Registration Dossier

Administrative data

Description of key information

Chronic oral toxicity (similar to OECD TG 453, Read across from Citral)
Rat: NOAEL 100 mg/kg bw/day
Mouse: LOAEL  60 mg/kg bw/day

Subchronic oral toxicity (similar to OECD TG 408, Read across from Citral)

Rat: LOAEL 335 mg/kg bw/day

Mouse: LOAEL 745 mg/kg bw/day

Subchronic inhalation toxicity (Weight of evidence, Read across from Citral: Gaworski 1992,1993)

rat: NOAEC 34 ppm = 215 mg/m3

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Referenceopen allclose all

Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
June 1995 - September 1995
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Comparable to guideline study with minor restrictions.
Reason / purpose:
reference to same study
Reason / purpose:
reference to same study
Reason / purpose:
reference to same study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents)
Deviations:
yes
Remarks:
(partly other organ weights and clinical chemistry parameters, no urinalysis or ophthalmological examination)
GLP compliance:
yes
Remarks:
FDA GLP regulations
Species:
mouse
Strain:
B6C3F1
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Taconic Laboratory Animals and Services, Germantown, N.Y.
- Age at study initiation: 6 weeks
- Weight at study initiation: males ca. 20 g, females ca. 16.5 g
- Fasting period before study: no
- Housing: males inidividually, females 5 per cage
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 13 to 14 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 °C (calculated from 72° +- 3° F)
- Humidity (%): 50% +- 15%
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12 / 12


IN-LIFE DATES: From: June 7 or 8, 1995 To: September 7 or 8, 1995
Route of administration:
oral: feed
Vehicle:
other: microcapsules loaded with citral
Details on oral exposure:
DIET PREPARATION
- Rate of preparation of diet (frequency): every 2 to 4 weeks
- Mixing appropriate amounts with nonirradiated NTP-2000 feed: final concentrations of 3,900, 7,800, 15,600, or 31,300 ppm citral were achieved by adding loaded and/or placebo microcapsules at a total concentration of 10% microcapsules
- Storage temperature of food: room temperature

VEHICLE
- Justification for use and choice of vehicle: microcapsules prepared from food-grade sugar and starch were loaded with citral to prevent loss of test substance
- Concentration in vehicle: 31.3 % citral (analytical method GC)
- Lot/batch no.: 20295
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
periodic verification by GC
Duration of treatment / exposure:
14 weeks
Frequency of treatment:
continuously
Remarks:
Doses / Concentrations:
3900, 7800, 15600, or 31300 ppm
Basis:
nominal in diet
Remarks:
Doses / Concentrations:
745, 1840, 3915, and 8110 mg/kg bw/d
Basis:
other: actual ingested by male mice
Remarks:
Doses / Concentrations:
790, 1820, 3870, and 7550 mg/kg bw/d
Basis:
other: actual ingested by female mice
No. of animals per sex per dose:
10
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: based on pre-study of Dieter et al., 1993
Positive control:
Not necessary
Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: weekly

BODY WEIGHT: Yes
- Time schedule for examinations: initially, weekly, and at termination of study

FOOD CONSUMPTION AND COMPOUND INTAKE : weekly
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: day 4, 22 and after 14 weeks of treatment
- Anaesthetic used for blood collection: Yes (carbon dioxide)
- Animals fasted: No data
- How many animals: 10 per dose
- Parameters: erythrocyte, reticulocyte, platelet counts, hematocrit, hemoglobin concentration, erythrocyte morphology, mean cell volume, mean cell hemoglobin, mean cell hemoglobin concentration, leukocyte counts and differentials

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: day 4, 22 and after 14 weeks of treatment
- Anaesthetic used for blood collection: Yes (carbon dioxide)
- Animals fasted: No data
- How many animals: 10 per dose
- Parameters: urea nitrogen, creatinine, total protein, albgumin, alanine aminotransferase, alkaline phosphatase, creatinine kinase, sorbitol dehydrogenase, bile acids

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No
Sacrifice and pathology:
GROSS PATHOLOGY: Yes

ORGAN WEIGHTS: Yes
heart, right kidney, liver, lung, right testis, thymus

HISTOPATHOLOGY: Yes
Complete histopathology performed on untreated controls, vehicle controls, dose groups with food concentrations of 15,600, or 31,300 ppm;
examined tissues: gross lesions and tissue masses, adrenal gland, bone with marrow, brain, clitoral gland, esophagus, gallbladder, heart and aorta, large intestine, small intestine, kidney, liver, lung and mainstem bronchi, lymph nodes , mammary gland (females only), nose, ovary, pancreas, parathyroid gland, pituitary gland, preputial gland, prostate gland, salivary gland, skin, spleen, stomach, testis with epididymis and seminal vescicles, thymus, thyroid gland, trachea, urinary bladder, uterus
In addition, examination of forestomach and of ovaries of lower dose groups to find a NOEL
Statistics:
Body weights: Williams' or Dunnett's test
Hematology or clinical chemistry data: Dunn's or Shirley's test
Details on results:
CLINICAL SIGNS AND MORTALITY
31300 ppm: 4 males killed moribund in second week of treatment
clinical signs: at 15600 and 31300 ppm animals were generally thin and appeared lethargic; at 7800 ppm few males were also thin
other dose groups: all animals survived to the end of the study

BODY WEIGHT AND WEIGHT GAIN (for details see Table 1)
all dose groups: significant dose-dependent decreases of final mean body weight and of body weight gain
31300 ppm: final weight < initial weight

FOOD CONSUMPTION AND COMPOUND INTAKE (for details see Table 1)
from 7800 ppm: females showed decreased food consumption during first study week
all doses: by the end of the study, food consumption was greater than by vehicle control
Evaluation: increased food consumption may have been due to the mice scattering feed, an indication of poor palatability

HAEMATOLOGY
week 14: from 15600 ppm: significant dose-dependent decreases of leukocyte and lymphocyte counts; in male mice lymphocyte counts were already decreased at 3900 and 7800 ppm without a dose-dependency, however, some other parameters were increased at single dosages showing no biological relevance.
Evaluation: These changes together with marked suppression in mean body weights may reflect a physiological response consistent with a stress-related and/or corticosteroid-induced lymphopenia.

ORGAN WEIGHTS
Significant decreases of absolute organ weights, increases of relative organ weights (for details see Table 1)
Evaluation: differences in organ weights between exposed mice and vehicle controls reflected body weight differences and were not toxicologically significant

GROSS PATHOLOGY
No exposure-related changes

HISTOPATHOLOGY: NON-NEOPLASTIC
Forestomach:
from 15,600 ppm: wall of forestomach of many males and females (incidences not given) variably thickened (2 to 5times normal), mucosa (squamous epithelium) and submucosa were often rugose; additionally, minimal hyperkeratosis of epithelium being insignificant
Evaluation: Although thickened, all three main components (mucosa, submucosa, and muscle) appeared proportional to each other and to those of control animals. Therefore alteration considered to be the result of a contradicted stomach rather than a pathological alteration.
Ovaries:
from 15,600 ppm: increased incidences of ovarian atrophy characterized by absence of or reduction in the number of corpora lutea with no effect on primary, secondary, or antral follicles; incidences 0/10, 0/10, 7/10, 10/10, vehicle control 0/10
Evaluation: NTP Pathology Working group considered these lesions most probably to represent hypoplasia being most likely a secondary effect due to the poor condition of female mice in these dose groups.
Dose descriptor:
LOAEL
Effect level:
745 mg/kg bw/day (actual dose received)
Sex:
male
Basis for effect level:
other: reduced final body weight and body weight change / dose corresponds to 3900 ppm in diet
Dose descriptor:
LOAEL
Effect level:
790 mg/kg bw/day (actual dose received)
Sex:
female
Basis for effect level:
other: reduced final body weight and body weight change / dose corresponds to 3900 ppm in diet
Critical effects observed:
not specified

