Octanoic acid, compound with dicyclohexylamine (1:1)

Endpoint summary

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1968

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Sufficient information to take into account for evaluation.

Objective of study:

absorption

excretion

Qualifier:

no guideline followed

Principles of method if other than guideline:

2 rats were exposed to vapor; then amine concentration in blood was determined

GLP compliance:

no

Radiolabelling:

not specified

Species:

rat

Strain:

not specified

Sex:

not specified

Route of administration:

inhalation: vapour

Vehicle:

not specified

Duration and frequency of treatment / exposure:

80 minutes

Remarks:

doses not specified

No. of animals per sex per dose / concentration:

2

Type:

absorption

Results:

0.014 and 0.026 mg DCHA/ml blood were determined indicating that dicyclohexylamine penetrate the alveolar membrane and enter the blood.

Details on absorption:

0.014 and 0.026 mg DCHA/ml blood were determined indicating that dicyclohexylamine penetrate the alveolar membrane and enter the blood.

Metabolites identified:

not specified

Conclusions:

Inhalation exposure (concentration not given) for 80 minutes resulted in 0.014 and 0.026 mg dicyclohexylamine /ml blood, respectively, indicating that dicyclohexylamine penetrates the alveolar membranes and enters the blood.

Executive summary:

Inhalation exposure (concentration not given) for 80 minutes resulted in 0.014 and 0.026 mg dicyclohexylamine /ml blood, respectively, indicating that dicyclohexylamine penetrates the alveolar membranes and enters the blood.

Reference 2

Endpoint:

basic toxicokinetics, other

Type of information:

other: theoretical assessment

Adequacy of study:

key study

Study period:

2013-06-06

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Objective of study:

other: theoretical assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

theoretical assessment based on literature data

GLP compliance:

no

Radiolabelling:

not specified

Species:

other: not specified

Strain:

not specified

Sex:

not specified

Route of administration:

not specified

Vehicle:

not specified

Duration and frequency of treatment / exposure:

no data

No. of animals per sex per dose / concentration:

no data

Type:

absorption

Results:

100%

Details on absorption:

Citation from the CLH-report: "After oral ingestion of medium chain triglycerides (MCTs) they are hydrolyzed by lingual lipase in the
stomach and then rapidly and efficiently by pancreatic lipase within the intestinal lumen. Free medium-chain fatty acids may be expected to be quickly and completely absorbed from the intestine. For oral application of Octanoic acid or MCTs 100% absorption can therefore be assumed.Undissociated Octanoic acid with a log POW of 3.03 as well as undissociated Decanoic acid with a log Pow of 4.09 is expected to easily penetrate and cross cell membranes.
As it is found with absorption from the gut, it is appropriate to assume that the permeation through skin is easy. Nevertheless in the absence of a dermal uptake study for the purpose of risk assessment 100% absorption of C8 and C10 fatty acids through the skin will be assumed."

Details on distribution in tissues:

Citation from CLH-report:
"After absorption from the gut C8 and C10 fatty acids are extensively metabolised in the liver. Only a minor fraction bypasses the liver and becomes distributed to peripheral tissues via the general circulation. C8 and C10 fatty acids are catabolised predominantly in the liver to C2 fragments, which are further converted to CO2 or used to synthesize longer-chain fatty acids. C8 and C10 fatty acids not absorbed from the gut, but entering the body by dermal absorption can be expected to become absorbed into the blood stream and transported to the liver.

Conclusions:

Octanoic acid is a linear saturated fatty acid and is ubiquitous in nature. The metabolic pathways is well established, similar for all fatty acids: complete catabolism for energy supply or conversion to fat suitable for storage.
Complete and rapid oral absorption can be expected.
For the purpose of risk assessment 100% dermal absorption of octanoic acid can be assumed too. C8 and C10 fatty acids are catabolised predominantly in the liver to C2 fragments, which are further converted to CO2 or used to synthesize longer-chain fatty acids.The metabolites formed in the liver from C8 and C10 fatty acids are also substances normally present and part of the physiological system.

