1,3-dichloropropan-2-ol

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

2008

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

GLP compliance:

not specified

Remarks:

Study is an open literature publication

Limit test:

no

Test material

Test material information

1

Reference substance name:

1,3-dichloropropan-2-ol

EC Number:

202-491-9

EC Name:

1,3-dichloropropan-2-ol

Cas Number:

96-23-1

Molecular formula:

C3H6Cl2O

IUPAC Name:

1,3-dichloropropan-2-ol

Test material form:

liquid

Specific details on test material used for the study:

purchased from Acros Organics (Fisher Scientific, Korea)

Test animals

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

Male and nulliparous female Sprague–Dawley rats were obtained
from a specific pathogen free colony at Bio Genomics Inc.
(Seoul, South Korea) and used after quarantine and acclimatization.
Animals were housed at a temperature of 23 ± 3 C and a relative
humidity of 50 ± 10%. Artificial lighting was present from 8:00
a.m. to 8:00 p.m. and the room had 13–18 air changes per hour.
All rats included in the study were healthy. Mating was achieved
by placing 2 females and 1 male in a cage overnight, and successful
mating was confirmed by the presence of sperm in vaginal cytology
on the following morning. The first 24 h after mating was designated
as day 0 of gestation (GD 0). Inseminated females were
singly housed in clear polycarbonate cages with stainless steel wire
lids and were given sterilized tap water and commercial rodent
chow (Samyang Feed Co, Wonju, Korea) ad libitum. The Institutional
Animal Care and Use Committee of Chonnam National University
approved protocols for the animal study, and the animals
were cared for in accordance with the Guidelines for Animal Experiments
of Chonnam National University.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

The test chemical was dissolved in sterilized distilled water
and was freshly prepared daily before the treatment. 1,3-DCP was
orally administered to the rats, and this route is a major exposure
route in humans as well. Daily application volumes were calculated
in advance based on the most recently recorded body weights
of the individual animals. 1,3-DCP was orally administered to pregnant
rats from GD 6 through GD 19 at a dose volume of 5 ml/kg
body weight. Vehicle control rats received equivalent volumes of
distilled water.

Analytical verification of doses or concentrations:

no

Details on mating procedure:

All rats included in the study were healthy. Mating was achieved
by placing 2 females and 1 male in a cage overnight, and successful
mating was confirmed by the presence of sperm in vaginal cytology
on the following morning. The first 24 h after mating was designated
as day 0 of gestation (GD 0)

Duration of treatment / exposure:

GD 6 through GD 19

Frequency of treatment:

once daily

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

10 mg/kg bw/day

Doses / concentrations 2

Dose / conc.:

30 mg/kg bw/day

Doses / concentrations 3

Dose / conc.:

90 mg/kg bw/day

No. of animals per sex per dose:

10 (ten)

Control animals:

yes, concurrent vehicle

Examinations

Maternal examinations:

All pregnant females were observed daily throughout gestation
for mortality, morbidity, general appearance, and behavior. Maternal
body weights were measured on GD 0, 6, 9, 12, 15, and 20 and
individual food consumption was determined on GD 0, 6, 9, 12, 15,
and 19. The amount of food was calculated before they were supplied
to each cage and the remnant was measured next day to calculate
the difference, which was regarded as daily food
consumption (g/rat/day). Pregnant females were euthanized on
GD 20 by ether inhalation, necropsies were conducted, and bodies
were subjected to external and internal macroscopic examination.
Blood samples were drawn from the posterior vena cava by using a
syringe with 24-gauge needle under ether anesthesia for further
biochemical analysis. The absolute and relative (organ-to-body
weight ratios) weights of the following organs were measured:
lung, adrenal gland, liver, spleen, kidney, thymus, heart, and ovary.

Ovaries and uterine content:

The ovaries and uterus from each female were removed and
examined corpora lutea number and implantation site status,
including fetal viability, early and late resorptions, and total
implantations. The uteri with no evidence of implantation were
stained with 2% sodium hydroxide to identify the presence of early
resorption sites (Yamada et al., 1985). The rat was considered ‘‘not
pregnant” if no stained implantation sites were present. Resorptions
were classified as ‘‘early” when dark brown blood clots and
no embryonic tissues were visible, and as ‘‘late” when both placental
and embryonic tissues were visible at the postmortem examination.

Fetal examinations:

All live fetuses were individually weighed, sexed, and
examined for morphological abnormalities. Alternate fetuses were
selected for either skeletal or visceral examinations. Approximately
half of the live fetuses from each litter were fixed in 5% formalin
solution, eviscerated, and processed for skeletal staining
with Alizarin Red S using a modified Dawson’s method for
subsequent skeletal examination. The remaining fetuses were preserved
in Bouin’s solution and examined for internal soft tissue
changes with a freehand razor sectioning technique. Fetal morphological alterations
observed in this study were classified as developmental malformations
or variations. A malformation was defined as a
permanent structural change that was likely to adversely affect
survival or health. A variation was defined
as a change which occurred within the normal population under
investigation and was unlikely to adversely affect survival or
health. In fetuses with supernumerary rib (SNR), the lengths of
the ossified portions of the supernumerary ribs were measured
using an ocular micrometer. We used an actual length of 0.6 mm
to separate short (rudimentary) from long (extra) SNR according
to the method of Rogers et al. (2004). The terminology suggested
in an internationally developed glossary of terms was used to classify
the structural developmental abnormalities in common laboratory
mammals.

