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Toxicological information

Toxicity to reproduction

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Administrative data

Endpoint:
three-generation reproductive toxicity
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: acceptable, well-documented publication which meets basic scientific principles

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1986

Materials and methods

Principles of method if other than guideline:
Assessing the effect of ethylene glycol (EG) on fertility and general reproductive performance in male and female rats.
GLP compliance:
not specified
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Ethane-1,2-diol
EC Number:
203-473-3
EC Name:
Ethane-1,2-diol
Cas Number:
107-21-1
Molecular formula:
C2H6O2
IUPAC Name:
ethylene glycol

Test animals

Species:
rat
Strain:
Fischer 344
Sex:
male/female
Details on test animals or test system and environmental conditions:
Young adult nulliparous Fischer 344 rats were housed two per cage in stainless-steel wire cages at 20-24°C with controlled lighting (12 hr light) and fed Purina Formulab and city water ad libitum. During mating, each male was housed with 2 females. After mating and during lactation, the female rats were housed individiually in plastic showbox cages with hardwood chips for nesting. At study initiation the animals were randomly assigned to receive dietary EG at approximate dosages of 1.0, 0.2, or 0.04 g/kg/day.

Administration / exposure

Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Details on exposure:
Fresh diet was prepared every 2 weeks with the percentage of EG adjusted, based on the group mean body weight and food consumption, so as to maintain a relatively constant dosage level. However, the concentration of EG in the diet was not changed during gestation or during the first week of lactation, but was reduced two- and threefold during the second and third weeks of lactation, respectively, to adjust for increased food consumption by the dams. This change in concentration as based on earlier unpublished results from the laboratory. Increased food consumption during lactation has since been reported in another study performed at the laboratory.
Details on mating procedure:
At approximately 100 days of age, 10 males were added to 20 females in each dosage group. The date of parturition and the number of live and dead newborn were recorded for each litter. The appearance and behavior of dams and pups were observed daily. Litter size was randomly reduced to 10,
if necessary, on Day 4 postpartum. Offspring were weighed as litters at 4 and 14 days and individualiy at 21 days postpartum, the day they were weaned.
F1 rats were randomly selected within each dosage group for the next mating. Each litter was represented except for those conceived very late in the mating period. The F1 and F2 rats were treated as described for the F0 animals until approximately 100 days of age, at which time the animals were cohabited. Brother and sister matings were avoided for each generation.
Duration of treatment / exposure:
3 generations
Frequency of treatment:
daily
Doses / concentrationsopen allclose all
Dose / conc.:
40 mg/kg diet
Dose / conc.:
200 mg/kg diet
Dose / conc.:
1 000 mg/kg diet
No. of animals per sex per dose:
30
Control animals:
yes, concurrent no treatment
Details on study design:
Reproductive function was tested in a protocol that allowed continuous breeding during a 14-week period. Small, but statistically significant, decreases were found in the numbers of litters per fertile pair and in live pups per litter in the 1.0% dose group and in live pup weight at the 0.5 and 1.0% concentrations. Facial anomalies were noted in the offspring of mice at the high concentration of EG. Skeletal examination revealed a pattern of reduction in the size of bones in the skull, fused ribs, and abnormally shaped sternebrae and vertebrae in the highest dose group.
Positive control:
yes

Examinations

Parental animals: Observations and examinations:
Body weights and diet consumption were recorded weekly except during gestation and lactation.
Litter observations:
Offspring were weighed as litters at 4 and 14 days and individually at 21 days post partum, the day they were weaned. F1 rats were randomly selected within each dosage group for the next mating.
Postmortem examinations (offspring):
Necropsies were performed on five males and five females randomly selected from each dosage level of the F2 parents and the F3 weanlings. Microscopic examulations were performed on sections of liver, kidneys, lung, heart, adrenals, thyroid, trachea, accessory sex glands, adipose tissue, lymph nodes, pituitary, thymus, and testes and epididymis, or uterus and ovaries.
Statistics:
Continuous data such as body weights were compared by analysis of variance validated by Bartlett's test for homogeneity of variance. Duncan's multiple range test was used to identify individual mean differences when indicated by a significant F value. Where Bartlett's test indicated heterogeneous variances, t tests for equal or unequal variances were used to delineate differences between groups. Pup weights were compared by the method of Weil (Weil, 1970). Discontinuous data such as implantations and reproductive indices were compared by a multiple sum of ranks test. Frequency data were compared by the X2 test and by Fisher's exact test. The following reproductive indices were calculated and evaluated statistically by the previously described nonparametric methods: fertility index (male and female), days from first mating to parturition, gestation index (fraction of pregnancies that resulted in litters with live pups), gestation survival index (fraction of newborn pups alive at birth), 0 to 4-day survival index, 4 to 14-day survival index, 4 to 21day survival index. The last four indices are summarized in the tables as means for ease of understanding and presentation, although the nonparametric statistical methods did not include a comparison of means.
Reproductive indices:
yes