Table 1: Survival, body weights, feed consumption, and organ weights of mice in the 14-week feed study of citral

 Concentration  Survival  Final body weight (g)  Weight change (g)  Feed consumption (g/animal/d)     Organ weight changes e
         Week 1  Week 14  absolute  relative
Males              
 Vehicle control  10/10  33.2 +- 0.8  12.6 +- 0.7  4.4  4.5  -  -
 3900 ppm  10/10  28.1 +- 0.6b  7.9 +- 0.6b  4.6  5.0  -  kidneyclivercthymusd
 7800 ppm  10/10  25.6 +- 0.6b 5.2 +- 0.4b  4.3  5.9  kidneybthymusa heartckidneycliverclungd
 15600 ppm  10/10  21.3 +- 0.6b  1.3 +- 0.5b  4.0  6.2  kidneybliverbtestisbthymusa heartckidneycliverlungcthymusc
 31300 ppm  6/10 17.1 +- 0.4b  -2.9 +- 0.4b  4.1  6.2   kidneybliverblungbtestisbthymusb    heartckidneycliverlungcthymusd
  Females            
  Vehicle control  10/10   29.8 +- 0.7   13.4 +- 0.8   3.4   3.6  -   -
  3900 ppm  10/10   26.1 +- 0.4b   9.5 +- 0.4b   3.3   5.1  -    heartckidneycliverthymusd
  7800 ppm    10/10   21.2 +- 0.4b   4.2 +- 0.4b   2.3   6.4  -    heartckidneycliverlungcthymusc
  15600 ppm   10/10  18.2 +-0.2b  1.4 +- 0.3b  2.3  6.5   kidneyb  heartckidneycliverlungcthymusc
31300 ppm   10/10  16.2 +- 0.2b  -0.2 +- 0.2b  2.1  5.3   kidneybliverblunga  heartckidneycliverlungcthymusc 

Significant changes in comparison to vehicle control:

a significant decrease, p=0.05; b significant decrease, p=0.01; c significant increase, p=0.01; d significant increase, p=0.05

e The relevance of observed organ weight changes is discussed in "Details on results"

Conclusions:
Based on the results of the study, the LOAELs of Citral were set at 745 and 790 mg/kg bw/day (3900ppm) in males and females respectively (based on decreased body weight).
Executive summary:

The substance Citral (Reaction mass of (E)-3,7-dimethylocta-2,6-dienal and (Z)-3,7-dimethylocta-2,6-dienal) has been tested in a study similar to OECD TG 453. Groups of male and female B6C3 mice were exposed to microencapsulated citral (greater than 96% pure) in feed for 14 weeks. The concentration of Citral in the diet was equivalent to average daily doses of approximately 745 - 8,110 mg/kg to males and 790 -  7,550 mg/kg to females.

Effects observed:In the second week of the study, four males in the high dose group were killed moribund. Lower mean body weights. Mice in the mid and high dose groups were generally thin and lethargic. The incidences of ovarian atrophy were significantly increased in females exposed to mid and high doses.

The LOAELs at 14 weeks were determined at 745 and 790 mg/kg bw/day (3900ppm) in males and females respectively (based on decreased body weight).

Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
June 1995 - September 1995
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Comparable to guideline study with minor restrictions
Reason / purpose:
reference to same study
Reason / purpose:
reference to same study
Reason / purpose:
reference to same study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents)
Deviations:
yes
Remarks:
(exposure 98 days, partly other organ weights and other clinical chemistry parameters, no urinalysis or ophthalmological examination)
GLP compliance:
yes
Remarks:
FDA GLP regulations
Species:
rat
Strain:
Fischer 344
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Taconic Laboratory Animals and Services, Germantown, N.Y.
- Age at study initiation: ca. 6 weeks
- Weight at study initiation: ca. 80 g
- Fasting period before study: no
- Housing: 5 per cage
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 11 to 12 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 °C (calculated from 72° +- 3° F)
- Humidity (%): 50% +- 15%
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12 / 12


IN-LIFE DATES: From: June 5 or 6, 1995 To: September 5 or 6, 1995
Route of administration:
oral: feed
Vehicle:
other: microcapsules loaded with citral
Details on oral exposure:
DIET PREPARATION
- Rate of preparation of diet (frequency): every 2 to 4 weeks
- Mixing appropriate amounts with nonirradiated NTP-2000 feed: final concentrations of 3900, 7800, 15600, or 31300 ppm citral were achieved by adding loaded and/or placebo microcapsules at a total concentration of 10% microcapsules
- Storage temperature of food: room temperature

VEHICLE
- Justification for use and choice of vehicle: microcapsules prepared from food-grade sugar and starch were loaded with citral to prevent loss of test substance
- Concentration in vehicle: 31.3 % citral (analytical method GC)
- Lot/batch no.: 20295
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
periodic verification by GC
Duration of treatment / exposure:
14 weeks
Frequency of treatment:
continuously
Remarks:
Doses / Concentrations:
3900, 7800, 15600, 31300 ppm
Basis:
nominal in diet
Remarks:
Doses / Concentrations:
ca. 345, 820, 1785, and 1586 mg/kg bw
Basis:
other: actual ingested by male rats
Remarks:
Doses / Concentrations:
ca. 335, 675, 1330, and 1215 mg/kg bw
Basis:
other: actual ingested by female rats
No. of animals per sex per dose:
10
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale:based on pre-study of Dieter et al., 1993
Positive control:
not necessary
Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: weekly

BODY WEIGHT: Yes
- Time schedule for examinations: initially, weekly, and at termination of study

FOOD CONSUMPTION AND COMPOUND INTAKE : weekly
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: day 4, 22 and after 14 weeks of treatment
- Anaesthetic used for blood collection: Yes (carbon dioxide)
- Animals fasted: No data
- How many animals: 10 per dose
- Parameters: erythrocyte, reticulocyte, platelet counts, hematocrit, hemoglobin concentration, erythrocyte morphology, mean cell volume, mean cell hemoglobin, mean cell hemoglobin concentration, leukocyte counts and differentials

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: day 4, 22 and after 14 weeks of treatment
- Anaesthetic used for blood collection: Yes (carbon dioxide)
- Animals fasted: No data
- How many animals: 10 per dose
- Parameters: urea nitrogen, creatinine, total protein, albgumin, alanine aminotransferase, alkaline phosphatase, creatinine kinase, sorbitol dehydrogenase, bile acids

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No
Sacrifice and pathology:
GROSS PATHOLOGY: Yes

ORGAN WEIGHTS: Yes
heart, right kidney, liver, lung, right testis, thymus

HISTOPATHOLOGY: Yes
Complete histopathology performed on untreated controls, vehicle controls, dose groups with food concentrations of 15,600, or 31,300 ppm;
examined tissues: gross lesions and tissue masses, adrenal gland, bone with marrow, brain, clitoral gland, esophagus, heart and aorta, large intestine, small intestine, kidney, liver, lung and mainstem bronchi, lymph nodes , mammary gland, nose, ovary, pancreas, parathyroid gland, pituitary gland, preputial gland, prostate gland, salivary gland, skin, spleen, stomach, testis with epididymis and seminal vescicles, thymus, thyroid gland, trachea, urinary bladder, uterus
In addition, examination of bone marrow and forestomach (both sexes) and of kidney (male rats) of lower dose groups to find a NOEL.
Specific staining of hyaline droplets in renal tubules with H&E and Mallory Heidenhain stains
Statistics:
Body weights: Williams' or Dunnett's test
Hematology or clinical chemistry data: Dunn's or Shirley's test
Details on results:
CLINICAL SIGNS AND MORTALITY
31300 ppm: all rats killed moribund in second week of treatment; clinical signs were listlessness, hunched posture, absent or slow paw reflex, dull eyes
other dose groups: all animals survived to the end of the study, no clinical signs reported