Executive summary:

Citation from CLH report:

" Absorption

Oral

After oral ingestion of medium chain triglycerides (MCTs) they are hydrolyzed by lingual lipase in the stomach and then rapidly and efficiently by pancreatic lipase within the intestinal lumen. Free medium-chain fatty acids may be expected to be quickly and completely absorbed from the intestine. For oral application of Octanoic acid or MCTs 100% absorption can therefore be assumed.

Dermal

Undissociated Octanoic acid with a log POW of 3.03 as well as undissociated Decanoic acid with a log Pow of 4.09 is expected to easily penetrate and cross cell membranes. As it is found with absorption from the gut, it is appropriate to assume that the permeation through skin is easy. Also the skin irritating effects of the C8 and C10 fatty acids would support dermal absorption, on the other hand the low water solubility would limit dermal absorption. However after skin contact, the formation of a reservoir of the active substance in the stratum corneum and desquamation of the stratum corneum in time will result in less than 100% systemic availability. Nevertheless in the absence of a dermal uptake study for the purpose of risk assessment 100% absorption of C8 and C10 fatty acids through the skin will be assumed.

Metabolism and distribution

After absorption from the gut C8 and C10 fatty acids are extensively metabolised in the liver. Only a minor fraction bypasses the liver and becomes distributed to peripheral tissues via the general circulation. C8 and C10 fatty acids are catabolised predominantly in the liver to C2 fragments, which are further converted to CO2 or used to synthesize longer-chain fatty acids. C8 and C10 fatty acids not absorbed from the gut, but entering the body by dermal absorption can be expected to become absorbed into the blood stream and transported to the liver.

The metabolites formed in the liver from C8 and C10 fatty acids are also substances normally present and part of the physiological system.

Decanoic acid and Octanoic acid are naturally present in many types of food in its free form or as triglyceride (see Gubler 2006, Ref A 6/05). Uptake as natural food source from cheese or coconut oil may be estimated to be significantly above 10 mg/ person day."

Reference 3

Endpoint:

basic toxicokinetics in vivo

Type of information:

other: publication

Adequacy of study:

key study

Study period:

1968

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Sufficient information to take into account for evaluation

Objective of study:

absorption

excretion

Qualifier:

no guideline followed

Principles of method if other than guideline:

Absorption from gastrointestinal tract was investigated following single gavage application to rabbits

GLP compliance:

no

Radiolabelling:

not specified

Species:

rabbit

Strain:

not specified

Sex:

not specified

Route of administration:

oral: gavage

Vehicle:

not specified

Duration and frequency of treatment / exposure:

single

Dose / conc.:

63 mg/kg bw/day (nominal)

Remarks:

approximately 63-106 mg/kg bw

Dose / conc.:

106 mg/kg bw/day (nominal)

Remarks:

approximately 63-106 mg/kg bw

No. of animals per sex per dose / concentration:

5

Details on study design:

single oral application by gavage, determination of amine in blood and urine

Type:

absorption

Results:

No dicyclohexylamine was detected in the blood, but 130 minutes post application >1mg dicyclohexylamine /ml urine was detected.

Details on absorption:

No dicyclohexylamine was detected in the blood, but 130 minutes post application >1mg dicyclohexylamine /ml urine was detected. 27-44 % of the dose was found unchanged in the urine within 3 days.

Details on excretion:

No dicyclohexylamine was detected in the blood, but 130 minutes post application >1mg dicyclohexylamine /ml urine was detected. 27-44 % of the dose was found unchanged in the urine within 3 days.

Metabolites identified:

no

Conclusions:

Dicyclohexylamine is readily absorbed after oral application and is excreted via urine.

Executive summary:

Dicyclohexylamine is readily absorbed after oral application and is excreted via urine.

