Juniper, Juniperus mexicana, ext.

Endpoint summary

Description of key information

Toxicokinetic evaluation of Cedarwood Texas oil – crude(CAS#: 91722-61-1) based on existing data

 REACH indicates that an “assessment of the toxicokinetic behaviour of the substance to the extent that can be derived from the relevant available information” should be performed at Annex VIII level.

 

General information

Cedarwood Texas oil - Crude is a substance of Unknown or Variable composition, Complex reaction products or Biological material (UVCB substances), or more specifically a NCS (Natural Complex Substance). As such, the essential oil of Cedarwood Texas obtained from the wood of Juniperus mexicana (Cupressaceae) by distillation.

Name-Constituent	CAS Number-Constituent	EC Number-Constituent	Concentration range %
Bergamotene alpha (cis + trans)	17699-05-7	241-702-9	0.01-1
α-Cedrene β-Cedrene	469-61-4 546-28-1	207-418-4 208-898-8	1-25 1-8
Cedrol	77-53-2	201-035-6	16-40
Cuparene	16982-00-6	241-061-5	0.01-5
Thujopsene	470-40-6	207-426-8	18-45
α-Himachalene β-Himachalene γ-Himachalene	3853-83-6 1461-03-6 53111-25-4		0.01-2 0.01-2 0.01-2
α-Chamigrene	19912-83-5		0.01-4
Diepi-alpha-cedrene	50894-66-1		0.01-2
Widdrol	6892-80-4		0.5-5
Unknown and other minor consituents			0-15

ADME data

Absorption, distribution, metabolism and excretion data onCedarwood Texas oil - Crude itself are not available and therefore the toxicokinetic assessment is based on the available toxicology data forCedarwood Texas oil - Crude, as well as data for the main constituents. 

 

Information from physico chemical and toxicity studies

An overview of the relevant physicochemical parameters for Cedarwood Texas oil - Crude is provided below:

	Cedarwood Texas oil - Crude
Physical state	Liquid
Structure	UVCB
Molecular weights	202.34 - 222.37 g/mol
Particle size	Not relevant
Log Kow	4.33 - 6.94. 100 % of the identified constituents in the substance log Kow >= 4.0.
Water solubility (mg/l)	0.03 - 29.25 mg/L at 25°C. 100 % of the identified constituents in the substance has a water solubility < 100 mg/L.
Boiling point (°C)	262.9°C at 1003 ± 5 hPa
Initial vapour pressure	3.96 Pa at 25°C. The vapour pressure of the constituents ranges from 0.01 - 9.37 Pa.

Absorption

Oral: As the molecular weight range of this UVCB is below 500, the molecules in this UVCB are likely to be absorbed via the oral/GI tract. Uptake throughaqueous pores or carriage of such molecules across membranes with the bulk passage of waterin the GI tract can be expected. Furthermore uptake by passive diffusion is likely based on the moderate log Kow values of Cedarwood Texas oil - Crude. The oral absorption of the more highly lipophilic constituents of this UVCB (log Kow > 4) may be more dependent on micellar solubilisation.

Based on the previous,the substancecould be absorbed in the human body via the oral route. This is supported by the findingsin an OECD TG 422 feeding study that was performed with the read across source substance Cedarwood Virginia oil, which contains the same constituents with some variations in their concentration. The source substance induced systemic effects such as nephropathy in male rats. Furthermore, liver effects and reduced T4 levels were observed. These findings confirm that systemic absorption of the constituents of the UVCB via the gastrointestinal tract takes place.

 

Dermal:No acute dermal toxicity was observed in rabbits exposed to 5000 mg/kg bwCedarwood Texas oil - Crude. Even though it is not a corrosive, the skin irritating propertiesobserved in the OECD TG 439in vitro skin irritation test performed with the read across substance Cedarwood Texas oil - Cedrol suggest that this UVCB may damage the skin and therebyincrease its penetrating potential.Furthermore, sensitisation is also observed for this substance in an OECD TG 429 study, therefore some uptake of (constituents of) this UVCB ought to occur.Based on the physico chemical properties of the substance, its molecular weight would not exclude dermal uptake, and its water solubility and logP value would predict low to moderate absorption of at least a part of its constituents (ECHA guidance, 7.12, Table R.7.12-3).