BODY WEIGHT AND WEIGHT GAIN (for details see Table 1)
all dose groups: significant decrease of final mean body weight; signifcant decrease of body weight gain in all dosed males
from 7800 ppm: signifcant decrease of body weight gain in females

FOOD CONSUMPTION AND COMPOUND INTAKE (for details see Table 1)
from 15600 ppm: decreased food consumption during first study week resulting in lowered average daily doses of the rats of the 31,300 ppm-group which were killed untimely

HAEMATOLOGY
Changes tended to be transient and to improve with increased duration of exposure. They were in general not observed after day 22:
day 4: from 7800 ppm significant increases in hematocrit values, hemoglobin concentrations, erythrocyte and platelet counts; significant decreases in mean cell volumes, mean cell hemoglobin values, reticulocyte and nucleated erythrocyte counts
day 22: 15600 ppm significant decreases in mean cell volumes and mean cell hemoglobin values
week 14: male rats: significant increase of mean cell volume; female rats: significant decrease of mean cell volumes, significant increase of erythrocyte counts
Evaluation - no effects: Changes in erythrocyte and platelet counts were consistent with known physiologic responses related to decreased food and water consumption, and were not considered to be a direct cause of a toxic action of citral.

CLINICAL CHEMISTRY
Generally, the changes tended to be transient and to improve with increased duration of exposure:
day 4: from 3900 ppm: both sexes: significant increase of urea nitrogen; male rats: significant increase of albumin
from 15600 ppm: both sexes: significant decrease of alkaline phosphatase; male rats: significant increase of total protein;
female rats: significant increase of bile acids
day 22: from 3900 ppm: male rats: significant increase of urea nitrogen
from 7800 ppm: female rats: significant increase of alkaline phosphatase
15,600 ppm: both sexes: significant increase of albumin; female rats: significant increase of urea nitrogen and bile acids
week 14: 7800 ppm: male rats: significant increase of albumin
from 7800 ppm: female rats: significant increase of alkaline phosphatase
15600 ppm: male rats: significant increase of urea nitrogen
Evaluation - no effects: Decreased food consumption (see Table 1) and possibly water consumption (no data available) were discussed as causes of physiological responses leading to the changes of serum biochemical parameters. Alterations in albumin, total protein, and urea nitrogen concentrations may be related to possible dehydration or to decreased glomerular filtration rates due to renal damage. The decreases in alkaline phosphatase activity may reflect a loss of circulating intestinal isoenzyme fraction related to decreased feed consumption. In females, bile acid concentration and alkaline phosphatase were increased at 15600 ppm and 31300 ppm. In general, these parameters are considered indicators of bile stasis and would suggest that a cholestatic event may have occurred. However, alterations were of minimal severity and transient, and there was no histopathologic evidence of cholestasis, suggesting that these changes were not biologically significant.

ORGAN WEIGHTS (for details see Table 1)
Evaluation - no effects: Changes were minor with significant decreases of absolute organ weights and significant increases of relative organ weights. These were considered to be related to the significant decreases of final body weight and to be of no biological relevance or toxicologically significance.

GROSS PATHOLOGY
No exposure-related changes

HISTOPATHOLOGY: NON-NEOPLASTIC
Forestomach:
at 31300 ppm after premature sacrifice in the second week epithelial hyperplasia (2/10 m, 4/10 f) and hyperkeratosis (2/10 m, 4/10 f) , with thickening of stratified squamous epithelium and of the cornified superficial layer of the mucosa were observed, no signs of inflammation; significant increase in f, p<=0.01
Bone marrow:
at 15600 ppm increased incidence of minimal grade of atrophy in 7/10 m and 8/10 f, p<=0.01;
31,300 ppm: all males showed atrophy and hemorrhage; incidences in f: atrophy 4/10, p<=0.05, hemorrhage 9/10, p<=0.01
Thymus:
at 31300 ppm atrophy in 5/10 m and 4/10 f, p<=0.05
Kidney:
minimal to mild nephropathy present in males of all dose groups with incidences of 3/10, 10/10, 8/10, 0/10 (premature termination of high dose group), vehicle control 0/10, with significant increases at 7800 and 15600 ppm, p<=0.01; changes characterized by foci of regenerative epithelium, occasional eosinophilic casts, peritubular mononuclear inflammation, and dilated tubules;
Granular casts in renal tubules in males of all dose groups with incidences of 3/10, 10/10, 10/10, 0/10 (premature termination of high dose group), vehicle control 0/10, with significant increases at 7800 and 15600 ppm, p<=0.01; changes characterized by few and scattered granular casts within the outer strip of the medulla, dilated tubules filled with granular eosinophilic material presumed to be proteinacious material and cellular debris; no apparent increase in the amount of hyaline droplets.
Testes:
aspermia in all males at 31000 ppm
Evaluation: Findings in the forestomach, thymic atrophy, and aspermia in the testes were limited to the high dose group that had to be sacrificed in the second study week due to moribundity. It was not clear if the bone marrow lesions in the same dose group were a direct effect of citral toxicity or due to inanition. At the lower dose of 15600 ppm minimal atrophy of bone marrow without accompanying hemorrhage was considered a borderline lesion. Concerning the renal changes in male rats of all dose groups, the presence of granular casts and exacerbation of spontaneous nephropathy would be suggestive of an alpha2µ globulin nephropathy. However, it was considered that renal lesions were not mediated by alpha2µ globulin as there was no increased incidence of hyaline droplets.
Dose descriptor:
LOAEL
Effect level:
345 mg/kg bw/day (actual dose received)
Sex:
male
Basis for effect level:
other: decrease of final body weight and body weight change / dose corresponds to 3900 ppm in diet
Dose descriptor:
LOAEL
Effect level:
335 mg/kg bw/day (actual dose received)
Sex:
female
Basis for effect level:
other: decrease of final body weight / dose corresponds to 3900 ppm in diet
Critical effects observed:
not specified

Table 1: Survival, body and organ weight data, and feed consumption in the 14-day feeding study with citral

 Concentration  Survival  Final body weight (g)  Weight change (g)  Feed consumption (g/animal/d)     Organ weight changes e
         Week 1  Week 14  absolute  relative
Males              
 Vehicle control  10/10  336 +-6  255 +-6  15.4  18.7  -  -
 3900 ppm  10/10  318 +-6a  238 +-5b  15.9  19.9  -  kidneyctestisc
 7800 ppm  10/10  292 +-4b  208 +-3b  15.1  20.1  heartblungathymusb kidneycliverctestisc
 15600 ppm  10/10  247 +-4b  163 +-4b  8.4  15.6  heartbliverblungbthymusb kidneyclivertestisc
 31300 ppm  0/10  -  -  4.0  -  -  -
  Females            
  Vehicle control  10/10   190 +-4   108 +-4   12.8   10.7  -   -
  3900 ppm  10/10   180 +-4a   101 +-4   11.6   9.6  -   kidneyc
  7800 ppm    10/10   181 +-2a   97 +-2a   11.8   10.8  -   kidneyc
  15600 ppm   10/10  166 +-2b  82 +-2b  6.5  10.2  heartc  kidneycliverd
31300 ppm   0/10  -  -  4.7  -  -  -

Significant changes in comparison to vehicle control:

a significant decrease, p<=0.05; b significant decrease, p<=0.01; c significant increase, p<=0.01; d significant increase, p<=0.05

e The relevance of observed organ weight changes is discussed in "Details on results"

Conclusions:
Based on the results of the study, the LOAELs of Citral were set at 345 and 335 mg/kg bw (3900ppm) for male and female rats based on decreased body weight.
Executive summary:

The substance Citral (Reaction mass of (E)-3,7-dimethylocta-2,6-dienal and (Z)-3,7-dimethylocta-2,6-dienal) has been tested in a study similar to OECD TG 408. Groups of male and female F344/N rats were exposed to microencapsulated citral (greater than 96% pure) in feed for 14 weeks. Dose used in rats were equivalent to 345-1,585 mg citral/kg body weight for males and 335- 2,125 mg/kg for females.

