2-chlorobenzaldehyde

Endpoint summary

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

dermal absorption in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

year of publication: 1988

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: sufficiently documented literature data

Reason / purpose for cross-reference:

reference to same study

Principles of method if other than guideline:

percutaneous absorption

GLP compliance:

not specified

Radiolabelling:

yes

Remarks:

2-Chloro(carbonyl-14C)benzaldehyde

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: TNO, Zeist (The Netherlands)
- Age at study initiation: about 6 weeks
- Individual metabolism cages: yes
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: at least three days prior to experiments rats were housed in individual glass metabolism cages
- Air was drawn through the metabolism cage (volume 24 l) at a rate of 400 ml/min; pressure inside the cage was somewhat lower than outside
- polyethylene catheters (I.D. 0.4 mmmm; O.D. 0.8 mm) were placed into the femoral artery and the jugular vein and led subcutaneously to the nuchal area where they went out of the body

Type of coverage:

other: non-occluding glass cup

Vehicle:

unchanged (no vehicle)

Duration of exposure:

72 hours

Doses:

75 µl/kg (1.83 mCi/ml)

No. of animals per group:

8

Control animals:

no

Details on study design:

Preparation of dose:
- radiolabelled substance was pipetted undiluted in the cup, which was closed immediatly afterwards with a glass cover using the cyanoacrylate adhesive

TEST SITE
- Preparation of test site: shaved, 16 hours before application
- Area of exposure: right dorsal skin,
- Type of cover: with a glass cup (I.D. 16 mm, O.D. 24 mm, height: 10 mm) which was fixed to the skin with cyanoacrylate adhesive; the cup was glued in such a way that no contact between the glass or the adhesive with the treated skin was possible.


SITE PROTECTION / USE OF RESTRAINERS FOR PREVENTING INGESTION: yes: glass cup

REMOVAL OF TEST SUBSTANCE
- Washing procedures and type of cleansing agent: the glass was rinsed with methanol
- exposed skin was widely excised, cut into small pieces and solubilized bevor counting of radioactivity


SAMPLE COLLECTION
- Collection of blood: from femural artery
- Collection of urine and faeces: urine was colleted for 72 hours after the administration; faeces was collected at daily intervals


ANALYSIS
- radioactivity was measured by liquid scintillation counting (for details see below)

Signs and symptoms of toxicity:

not specified

Dermal irritation:

no effects

Absorption in different matrices:

Plasma radioactivity increases slowly after percutaneous application. Peak-plasma concentrations of 4000-6000 dpm/g (approximately 0.1 % of dose) were reached 10-15 hours post dosing. Plasma-radioactivity declined slowly, the calcualted half-life ranged between 20 and 40 h.

Total recovery:

- Total recovery: 102.7% +/- 9.12
- Recovery of applied dose acceptable: yes
- Results adjusted for incomplete recovery of the applied dose: no

Dose:

75 µl/kg bw

Parameter:

percentage

Absorption:

ca. 85 %

Remarks on result:

other: 72 hours

Remarks:

calculated as difference between applied dose and residual dose on the skin survace and glass-cup

Percent of administered radioactivity after percutaneous application (values are means +/- SD)

	Skin (n=8)
Dose (µl/kg)	75
Urine
0 -12 h	21.1 +/- 14.62
12 -24 h	24.3 +/- 6.33
24 -48 h	22.7 +/- 6.65
48 -72 h	13.0 +/- 6.25
Total Urine	81.1 +/- 13.98
Faeces Total	3.1 +/- 1.25
14CO2 Total (Exhaled)	1.1 +/- 0.48
Glasscup	11.7 +/- 8.27
On Skin	4.1 +/- 5.15
In Skin	1.6 +/- 1.27
Recovery	102.7 +/- 9.12

Conclusions:

The test substance was almost entirely absorbed into the rat-skin within 72 hours, although the percutaneous absorption process was slow. The total absorbed dose was mainly excreted via urine. There was no evidence of storage in the skin or skin toxicity after cutaneous application of the test item.

Executive summary:

Rats were exposed to 14C-radiolabelled 2-chlorobenzaldehyde via percutaneous application (75 µl/kg). After dermal application of the test item in a glass-cup a slow skin penetration was observed as indicated by plasma radioactivity levels. The slow increase in plasma radioactivty was followed by a slow decline of radioactivity in plasma over a 3-day period. Percutaneous absorption was nearly complete (about 85%), as could be calculated from the difference between the applied dose and the residual dose. The test item was mainly eliminated via urine (about 81% of the administered dose), radioactivity in faeces and exhaled air were below 5% of the administered dose. There was no evidence of skin toxicity or storage in the skin after test substance application.

