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Description of key information

The acute toxicity of [ω-hydroxy-C16 (saturated and unsaturated) and C16 (unsaturated)] fatty acids to rats via the oral route of administration was predicted using the Commercial ACD/Labs QSAR model for acute toxicity. Seven individual UVCB constituents are predicted to each have oral LD50 values ≥3900 mg/kg bodyweight in rats. The acute toxicity of a similar UVCB substance (EC/List number 943-164-7) was tested in female Wistar rats via oral administration according to OECD method 423 (2001) in 2016. In this study, the oral LD50 value of the test material was determined to be >2000 mg/kg body weight.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Referenceopen allclose all

Endpoint:
acute toxicity: oral
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Study period:
March, 2018
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
See attached QPRF and QMRF documents.
Qualifier:
equivalent or similar to
Guideline:
other: QSAR models predicts acute toxicity consistent with OECD 401 Acute Oral Toxicity
Version / remarks:
Use of QSAR model is consistent with ECHA "Guidance on information requirements and chemical safety assessment Chapter R.6: QSARs and grouping of chemicals".
Principles of method if other than guideline:
Use of QSAR model is consistent with ECHA "Guidance on information requirements and chemical safety assessment Chapter R.6: QSARs and grouping of chemicals".
Key result
Sex:
not specified
Dose descriptor:
LD50
Effect level:
> 2 000 mg/kg bw
Based on:
other: seven UVCB constituents
Remarks on result:
not measured/tested
Interpretation of results:
GHS criteria not met
Remarks:
Not classified according to Regulation (EC) No 1272/2008
Conclusions:
All seven of the UVCB constituents present in the Danish (Q)SAR database are predicted to have LD50 values ≥3900 mg/kg bodyweight in rats via oral administration. The acute toxicity of [ω-hydroxy-C16 (saturated and unsaturated) and C16 (unsaturated)] fatty acids to rats via the oral route is > 2000 mg/kg bodyweight.
Executive summary:

The acute toxicity of [ω-hydroxy-C16 (saturated and unsaturated) and C16 (unsaturated)] fatty acids to rats via the oral route of administration was predicted using the Commercial ACD/Labs model for acute toxicity. Acute toxicity was predicted for seven (7) individual components of the substance. These components, along with water, comprise ca. 98% of the quantified constituents and ca. 78% of the total UVCB composition. All of the predicted LD50 values are greater than 2000 mg/kg bodyweight, which is the minimum concentration for acute oral toxicity classification according to Regulation (EC) No 1272/2008 on classification, labelling and packaging (CLP) of substances and mixtures. Although three of the Reliability Index values for these predictions were below 0.5, the lowest LD50 prediction of 3900 mg/kg is still nearly twice the classification threshold. This affords a wide margin for error in the prediction before any single constituent could be classifiable as acutely toxic under GHS or CLP guidelines. The relatively high predicted LD50 values provides sufficient weight of evidence to adequately assess the acute toxicity of the UVCB substance to rats via the oral route of administration.

Endpoint:
acute toxicity: oral
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
weight of evidence
Study period:
23 August 2016 - 13 September 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
The material tested in this study (EC/List number 943-164-7) is compositionally and functionally similar to [ω-hydroxy-C16 (saturated and unsaturated) and C16 (unsaturated)] fatty acids. The test substance was produced by the same E. coli fermentation process as [ω-hydroxy-C16 (saturated and unsaturated) and C16 (unsaturated)] fatty acids, but was extracted from the fermentation broth using a different solvent resulting in methyl esterification of some carboxylic fatty acid constituents. The test substance and [ω-hydroxy-C16 (saturated and unsaturated) and C16 (unsaturated)] fatty acids share ca. 8.5% composition, with the difference in the remaining constituents being only an ester at the terminal end of the carbon chain instead of carboxyl group(s). Otherwise, the basic chemical structures and their ratios to one another in the composition are entirely comparable. This read-across study is utilized to support the qualitative determination that the LD50 in rats is predicted to exceed 2000 mg/kg body weight.
Qualifier:
according to
Guideline:
OECD Guideline 423 (Acute Oral toxicity - Acute Toxic Class Method)
Version / remarks:
version 2001
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.1 tris (Acute Oral Toxicity - Acute Toxic Class Method)
Version / remarks:
version May 2008
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 870.1100 (Acute Oral Toxicity)
Version / remarks:
version 2002
Deviations:
no
GLP compliance:
yes
Test type:
acute toxic class method
Limit test:
yes
Species:
rat
Strain:
Wistar
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Deutschland, Sulzfeld, Germany
- Females (if applicable) nulliparous and non-pregnant: yes
- Age at study initiation: approx. 8-9 weeks old
- Weight at study initiation: 147-202 g
- Fasting period before study: overnight prior to dosing and until 3-4 hours after administration of the test item
- Housing: Group housing of 3 animals per cage in labeled Makrolon cages
- Diet: Free access to pelleted rodent diet (SM R/M-Z from SSNIFF® Spezialdiäten GmbH, Soest, Germany)
- Water: Free access to tap water
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS set to maintain
- Temperature (°C): 18 to 24
- Humidity (%): 40 to 70
- Air changes (per hr): at least 10
- Photoperiod (hrs dark / hrs light): 12/12
Route of administration:
oral: gavage
Vehicle:
other: 1% aqueous carboxymethyl cellulose
Details on oral exposure:
MAXIMUM DOSE VOLUME APPLIED: 10 mL/kg bw