Effects observed: Lower mean body weights, and feed consumption. Males and females in the high dose group exhibited listlessness, hunched posture, absent or slow paw reflex, and dull eyes. Some evidence of forestomach epithelial hyperplasia and hyperkeratosis, bone marrow atrophy and hemorrhage, and nephrotoxicity was observed.

Based on these results the LOAEL of rats at 14 weeks was set at 345 and 335 mg/kg bw (3900ppm) based on decreased body weight.

Endpoint:
chronic toxicity: oral
Remarks:
combined repeated dose and carcinogenicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
June 1995 - September 1995
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Comparable to guideline study with acceptable restrictions.
Reason / purpose:
reference to same study
Reason / purpose:
reference to same study
Reason / purpose:
reference to same study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 453 (Combined Chronic Toxicity / Carcinogenicity Studies)
Deviations:
yes
Remarks:
(complete histopathology for all dose groups; no parameters of hematology, clinical chemistry or urinalyses measured)
GLP compliance:
yes
Remarks:
FDA GLP regulations
Species:
mouse
Strain:
B6C3F1
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Taconic Laboratory Animals and Services, Germantown, N.Y.
- Age at study initiation: 6 weeks
- Weight at study initiation: males ca. 20 g, females ca. 16.5 g
- Fasting period before study: no
- Housing: males inidividually, females 5 per cage
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 13 to 15 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 °C (calculated from 72° +- 3° F)
- Humidity (%): 50% +- 15%
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12 / 12

IN-LIFE DATES: From: June 19 or 20, 1996 To: June 15-19 (males) or June 22-24 (females), 1998
Route of administration:
oral: feed
Vehicle:
other: microcapsules loaded with citral
Details on oral exposure:
DIET PREPARATION
- Rate of preparation of diet (frequency): every 4 weeks
- Mixing appropriate amounts with nonirradiated NTP-2000 feed: final concentrations of 0, 500, 1000, or 2000 ppm citral were achieved by adding loaded and/or placebo microcapsules at a total concentration of 1.25% microcapsules
- Storage temperature of food: room temperature

VEHICLE
- Justification for use and choice of vehicle: microcapsules prepared from food-grade sugar and starch were loaded with citral to prevent loss of test substance
- Concentration in vehicle: 31.9 % citral (analytical method GC)
- Lot/batch no.: MRI 020196MC
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
periodic verification by GC
Duration of treatment / exposure:
104-105 weeks
Frequency of treatment:
continuously
Remarks:
Doses / Concentrations:
0, 500, 1000, 2000 ppm
Basis:
nominal in diet
Remarks:
Doses / Concentrations:
ca. 0, 60, 120, 260 mg/kg bw/d
Basis:
actual ingested
No. of animals per sex per dose:
50
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: based on 14-week pre-study described in same study report
Positive control:
Not necessary
Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: day 8, 36, and every 4 weeks thereafter, at end of study

BODY WEIGHT: Yes
- Time schedule for examinations: day 0, 8, 36, and every 4 weeks thereafter, at end of study

FOOD CONSUMPTION AND COMPOUND INTAKE : weekly
- Food consumption for each cage determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes, approximately every 4 weeks for a 1-week period
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: No

CLINICAL CHEMISTRY: No

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No
Sacrifice and pathology:
GROSS PATHOLOGY: Yes

HISTOPATHOLOGY: Yes
Complete histopathology performed on all mice:
examined tissues: gross lesions and tissue masses, adrenal gland, bone with marrow, brain, clitoral gland, esophagus, gallbladder, heart and aorta, large intestine, small intestine, kidney, liver, lung and mainstem bronchi, lymph nodes , mammary gland (females only), nose, ovary, pancreas, parathyroid gland, pituitary gland, preputial gland, prostate gland, salivary gland, skin, spleen, stomach, testis with epididymis and seminal vescicles, thymus, thyroid gland, trachea, urinary bladder, uterus
Statistics:
Probability of survival: product-limit procedure of Kaplan and Meier
dose-related effects on survival: Cox's method, Tarone's life table test
Body weight data: parametric multiple comparison procedures of Dunnett and Williams
Incidences of non-neoplastic lesions: Poly-3 test (Bailer and Portier, 1988)
Details on results:
CLINICAL SIGNS AND MORTALITY
Survival of all dosed groups similar to vehicle control groups; no clinical findings attributable to citral exposure

BODY WEIGHT AND WEIGHT GAIN (for details see Table 1)
Mean body weights were generally less compared to those of the vehicle controls in the following dose groups and study periods:
females: at 500 ppm from week 30-102, at 1000 ppm from week 14-102, at 2000 ppm during whole study period;
males: at 1000 ppm from year 2, at 2000 ppm during whole study period.
Final body weights (101 w): females: 91%, 88% and 78% of controls; males: 93%, 91% and 84% of controls for 500, 1000, 2000 ppm respectively.

FOOD CONSUMPTION AND COMPOUND INTAKE (for details see Table 1)
Comparable to vehicle control

PATHOLOGY: NON-NEOPLASTIC
- Oral mucosa: Inflammation and ulceration
Incidences: present in all groups including vehicle controls with significantly increased incidences in all exposed female mice and 2000 ppm male mice (for incidences see Table 2)
Location: areas of inflammation and ulceration directly medial to the molar teeth in most cases; ulceration almost always located at the points were hair shafts penetrated the oral mucosa
Characterization of inflammation: minimal to mild severity (see Table 2), accumulation of mixed inflammatory cells within and just beneath the oral mucosa adjacent to the medial aspect of the teeth; in a majority of cases hair shafts present in the inflamed areas and appeared to have penetrated the tooth socket
Characterization of ulceration: minimal to mild severity (see Table 2), focal areas with loss of mucosa
Evaluation: inflammation and ulceration were considered to be secondary to embedded hair shafts. The same lesions, with similar severity, were present in vehicle controls. Thus, lesions in the oral mucosa were considered probably not a direct toxic effect of citral, but citral may have exacerbated the secondary inflammatory response in females. The significance of this effect is unknown.

- Adrenal cortex: focal hyperplasia, significant increase in 2000 ppm male mice (for incidences see Table 2)
Evaluation: Incidences were very low for this common background lesion and are therefore not considered to reflect a toxic response to citral exposure.

- Bone: fibrosis, significant increase in 500 and 1000 ppm female mice (see Table 2)
Evaluation: The significance of this effect without dose-relationship is unknown.

- Kidney: minimal nephropathy with significant increase in 2000 ppm females and minimal renal tubule mineralization with significant increase in 500 and 1000 ppm females (for incidences see Table 2)
Evaluation: The toxicological significance of increased incidences of these minimal changes also present in vehicle controls is unclear.

