Registration Dossier

Administrative data

Endpoint:
toxicity to reproduction: other studies
Type of information:
other: Literature data
Adequacy of study:
other information
Study period:
2001
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Bibliographical data.

Data source

Reference
Reference Type:
publication
Title:
Effects of ethylene glycol and metabolites on in vitro development of rat embryos during organogenesis
Author:
Klug S., Merker H.J., Jäckh R.
Year:
2001
Bibliographic source:
Toxicology in vitro, 15, 635-642.

Materials and methods

Principles of method if other than guideline:
The aim of this study was to investigate in vitro the relative impact of ethylene glycol, a major industrial chemical, and its individual metabolites on the embryonic development of rats.
Rat whole embryos were exposed for 48 h (Day 9.5-11.5 of gestation) to ethylene glycol (EG), and its metabolites glycolaldehyde (GAI), glycolic acid (GA), glyoxylic acid (GXA), glyoxal (GXAI) and oxalic acid (OXA) at increasing concentrations.
GLP compliance:
not specified
Type of method:
in vitro

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Aqueous concentration not precised

Test animals

Species:
rat
Strain:
Wistar
Details on test animals and environmental conditions:
Wistar rats (Bor: Wisw/SPF, TNO) were kept under SPF conditions under a constant day/night cycle from 9.00 to 21.00 at 21 +/- 1°C and 50 +/- relative humidity. The animals received pellet feed and tap water ad lib.
Three females were caged together with one male from 6.00 to 8.00 am; if sperm was detected in the vaginal smear, the following 24 h were determined as day 0 of pregnancy.

Pregnant Wistar rats were killed on gestation day 9.5.
Head-fold-stage conceptuses were removed under aseptic conditions from the uterine wall and transferred to a petri dish filled with preparation medium

Administration / exposure

Route of administration:
other:
Duration of treatment / exposure:
48 h
Details on study design:
Wistar rats (Bor: Wisw/SPF, TNO) were kept under SPF conditions under a constant day/night cycle from 9.00 to 21.00 at 21 +/- 1°C and 50 +/- relative humidity. The animals received pellet feed and tap water ad lib.
three females were caged together with one male from 6.00 to 8.00 am; if sperm was detected in the vaginal smear, the following 24 h were determined as day 0 of pregnancy.
Pregnant Wistar rats were killed on gestation day 9.5. Head-fold-stage conceptuses were removed under aseptic conditions from the uterine wall and transferred to a petri dish filled with preparation medium.
Embryos were cultured for 48 h in suplemented bovine serum as culture medium at 38.5°C in a roller device (25 rpm).
The serum was delayed centrifuged (30 min), heat inactivated, sterile filtered and supplemented with Tyrode's buffer (6:1) and enriched with methionine (75 µg/ml). The culture bottles were initially gassed with 10 vol% O2, 5 vol% CO2 and 85 vol% N2. After 36 h, the O2 concentration was increased to 50 vol%. All substances were tested twice after dissolution in bi-distilled water, in at least two concentrations in two independent experimental series.
The studied concentrations were as follows:
Ethylene glycol: 50, 100 and 200 mM,
Glyoxal: 3 and 6 mM,
Glycolic acid: 1, 3, 6 and 10 mM,
Oxalic acid: 1 and 2 mM,
Glyoxylic acid: 0.3 and 1 mM,
Glycolaldehyde: 0.03, 0.1, 0.2 and 0.3 mM.

Results and discussion

Any other information on results incl. tables

Glyoxylic acid (GXA) revealed no detectable effects at a 0.3 mM concentration in the culture medium. The slight but significant reduction of the yolk sac diameter is considered to be biologically insignificant since the growth parameters crown rump and protein content were not affected.
At 1 mM, all values for growth and differentiation were severely affected and a 100 % rate of dysmorphogenesis embryos (concerning the shape) was recorded. 13 embryos showed a retardation of the head anlage and six embryos an open ear vesicle. In nine embryos, accurate counting of the somite anlage was not possible.

The pattern of dysmorphogenesis with all compounds including EG showed a general embryotoxicity with diffusely distributed cell necrosis with no specific target tissues selectively affected.

Embryotoxic concentrations were achieved within the following range:
Ethylene glycol: 100 and 200 mM,
Glycolic acid: 3 mM,
Glyoxal: 6 mM,
Oxalic acid: 1 and 3 mM,
Glyoxylic acid: 0.3 and 1 mM,
Glycolaldehyde: 0.1 and 0.2 mM.

Applicant's summary and conclusion

Conclusions:
The results obtained in this study emphasize the hypothesis that the metabolites and not ethylene glycol itself are responsible for the embryotoxicity of ethylene glycol in rats. And in conclusion the Authors hypothesized that Glycolic acid concentrations in plasma and extra-embryonic fluids are the predominant factor for ethylene glycol developmental effects in rats.