Benzyldimethyl(octadecyl)ammonium chloride

Acute Toxicity: dermal

Administrative data

Endpoint:

acute toxicity: dermal

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Based on the available weight of evidence experimental studies, the test substance, C18 ADBAC, is expected to be have a poor absorption potential through oral and dermal routes and primarily excreted via faeces. Based on QSAR predictions, it is likely to undergo aliphatic hydroxylation as the first metabolic reaction. Further, based on the MW and key physico-chemical properties it is likely to have low bioaccumulation potential.

Bioaccumulation potential:

low bioaccumulation potential

Absorption rate - oral (%):

10

Absorption rate - dermal (%):

10

Absorption rate - inhalation (%):

100

ABSORPTION:

Oral absorption

Based on physicochemical properties:

According to REACH guidance document R7.C (May 2014), oral absorption is maximal for substances with molecular weight (MW) below 500. Water-soluble substances will readily dissolve into the gastrointestinal fluids; however, absorption of hydrophilic substances via passive diffusion may be limited by the rate at which the substance partitions out of the gastrointestinal fluid. Further, absorption by passive diffusion is higher at moderate log Kow values (between -1 and 4). If signs of systemic toxicity are seen after oral administration (other than those indicative of discomfort or lack of palatability of the test substance), then absorption has occurred.

The test substance, C18 ADBAC is a mono-constituent substance, which is an alkyl benzyl dimethyl ammoniumchloride (ADBAC) type of cationic surfactant with C18 as major alkyl chains. Its MW is 424.15 g/mol. The purified form of the substance is a white solid, with low water solubility of 19-20.8 mg/L at 20°C (based on CMC) and a moderate log Kow of 3.89 (calculated based on solubility in octanol and water/CMC).

Based on the R7.C indicative criteria, and considering that the test substance is highly ionic therefore, it is expected not to be readily absorbed from the gastrointestinal tract.

Based on experimental data on read across substances:

A toxicokinetic study was conducted with the radiolabelled read across substance, C12-16 ADBAC, according to OECD Guideline 417, in compliance with GLP. Rats were treated with single and repeated oral doses (50 or 200 mg/kg bw) as well as a single dermal dose of 1.5 or 15 mg/kg bw. Following single and/or repeated oral doses, the plasma, blood and organ radioactivity levels were essentially non-quantifiable, indicating a low oral bioavailability. The actual fraction of the oral dose absorbed was about 8% (urine and bile fractions). This was eliminated rapidly, essentially within a 48 to 72 hour period. The majority of the oral dose was excreted in the faeces. At the high oral dose level only, quantifiable levels of radioactivity (2,386 to 23,442 ηg equivalent/g) were found in some central organs at 8 hour post-dosing; otherwise, the vast majority of the dose was confined to the intestines and levels decreased over time. Only about 4% of the oral dose was eliminated in the bile in a 24 hour period, of which 30% was eliminated during the first 3 hours (Appelqvist, 2006).

Conclusion:Overall, based on the available weight of evidence information, the test substance can be expected to overall have low absorption potential through the oral route. Therefore, as a conservative approach a value of 10% has been considered for the risk assessment.

Dermal absorption

Based on physicochemical properties:

According to REACH guidance document R7.C (ECHA, 2017), dermal absorption is maximal for substances having MW below 100 together with log Kow values ranging between 2 and 3 and water solubility in the range of 100-10,000 mg/L. Substances with MW above 500 are considered to be too large to penetrate skin. Further, dermal uptake is likely to be low for substances with log P values <0 or <-1, as they are not likely to be sufficiently lipophilic to cross thestratum corneum (SC). Similarly, substances with water solubility below 1 mg/L are also likely to have low dermal uptake, as the substances must be sufficiently soluble in water to partition from the SC into the epidermis.

The test substance is a white solid, with an MW exceeding 100 g/mol, low water solubility and a calculated log Kow greater than 3. This together with the fact that the test substance is highly ionic suggests that the test substance is likely to have a low penetration potential through the skin.