PATHOLOGY: NEOPLASTIC
Equivocal evidence of treatment-related induction of malignant lymphoma in female mice: Findings are presented in Section 7.7 in detail.

Dose descriptor:
LOAEL
Effect level:
60 mg/kg bw/day (actual dose received)
Sex:
female
Basis for effect level:
other: reduction of body weights / dose corresponding to 500 ppm in diet
Dose descriptor:
LOAEL
Effect level:
120 mg/kg bw/day (actual dose received)
Sex:
male
Basis for effect level:
other: reduction of body weights/ dose corresponding to 1000 ppm in diet
Key result
Dose descriptor:
NOAEL
Effect level:
60 mg/kg bw/day (actual dose received)
Sex:
male
Basis for effect level:
other: dose corresponding to 500 ppm in diet
Critical effects observed:
not specified

Table 1: Body weight data for mice in the 2-year feed study of citral

Sex

Timepoint

Vehicle control

500 ppm

1000 ppm

2000 ppm

Av wt (g)

Av wt (g)

Rel wt (%)a

Av wt (g)

Rel wt (%)a

Av wt (g)

Rel wt (%)a

m

Mean w 1-13

25.3

25.2

100

24.7

98

24.2

96

Mean w 14-52

40.0

39.2

98

38.2

96

36.7

92

Mean w 53-101

46.6

44.9

96

43.5

93

40.5

87

Final w 102

45.9

42.8

93

41.6

91

38.6

84

f

Mean w 1-13

21.1

20.9

99

21.0

100

20.5

97

Mean w 14-52

35.3

33.1

94

32.7

93

30.7

87

Mean w 53-101

44.3

41.1

93

39.6

89

36.3

82

Final w 101

47.1

42.9

91

41.4

88

36.6

78

a weight as % of control group’s weight

Table 2: Incidences of selected non-neoplastic lesions of the oral mucosa in mice in the 2 -year feed study of citral

 Type of lesion  Vehicle control     500 ppm     1000 ppm     2000 ppm   
   Incidence  Severity gradec  Incidence    Severity gradec  Incidence    Severity gradec  Incidence    Severity gradec
 Males                
 Oral mucosa, inflammation  12/50  1.8  16/50  1.9  21/50  1.9  21/50a  1.5
Oral mucosa, ulcer  9/50  1.8  8/50  1.6  12/50  1.4  10/50  1.6
 Adrenal cortex, focal hyperplasia  0/50    3/50    2/50    5/50d  
 Females            
 Oral mucosa, inflammation   14/49   1.4  32/50b   1.9   35/50b    1.8   32/50b   1.5
  Oral mucosa, ulcer   6/49   1.2   15/50b   1.9  22/50b   1.6   15/50a   1.5
 Bone, fibrosis  11/49    22/50d    21/50d    18/50  
 Kidney, nephropathy  9/49  1.0  16/50  1.0  15/50  1.2  17/50a  1.0
 Kidney, renal tubule mineralization  4/50  1.0  14/50a  1.0  18/50b  1.0  6/50  1.2

Significant changes in comparison to vehicle control: a significant increase, p<=0.05; b significant increase, p<=0.01; d significant increase, p not specified; relevance of findings is discussed in "Details on results"

c Grading of severity: 1=minimal, 2=mild

Conclusions:
Based on the results of the study, the LOAELs of Citral were set at 120 and 60 mg/kg bw/day (1000 and 500 ppm) for male and female rats based on decreased body weight.
Executive summary:

The substance Citral (Reaction mass of (E)-3,7-dimethylocta-2,6-dienal and (Z)-3,7-dimethylocta-2,6-dienal) has been tested in a study similar to OECD TG 453. Groups of male and female B6C3 mice were exposed to microencapsulated citral (greater than 96% pure) in feed for 2 years. Dose used in the 2 year study were 60 - 260 mg/kg to males and females.

Effects observed: Lower mean body weights in the treated group. The incidences of malignant lymphoma occurred with a positive trend in female mice, and the incidence in 2,000 ppm females was significantly greater than that in the vehicle control group. Tissues most commonly affected by malignant lymphoma were the spleen, mesenteric lymph node, thymus, and, to a lesser extent, the ovary.

Based on these results the LOAELs were determined to be 120 and 60 mg/kg bw/day (1000 and 500 ppm) for males and females respectively, based on reduced body weights.

Endpoint:
chronic toxicity: oral
Remarks:
combined repeated dose and carcinogenicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
June 1995 - September 1995
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Reason / purpose:
reference to same study
Reason / purpose:
reference to same study
Reason / purpose:
reference to same study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 453 (Combined Chronic Toxicity / Carcinogenicity Studies)
Deviations:
yes
Remarks:
(complete histopathology of all dose groups; no parameters of hematology, clinical chemistry or urinalyses measured)
GLP compliance:
yes
Remarks:
FDA GLP regulations
Species:
rat
Strain:
Fischer 344
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Taconic Laboratory Animals and Services, Germantown, N.Y.
- Age at study initiation: ca. 6 weeks
- Weight at study initiation: males ca. 120 g, females ca. 100 g
- Fasting period before study: no
- Housing: 2 or 3 males, or 5 females per cage
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 14 to 15 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 °C (calculated from 72° +- 3° F)
- Humidity (%): 50% +- 15%
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12 / 12


IN-LIFE DATES: From: June 6 or 7, 1996 To: June 1-5 (males) or June 8-10 (females), 1998
Route of administration:
oral: feed
Vehicle:
other: microcapsules loaded with citral
Details on oral exposure:
DIET PREPARATION
- Rate of preparation of diet (frequency): every 4 weeks
- Mixing appropriate amounts with nonirradiated NTP-2000 feed: final concentrations of 0, 1000, 2000 or 4000 ppm citral were achieved by adding loaded and/or placebo microcapsules at a total concentration of 1.25% microcapsules
- Storage temperature of food: room temperature

VEHICLE
- Justification for use and choice of vehicle: microcapsules prepared from food-grade sugar and starch were loaded with citral to prevent loss of test substance
- Concentration in vehicle: 31.9 % citral (analytical method GC)
- Lot/batch no.: MRI 020196MC
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
periodic verification by GC
Duration of treatment / exposure:
104-105 weeks
Frequency of treatment:
continuously
Dose / conc.:
0 ppm
Remarks:
0 mg/kg bw/day
Dose / conc.:
1 000 ppm
Remarks:
50 mg/kg bw/day (nominal)
Dose / conc.:
2 000 ppm
Remarks:
100 mg/kg bw/day (nominal)
Dose / conc.:
4 000 ppm
Remarks:
210 mg/kg bw/day (nominal)
No. of animals per sex per dose:
50
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: based on 14-week pre-study described in same study report
Positive control:
not necessary
Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: day 8, 33, and every 4 weeks thereafter, at end of study

BODY WEIGHT: Yes
- Time schedule for examinations: day 0, 8, 33, and every 4 weeks thereafter, at end of study

FOOD CONSUMPTION AND COMPOUND INTAKE : weekly
- Food consumption for each cage determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes, approximately every 4 weeks for a 1-week period
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: No

CLINICAL CHEMISTRY: No

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No
Sacrifice and pathology:
GROSS PATHOLOGY: Yes

