Propanoic acid, 2-hydroxy-, propyl ester, (2S)-

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

publication

Title:

Behavioral Teratology Investigation of 1-Propanol Administered by Inhalation to Rats

Author:

Nelson B.K. et al.

Year:

1989

Bibliographic source:

Neurotoxicology and Teratology Vol. 11, 153-159

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

- Principle of test: In a behavioural teratology study, 1-propanol at concentrations of 3500 and 7000 ppm was administered by inhalation to groups of 15 pregnant Sprague-Dawley rats for 7 h/day throughout gestation. Similarly, 18 male rats were exposed with the same concentrations for 7 h/day for 6 weeks and mated to unexposed females.
- Parameters analysed/observed: The offspring of both cohorts were evaluated for signs of developmental neurotoxicity (ascent on a wire mesh screen, rotorod, open field and photoelectrically-monitored activity, running wheel, avoidance conditioning and operant conditioning). Further, brains from 10 offspring were dissected into cerebrum, cerebellum, brainstem, and midbrain on post-natal day 21. Each sample was assayed for protein and the neurotransmitters acetylcholine, dopamine, norepinephrine, serotonin, met-enkephalin, beta-endorphin, and substance P.

GLP compliance:

no

Limit test:

no

Test material

Test material information

1

Reference substance name:

Propan-1-ol

EC Number:

200-746-9

EC Name:

Propan-1-ol

Cas Number:

71-23-8

Molecular formula:

C3H8O

IUPAC Name:

1-propanol

Specific details on test material used for the study:

- Name of test material in the study:1-Propanol
- Source: Matheson, Coleman, and Bell Manufacturing Chemists, Cincinnati, OH
- Purity : >99%

Test animals

Species:

rat

Strain:

Sprague-Dawley

Remarks:

VAF/plus

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Wilmington, MA
- Age at study initiation: young adult
- Weight at study initiation: males: >300 g females: 175-200 g
- Fasting period before study: no data
- Housing: suspended wire mesh cages equipped with automatic water dispensers (Hoeltge Inc., Cincinnati, OH).
- Diet: rodent pellets (NIH-07, Zeigler Bros., Inc., Gardner, PA), ad libitum
- Water: tap water, ad libitum
- Acclimation period: 1-2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 24 ± 2
- Humidity (%): 50 ± 10
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): 12 / 12

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure (if applicable):

whole body

Vehicle:

air

Details on exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: 0.5 cubic meter Hinners exposure chambers (Charles Spengler and Associates, Cincinnati, OH).
- System of generating particulates/aerosols: a micrometering pump controlled injection of a specified amount of reagent grade 1-propanol into one inlet of a three-way valve. Through a second inlet, heated compressed air was introduced, and the liquid-air mixture was forced through the outlet into a Greensmith impinger for evaporation and mixing. The concentration was controlled by modifying the flow of the chemical and the temperature of the compressed air. This vapor mixture was introduced into the
exposure chamber air flow upstream from an orifice plate, and the resulting turbulence provided uniform mixing of the vapor and air before it entered the chamber.
- Air flow rate: Air flow was approximately 0.5 m³ per minute.
- Temperature, humidity, pressure in air chamber: Chamber temperatures were maintained at 76 ± 2 °C and humidity at 50 ± 10%.

TEST ATMOSPHERE
- Brief description of analytical method used: The concentration within the chamber was continuously monitored by a Miran 1A infrared analyzer (Wilkes/Foxboro Analytical, South Norwalk, CT) that had been calibrated within the concentration range being administered, and was connected to a stripchart recorder. Daily mean, range, and time-weighted average concentrations were calculated. These daily values were averaged for an overall mean for each concentration. In addition, the analyzer was interfaced with an Apple II+ computer which recorded five-minute 1-propanol concentration means for each five-minute period. For independent verification of exposure chamber concentrations, charcoal tube samples were collected from the chamber atmosphere. Sampling times varied from 10 to 30 min, and approximately 13 samples were collected over a two-day period each week. The samples were subsequently analyzed using standard methods.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The concentration within the chamber was continuously monitored by a Miran 1A infrared analyzer (Wilkes/Foxboro Analytical, South Norwalk, CT) that had been calibrated within the concentration range being administered, and was connected to a stripchart recorder. Daily mean, range, and time-weighted average concentrations were calculated. These daily values were averaged for an overall mean for each concentration. In addition, the analyzer was interfaced with an Apple II+ computer which recorded five-minute 1-propanol concentration means for each five-minute period. For independent verification of exposure chamber concentrations, charcoal tube samples were collected from the chamber atmosphere. Sampling times varied from 10 to 30 min, and approximately 13 samples were collected over a two-day period each week. The samples were subsequently analyzed using standard methods.