Based on experimental data on read across substance:

In theAppelqvist (2006) study,following single dermal application at 1.5 and 15 mg/kg bw, the plasma and blood radioactivity levels were non-quantifiable at nearly all time-points. For the 1.5 mg/kg bw group, around 2% and 43% of the dose was eliminated in the urine and faeces, respectively, mostly within a 48h period, suggesting that the dermal dose was highly absorbed via the skin. However, as the test site was not protected with an Elizabethan collar during the main part of the collection period (the collar was worn during the 6h exposure period only), this may have been due to the animal licking the test site. This is also supported with the finding that after oral dosing only about 4% was excreted via bile back to intestine, and 4% excreted via urine. If similar routes of excretion are expected for dermal absorbed doses, it would not be possible to find levels of 50% of applied doses in intestine with only 2% excreted via urine. This indicates that about 50% of the dermal applied dose was taken up orally after all, which following the same oral kinetics leads to the 2% excretion in urine as indeed was observed. At 24h post-dosing, most of the radioactivity was in the "stripped" skin (dermis/epidermis) application site (15.02/8.74% [male/female] and 33.8/24.2% of the dose for the high and low dose groups respectively) and intestines for both dose-levels (5.76/8.32% and 5.61/7.79% of the dose for the high and low dose groups respectively), though some radioactivity was in the skin adjacent to the application site and minor traces were in the eyes (both most likely from cross-contamination due to grooming). At 168 h, levels in the application site of the individual animals of the low dose were 5.19 to 9.21% of the radioactive dose, suggesting the skin acted as a drug reservoir. In the stratum corneum of the application site, the levels of radioactivity were of similar magnitude in the different layers at each time-point. For all tissues/organs, the radioactivity levels essentially decreased over time.

Based on QSAR prediction:

The two well-known parameters often used to characterise percutaneous penetration potential of substances are the dermal permeability coefficient (Kp[1]) and maximum flux (Jmax). Kp reflects the speed with which a chemical penetrates across SC and Jmax represents the rate of penetration at steady state of an amount of permeant after application over a given area of SC. Out of the two, although Kp is more widely used in percutaneous absorption studies as a measure of solute penetration into the skin. However, it is not a practical parameter because for a given solute, the value of Kp depends on the vehicle used to deliver the solute. Hence, Jmax i.e., the flux attained at the solubility of the solute in the vehicle is considered as the more useful parameter to assess dermal penetration potential as it is vehicle independent (Robert and Walters, 2007).

In the absence of experimental data, Jmax can be calculated by multiplying the estimated water solubility with the Kp values from DERMWIN v2.01 application of EPI Suite v4.11. The calculated Jmax for the main constituent was 2.22E-08 μg/cm2/h. As per Shenet al.2014, the default dermal absorption for substances with Jmax is ≤0.1 μg/cm2/h can be considered to be less than 10%. Based on this, the test substance can be predicted to have low absorption potential through the dermal route.

Conclusion: Overall, based on all the available weight of evidence information, the test substance can be expected to have a low absorption potential absorption through the dermal route. Therefore, as a conservative approach a default value of 10% has been considered for the risk assessment.

Inhalation absorption

Based on physicochemical properties:

According to REACH guidance document R7.C (ECHA, 2017), inhalation absorption is maximal for substances with VP >25 KPa, particle size (<100 μm), low water solubility and moderate log Kow values (between -1 and 4). Very hydrophilic substances may be retained within the mucus and not available for absorption.

Based on estimated vapour pressure values from different QSAR models (see section 1.3 of CSR) overall the test substance is considered to have low volatility potential under ambient conditions. Therefore, the substance is expected neither to be available for inhalation as vapours nor as aerosols. Further, if at all there is any inhalation exposure, considering the low water solubility of the substance, it is not expected to be retained in the mucus and almost the entire test substance amount is likely to reach the lower respiratory tract followed by absorption into the blood stream. The absorption fate of the deposited material thereafter is expected to be similar to the oral route/gastrointestinal tract.