 

In order to assess the potential for dermal absorption, the absorption of all components in this UVCB was calculated using the IH Skinperm tool version 2.0. In the model the following input was used as a worst-case, which resulted in the highest dermal absorption:

Instantaneous deposition: 100 mg;

Affected skin area: 1,000 cm2;

Maximum skin adherence: 3 mg/cm2 (due to the high melting points of constituents);

Thickness of stagnant air: 10 cm;

Weight fraction: 1;

Observation time: up to complete absorption (taking into account evaporation);

Calculated intervals: 10,000.

     

The substance specific input for Skinperm was taken from the QPRF document and Substance Identity Profile. Missing information was taken from reliable sources such as the ECHA substance database, the Gestis substance database, Dohsbase or Chemspider. The following input was used.

 

Name	CAS	Typical conc.(%)	MW	Vapour pressure(Pa)	Water solubility (mg/L)	Log Kow	Density(g/mL)	Melting point	Max skin adh. (mg/cm^2)	Weighted max. Dermal fraction absorbed
Bergamotene alpha	17699-05-7	0.60%	204.36	3.69	0.27926	6.57	0.9	33.68	9	0.0080%
Cedrene alpha	469-61-4	20.00%	204.36	0.0184	0.042587	5.74	0.9	43.77	9	1.4080%
Cedrene beta	546-28-1	6.80%	204.36	6.08	0.032021	5.82	0.9	41.79	9	0.0135%
Cedrol	77-53-2	23.00%	222.37	0.0165	8.7229	4.33	1	75.52	10	3.7490%
Cuparene	16982-00-6	3.50%	202.34	0.773	0.50078	6.19	0.9	60.05	9	0.0101%
Thujopsene	470-40-6	31.50%	204.36	9.37	0.059998	6.12	1	48.5	10	0.0721%
Himachalene alpha	3853-83-6	0.90%	204.35	2.8	0.54268	6.3	0.9	43.42	9	0.0116%
Himachalene beta	1461-03-6	1.00%	204.35	1.47	1.1378	6.35	0.9	54.06	9	0.0195%
Himachalene gamma	53111-25-4	1.20%	204.35	2.13	0.72174	6.22	0.9	44.68	9	0.0185%
Chamigrene alpha	19912-83-5	1.50%	204.35	2.28	1.0168	6.94	0.9	50.66	9	0.0309%
Diepi-alpha-cedrene	50894-66-1	1.23%	204.35	0.0184	0.042587	5.74	0.9	106	9	0.0239%
Widdrol	6892-80-4	2.00%	222.37	0.00951	29.254	4.84	1	78.8	10	0.6140%

The weighted permeability of the whole UVCB, calculated using the IH Skinperm tool was 6.41% and this will be used for risk assessment. This number is corrected for the unknown and minor constituents (6.77%) not taken into account in the Skinperm modelling.

 

Inhalation: The lipophilicity of the main constituents (log Kow >4), and a low water solubility indicate that uptake via the lungs may be mainly via micellular solubilisation. These physico-chemical propertieswould also facilitate absorption directly across the respiratory tract epithelium following aspiration.

 

Distribution

Distribution of Cedarwood Texas oil - Crude and its major constituents is expected based on their relatively low molecular weights. Also distribution throughout the body would be possible due to the low to moderate water solubility, while the higher Log Kow range also suggests possible distribution into cells. A higher intracellular concentration is expected, especially in fatty tissues. Signs of toxicity and target organs suggest that the substance is at least distributed to the liver and kidney.

 

Metabolism

No information on metabolism can be derived from the physicochemical data that is available for Cedarwood Texas oil - Crude. No information on metabolism of the UVCB is available from studies, but the main constituents of the UVCB substance Cedarwood Texas oil - Crude; Thujopsene, Cedrol and Cedrene α/β are known to have an (inhibitory) effect on Cytochrome p450 enzyme activities[1]. Hepatic phase 1 metabolism mediated by P450 is therefore a likely mechanism. This is expected to be followed by attachment of the phase II polar groups in the liver before elimination. Hepatic involvement is supported by the liver effects that were observed in the OECD TG 422 read-across study.