Details on mating procedure:

- M/F ratio per cage: 1/1
- Proof of pregnancy: sperm in vaginal smear referred to as day 0 of pregnancy
Additionally exposed males (7hrs/day, 7 days/week for 6 weeks) were mated (1:1) with unexposed virgin females for a maximum of 5 days. Because of infertility observed in the males exposed to the high level of propanol, the final six exposed males were remated at biweekly intervals to see if the infertility was reversible.

Duration of treatment / exposure:

Males ("paternal exposure group"): 6 weeks
Females ("maternal exposure group"): gestation days (GD) 1-19

Frequency of treatment:

7 hours/day, 7 days/week

Duration of test:

Offspring were evaluated from days 10-90 post delivery.

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 ppm (nominal)

Remarks:

control

Doses / concentrations 2

Dose / conc.:

3 500 ppm (nominal)

Remarks:

= 8730 mg/m³

Doses / concentrations 3

Dose / conc.:

7 000 ppm (nominal)

Remarks:

= 17460 mg/m³

No. of animals per sex per dose:

18 males (paternal exposure group) and 15 females (maternal exposure group)

Control animals:

yes, sham-exposed

Details on study design:

- Dose selection rationale: based upon the results of beforehand conducted teratology study, 7000 ppm was selected as the high concentration (due to maternal toxicity). For the low concentration, an absence of maternal and embryo/fetal toxicity was desired.

Examinations

Maternal examinations:

See box "Any other information on materials and methods incl. tables".

Ovaries and uterine content:

not applicable

Blood sampling:

not applicable

Fetal examinations:

See box "Any other information on materials and methods incl. tables".

Statistics:

Behavioral data were analyzed using multivariate analysis of variance (MANOVA) where the data fit normal distributional assumptions required for parametric analyses. Because of the time difference between exposures in the 7000 and 3500 ppm 1-propanol groups, no direct comparisons between the groups were deemed justified. In all cases, p≤ 0.05 was required for significance. When the same group of animals was used for multiple comparisons, Bonferroni corrections were made to adjust the probabilities required for significance. The neurochemical data were also analyzed using MANOVA, followed by analysis of variance (ANOVA), if the MANOVA was significant.

Historical control data:

No data provided

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

not specified

Dermal irritation (if dermal study):

not examined

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Weight gain of exposed females (compared using multivariate analysis) was not affected by exposure to 1-propanol.
Weekly mean weights (±SD) for the six weeks in which the males were exposed to 7000 ppm propanol were 444 (± 40) g, 444 (± 38) g, 466 (± 36) g, 489 (± 38) g, 511 (± 38) g, and 528 (± 40) g. For those exposed to 3500 ppm propanol, the weights were 510 (± 24) g, 504 (± 26) g, 514 (± 29) g, 527 (± 30) g, 539 (± 32) g, and 554 (± 34) g.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Feed intake was reduced was reduced in the females (p< 0.05) exposed to 7000 ppm 1-propanol (weekly means ± SD for the exposed vs. control groups were 107 (± 13) vs. 134 (± 20) g, 122 (± 12) vs. 145 (± 18) g, and 137 (± 14) vs. 158 (± 18) g.
At 3500 ppm 1-propanol, there were no significant effects on maternal weight gain or feed intake.

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not specified

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Endocrine 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:

not examined

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Other effects:

effects observed, treatment-related

Description (incidence and severity):

Exposure of male rats to 7000 ppm 1-propanol for 6 weeks produced reversible infertility.

Maternal developmental toxicity

Number of abortions:

not examined

Pre- and post-implantation loss:

not examined

Total litter losses by resorption:

not examined

Early or late resorptions:

not examined

Dead fetuses:

no effects observed

Changes in pregnancy duration:

no effects observed

Description (incidence and severity):

No significant differences were found among any of the groups for the number of live pups per litter, the length of gestation, the birth weights, or neonatal survival.

Changes in number of pregnant:

no effects observed

Description (incidence and severity):

The number pregnant/number bred were 17/17 for maternally-exposed rats, 2/16 for paternally-exposed rats, 18/18 for controls, and 38/40 for foster rats in the 7000 ppm 1-propanol group.

Other effects:

no effects observed

Description (incidence and severity):

No significant differences were found among any of the groups for the number of live pups per litter, the length of gestation, the birth weights, or neonatal survival.

Effect levels (maternal animals)

Dose descriptor:

NOAEC

Effect level:

3 500 ppm (analytical)

Based on:

test mat.

Basis for effect level:

food consumption and compound intake

Remarks on result:

other: decreased food consumption at 7000 ppm

Maternal abnormalities

Abnormalities:

not examined

Results (fetuses)

Fetal body weight changes:

not examined

Reduction in number of live offspring:

no effects observed

Changes in sex ratio:

not specified

Changes in litter size and weights:

no effects observed

Description (incidence and severity):

No significant differences were found among any of the groups for the number of live pups per litter, the length of gestation, the birth weights, or neonatal survival.