Conclusion:Based on the above information, if exposed the test substance can be expected to have moderate to high absorption through the inhalation route. Therefore, as a conservative approach, a default value of 100% has been considered for the risk assessment.

METABOLISM:

Based on QSAR modelling:

The OECD Toolbox was used to predict the first metabolic reaction, since the rat liver S9 metabolism simulator performs predictions for salts, while SMARTCyp and MetaPrint2D are not powered enough for this type of substances. The second simulator of the OECD Toolbox (in vivo rat metabolism simulator) was not used as it does not consistently perform predictions for salts. As per the rat liver S9 metabolism simulator, all the major constituents (present at >5%) are primarily predicted to undergo ω or ω-1 aliphatic hydroxylation reactions. See table in CSR for the reaction sites. For further details, refer to the RA read across justification.

Similar reactive sites were predicted for structurally similar ADBACs.

BIOACCUMULATION:

Based on the MW and physicochemical information and metabolism prediction, the bioaccumulation potential of the substance is expected to be low.

EXCRETION:

Based on the evidence from the available toxicokinetic study (Appelqvist, 2006), the test substance is primarily expected in faeces (>90%) and less via urine (<10%).

[1]Log Kp = -2.80 + 0.66 log kow – 0.0056 MW

Cross-reference 2

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Remarks:

Modified Draize test

Type of information:

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

Adequacy of study:

key study

Study period:

1974

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Justification for type of information:

Refer to the section 13 of IUCLID dataset for details on the read across justification. The algae study with the read across substance is considered sufficient to fulfil the information requirements as further explained in the provided endpoint summary.

Reason / purpose for cross-reference:

read-across source

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Version / remarks:

Cited as Directive 84/449/EEC, B.6

Deviations:

no

GLP compliance:

no

Type of study:

other: Modification of the Draize technique (Draize, Woodward and Calvery 1944 NAS-NRC 1964).

Justification for non-LLNA method:

The Local Lymph Node Assay (LLNA; TG 429) was adopted in 2002.

Species:

guinea pig

Route:

intradermal

Vehicle:

water

Concentration / amount:

Induction 0.1% intracutaneous
Challenge 0.1% intracutaneous

Day(s)/duration:

1 day

Route:

intradermal

Vehicle:

water

Concentration / amount:

Induction 0.1% intracutaneous
Challenge 0.1% intracutaneous

Day(s)/duration:

1 day

No. of animals per dose:

6

Details on study design:

- 1st application: Induction 0.1 % intracutaneous
- 2nd application: Challenge 0.1 % intracutaneous
For the induction phase, 0.1 mL of a concentration of 0.1% of test substance in water was injected intradermally into the back of each six guinea pigs. This procedure was repeated every other days, using a different injection site on each occasion, until a total of nine injections had been given. Injection sites were examined 24h after each injection and scored for erythema and oedema using the Draize scale.
After completion of this series of priming injections the animals remained untreated for two weeks, and were then given a single challenge intradermal injection of the same concentration and volume as for induction. Injection sites were examined 24h after this challenge dose as before for erythema and oedema. The effects were compared to those produced by the priming doses in order to determine whether sensitisation had been produced.

Positive control substance(s):

no

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

0.1%

No. with + reactions:

0

Total no. in group:

6

Remarks on result:

other: See 'Any other information on results incl. tables'

Key result

Reading:

1st reading

Group:

negative control

Remarks on result:

not measured/tested

Key result

Reading:

1st reading

Group:

positive control

Remarks on result:

not measured/tested

Modified Draize test:

- The priming injections elicited very slight to well defined erythema, and very slight to slight oedma on all occasions.
- The challenge dose produced a well defined erythema and very slight oedema in all occasions.

As the challenge doses did not produce any greater reaction in any animal, it may be concluded that is not a sensitising
agent under the conditions of this experiment.

Interpretation of results:

other: CLP criteria not met

Remarks:

not classified

Conclusions:

Based on the results of the study, the test substance is considered to be non-sensitizing to guinea pig skin.