This well performed study was judged to be reliable with restriction (RL2) and has been selected as key study.

Reference 2

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

year of publication: 1988

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Sufficently documented literature data

Reason / purpose for cross-reference:

reference to same study

Objective of study:

metabolism

Principles of method if other than guideline:

investigation of metabolism in vivo

GLP compliance:

not specified

Radiolabelling:

yes

Remarks:

2-Chloro(carbonyl-14C)benzaldehyde

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

- Source: TNO, Zeist (The Netherlands)
- Age at study initiation: about 6 weeks
- Individual metabolism cages: yes
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: at least three days prior to experiments rats were housed in individual glass metabolism cages
- Air was drawn through the metabolism cage (volume 24 l) at a rate of 400 ml/min; pressure inside the cage was somewhat lower than outside
- polyethylene catheters (I.D. 0.4 mmmm; O.D. 0.8 mm) were placed into the femoral artery and the jugular vein and led subcutaneously to the nuchal area where they went out of the body

Route of administration:

other: dermal, intravenous, intraperitoneal

Vehicle:

water

Details on exposure:

DERMAL EXPOSURE:
Preparation of dose:
- radiolabelled substance was pipetted undiluted in the cup, which was closed immediatly afterwards with a glass cover using the cyanoacrylate adhesive

TEST SITE
- Preparation of test site: shaved, 16 hours before application
- Area of exposure: right dorsal skin,
- Type of cover: with a glass cup (I.D. 16 mm, O.D. 24 mm, height: 10 mm) which was fixed to the skin with cyanoacrylate adhesive; the cup was glued in such a way that no contact between the glass or the adhesive with the treated skin was possible.


SITE PROTECTION / USE OF RESTRAINERS FOR PREVENTING INGESTION: yes: glass cup

REMOVAL OF TEST SUBSTANCE
- Washing procedures and type of cleansing agent: the glass was rinsed with methanol
- exposed skin was widely excised, cut into small pieces and solubilized bevor counting of radioactivity


SAMPLE COLLECTION
- Collection of blood: from femural artery
- Collection of urine and faeces: urine was colleted for 72 hours after the administration; faeces was collected at daily intervals

INTRAVENOUS AND INTRAPERITONEAL EXPOSURE:

25 µl/kg bw of the radiolabelled test substance (specific radioactivity 1.83 mCi/ml dissolved in 1 ml of 2% aqueous solution of Tween-60) were injected into the jugular vein catheter, duration about 4 minutes; 37.5 µl/kg were applied intraperitoneally.

Duration and frequency of treatment / exposure:

72 hours (dermal application)
single exposure (i.v. and i.p. application)

Remarks:

Doses / Concentrations:
75 µl/kg (dermal application)
25 µl/kg (i.v. application)
37.5 µl/kg (i.p. application)

No. of animals per sex per dose / concentration:

8 (dermal application),
6 (i.v. application),
2 (i.p application)

Control animals:

no

Positive control reference chemical:

none

Details on dosing and sampling:

METABOLITE CHARACTERISATION STUDIES
- Tissues and body fluids sampled: urine
- Time and frequency of sampling: dermal application: 0-12 h, 12-24 h, 24-48 h, 48-72 h; i.v. and i.p. application: 0-6 h, 6-24 h
- From how many animals: no data
- Method type(s) for identification: thin layer chromatography
- Limits of detection and quantification: no data

Metabolites identified:

yes

Details on metabolites:

More than 95% of the radioactivity in the urine was ethyl acetate extractable. Metabolic patterns of urinary excreted metabolites of the test item were quite similar after dermal, i.v. and i.p. application, apart from some quantitative differences. None 14C-2-chlorobenzaldehyde was identified in the urine. 2-Chlorohippuric acid was the main metabolite excreted (about 65% to 75% depending on the application route). Additionally, 2-chlorobenzylmercapturic acid, 2-chlorobenzoic acid and 2-chlorobenzyl alcohol were identified as urinary metabolites. 14C-2-chlorobenzyl alcohol was mostly excreted in the urine collected on the second day (24-48 h) of cutaneously treated rats. This metabolite was found in much smaller amounts in the urin of rats which were treated i.v. or i.p. 2-Chlorobenzyl alcohol and 2-chlorobenzoic acid accounted for abour 15% of the total urinary radioactivity.