Anogenital distance of all rodent fetuses:

not examined

Changes in postnatal survival:

no effects observed

External malformations:

effects observed, treatment-related

Description (incidence and severity):

Examination of the offspring revealed that 2 of 15 litters from the 7000 ppm l-propanol maternally exposed group had several pups (2-3/litter) with crooked tails (noted soon after birth), and these defects persisted.

Skeletal malformations:

not specified

Visceral malformations:

not specified

Other effects:

no effects observed

Description (incidence and severity):

Behavior:
There were few differences from controls in this study.
At 7000 ppm 1-propanol, exposed animals were not significantly different from controls on any of the tests. At 3500 ppm 1-propanol, the only significant differences between exposed animals and controls were in the activity measures.
In the Open Field test, females from the paternally-exposed group were less active than the controls on days 44, 45, and 46. On the activity wheel, this same group was less active than the controls. In the optical activity monitor, males in the maternally-exposed group were less active than control males on days 44, 45, and 46. No other significant differences were observed.
Neurochemistry:
No treatment related effects were observed .

Effect levels (fetuses)

Dose descriptor:

NOAEC

Effect level:

3 500 ppm (analytical)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

external malformations

Fetal abnormalities

Abnormalities:

effects observed, treatment-related

Localisation:

external: tail

Description (incidence and severity):

Examination of the offspring revealed that 2 of 15 litters from the 7000 ppm 1-propanol maternally exposed group had several pups (2-3/litter) with crooked tails (noted soon after birth), and these defects persisted.

Overall developmental toxicity

Developmental effects observed:

yes

Lowest effective dose / conc.:

7 000 ppm (nominal)

Treatment related:

yes

Relation to maternal toxicity:

developmental effects as a secondary non-specific consequence of maternal toxicity effects

Dose response relationship:

yes

Relevant for humans:

no

Any other information on results incl. tables

Analytical results:

Concentrations measured in the exposure chambers (hourly infrared analyzer readings) approximated the target concentrations of 3500 and 7000 ppm. Mean concentrations were 3510 ± 20 and 7300 ± 80 ppm. Results of periodic confirmatory charcoal tube samples were 3510 ± 20 and 3510 ± 10 ppm.

Applicant's summary and conclusion

Conclusions:

No behavioural adverse effects were observed in a behavioural teratology study in rats after exposure to 1-propanol at concentrations of 3500 and 7000 ppm via inhalation.

Executive summary:

In a behavioral teratology study female Sprague-Dawley rats were exposed to 1-propanol (vapor), (≥ 99 % purity) at concentrations 0, 3500 and 7000 ppm for 7 hrs/day, on gestation days 1-19 in inhalation exposure chambers and were allowed to deliver. In addition, 18 male rats were exposed with the same concentrations for 7 h/day for 6 weeks and were then mated to non-exposed females.

Maternal weights, feed intake, and water intake were measured over weekly intervals The offspring of both cohorts were observed during postnatal days 10–90 for signs of developmental neurotoxic effects by measuring ascent on a wire mesh screen, rotorod, open field and optically monitored activity, running wheel, avoidance conditioning, and ID progressive fixed ratio schedule of reinforcement.

Additionally brains from 10 rats per group were dissected into cerebrum, cerebellum, brainstem, and midbrain, and were assayed for protein levels of acetylcholine, dopamine, norepinephrine, serotonin, beta-endorphin, Met-enkephalin, and substance P.

Weight gain of maternal animals was not affected by treatments. Feed intake was statistically significant (p< 0,05) reduced at 7000 ppm. At 3500 ppm, there were no significant effects on maternal weight gain or feed intake. No significant differences were found among any of the groups for the number of live pups per litter, the length of gestation, the birth weights, or neonatal survival.

Examination of the offspring revealed that 2 of 15 litters from the 7000 ppm of 1-propanol maternally exposed group had several pups (2-3/litter) with crooked tails (noted soon after birth), and these defects persisted. No statistically significant effects on behavior were observed at exposure to 7000 ppm of 1-propanol. No effects on neurochemistry measurements were noted upon the treatment.

Exposure of male rats to 7000 ppm 1-propanol for 6 weeks produced reversible infertility.

Under the conditions of this study, the NOEC maternal and developmental can be considered to be 3500 ppm (8730 mg/m³). With the assumption for rats of a respiratory rate of 0.8 mL/kg bw, the effective concentrations (reversible effects on male fertility) of 7000 ppm for 7 h/ day can be re-calculated to an oral exposure of ca. 5800 mg/kg bw/day. Thus, it is obvious that the effects observed at 7000 ppm occurred at very high inhalatory concentrations and clearly exceed the limit dose of the respective OECD test guidelines (1000 mg/kg bw/day) and are thus not appropriate to be used for classification and labelling.

.