Statistics:

The unit for statistical measurement was the pregnant female
or the litter (Weil, 1970). Quantitative continuous data such as
maternal body weights, food consumption, fetal body weights,
and placental weights were subjected to a one-way analysis of
the variance (ANOVA). Scheffe’s multiple comparisons test was
used when differences were significant (Scheffe, 1953). The number
of corpora lutea, total implantations, live and dead fetuses,
and fetal alterations were statistically evaluated with the Kruskal–Wallis
nonparametric ANOVA (Kruskal and Wallis, 1952), followed by the Mann–Whitney
U test when appropriate. The sex ratios and the proportions of litters with malformations
and developmental variations were compared using a chi-square test and the
Fisher’s exact probability test (1970). Statistical analyses were performed
by comparisons of the treatment groups with the control
group using the GraphPad InStat v. 3.0 (GraphPad Software, Inc.,
CA, USA). Statistical significance was defined at p values < 0.05.

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Pregnant dams in both the 30 and 90 mg/kg groups showed
treatment-related clinical signs such as piloerection, abnormal
gait, decreased locomotor activity, reddish tears, fur loss, and nasal
discharge. In the control group, reddish tears and loss of fur were
observed in 1 case each. Loss of fur was also noted in 1 case of
the 10 mg/kg group. In the 30 mg/kg group, 1 case of piloerection,
2 cases of loss of fur, and 3 cases of decreased locomotor activity
were found. In the 90 mg/kg group, 2 cases each of reddish tears
and nasal discharge, 3 cases each of piloerection, abnormal gait
and loss of fur, and 5 cases of decreased locomotor activity were
found. The maternal clinical signs were mainly observed after
treatment and were dose-dependent in both incidence and
severity.

Dermal irritation (if dermal study):

not examined

Mortality:

mortality observed, treatment-related

Description (incidence):

Dosages of 10, 30, 90, and 120 mg/kg/day were given to six
pregnant rats per group. Severe systemic toxicity and mortality occurred
in 3 of 6 females administered the test chemical at 120 mg/
kg/day between GD 13 through GD 17. A dose of 90 mg/kg/day produced
tendencies towards decreases in maternal body weight gain
and fetal body weight. In contrast, there were no treatment-related
effects on the maternal and developmental parameters at 630 mg/
kg/day. Therefore, the high dose was 90 mg/kg/day, and doses of 30
and 10 mg/kg/day were selected as the medium and low doses,
respectively, with a scaling factor of 3.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

The body weight of pregnant rats was significantly decreased
in the 90 mg/kg group compared with the control group on GD
9(Table 1). Although the body weight of pregnant rats in the
30 mg/kg group was also slightly decreased, no significant difference
was detected compared with controls. Corrected body
weight (i.e., body weight at sacrifice minus gravid uterine weight)
was significantly decreased in the 90 mg/kg group compared with he control group.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Food consumption was significantly lower on
GD 6 in the 30 mg/kg group and on GD 6 and GD 9 in the
90 mg/kg group when compared with control group in a dosedependent
manner

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:

effects observed, treatment-related

Description (incidence and severity):

Absolute liver weight in the 30 and 90 mg/kg groups were significantly
increased in a dose-dependent manner compared with
that of the control group (Table 3). The relative weights of the adrenal
glands, liver, and kidneys in the 90 mg/kg group were significantly
higher than the control group in a dose-dependent
manner. Absolute and relative liver weights in the 30 mg/kg group
were also significantly increased in comparison to the control
group.

Gross pathological findings:

not specified

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Maternal developmental toxicity

Number of abortions:

no effects observed

Pre- and post-implantation loss:

no effects observed

Total litter losses by resorption:

no effects observed

Early or late resorptions:

no effects observed

Dead fetuses:

no effects observed

Changes in pregnancy duration:

no effects observed

Changes in number of pregnant:

no effects observed

Other effects:

no effects observed

Details on maternal toxic effects:

The maternal toxicity of 1,3-DCP was observed in the 30 and
90 mg/kg groups as evidenced by clinical signs, decreases in body
weight, corrected body weight, and level of food consumption,
and/or increased weights of adrenal glands and liver.
Treatment-related clinical signs were observed in the 30 and
90 mg/kg groups as evidenced by dose-dependent increases in
the incidence and severity of piloerection, abnormal gait, decreased
locomotor activity, reddish tears, fur loss, and nasal discharge.
These findings were suggestive of severe stress induced
by 1,3-DCP treatment, supported by increased relative adrenal
weights associated with decreased food intake and suppressed
body weight gain. Clinical signs may be attributed to gastrointestinal
irritation and systemic toxic effects of 1,3-DCP. The dose dependent
decreases in body weight observed in the90 mg/kg group was
attributed to exposure to the test chemical.
This is consistent with decreased food consumption observed in
the group during the study period. This is a clear indication of
the general toxicity induced by 1,3-DCP, and suggests that oral
exposure to this chemical results in mild anorexia and the suppression
of body weight gain.