ORGAN WEIGHTS: No

HISTOPATHOLOGY: Yes
Complete histopathology performed on untreated controls, vehicle controls, and all dosed animals:
examined tissues: gross lesions and tissue masses, adrenal gland, bone with marrow, brain, clitoral gland, esophagus, heart and aorta, large intestine, small intestine, kidney, liver, lung and mainstem bronchi, lymph nodes, mammary gland, nose, ovary, pancreas, parathyroid gland, pituitary gland, preputial gland, prostate gland, salivary gland, skin, spleen, stomach, testis with epididymis and seminal vescicles, thymus, thyroid gland, trachea, urinary bladder, uterus
Statistics:
Probability of survival: product-limit procedure of Kaplan and Meier
dose-related effects on survival: Cox's method, Tarone's life table test
Body weight data: parametric multiple comparison procedures of Dunnett and Williams
Incidences of non-neoplastic lesions: Poly-3 test (Bailer and Portier, 1988)
Dose descriptor:
LOAEL
Effect level:
210 mg/kg bw/day (actual dose received)
Sex:
male/female
Basis for effect level:
other: decrease of mean body weight; dose corresponds to 4000 ppm in diet
Key result
Dose descriptor:
NOAEL
Effect level:
100 mg/kg bw/day (actual dose received)
Sex:
male/female
Basis for effect level:
other: dose corresponds to 2000 ppm in diet
Critical effects observed:
not specified

Table 1: Body weight data for rats in the 2-year feed study of citral

Sex

Timepoint

Vehicle control

1000 ppm

2000 ppm

4000 ppm

Av wt (g)

Av wt (g)

Rel wt (%)

Av wt (g)

Rel wt (%)

Av wt (g)

Rel wt (%)

m

Mean w 1-13

249

248

100

244

98

241

97

Mean w 14-52

440

436

99

429

98

418

95

Mean w 53-101

483

478

99

473

98

453

94

Final w 101

479

470

98

461

96

440

92

f

Mean w 1-13

157

155

99

155

99

151

96

Mean w 14-52

232

227

98

227

98

216

93

Mean w 53-101

311

301

97

299

96

270

87

Final w 101

335

326

97

323

96

298

89

Av wt: average weight

Rel wt: relative weight as % of the control group's weight

Table 2: Incidences of non-neoplastic lesions in the 2 -year feeding study with citral

  Vehicle control 1000 ppm 2000 ppm 4000 ppm

Type of lesion

 Incidence  Incidence  Incidence  Incidence
 Males        
Kidney, renal tubule mineralization  42/50  45/50  48/50  50/50
 Females        
Adrenal cortex, angiectasis  1/50  1/50   3/50  10/50*

Significant changes in comparison to vehicle control:

* significant increase, level of significance not specified

The evaluation of observed effects is discussed in "Details on results"

Conclusions:
Based on the results of the study, the LOAEL and NOAEL were set at 210 mg/kg bw (4000 ppm) and 100 mg/kg bw (1000ppm) for males and females respectively, based on decreased body weight.
Executive summary:

The substance Citral (Reaction mass of (E)-3,7-dimethylocta-2,6-dienal and (Z)-3,7-dimethylocta-2,6-dienal) has been tested in a study similar to OECD TG 453. Groups of male and female F344/N rats were exposed to microencapsulated citral (greater than 96% pure) in feed for 2 years. Doses used in rats in the 2 year study were 50 - 210 mg/kg to males and females.

Effects observed: Higher survival of all exposed groups of males compared to controls. Lower mean body weights in exposed groups. No neoplasms or non-neoplastic lesions were attributed to exposure to citral.

Based on these results the LOAEL and NOAEL were set at 210 mg/kg bw (4000 ppm) and 100 mg/kg bw (1000ppm) respectively for males and females, based on decreased body weights.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
LOAEL
60 mg/kg bw/day
Study duration:
chronic
Species:
mouse
Quality of whole database:
comparable to guideline study with acceptable restrictions
System:
other: Body weight effects
Organ:
not specified

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Referenceopen allclose all

Endpoint:
repeated dose toxicity: inhalation, other
Remarks:
inhalation during developmental toxicity study (GD 6-15)
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Remarks:
Developmental toxicity study comparable to guideline study (OECD Guideline 414) with sufficient documentation, well documented
Reason / purpose:
reference to other study
Qualifier:
equivalent or similar to
Guideline:
other: OECD414
Deviations:
yes
Remarks:
Mortalities, clinical signs of intoxication, body weight gains and gross lesions were investigated as signs of maternal toxicity during a developmental toxicity study.
GLP compliance:
not specified
Limit test:
no
Species:
rat
Strain:
Sprague-Dawley
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Laboratory, Inc. (Raleigh, NC, USA)
- Age at study initiation: 9-11 w
- Weight at study initiation: females ca. 230 g
- Fasting period before study: no
- Housing: individually
- Diet: ad libitum during non-exposure periods
- Water: ad libitum during non-exposure periods
- Acclimation period: 2 w

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +- 1
- Humidity (%): 31 +- 8
- Photoperiod (hrs dark / hrs light): 12/12
Route of administration:
inhalation
Type of inhalation exposure:
whole body
Vehicle:
other: nitrogen
Remarks on MMAD:
no data
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Rochester-type stainless steel inhalation chambers of 1 cubic meter volume
- Method of conditioning air: filtered through coarse particulate and HEPA filters and an activated carbon cartridge
- System of generating particulates/aerosols: aerolization of liquid citral with a DeVilbiss Model 41 nebulizer using nitrogen as a carrier gas to prevent degradation, which had been observed during nebulization in the presence of air
- Temperature, humidity, pressure in air chamber: no data
- Air flow rate: not data
- Air change rate: 15 +- 3 changes/hr
- Method of particle size determination: cascade impactor; MMAD 4.2 µm, geometric standard deviation 1.9; about 90% of the aerosol with aerodynamic diameter < 10 µm
- Treatment of exhaust air: no data

TEST ATMOSPHERE
- Brief description of analytical method used: gas chromatography with flame ion detection
- Samples taken from breathing zone: not specified

VEHICLE
- Justification for use and choice of vehicle: to prevent degradation of citral
- Composition of vehicle: nitrogen
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Analysis of vapour and aerosol samples indicated that citral purity degraded less than 5% with nitrogen nebulization, with only a slight entrichment of the neral isomer (< 3%) in the vapour phase Chamber vapour atmospheres sampled by cryogenic trapping. Sampling was performed at a flow rate of 400 mL/min for 25 min through two all-glass and teflon traps immersed in a dry-ice methanol bath. The tubes were rinsed with 10 mL of isopropanol containing n-octanol as internal standard. Analysis performed by gas chromatography and flame ion detection.
Duration of treatment / exposure:
6 h/d, gestation day 6-15
Frequency of treatment:
daily
Dose / conc.:
10 ppm
Remarks:
nominal conc. corresponding to 63 mg/m3 (=MW*ppm/24.1*1000); MW=152,2 g/mol
Dose / conc.:
34 ppm
Remarks:
nominal conc. corresponding to 215 mg/m3 (=MW*ppm/24.1*1000); MW=152,2 g/mol
Dose / conc.:
68 ppm
Remarks:
nominal conc. corresponding to 430 mg/m3 (=MW*ppm/24.1*1000); MW=152,2 g/mol
No. of animals per sex per dose:
25
Control animals:
yes, sham-exposed
Details on study design:
- Dose selection rationale: highest selected to produce maternally toxic effects
Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: twice daily

BODY WEIGHT: Yes
- Time schedule for examinations: days 0, 2 4, 6, 8 (exposure), 12, 16, 20 (post-exposure)

