorrhage, minimal to moderate oedema, minimal to slight alveolar macrophages minimal to slight alveolar inflammation and minimal to moderate acute perivascular inflammation. There were no findings in the trachea of decedent animals.

The histopathological findings are consistent with a conclusion that the observed mortalities were related to hydrocarbon aspiration-induced inflammation (i.e. chemical pneumonitis), rather than being indicative of systemic or acute toxicity. The substance is therefore classified as Aspiration Toxicity Category 1. It was concluded that the LD50 was <1 - 5 mg/ml air, administered as an aerosol.

Supporting data are available for GTL Gasoil (C8-C26) which was tested using a method that was compatible with that described in the OECD Guidelines for Testing of Chemicals (2009) No. 436 “Acute Inhalation Toxicity – Acute Toxic Class Method” (Harlan, 2013). It was considered that the acute inhalation median lethal concentration (4 hr LC50) of the test material in the RccHanTM: WIST strain rat, was >5 mg/L air. The microscopic findings observed in the lungs (alveolar and perivascular inflammation, edema, congestion and hemorrhage) were all consistent with hydrocarbon aspiration induced inflammation (i.e. a chemical pneumonitis).

Dermal

GTL Gasoil (C8-C26) was tested in an acute dermal toxicity study in a reliable test performed in accordance with OECD 402 and in compliance with GLP. 2000 mg/kg bw of test substance was applied to five male and five female Wistar rats for a twenty-four hour exposure period under semiocclusive conditions (Harlan, 2015). The animals were observed for deaths or overt signs of toxicity, and the test sites were observed for primary irritation for fourteen days before sacrifice and necroscopy. No deaths occurred and no signs of overt toxicity were observed. There were no abnormalities noted at necroscopy. Very slight erythema and crust formation and/or small superficial scattered scabs were noted at the test sites of four females. There were no signs of dermal irritation noted at the test sites of the remaining animals. The LC50 was concluded to be >2000 mg/kg bw.

GTL Base Oil Distillates (Distillates (Fischer-Tropsch), heavy, C18-50-branched, cyclic and linear) has been tested in a reliable test performed in accordance with OECD 402 and in compliance with GLP. 2000 mg/kg bw of test substance was applied to five male and five female Wistar rats for a twenty-four hour exposure period under semiocclusive conditions (Harlan, 2014). No animals died and no overt signs of toxicity were observed. The LC50 was concluded to be >2000 mg/kg bw.

The acute dermal toxicity of GS310 is expected to be similar or lower but not greater than that of GTL Gasoil because of the expected low dermal absorption of alkane constituents contained in GS310 compared to those of GTL Gasoil. The extrapolation is justified on the following basis.

Quantitative studies, in vitro or in vivo models demonstrated that hexadecane and docosane, regardless of the vehicle used, do not penetrate below the dermis, and are retained primarily in the stratum corneum (Brown et al., 1995). Further studies show that dermal absorption of C10-C12 is low with permeability coefficients inversely proportional to carbon number [(Kim et al., 2006)]. Therefore, the low dermal toxicity of GTL Gasoil is explained by the lack of dermal penetration with increasing carbon chain length contained in the substance. Similarly, GS310 with carbon numbers > C18 indicate that most of the applied material will remain in the stratum corneum with negligible systemic exposure leading to an acute dermal toxicity expected as LD50 > 2000 mg/kg bw.

Taken all together, it is concluded that because of the low penetration of the alkanes contained in GS310, it will be of low acute dermal toxicity and its effects will be lower or similar (but not greater) than those observed with GTL Gasoil for which the acute dermal LD50 is > 2000 mg/kg bw.

Taking all available acute toxicity data for relevant carbon numbers into consideration it can be concluded that the acute oral and dermal LD₅₀ values for Hydrocarbons, C18-C24, isoalkanes, <2% aromatics are >5000 mg/kg bw and >2000 mg/kg bw, respectively.

Brown, B. E., W. Diembeck, U. Hoppe and P. M. Elias, 1995: Fate of topical hydrocarbons in the skin. Journal of the Society of Cosmetic Chemists, 46, 1-10.

Justification for classification or non-classification

On the basis of the available data, Hydrocarbons, C18-C24, isoalkanes, <2% aromatics does not require classification for lethal effects following a single exposure according to Regulation (EC) No. 1272/2008.

Since the substance is composed of aliphatic hydrocarbons and has low viscosity (kinematic viscosity: 5.9 mm²/s at 40°C), it may present an aspiration hazard in humans following oral exposure. This is supported by macroscopic and microscopic examinations performed following an acute inhalation study with an aerosol atmosphere of the registered substance. It is therefore appropriate to classify the substance as Aspiration Toxicity Category 1 according to Regulation (EC) No. 1272/2008.