Effect levels (maternal animals)

Dose descriptor:

NOAEL

Effect level:

ca. 10 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

clinical signs

Maternal abnormalities

Abnormalities:

no effects observed

Results (fetuses)

Fetal body weight changes:

effects observed, treatment-related

Description (incidence and severity):

fetal body weight was significantly lower in the 90 mg/kg group than in the control group.

Reduction in number of live offspring:

no effects observed

Changes in sex ratio:

no effects observed

Changes in litter size and weights:

no effects observed

Changes in postnatal survival:

no effects observed

External malformations:

no effects observed

Description (incidence and severity):

There were no externally malformed fetuses in any groups.

Skeletal malformations:

no effects observed

Description (incidence and severity):

A single fetus in the control
group displayed sternoschisis, but no skeletal malformations were
observed in any of the treatment groups. The total number of fetuses
with skeletal variations in the 90 mg/kg group was significantly
higher than the control group. The characteristic skeletal
variations observed in the 90 mg/kg group were long supernumerary
rib and dumbbell/bipartite ossification of the thoracic centrum.
Other types of skeletal variations were enlarged fontanel and
dumbbell ossification of the lumbar centrum at a low frequency
in all of treatment groups. There was no evidence of treatmentrelated
reductions in fetal skeletal ossification.

Visceral malformations:

no effects observed

Description (incidence and severity):

Fetuses with visceral malformations were not observed in any groups. There was a significant
increase in the incidence of fetuses with visceral variations
in the 90 mg/kg group. The prominent visceral variations observed
were a misshapen thymus and a dilated ureter. One single case of
dilated renal pelvis was seen in the 90 mg/kg group.

Other effects:

no effects observed

Details on embryotoxic / teratogenic effects:

No embrotoxic effects or teratogenic effect were noted, however there was a decrease in pup weight at the highest dose and an increase in variaitons observed.

Effect levels (fetuses)

Dose descriptor:

NOAEL

Effect level:

ca. 30 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

fetal/pup body weight changes

Fetal abnormalities

Abnormalities:

effects observed, treatment-related

Localisation:

skeletal: supernumerary rib

Description (incidence and severity):

The total number of fetuses with skeletal variations in the 90 mg/kg group was significantly higher than the control group. The characteristic skeletal
variations observed in the 90 mg/kg group were long supernumerary
rib and dumbbell/bipartite ossification of the thoracic centrum.
Other types of skeletal variations were enlarged fontanel and

Overall developmental toxicity

Developmental effects observed:

yes

Lowest effective dose / conc.:

90 mg/kg bw/day

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

Applicant's summary and conclusion

Conclusions:

The developmental toxicity of 1,3-DCP was observed only in the presence of maternal toxicity, it is concluded that
the developmental findings observed in the present study are secondary effects to maternal toxicity.
Under these experimental conditions, the no-observed-adverse-effect level of 1,3-DCP is considered to
be 10 mg/kg/day for dams and 30 mg/kg/day for embryo-fetal development.

Executive summary:

This study investigated the potential adverse effects of 1,3-dichloro-2-propanol (1,3-DCP) on pregnant

dams and the embryo-fetal development after maternal exposure on gestational days (GD) 6 through

19 in Sprague–Dawley rats. The test chemical was administered to pregnant rats by gavage at dose levels

of 0, 10, 30, and 90 mg/kg per day (n = 10 for each group). All dams underwent Caesarean sections on GD

20, and their fetuses were examined for morphological abnormalities. Maternal toxicity was noted at

90 mg/kg/day. Manifestations of toxicity included clinical signs of illness, lower body weight gain,

decreased food intake, and increases in the weight of the adrenal glands and the liver. Developmental

toxic effects including decreases in fetal body weight and increases in visceral and skeletal variations also

occurred at the highest dose. At 30 mg/kg, only a minimal maternal toxicity, including a decrease in

maternal food intake and an increase in the liver weight, was observed. No adverse maternal or developmental

effects were observed at 10 mg/kg/day. These results revealed that a 14-day repeated oral dose of

1,3-DCP was minimally embryotoxic but not teratogenic at a maternal toxic dose (90 mg/kg/day), and

was not embryotoxic at a minimally maternal toxic dose (30 mg/kg/day) in rats. Because the developmental

toxicity of 1,3-DCP was observed only in the presence of maternal toxicity, it is concluded that

the developmental findings observed in the present study are secondary effects to maternal toxicity.

Under these experimental conditions, the no-observed-adverse-effect level of 1,3-DCP is considered to

be 10 mg/kg/day for dams and 30 mg/kg/day for embryo-fetal development.