Conclusions:

Interpretation of results (migrated information): no bioaccumulation potential based on study results concluded by supplier
2-Chlorobenzaldehyde is extensively metabolised in rats. 2-Chlorohippuric acid is the main metabolite. 2-Chlorobenzyl alcohol, 2-chlorbenzoic acid and 2-chlorobenzylmercapturic acid were identified as further metabolites. No unchanged compound was identified in the urine.

Executive summary:

Urinary metabolites of 14C-2-chlorobenzaldehyde were identified in rats treated percutaneously, intravenously or intraperitoneally. The principal metabolite in rat urine was 2-chlorohippuric acid. Additionally, 2-chlorobenzyl alcohol, 2-chlorobenzoic acid, which accounted for about 15% of urinary radioactivity, and 2-chlorobenzylmercapturic acid were identified in the urine by means of thin layer chromatography. No unchanged compound was detected in the urine.

The study has been judged to be reliable with restrictions (RL2). It was selected as key study.

Reference 3

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

year of publication: 1988

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Sufficently documented literature data

Reason / purpose for cross-reference:

reference to same study

Objective of study:

toxicokinetics

Principles of method if other than guideline:

elimination after intravenous or intraperitoneal application

GLP compliance:

not specified

Radiolabelling:

yes

Remarks:

2-Chloro(carbonyl-14C)benzaldehyde

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: TNO, Zeist (The Netherlands)
- Age at study initiation: about 6 weeks
- Individual metabolism cages: yes
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: at least three days prior to experiments rats were housed in individual glass metabolism cages
- Air was drawn through the metabolism cage (volume 24 l) at a rate of 400 ml/min; pressure inside the cage was somewhat lower than outside
- polyethylene catheters (I.D. 0.4 mmmm; O.D. 0.8 mm) were placed into the femoral artery and the jugular vein and led subcutaneously to the nuchal area where they went out of the body

Route of administration:

other: intravenous and intraperitoneal

Vehicle:

water

Details on exposure:

25 µl/kg bw of the radiolabelled test substance (specific radioactivity 1.83 mCi/ml dissolved in 1 ml of 2% aqueous solution of Tween-60) were injected into the jugular vein catheter, duration about 4 minutes; 37.5 µl/kg were applied intraperitoneally.

Duration and frequency of treatment / exposure:

single application

Remarks:

Doses / Concentrations:
25 µl/kg (i.v. application)
37.5 µl/kg (i.p. application)

No. of animals per sex per dose / concentration:

6 (i.v. application), 2 (i.p application)

Control animals:

no

Positive control reference chemical:

none

Details on dosing and sampling:

Urine, faeces and gas-washing bottle samples containing expired 14CO2 were collected over a 24 hour experimental period.

Details on excretion:

After i.v. or i.p. administration the radioactivity in plasma declined in a bi-exponential fashion over a period of 24 h. Plasma radioactivity time profiles were very similar after i.v. and i.p. dosing. The first elimination phase with a 14C-half life of 15.6 minutes was followed by a slower second one. No radioactivity was retained in the red blood cells.
The test item was mainly excreted via urine, only small amounts were found in the faeces and in the exhaled air. Excretion was complete (> 99%) within 24 hours, the majority of the radioactivity (about 90%) was recovered in the 0-6 h urine.

Toxicokinetic parameters:

half-life 1st: 15.6 min

Percent of administered radioactivity after intravenous (i.v.) and intraperitoneal (i.p.) application (values are means +/- SD)    i.v. (n=6)  i.p. (n=2)  Dose (µl/kg)  25  37.5  Urine        0 -6 h  88.7 +/- 4.59  95.8 +/- 0.71   6 -24 h  8.8 +/- 2.33  6.0 +/- 0.28  Total Urine  97.5 +/- 3.57  101.8 +/- 0.99  Faeces Total  2.2 +/- 0.91  2.4 +/- 0.14  14CO2 Total (Exhaled)  0.4 +/- 0.32  0.3 +/- 0.0  Recovery  100.1 +/- 3.56  104.5 +/- 0.85

Conclusions:

Interpretation of results (migrated information): no bioaccumulation potential based on study results
The test item is rapidly and completely eliminated within 24 hours after intravenous and intraperitoneal application to rats. Excretion is mainly via urine and only small amounts were found in the faeces and exhaled air.

Executive summary:

Radiolabelled 14C-2-chlorobenzaldehyde was applied intravenously (25 µl/kg) or intraperitoneally (37.5 µl/kg) to male Wistar rats. Radioactivity was measured in blood, urine, faeces and exhaled air. The test item was rapidly and completely eliminated within 24 hours after intravenous and intraperitoneal application to rats. Excretion was mainly via urine (about 98%) and only small amounts were found in the faeces and exhaled air. Plasma elimination followed a bi-exponential fashion, the 14C half-life during the first elimination phase was 15.6 min.

