3-methyl-2-butenal

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP and guideline study. According to OECD 415. Provides valuable information for subchronic toxicity.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2002

Report date:

2002

Materials and methods

Principles of method if other than guideline:

according to OECD Guideline for Testing of Chemicals, No . 415: One-Generation Reproduction Toxicity Study (May 1983)

GLP compliance:

yes (incl. QA statement)

Remarks:

testing lab.

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

3-methyl-2-butenal

EC Number:

203-527-6

EC Name:

3-methyl-2-butenal

Cas Number:

107-86-8

Molecular formula:

C5H8O

IUPAC Name:

3-methyl-2-butenal

Details on test material:

- Name of test material (as cited in study report): 3-Methyl-2-butenal, CAS: 107-86-8 Substance No. 00/0680-2
- Physical state: Liquid/colorless to yellowish-clear
- Analytical purity: 99.7%
- Lot/batch No.: 00/12 from November 16, 200 0
- Stability under test conditions: The stability under storage conditions was confirmed by reanalysis
- Storage condition of test material: Refrigerator, under N2 without light
- Other: Homogeneous (analytical report: 00L00514)

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Germany
- Age at study initiation: 28 (± 1) days
- Weight at study initiation:
- Fasting period before study:
- Housing: singly from day 0- 20 p.c. in type DK III stainless steel wire mesh cages
- Diet : diet rat/mouse/hamster meal, supplied by PROVIMI KLIBA SA, Kaiseraugst, Switzerland ad libitum
- Water: Drinking water used to prepare aqueous 3-Methyl-2-buten-1-al (Prenal) solutions was of tap water quality. Water was supplied to the animals in the control group, and aqueous 3-Methyl-2-buten-1-al (Prenal) solutions were supplied to the animals in test groups 1-3 (50 ; 200 and 800 ppm)5, using Makrolon drinking bottles.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24°C
- Humidity (%): 30-70
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: drinking water

Vehicle:

CMC (carboxymethyl cellulose)

Details on oral exposure:

Drinking water solutions were prepared once or twice a week. The required weight of test substance was added to the appropriate amount of drinking water and agitated with a magnetic stirrer until the test substance was completely dissolved (about 3 minutes).

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

All analyses of the test substance preparations were carried out in the Analytical Chemistry Laboratory of the Experimental Toxicology and Ecology of BASF Aktiengesellschaft, Ludwigshafen, Germany.
Analytical verification of the stability of the test substance in the drinking water for a period of 4 days at room temperature was carried out. The homogeneity of the test substance in the drinking water was guaranteed due to the fact that 3-Methyl-2-buten-1-al (Prenal) is completely soluble in water. Samples of each concentration were drawn for concentration control analyses twice at the start of the administration period for the FO generation parental animals, after about 2 months and at the end of the study.

Duration of treatment / exposure:

18 weeks

Frequency of treatment:

7 days per week

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 50, 200, 800 ppm (ca. 0, 6, 21, 77 mg/kg bw/d)
Basis:
nominal in water

No. of animals per sex per dose:

25

Control animals:

yes, concurrent no treatment

Details on study design:

Post-exposure period: none

Positive control:

none

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: no data

BODY WEIGHT: Yes
- Time schedule for examinations: once a week

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
During the premating period of the F0 generation parental animals food consumption was determined once a week (each time for a period of 7 days). After the 10th week food consumption of the females during pregnancy (animals with evidence of sperm) was determined for days 0-7, 7-14 and 14-20 p.c. During the lactation period (animals with litter) food consumption was determined for days 1-4, 4-7, and 7-14 p.p. Food consumption was not determined between days 14 and 21 after parturition as required in the test guidelines, since during this time pups begin to consume considerable amounts of solid food offered, and therefore there was no point in such a measurement. Food consumption of the FO males was not determined after the 10th test week through sacrifice. Furthermore, there was no determination of food consumption in the females during the mating periods, in the females without positive evidence of sperm during the programmed gestation phase, or in the females without li tters during the lactation phase.

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: Yes

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes
During the premating period of the FO generation parental animals water consumption was determined once a week (each time for a period of 3 days) . After the 10th week, water consumption of the females during gestation (animals with evidence of sperm) was determined for days 0-1, 6-7, 13-14 and 19-20 p .c. During the lactation period (animals with litter) water consumption was determined for days 1-2, 4-5, 7-8, 14-15 p.p.

OPHTHALMOSCOPIC EXAMINATION: No
HAEMATOLOGY: No
CLINICAL CHEMISTRY: No
URINALYSIS: No
NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
Animals were necropsied and assessed by gross pathology. No weight parameters were determined.