DOSAGE PREPARATION: The preparations (w/w) were kept at room temperature and were dosed within 4 hours after adding the vehicle to the test item. Homogeneity was assessed by visual inspection of the solutions and the formulations were stirred during dosing, which ensures homogeneity sufficient for these kinds of studies. No correction was made for purity of the test item.
Doses:
Two groups of 2000 mg/kg bw
No. of animals per sex per dose:
3
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing:
Mortality/Viability: Twice daily
Body weights: Days 1 (pre-administration), 8 and 15
Clinical signs At periodic intervals on the day of dosing (Day 1) and once daily thereafter, until Day 15. The signs were graded according to fixed scales and the time of onset, degree and duration were recorded.
- Necropsy of survivors performed: Yes, at the end of the observation period, all animals were sacrificed by oxygen/carbon dioxide procedure and subjected to necropsy. Descriptions of all internal macroscopic abnormalities were recorded.
Statistics:
No statistical analysis was performed.
Key result
Sex:
female
Dose descriptor:
LD50
Effect level:
> 2 000 mg/kg bw
Based on:
test mat.
Mortality:
No mortality occurred.
Clinical signs:
Hunched posture and piloerection were noted for five out of six animals on Days 1 and/or 2.
Body weight:
The mean body weight gain shown by the surviving animals over the study period was considered to be similar to that expected for normal untreated animals of the same age and strain.
Gross pathology:
No abnormalities were found at macroscopic post mortem examination of the animals.
Interpretation of results:
GHS criteria not met
Remarks:
Not classified according to Regulation (EC) No 1272/2008
Conclusions:
In an acute oral toxicity study with female rats, performed according to OECD 423 test guideline and GLP principles, an LD50 >2000 mg/kg bw was determined.
Executive summary:

Test substance was tested in an acute oral toxicity study with female rats, performed according to OECD 423 test guideline and GLP principles. No mortality occurred. Hunched posture and piloerection were noted for five out of six animals on Days 1 and/or 2. No abnormalities were found at macroscopic post mortem examination of the animals. The oral LD50 value of the substance in Wistar rats was established to exceed 2000 mg/kg body weight. Based on the results, the test substance is not classified and has no obligatory labelling requirement for acute oral toxicity according to Regulation (EC) No 1272/2008 on classification, labelling and packaging of items and mixtures (including all amendments).

Endpoint conclusion
Dose descriptor:
LD50
3 900 mg/kg bw

Additional information

Justification for classification or non-classification

[ω-hydroxy-C16 (saturated and unsaturated) and C16 (unsaturated)] fatty acids is a UVCB substance of biological origin. The substance is a complex mixture of long-chain fatty acids produced and excreted by an engineered Escherichia coli K-12 organism through an aqueous microbial fermentation process. The fatty acids are extracted from the fermentation broth by centrifugation. The substance is predominantly comprised of linear unbranched long-chain organic fatty acids differentiated only by saturation and number of terminal carboxyl or hydroxyl groups. All of the quantified constituents are comprised of only carbon, hydrogen, and oxygen.

Many of the UVCB constituents are either naturally produced or obtained through the food chain of a broad range of organisms and have been positively identified in algae [4], plant cuticular waxes [1], seeds [3], fish [9], avian eggs [10], edible nuts [7], and berries [11]. Palmitic acid is synthesized endogenously and serves essential cellular functions in humans [5]. Palmitic acid and oleic acid comprise more than half of the fatty acid content in human breast milk [8].

Excess dietary intake of unsaturated fatty acids including palmitic acid, which is present in [ω-hydroxy-C16 (saturated and unsaturated) and C16 (unsaturated)] fatty acids, has been shown to affect metabolism and body weight regulation in both experimental animals and humans [2]. However this is not an acute toxicity effect.  A literature review of rodent feeding studies published in 2016 summarized consistent tolerance for a diet high in long-chain fatty acids. The rats and mice in these studies routinely survive the full 4-12 week duration of the study on a diet providing 40-70% of dietary energy from vegetable oils [6]. Dietary ingestion of long-chain saturated and unsaturated organic fatty acids is not known to result in acute toxicity.