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: No

CLINICAL CHEMISTRY: No

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

FOOD CONSUMPTION: No data

WATER CONSUMPTION: No data
Sacrifice and pathology:
GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: No data
Statistics:
Maternal body weights and body-weight gains were analysed by a one-way analysis of variance (ANOVA), followed by a Dunnett's when applicable ( Steel and Torrie, 1960).
Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
Ocular opacity, difficulty in breathing during the exposure phase of the study indicating stress of severe respiratory tract irritation; normal breathing returned in most of affected animals by gestation day 20; other frequently observed clinical signs: nasal discharge, salivation, redness around eyes, discolored facial fur, scrubby hair coat
However, after completion of the exposure period recovery clinical signs of toxicity occurred.
Mortality:
mortality observed, treatment-related
Description (incidence):
68 ppm: moribund condition of 1/25 animals (killed on gestation day 17);
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
68 ppm:
- Body weight loss during exposure period from gestation day (GD) 6 to 15; after exposure period body weight gain was comparable to other groups;
- Overall mean body weight (GD 20) significantly decreased
- Body weight gain (GD0-20) decreased by 39% compared to controls.
However, after completion of the exposure period recovery of body weight occurred.
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
no effects observed
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined
Dose descriptor:
NOAEC
Effect level:
34 ppm
Based on:
test mat.
Sex:
female
Basis for effect level:
body weight and weight gain
Remarks on result:
other: corresponds to 215 mg/m3
Dose descriptor:
LOAEC
Effect level:
68 ppm
Based on:
test mat.
Sex:
female
Basis for effect level:
other: severe respiratory tract irritation with reduced body weight gain and clinical signs as secondary effects in pregant rats; corresponds to 430 mg/m3
Critical effects observed:
not specified
Conclusions:
The results of the present study revealed no significant maternal toxicity or adverse developmental effects in rats exposed to citral vapour at concentrations up to 34 ppm (NOAEL: 215 mg/m3).
Executive summary:
The repeated dose inhalation toxicity of citral was evaluated based on maternal toxicity data from a OECD TG 414 developmental toxicity inhalation study in rats. Exposure atmospheres contained citral concentrations of 1, 3, 10 and 34 ppm (both as vapour), or 68 ppm (aerosol/vapour mixture) corresponding to 6, 19, 63, 215, 430 mg/m3. The exposure condition at 68 ppm comprised an aerosol/vapour mixture with the intention to produce signs of toxicity. Maternal toxicity was indicated at 68 ppm (430 mg/m3) by decreased body weights and by clinical signs as ocular opacity, breathing difficulty, nasal discharge and salivation. These signs of maternal toxicity were secondary to the stress produced by severe respiratory tract irritation, as recovery of body weight and clinical signs of toxicity occurred after completion of the exposure period. At 10 and 34 ppm, findings were incidental and not siginficantly different from control animals.
Endpoint:
sub-chronic toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1993
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: See remarks:
Remarks:
Although this investigation has only been published as an abstract, additional data on the test conditions are available from a valid developmental toxicity study (Gaworski et al., 1992) from the same working group. The results on maternal toxicity in the developmental toxicity study confirm the test results of the repeated dose inhalation toxicity study. Acceptable restrictions in documentation are: number of exposed animals not given, no details on test results given; study acceptable for derivation of a NOAEL for local and systemic effects based on weight of evidence approach
Reason / purpose:
reference to other study
Qualifier:
no guideline followed
Principles of method if other than guideline:
F344/N rats were expo 6 hrs/day for either 21 consecutive days at concentrations of 10 & 34 ppm, or 68 ppm, or for 13 weeks at concentrations of 1, 3, or 10 ppm. No mortalities occurred during the 21 day study. Investigated endpoints were mortality, body weight, organ weigths (13 week study only), signs of ocular, nasal and oral irritation, and histological examination of nose tissues, larynx, trachea and lungs. Reversibility was investigated after a 5-week recovery period.
GLP compliance:
not specified
Limit test:
no
Species:
rat
Strain:
Fischer 344
Sex:
not specified
Route of administration:
other: exposure to vapours for low concentrations; exposure to vapour/aerosol mixtures to achieve higher concentrations
Type of inhalation exposure:
whole body
Vehicle:
other: nitrogen
Remarks on MMAD:
MMAD / GSD: no data
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION (Information taken from Gaworski et al., 1992)

- Exposure apparatus: Rochester-type stainless steel inhalation chambers of 1 cubic meter volume
- Method of conditioning air: filtered through coarse particulate and HEPA filters and an activated carbon cartridge
- System of generating particulates/aerosols: aerolization of liquid citral with a DeVilbiss Model 41 nebulizer using nitrogen as a carrier gas to prevent degradation, which had been observed during nebulization in the presence of air
- Temperature, humidity, pressure in air chamber: no data
- Air flow rate: not data
- Air change rate: 15 +- 3 changes/hr
- Method of particle size determination: cascade impactor; MMAD 4.2 µm, geometric standard deviation 1.9; about 90% of the aerosol with aerodynamic diameter < 10 µm
- Treatment of exhaust air: no data

TEST ATMOSPHERE
- Brief description of analytical method used: gas chromatography with flame ion detection
- Samples taken from breathing zone: not specified

VEHICLE
- Justification for use and choice of vehicle: to prevent degradation of citral
- Composition of vehicle: nitrogen
Analytical verification of doses or concentrations:
yes
Remarks:
(Information taken from Gaworski et al., 1992)
Details on analytical verification of doses or concentrations:
Analysis of vapour and aerosol samples indicated that citral purity degraded less than 5% with nitrogen nebulization, with only a slight entrichment of the neral isomer (< 3%) in the vapour phase
Chamber vapour atmospheres sampled by cryogenic trapping. Sampling was performed at a flow rate of 400 mL/min for 25 min through two all-glass and teflon traps immersed in a dry-ice methanol bath. The tubes were rinsed with 10 mL of isopropanol containing n-octanol as internal standard. Analysis performed by gas chromatography and flame ion detection.
Duration of treatment / exposure:
21 days or 13 weeks
Frequency of treatment:
Daily for 21 days, 6 h/d
13 w, 5 d/w, 6 h/d
additional group with 5 week recovery period after the 13 week treatment
Dose / conc.:
10 ppm
Remarks:
63 mg/m3
21 Days exposure
Dose / conc.:
34 ppm
Remarks:
215 mg/m3
21 Days exposure
Dose / conc.:
68 ppm
Remarks:
430 mg/m3
21 Days exposure
Dose / conc.:
1 ppm
Remarks:
6 mg/m3, 13 week exposure
Dose / conc.:
3 ppm
Remarks:
19 mg/m3, 13 week exposure
Dose / conc.:
10 ppm
Remarks:
63 mg/m3, 13 week exposure
Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice a day

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: twice a day

BODY WEIGHT: Yes
- Time schedule for examinations: not specified

FOOD CONSUMPTION: No data

WATER CONSUMPTION: No data

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: No

CLINICAL CHEMISTRY: No

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No
Key result
Dose descriptor:
NOAEC
Remarks:
subchronic inhalation
Effect level:
34 ppm
Based on:
test mat.
Sex:
not specified
Remarks on result:
other: 215 mg/m3
Key result
Dose descriptor:
LOAEC
Effect level:
68 ppm
Based on:
act. ingr.
Sex:
not specified
Basis for effect level:
clinical signs
body weight and weight gain
Remarks on result:
other: 430 mg/m3
Critical effects observed:
not specified

Table: Overview on findings in a subacute and a subchronic inhalation study

Exposure time

 

Concen-

 

tration

(ppm)

Mortality

 

Body weight gain

 

Organ weights

 

Signs of irritation

 