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:
not specified
Mortality:
no mortality observed
Description (incidence):
Throughout the study there was no effect of ethylene glycol treatment on mortality among parental rats.
Body weight and weight changes:
no effects observed
Description (incidence and severity):
Throughout the study, there was no effect of ethylene glycol treatment on body weight gain.
Food consumption and compound intake (if feeding study):
no effects observed
Description (incidence and severity):
Throughout the study there was no effect of ethylene glycol treatment on diet consumption. The calculated dosages based on the nominal concentrations of EG in the diet were generally very close to the dosage goals. The weekly calculated dosages ranged from 1.0 to 1.3, 0.2 to 0.3, and 0.04 to 0.05 g/kg/day for males and from 0.9 to 1.2, 0.2 to 0.3, and 0.04 to 0.06 g/kg/day for females.
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
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined
Other effects:
not examined

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:
not specified
Reproductive function: sperm measures:
not specified
Reproductive performance:
no effects observed
Description (incidence and severity):
No treatment-related effect was observed for any of the reproductive indices.

Effect levels (P0)

Dose descriptor:
NOAEL
Effect level:
> 1 000 mg/kg bw/day
Sex:
male/female
Basis for effect level:
other: There were no reproductive effects associated with the inclusion of as much as 1.0 g/kg/day of EG in the diet.

Results: F1 generation

General toxicity (F1)

Body weight and weight changes:
no effects observed
Description (incidence and severity):
Ethylene glycol treatment did not affect neonatal body weight at days 4, 14, or 21 post partum.

Effect levels (F1)

Dose descriptor:
NOAEL
Generation:
F1
Effect level:
> 1 000 mg/kg bw/day
Sex:
male/female
Basis for effect level:
other: There were no reproductive effects associated with the inclusion of as much as 1.0 g/kg/day of EG in the diet.

Results: F2 generation

General toxicity (F2)

Histopathological findings:
no effects observed
Description (incidence and severity):
There were no treatment-related histopathologic findings in F2 parents or in F3 weanlings. Although the kidney has been shown to be the primary target organ for EG-induced toxicity, there was no increase in the incidence or severity of kidney lesions in this study. One high dose F2 animal of each sex had mild focal interstitial nephritis. However, this condition was also seen in a control male and a control female. Unilateral hydronephrosis occurred in another high-dose F2 male. In addition, mild focal tubular hyperplasia was observed in one high-dose male F3 pup but was also diagnosed in two control male pups.

Effect levels (F2)

Dose descriptor:
NOAEL
Generation:
F2
Effect level:
> 1 000 mg/kg bw/day
Sex:
male/female
Basis for effect level:
other: There were no reproductive effects

Overall reproductive toxicity

Reproductive effects observed:
not specified

Any other information on results incl. tables

Reproductive Indices

     1.0 g/kg/d  0.2 g/kg/d  0.04 g/kg/d  0.0A  0.0B
 F0 -> F1  Fertility index (%)  100  90  100  90  90
   Male  95  90  90  75  90
   Female  100  100  100  100  100
 F1 -> F2  Fertility index (%)  100  100  90  90  90
   Male  85  95  85  90  85
   Female  100  100  100  100  94
 F2 -> F3  Fertility index (%)  100  90  100  80  80
   Male  90  75  85  80  70
   Female  100  100  100  100  100

Neonatal body weight at day 21

     1.0 g/kg/d  0.2 g/kg/d  0.04 g/kg/d  0.0A  0.0B
 F1 pups  males  30.6 +/- 4.5  30.9 +/- 4.9  30.7 +/- 6.4  30.6 +/- 3.6  27.9 +/- 4.3
   females  29.0 +/- 4.5  29.2 +/- 4.5  29.5 +/- 4.7  27.9 +/- 3.3  27.0 +/- 3.5
 F2 pups  males  32.8 +/- 3.5  30.9 +/- 5.8  29.3 +/- 4.7  30.0 +/- 4.0  28.8 +/- 4.3
   females  30.8 +/- 3.4  30.2 +/- 4.9  28.8 +/- 3.8  28.5 +/- 3.1  27.5 +/- 3.4
 F3 pups  males  30.2 +/- 4.0  30.9 +/- 4.0  30.9 +/- 4.0  32.0 +/- 3.9  30.2 +/- 4.6
   females  28.6 +/- 3.8  28.2 +/- 3.4  29.7 +/- 4.0  30.1 +/- 3.5  27.7 +/- 3.9

Applicant's summary and conclusion

Conclusions:
In conclusion, there were no reproductive effects associated with the inclusion of as much as 1.0 g/kg/day of ethylene glycol in the diet. Therefore, the substance is considered not to be toxic to reproduction.