 

Elimination

Based on the systemic renal effects observed in the OECD TG 422 read-across study, excretion is expected to take place though the kidney. This is supported by the relatively low molecular weights. Excretion via bile is not likely, as in the rat it has been found that substances with molecular weights below around 300 do not tend to be excreted into the bile (Renwick, 1994)[2]. Some excretion via breast milk, saliva and sweat is cannot be excluded, as some constituents of the UVCP can be regarded as lipophilic (Log Kow > 4).

 

Accumulation

There is the potential for the more highly lipophilic constituents of this UVCB (log P >4) to accumulate in individuals that are frequently exposed (e.g. daily at work) to these substances. Once exposure stops, the concentration within the body will decline at a rate determined by the half-life of the substance (Rozman and Klaassen, 1996)[3].

[1]Hyeon-Uk Jeong, Soon-Sang Kwon, Tae Yeon Kong, Ju Hyun Kim & Hye Suk Lee. (2014) Inhibitory Effects of Cedrol, β-Cedrene, and Thujopsene on Cytochrome P450 Enzyme Activities in Human Liver Microsomes. Journal of Toxicology and Environmental Health, Part A Vol. 77 , Iss. 22-24.

[2]Renwick AG (1994) Toxicokinetics - pharmacokinetics in toxicology. In Hayes,A.W. (ed.) Principles and Methods of Toxicology. Raven Press, New York, USA, pp.103.

[3]Rozman KK and Klaassen CD (1996) Absorption, Distribution, and Excretion of Toxicants.In:Klaassen CD (Ed.) Cassarett and Doull's Toxicology: The Basic Science of Poisons. McGraw-Hill, New York, USA.

 

Data from other studies

	Cedarwood Texas oil - Crude
Skin irritation / corrosivity	Skin irrit. 2 (read across from Cedrol, Cedarwood Texas oil distilled)
Dermal toxicity data	Not classified. No symptoms or mortality observed.
Oral toxicity data	Not classified. No symptoms or mortality observed.
Skin sensitisation data	Skin Sens. 1B / H317 (read across from Cedrol, Cedarwood Texas oil distilled)
Repeated dose toxicity	Nephropathy in male rats (hyaline droplet accumulation), hepatocellular hypertrophy in female rats.(read across from Cedarwood Virginia oil)

Conclusion

Oral uptake expected based on information from available studies (acute and repeated dose oral toxicity) and favourable physico chemical parameters. Dermal absorption would be possible based on information from available (read-across) studies and physicochemical parameters. Relatively wide distribution and excretion through urine expected based on low/moderate water solubility and low  molecular weight. The absorption values to be used for hazard assessment are 100% for the inhalation route, 50% for the oral route and 6.41% for the dermal route.

[1]Hyeon-Uk Jeong, Soon-Sang Kwon, Tae Yeon Kong, Ju Hyun Kim & Hye Suk Lee. (2014) Inhibitory Effects of Cedrol, β-Cedrene, and Thujopsene on Cytochrome P450 Enzyme Activities in Human Liver Microsomes. Journal of Toxicology and Environmental Health, Part A Vol. 77 , Iss. 22-24.

[1]Renwick AG (1994) Toxicokinetics - pharmacokinetics in toxicology. In Hayes,A.W. (ed.) Principles and Methods of Toxicology. Raven Press, New York, USA, pp.103.

[1]Rozman KK and Klaassen CD (1996) Absorption, Distribution, and Excretion of Toxicants.In:Klaassen CD (Ed.) Cassarett and Doull's Toxicology: The Basic Science of Poisons. McGraw-Hill, New York, USA.

 

Key value for chemical safety assessment

Bioaccumulation potential:

low bioaccumulation potential

Absorption rate - oral (%):

50

Absorption rate - dermal (%):

6.41

Absorption rate - inhalation (%):

100