Histological findings

Nasal respiratory epithelium

Other

21 d

10a

no

No effect

No data

No effect

Dose related increase of chronic active inflammation, hyperplasia, squamous metaplasia and goblet cell atrophyc

No data

34a

no

No effect

No data

No effect

No data

68b

no

Significant reduction

No data

Severe nasal, oral and ocular irritation; corneal inflammation and ulceration

Signs of irritation in trachea and lungs

13 w

1a

no

No effect

No effect

No effect

No effect

No effect

3a

no

No effect

No effect

No effect

No effect

No effect

10a

no

No effect

No effect

No effect

No effect

Minimal hyperplasia and squamous metaplasia of the laryngeal epithelium

13 w + 5 w recovery

10

Effect in laryngeal epithelium fully reversible

avapour concentration

bconcentration of vapour/aerosol mixture

cno information given from which concentration up effects have to be considered as significant and biologically relevant

Conclusions:
Based on the results of the present study the NOAEC for Citral is set to 34 ppm or 215 mg/m3 based on evident local irritation and systemic effects, i.e. body weight changes, observed at 68 ppm or 430 mg/m3.
Executive summary:

To evaluate the potential toxic effects of inhaled citral, F344/N rats were expo 6 hrs/day for either 21 consecutive days at concentrations of 10 & 34 ppm, or 68 ppm, or for 13 weeks at concentrations of 1, 3, or 10 ppm. No mortalities occurred during the 21 day study. Rats exposed to 68 ppm citral displayed signs of severe ocular, oral & nasal irritation and had significantly reduced body weight gains compared to controls. Treatment related lesions consisted of dose-related chronic-active inflammation, hyperplasia, squamous metaplasia & goblet cell atrophy of the nasal respiratory epithelium. Animals exposed to 68 ppm citral also developed changes indicative of irritation in the tracheas and lungs, as well as corneal inflammation & ulceration. Exposure to citral for 13 wk at concentrations up to 10 ppm did not produce mortality or treatment related signs of tox. Body weight gains, clinical pathology indices and organ weight were not adversely affected by exposure. Rats exposed to 10 ppm citral developed minimal hyperplasia and squamous metaplasia of the laryngeal epithelium; however, these changes were completely reversed during a 5-wk recovery period. No significant lesions were observed in the rats exposed to 1 or 3 ppm citral.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
NOAEC
215 mg/m³
Study duration:
subchronic
Species:
rat
Quality of whole database:
Although the subchronic investigation has only been published as an abstract, additional data on the test conditions are available from a valid developmental toxicity study (Gaworski et al., 1992) from the same working group. The results on maternal toxicity in the developmental toxicity study confirm the test results of the repeated dose inhalation toxicity study. Acceptable restrictions in documentation are: number of exposed animals not given, no details on test results given; study acceptable for derivation of a NOAEL for local and systemic effects based on weight of evidence approach
System:
other: Body weight effects
Organ:
not specified

Additional information

Oral toxicity (similar to OECD TG 453 and OECD TG 408, Read across from Citral)

The source substance Citral (Reaction mass of (E)-3,7-dimethylocta-2,6-dienal and (Z)-3,7-dimethylocta-2,6-dienal) has been tested in a study similar to OECD TG 453. Groups of male and female F344/N rats and B6C3 mice were exposed to microencapsulated citral (greater than 96% pure) in feed for 14 weeks or 2 years. Dose used in rats were equivalent to 345-1,585 mg citral/kg body weight for males and 335- 2,125 mg/kg for females in the 14 week study and in the 2 year study 50 - 210 mg/kg to males and females. For mice the concentration of Citral in the diet was equivalent to average daily doses of approximately 745 - 8,110 mg/kg to males and 790 - 7,550 mg/kg to females in the 14 week study, and in the 2 year study 60 - 260 mg/kg to males and females.

2 Year study in mice and rats: Effects observed in the 2 year study in rats: higher survival of all exposed groups of males compared to controls. Lower mean body weights in exposed groups. No neoplasms or non-neoplastic lesions were attributed to exposure to citral. Effects observed in the 2 year study in mice: Lower mean body weights in treated group. The incidences of malignant lymphoma occurred with a positive trend in female mice, and the incidence in 2,000 ppm females was significantly greater than that in the vehicle control group. Tissues most commonly affected by malignant lymphoma were the spleen, mesenteric lymph node, thymus, and, to a lesser extent, the ovary. In the 2 year study, LOAELs were determined to be 120 and 60 mg/kg bw/day (1000 and 500 ppm) for males and females respectively, based on reduced body weights. The NOAEL was set at 60 mg/kg bw/day.

14 week study in mice and rats: Effects observed in 14 week study in rats: Lower mean body weights, and feed consumption. Males and females in the high dose group exhibited listlessness, hunched posture, absent or slow paw reflex, and dull eyes. Some evidence of forestomach epithelial hyperplasia and hyperkeratosis, bone marrow atrophy and hemorrhage, and nephrotoxicity was observed.

Effects observed in the 14 week study in mice:In the second week of the study, four males in the high dose group were killed moribund. Lower mean body weights. Mice in the mid and high dose groups were generally thin and lethargic. The incidences of ovarian atrophy were significantly increased in females exposed to mid and high doses.

Based on these results the LOAEL of rats at 14 weeks was set at 745 and 790 mg/kg bw (3900ppm) based on decreased body weight. At 2 years the LOAEL and NOAEL were set at 210 mg/kg bw (4000 ppm) and 100 mg/kg bw (1000ppm) respectively for males and females, based on decreased body weights. In mice the LOAELs at 14 weeks were determined at 345 and 335 mg/kg bw/day  (3900ppm) in males and females respectively (based on decreased body weight).

Subchronic inhalation toxicity (Weight of evidence, Read across from Citral: Gaworski 1992,1993)

The repeated dose inhalation toxicity of Litsea Cubeba was evaluated based on Read across from the source substance Citral. A weight of evidence approach was used, including data from a 21-day and 13-week inhalation toxicity study (Gaworski 1993) and maternal toxicity data from a developmental toxicity study (Gaworski 1992).

Groups of F344 rats were exposed for 6 hrs/day for 21 days at concentration of 10 and 34 ppm (both as vapour, corresponding to 63 and 215 mg/m3 or 68 ppm (aerosol/vapour mixture, 430 mg/m3), or for 13 w, 5 days per week, at concentrations of 1, 3, or 10 ppm (all vapour atmospheres, corresponding to6, 19, 63 mg/m3). During the 21 day study, no mortalities occurred. Rats in the 68 ppm-dose group displayed some clinical signs such as: severe ocular, oral and nasal irritation (dose-related chronic-active inflammation, hyperplasia, squamous metaplasia and goblet cell atrophy of the nasal respiratory epithelium), and significantly reduced body weights. In the subchronic inhalation toxicity study there was no mortality and no treatment related signs of toxicity

These findings were supported by a developmental toxicity study, in which maternal toxicity was indicated at 68 ppm (430 mg/m3) by decreased body weights and by clinical signs as ocular opacity, breathing difficulty, nasal discharge and salivation. The maternal toxicity was considered secondary to the stress produced by severe respiratory tract irritation, as recovery of body weight and clinical signs of toxicity occurred after completion of the exposure period. Overall, the NOAEC has been set to 34 ppm or 215 mg/m3 based on evident local irritation and systemic effects, i.e. body weight changes, observed at 68 ppm or 430 mg/m3.

Justification for classification or non-classification

Based on the available read-across data for repeated dose toxicity, Litsea cubeba does not need to be classified for STOT-RE according to the classification criteria outlined in Annex I of 1272/2008/EC (CLP).


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