Executive summary:

A study was conducted to determine the skin sensitisation potential of the read across substance, C12 -16 ADBAC (active: 50%), according to a method similar to EU Method B.6 (modified Draize test). For the induction phase, 0.1 mL of 0.1% test substance in water was injected intradermally into the back of each six guinea pigs. This procedure was repeated every other day, using a different injection site on each occasion, until a total of nine injections had been given. Injection sites were examined 24 h after each injection and scored for erythema and oedema using the Draize scale. After a two week interval, a single challenge intradermal injection of the same concentration and volume was given as for induction. Injection sites were examined 24 h after this challenge dose as before for erythema and oedema. The effects were compared to those produced by the priming doses in order to determine whether sensitisation had been produced. The priming injections elicited very slight to well defined erythema, and very slight to slight oedema on all occasions. The challenge dose produced a well-defined erythema and very slight oedema in all occasions. However, the challenge doses did not produce any greater reaction in any animal. Under the study conditions, the read across substance was cosidered to be non-sensitizing to guinea pig skin (Thomas, 1974). Based on the results of the read across study, a similar non-sensitising behaviour can be expected for the the test substance, C18 ADBAC.

Cross-reference 3

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

acute toxicity: oral

Type of information:

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

Adequacy of study:

key study

Study period:

From November 07, 1987 to December 03, 1987

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Justification for type of information:

Refer to section 13 of IUCLID for details on the read-across justification. The study with the read across substance is considered sufficient to fulfil the information requirements as further explained in the provided endpoint summary.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test type:

other: Acute oral toxicity

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Route of administration:

oral: gavage

Vehicle:

other: undiluted test substance

Doses:

500, 794, 1,260 and 2,000 mg/kg bw

No. of animals per sex per dose:

10

Details on study design:

Dose selection was based upon the results of a range-finding study. Animals, 5 males and 5 females per dose group, were administered the undiluted test substance in a single oral dose by gavage. Animals were observed 1 and 4h after dosing and subsequently once daily for 14 d. Deaths and evidence of overt toxicity were recorded at each observation. Individual body weights were recorded on the d of treatment (Day 0), Days 7 and 14, and at death. All animals were subjected to gross necropsy examination for any macroscopic abnormalities.

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

795 mg/kg bw

Based on:

test mat.

95% CL:

>= 585 - <= 1 081

Remarks on result:

other: (795 mg/kg bw equivalent to 397.5 mg a.i./kg bw

Gross pathology:

Necropsy of decedents revealed abnormally red lungs, dark livers, haemorrhage and ulceration of the gastric mucosa and congestion of the small intestines. Major abnormalities seen at necropsy of animals killed at termination were white thickened areas of the non-glandular region of the stomach. Scattered white raised areas were also noted.

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

Based on the results from the study, the LD50 was determined to be 795 mg/kg bw (equivalent to 397.5 mg a.i./kg bw) for male and females.

Executive summary:

A study was conducted to determine the acute oral toxicity of the read across substance, C12-16 ADBAC (active: 50%), according to OECD Guideline 401, in compliance with GLP. Five male and five female rats per dose group were administered the undiluted test substance (50% purity) in a single oral dose by gavage at the dose levels of 500, 794, 1260 and 2000 mg/kg bw. Animals were observed 1 and 4 h after dosing and subsequently once daily for 14 d. Mortality and evidence of overt toxicity were recorded at each observation. Individual body weights were recorded on the day of treatment (Day 0), Days 7 and 14, and at termination. All animals were subjected to gross necropsy examination for any macroscopic abnormalities. Under the study conditions, the LD50 of the read across substance was considered to be 795 mg/kg bw (equivalent to 397.5 mg a.i./kg bw) for male and females combined, with 95% confidence levels of 585 - 1081 (Jones, 1986). Based on the results of the read across study, similar oral LD50 value can be considered for the test substance, C18 ADBAC, for acute oral toxicity in rats.