HISTOPATHOLOGY: Yes
Of the F0 generation parental animals, the following organs or tissues were fixed in 4% formaldehyde solution or in BOUIN's solution. After sufficient fixation, the organs fixed in BOUIN's solution were embedded in paraplast: vagina, cervix uteri, uterus, ovaries, testes, epididymides, seminal vesicles, coagulating glands, prostate gland, pituitary gland, all gross lesions. After the organs were fixed, histotechnical processing, examination by light microscopy and assessment of findings was performed.

Statistics:

DUNNETT's test was used to compare treated and control groups (food intake, body weight data, number of pups/litter, etc.). FISHER's EXACT test for pairwise comparison of each dose group with control group (mating and fertility indices, pup viability data). Two-sided WILCOXON-test (proportion of affected pups/litter with necropsy observations).

Results and discussion

Results of examinations

Details on results:

CLINICAL SIGNS AND MORTALITY
Clinical findings:
No substance-related signs or any disturbance of behavior noted in all male and female F0 animals during the entire administration period.
Mortality:
One high dose female was found dead during premating wk 10. Erosions/ulceration of glandular stomach mucosa was found at necropsy, but this was assessed as being not causative for death. No other mortalities occurred.

BODY WEIGHT AND WEIGHT GAIN
Not influenced by Test substance in any group at any time interval.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study)
Test substance intake: Calculated intake at dose levels 50, 200, and 800 ppm in drinking water was
F0 males: 4.9, 19.0, 72.0 mg/kg bw/d (premating)
F0 females: 6.4, 23.5, 81.8 mg/kg bw/d (premating)
F0 females: 6.2, 23.2, 82.0 mg/kg bw/d (gestation)
F0 females: 8.3, 31.9, 123.5 mg/kg bw/d (lactation)

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study)
Water consumption: Unchanged at the low and intermediate dose level, significantly reduced during premating (-20% males, -24% females) and in females during gestation (-17%) and lactation (-10%). This was regarded as a substance-related effect, probably due to bad taste and/or smell of test substance solutions. Food consumption: Significantly reduced in high dose males during the first weeks of treatment (wk 0-4), and similar to control animals thereafter. No other relevant changes noted.

GROSS PATHOLOGY
Gross lesions were noted in glandular stomach (erosion/ulcer), cecum, liver, testes (size reduced) epididymides (size reduced) oviducts (cyst), uterus (cyst), eyes and skin. However, these were single observations or distributed over control and treated groups without evidence of relationship to treatment. The same applied to histopathology.

OTHER FINDINGS
The mean dose administered for both sexes during premating was about 5.7 mg/kg bw and day, about 21.3 mg/kg bw and day, and about 76.9 mg/kg bw and day in the low, mid and high dose groups, respectively.
No substance-related adverse effects were noted in F0 parental animals in groups at 50 and 200 ppm. Changes noted in F0 animals at 800 ppm were a decreased water intake in both sexes and a transient decrease of food intake of males during the first 4 weeks of treatment. There were no other differences in the high dose group F0 animals compared to controls.

Male fertility index for F0 males concerning F1 litters: unchanged
Female fertility index for F0 males concerning F1 litters: unchanged

Effect levels

1

Dose descriptor:

NOEL

Effect level:

ca. 21 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: water and food intake

2

Dose descriptor:

NOAEL

Effect level:

ca. 77 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: overall effects

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

3-methyl-2-buten-1-al was administered to Wistar rats of both sexes in drinking water at concentrations of 50, 200 and 800 ppm over a period of ca. 18 weeks in a one-generation study. The corresponding mean uptake of TS was ca. 6, 21, and 77 mg/kg/d for both sexes, respectively.

Due to palatibility problems water intake was reduced in animals receiving 800 ppm solutions by ca. 20%. This suggests that no higher dose levels can be achieved by administration of TS via drinking water. Reduced water intake over the entire test period in both sexes and a transient decrease of food intake in males were the only signs of substance-related effects which were noted in the high dose groups only.

No change of any other parameter was noted, i.e. clinical, histopathological, and pathological findings were not different from the controls of either sex at any dose or at any time. This includes the histopathological examination of the reproductive organs of both sexes. Consequently no target organ could be identified.

The no observed adverse effect level (NOAEL) was 77 mg/kg/d for systemic toxicity for male and female F0 parental animals.

The NOEL for the F0 parental animals was 21 mg/kg/d in this study, based on the reduced water and food consumption at the top dose level.