Reference 4

Endpoint:

basic toxicokinetics, other

Type of information:

other: theoretical assessment

Adequacy of study:

key study

Study period:

2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Objective of study:

other: theoretical assessment

Qualifier:

no guideline required

GLP compliance:

no

Radiolabelling:

not specified

Species:

other: not applicable

Strain:

other: not applicable

Details on species / strain selection:

not applicable

Sex:

not specified

Details on test animals or test system and environmental conditions:

not applicable

Route of administration:

other: not applicable

Vehicle:

other: not applicable

Details on exposure:

not applicable

Duration and frequency of treatment / exposure:

not applicable

No. of animals per sex per dose / concentration:

not applicable

Positive control reference chemical:

not applicable

Details on study design:

not applicable

Details on dosing and sampling:

not applicable

Statistics:

not applicable

Type:

absorption

Results:

100%

Metabolites identified:

not specified

Executive summary:

1.   Toxicokinetic behavior:

In aqueous systems Octanoic acid, compound with dicyclohexylamine (1:1) is hydrolytically very unstable so that in aqueous solution a decomposition to the educts can be observed (< 8 min). The substance will rapidly dissociate to octanoic acid and dicyclohexylamine. Therefore Octanoic acid, compound with dicyclohexylamine (1:1) is not stable at “standard” conditions representative for human and environmental exposure. Therefore the toxicocinetic assessment is based on thecorresponding breakdown products of Octanoic acid, compound with dicyclohexylamine (1:1): Octanoic acid and Dicyclohexylamine. Since no toxicokinetic studies are available the toxicokinetic behavior is based on the physico-chemical properties and the available literature data of the two substances.

a)    Absorption

Oral absorption:

Octanoic acid:

Octanoic acid is a linear saturated fatty acid and is ubiquitous in nature. The metabolic pathway is well established, similar for all fatty acids: complete catabolism for energy supply or conversion to fat suitable for storage.

Free medium-chain fatty acids can be expected to be quickly and completely absorbed from the intestine. For oral application of Octanoic acid 100% absorption can therefore be assumed.

DCHA:

According to the available information from animal studies dicyclohexylamine is readily absorbed after oral application (1).

The low molecular weight (181.3) of DCHA and the moderate water solubility favours absorption in the gastro-intestinal tract. However, the high log Pow (4.37; calculated by KOWWIN) of DCHA render absorption in the gastro-intestinal tract by passive diffusion to be unlikely. It can therefore be assumed that DCHA may be taken up by micellular solubilisation. For risk assessment purposes, the oral absorption of DCHA is set at 100%.

Dermal absorption:

 

Octanoic acid:

Undissociated Octanoic acid with a log POW of 3.03 (calculated with KOWWIN) is expected to easily penetrate and cross cell membranes. As it is found with absorption from the gut, it is appropriate to assume that the permeation through skin is easy.

In the absence of a dermal uptake study and for the purpose of risk assessment 100% absorption of octanoic acid through the skin will be assumed.

 

DCHA:

Since the log Pow is high (4.37;calculated with KOWWIN), DCHA is expected to be taken up in the stratum corneum, further transfer to the epidermis is predicted to be moderate based on the water solubility of ca. 1 g/l. For a water solubility between100 – 10,000 mg/l dermal absorption is anticipated to be moderate to high (2). According to the criteria given in the REACH guidance (2) 10% dermal absorption will be considered in case MW>500 and log Pow <-1 and >4, otherwise 100% dermal absorption is assumed.

In consequence, 100 % dermal absorption is proposed for DCHA.

 

Respiratory absorption:

 

The moderate water solubility of octanoic acid (789 mg/l) and DCHA (1 g/l) enhances readily diffusion/dissolution into the mucus lining the respiratory tract.

Lipophilic substances like octanoic acid and DCHA (log P >0) would then have the potential to be absorbed directly across the respiratory tract epithelium (2).

For risk assessment purposes the inhalation absorption of octanoic acid and DCHA is set at 100%.

b)   Distribution

 

Octanoic acid:

After absorption from the gut octanoic acid is extensively metabolised in the liver. Only a minor fraction bypasses the liver and becomes distributed to peripheral tissues via the general circulation.

 

DCHA:

DCHA may be expected to distribute widely throughout the body based on the small molecular weight, the lipophilicity and moderate water solubility.

The lipophilicity of DCHA also predicts that the intracellular concentration may be higher than the extracellular concentration, particularly in fatty tissues. Based on the relatively high lipophilicity DCHA may accumulate (2).