 

Acute oral toxicity of [ω-hydroxy-C16 (saturated and unsaturated) and C16 (unsaturated)] fatty acids was predicted using a QSAR model. The results of the predictive model are used as part of a weight of evidence approach to characterize acute toxicity of the substance. The Commercial ACD/Labs model for acute toxicity predicted oral LD50 values ≥3900 mg/kg bodyweight for each of seven UVCB constituents .  These constituents, along with water, comprise ca. 98% of the quantified UVCB constituents and ca. 77% of the total UVCB composition. The lowest constituent LD50 prediction is nearly double the classification threshold and provides a wide margin of error before even a single constituent would be predicted to have acute toxicity.

 

With respect to acute toxicity via oral administration, a similar UVCB test substance (EC/List number 943-164-7) and the [ω-hydroxy-C16 (saturated and unsaturated) and C16 (unsaturated)] fatty acids substance are considered to be within the same category of chemical substances. The two substances are produced by the same E. coli fermentation and have at least 8.5% of their compositions in common. The substances differ only in the extraction solvent, resulting in the esterification of some of the fatty acids. The chain lengths of the constituents and their relative ratios within the UVCB composition are otherwise very similar. Therefore, a chemical category approach is adopted as part of a weight of evidence approach to characterize acute oral toxicity. A qualitative read-across approach is employed in using the test results to support the acute toxicity determination predicted by the QSAR model.

 

The weight of evidence provided by the ubiquity of fatty acids in biological systems, the body of published literature demonstrating high tolerance for dietary intake of long-chain fatty acids, the predictive modeling results, and the test results of a similar UVCB substance is sufficient to classify the oral LD50 of [ω-hydroxy-C16 (saturated and unsaturated) and C16 (unsaturated)] fatty acids as greater than 2000 mg/kg bodyweight. The substance therefore has no obligatory classification or labelling requirement for acute oral toxicity according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) of the United Nations (2015) (including all amendments) and Regulation (EC) No 1272/2008 on classification, labelling and packaging of items and mixtures (including all amendments).

References:

1.   Fernandes, A. M. Silva, Baker, E.A., Martin, J.T. Studies on plant cuticle. Annals of Applied Biology 1964, 53(1):43-58

2.   Frago LM, Canelles S, Freire-Regatillo A, et al. Estradiol Uses Different Mechanisms in Astrocytes from the Hippocampus of Male and Female Rats to Protect against Damage Induced by Palmitic Acid. Frontiers in Molecular Neuroscience. 2017;10:330

3.   Hajghanbari et al. Essential oil constituents and fatty acids in Echium amoenum grown wild in Iran. International Journal of Biosciences 2015, 6(1): 156-161

4.   Hassain, J, et al. Effects of Different Biomass Drying and Lipid Extraction Methods on Algal Lipid Yield, Fatty Acid Profile, and Biodiesel Quality. Appl Biochem Biotechnol 2015, 175: 3048

5.   Innis, Sheila. Palmitic Acid in Early Human Development. Critical Reviews in Food Science and Nutrition 2016, 56(12): 1952-1959

6.   Kakimoto, Pamela and Kowaltowski, Alicia. Effects of high fat diets on rodent liver bioenergetics and oxidative imbalance. Redox Biology 2016, 8 (2016) 216–225

7.   Maguire LS, O’Sullivan SM, et al. Fatty acid profile, tocopherol, squalene and phytosterol content of walnuts, almonds, peanuts, hazelnuts and the macadamia nut. International Journal of Food Science Nutrition 2004, 5:171-178

8.   Martin, Camilia, Ling Pei-Ra, Blackburn, George. Review of Infant Feeding: Key Features of Breast Milk and Infant Formula. Nutrients 2016, 8(5), 279

9.   Ozogul Y, Ozogul F, Cicek E, Polat A, Kuley E: Fat content and fatty acid compositions of 34 marine water fish species from the Mediterranean Sea. International Journal of Food Science Nutrition 2008, 29:1-12

10.Toledo, A., Andersson, M.N., Wang, HL. et al. Fatty acid profiles of great tit (Parus major) eggs differ between urban and rural habitats, but not between coniferous and deciduous forests. Sci Nat 2016, 103: 5

11.Yang B, Kallio HP. Fatty acid composition of lipids in sea buckthorn (Hippophaë rhamnoides L.) berries of different origins. J Agricultural Food Chemistry 2001, 49:1939-1947