The study has been judged to be reliable with restrictions (RL2). It was selected as key study.

Description of key information

Short description of key information on bioaccumulation potential result: 
2-Chlorobenzaldehyde is nearly completely absorbed after oral application. It is is mainly excreted via urine (at least 95%) and only to a minor extend via faeces or exhaled air after oral, dermal, intraperitoneal and intravenous application. It is readily metabolised. There seems to be no potential for bioaccumulation.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Additional information

Data on basic toxicokinetics and metabolism of 2-chlorobenzaldehyde are provided in the following section. Additionally, toxicokinetic data on [(2-chlorophenyl)methylene]malononitrile (CS), which rapidly hydrolyzes to 2-chlorobenzaldehyde and is reduced to a minor extent (about 10%) to 2-chlorobenzyl malononitrile, are presented. Based on the observation, that CS mainly decomposes to 2-chlorobenzaldehyde the usefullness of toxicity data on CS in sections where data on 2-chlorobenzaldehyde are missing, is discussed.

Discussion on bioaccumulation potential result:

Toxicokinetics and metabolism of 2-chlorobenzaldehyde have been investigated in several studies. The test item is nearly completely absorbed after oral and dermal application (Brewster et al., 1987; Leadbeater, 1973; Rietveld et al., 1988). Percutaneous absorption of 2-chlorobenzaldehyde was nearly complete (about 85%) after 72 hours of exposure. 2-Chlorobenzaldehyde is mainly excreted via urine (about 95%) and only to a minor extend via faeces or exhaled air after oral, dermal, intraperitoneal and intravenous application (Rietveld et al., 1988; Brewster et al., 1987). Main metabolites identified in rat urine after oral application were 2-chlorohippuric acid (43%), 2-chlorobenzylcystein (23%), 2-chlorobenzoic acid (16%), and 2-chlorobenzylglucuronic acid (13%). Only 5% were identified as 2-chlorobenzyl alcohol. No unchanged compound was detected in the urine (Brewster et al., 1987). Similar findings were obtained after percutaneous, intraperitoneal and intravenous application (Rietveld et al., 1988). The test item was rapidly and completely eliminated within 24 hours after intravenous and intraperitoneal application to rats. Plasma elimination followed a bi-exponential fashion, the 14C half-life during the first elimination phase was 15.6 min (Rietveld et al., 1988). Even shorter half-life times were reported for cats in vivo (4.5 seconds) and for cats, rats and men in vitro (70 sec, 15 sec and 15 sec, respectively).

2-Chlorobenzaldehyde is a hydrolysis product of the riot control agent [(2-chlorophenyl)methylene]malononitrile (CS). CS is mainly hydrolyzed to 2-chlorobenzaldehyde and only to a lesser extent (about 10%) reduced to 2-chlorobenzyl malononitrile after oral application to rats or intravenous injection to rabbits (Brewster et al., 1987; Paradowski, 1979). Like 2-chlorobenzaldehyde CS is mainly excreted via urine (82%) and only to a lesser extent via faeces within 96 hours after oral application to rats. Less than 1% of the applied dose were detected in the expired air. Main metabolites identified in the urine of rats after oral application of CS were 2-chlorohippuric acid (49% of dose), 2-chlorobenzyl glucopyranosuric acid (9.8% of the administered dose), 2-chlorobenzylcystein (8.2% of the administered dose), 2-chlorobenzoic acid (8.2% of the administered dose), chlorophenyl acetylglycine (3.3% of the administered dose), 2-chlorobenzyl alcohol (1.6% of the administered dose), and 2 -chlorophenyl 2 cyanopropionate (1.6% of the administered dose). These data indicate that CS is mainly decomposed to 2-chlorobenzaldehyde after oral or intravenous injection.

2-chlorobenzyl malononitrile was the main metabolite identified in the blood of cats and rats after inhalative exposure to CS whereas 2-chlorobenzaldehyde was only detectable in smaller amounts than the dihydry product (Leadbeater, 1973). The reasons for these differences in dependence on the route of application are unknown.

Due to these exposure-path dependent differences in the blood concentrations of 2-chlorobenzaldehyde after exposure to CS it is concluded that data on inhalative exposure of CS are not appropriate for the evaluation of 2-chlorobenzaldehyde toxicity in a read across approach but that data after oral or parenteral exposure to CS may be usefull for the evaluation of 2-chlorobenzaldehyde in a read across approach.