.

 

c)    Metabolism

 

Octanoic acid:

It is well known that aliphatic linear carboxylic acids are metabolised in the fatty acid β-oxidation pathway, the tricarboxylic acid cycle, or the C1-tetrahydrofolate pathways.

C8 and C10 fatty acids are catabolised predominantly in the liver to C2 fragments, which are further converted to CO₂or used to synthesize longer-chain fatty acids.

The metabolites formed in the liver from C8 and C10 fatty acids are also substances normally present and part of the physiological system.

 

DCHA:

No further information is available.

 

d)   Excretion:

 

Octanoic acid:

In humans fatty acids are metabolised by different mechanism as an energy source. Fatty acids are stored as lipids in adipose tissue and used as components of cellular structure and signaling molecules. Therefore, fatty acids are not expected to be excreted in the urine or faeces under normal physiological conditions.

 

DCHA:

According to literature data Dicyclohexylamine is readily absorbed after oral application and is excreted via urine (1).

The metabolites are expected to be low molecular weight compounds.

 

 

Based on the present data no further conclusions about the toxicokinetic behavior of the substances can be drawn and no further assessment is possible.

 

 

2.   References:

 

(1)  Organisation for Economic Co-operation and Development (OECD): “SIDS Initial Assessment Report For SIAM 22, Dicyclohexylamine”, Paris, France, 18–21 April 2006

 

(2)  “Guidance for the implementation of REACH. Guidance on information requirements and

chemical safety assessment. Chapter R.7c: Endpoint specific guidance”,Version 3.0 June 2017 EuropeanChemical Agency, June 2017

 

(3)  V. A. Filov: “Die Untersuchung des Verhaltens von Cyclohexylamin (CHA) und Dicyclohexylamin (DCHA) im Körper“,Gig. Tr. Prof. Zabol. 7, 29-33 (1968)

Description of key information

1.   Substance identity:

 

Name:Octanoic acid, compound with dicyclohexylamine (1:1)

 

Molecular formula:               C₂₀H₃₉NO₂

 

Molecular weight (MW):         325.5 g/Mol

 

EC-Number:                           239-914-1

 

CAS-Number:                         15816-71-4

 

Description:                           solid

 

 

2.   Physico-chemical data:

 Melting point:                        78.8°C

 

Boiling point:                         decomposition at 180°C

 

Relative density:                    0.95 g/cm³(20 °C)

Vapour pressure:                  0.0733271 Pa

 

Water solubility:                    15.3 g/L

 

Partition coefficient:              log Pow: 5.79 (calculated)

 

3.   Toxicokinetic behavior:

In aqueous systems Octanoic acid, compound with dicyclohexylamine (1:1) is hydrolytically very unstable so that in aqueous solution a decomposition to the educts can be observed (< 8 min). The substance will rapidly dissociate to octanoic acid and dicyclohexylamine. Therefore Octanoic acid, compound with dicyclohexylamine (1:1) is not stable at “standard” conditions representative for human and environmental exposure.Therefore the toxicocinetic assessment is based on thecorresponding breakdown products of Octanoic acid, compound with dicyclohexylamine (1:1): Octanoic acid and Dicyclohexylamine.Since no toxicokinetic studies are available the toxicokinetic behavior is based on the physico-chemical properties and the available literature data of the two substances.

a)    Absorption

Oral absorption:

Octanoic acid:

Octanoic acid is a linear saturated fatty acid and is ubiquitous in nature. The metabolic pathway is well established, similar for all fatty acids: complete catabolism for energy supply or conversion to fat suitable for storage.

Free medium-chain fatty acids can be expected to be quickly and completely absorbed from the intestine. For oral application of Octanoic acid 100% absorption can therefore be assumed.

DCHA:

According to the available information from animal studies dicyclohexylamine is readily absorbed after oral application (1).

The low molecular weight (181.3) of DCHA and the moderate water solubility favours absorption in the gastro-intestinal tract. However, the high log Pow (4.37; calculated by KOWWIN) of DCHA render absorption in the gastro-intestinal tract by passive diffusion to be unlikely. It can therefore be assumed that DCHA may be taken up by micellular solubilisation. For risk assessment purposes, the oral absorption of DCHA is set at 100%.

Dermal absorption:

 

Octanoic acid:

Undissociated Octanoic acid with a log POW of 3.03 (calculated with KOWWIN) is expected to easily penetrate and cross cell membranes. As it is found with absorption from the gut, it is appropriate to assume that the permeation through skin is easy.

In the absence of a dermal uptake study and for the purpose of risk assessment 100% absorption of octanoic acid through the skin will be assumed.

 

DCHA:

Since the log Pow is high (4.37;calculated with KOWWIN), DCHA is expected to be taken up in the stratum corneum, further transfer to the epidermis is predicted to be moderate based on the water solubility of ca. 1 g/l. For a water solubility between100 – 10,000 mg/l dermal absorption is anticipated to be moderate to high (2). According to the criteria given in the REACH guidance (2) 10% dermal absorption will be considered in case MW>500 and log Pow <-1 and >4, otherwise 100% dermal absorption is assumed.

In consequence, 100 % dermal absorption is proposed for DCHA.

 

Respiratory absorption:

 

The moderate water solubility of octanoic acid (789 mg/l) and DCHA (1 g/l) enhances readily diffusion/dissolution into the mucus lining the respiratory tract.

Lipophilic substances like octanoic acid and DCHA (log P >0) would then have the potential to be absorbed directly across the respiratory tract epithelium (2).

For risk assessment purposes the inhalation absorption of octanoic acid and DCHA is set at 100%.

b)   Distribution

 

Octanoic acid:

After absorption from the gut octanoic acid is extensively metabolised in the liver. Only a minor fraction bypasses the liver and becomes distributed to peripheral tissues via the general circulation.

 

DCHA:

DCHA may be expected to distribute widely throughout the body based on the small molecular weight, the lipophilicity and moderate water solubility.

The lipophilicity of DCHA also predicts that the intracellular concentration may be higher than the extracellular concentration, particularly in fatty tissues. Based on the relatively high lipophilicity DCHA may accumulate (2).

.

 

c)    Metabolism

 

Octanoic acid:

It is well known that aliphatic linear carboxylic acids are metabolised in the fatty acid β-oxidation pathway, the tricarboxylic acid cycle, or the C1-tetrahydrofolate pathways.

C8 and C10 fatty acids are catabolised predominantly in the liver to C2 fragments, which are further converted to CO₂or used to synthesize longer-chain fatty acids.

The metabolites formed in the liver from C8 and C10 fatty acids are also substances normally present and part of the physiological system.

 

DCHA:

No further information is available.

 

d)   Excretion:

 

Octanoic acid:

In humans fatty acids are metabolised by different mechanism as an energy source. Fattyacids are stored as lipids in adipose tissue and used as components of cellular structure andsignaling molecules. Therefore, fatty acids arenot expected to be excreted in the urine orfaeces under normal physiological conditions.

 

DCHA:

According to literature data Dicyclohexylamine is readily absorbed after oral application andis excreted via urine (1).

The metabolites are expected to be low molecular weight compounds.

 

 

Based on the present data no further conclusions about the toxicokinetic behavior of thesubstances can be drawn and no further assessment is possible.

 

 

4.   References:

 

(1)  Organisation for Economic Co-operation and Development (OECD): “SIDS Initial Assessment Report For SIAM 22, Dicyclohexylamine”, Paris, France, 18–21 April 2006

 

(2)  “Guidance for the implementation of REACH. Guidance on information requirements and

chemical safety assessment. Chapter R.7c: Endpoint specific guidance”,Version 3.0 June 2017 EuropeanChemical Agency, June 2017

 

(3)  V. A. Filov: “Die Untersuchung des Verhaltens von Cyclohexylamin (CHA) und Dicyclohexylamin (DCHA) im Körper“,Gig. Tr. Prof. Zabol. 7, 29-33 (1968)

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Absorption rate - oral (%):

100

Absorption rate - dermal (%):

100

Absorption rate - inhalation (%):

100