Comparison of the teratogenic potential of inhaled ethylene glycol monomethyl ether in rats, mice, and rabbits
Toxicology Research Laboratory, Health and Environmental Science, The Dow Chemical Company, Midland, Michigan 48640 USA Toxicology and Applied Pharmacology
(Impact Factor: 3.71).
10/1984; 75(3):409-22. DOI: 10.1016/0041-008X(84)90178-9
Studies to assess the effects of inhaled ethylene glycol monomethyl ether (EGME) on embryonal and fetal development were conducted on groups of Fischer 344 rats, CF-1 mice, and New Zealand White rabbits. Rabbits and rats were exposed to vapor concentrations of 0, 3, 10, or 50 ppm for 6 hr/day on Days 6 through 18, or Days 6 through 15 of gestation, respectively; mice were exposed to 0, 10, or 50 ppm on Days 6 through 15 of gestation. Exposure of pregnant rabbits to 50 ppm produced significant increases in the incidence of malformations, minor variations, and resorptions, as well as a decrease in fetal body weight. Rats and mice exposed to 50 ppm showed no evidence of a teratogenic effect, although indications of slight fetotoxicity were observed in both species. Transient decreases in maternal body weight gain among rats, mice, and rabbits exposed to 50 ppm were the only consistent signs of maternal effects. No significant treatment-related effects on fetal development were observed in any of the species tested at 10 ppm of EGME or below.
Available from: Evert-Jan van den Brandhof
- "Some of them have been shown to have embryotoxic properties after exposure through several routes of administration in mice, rats and rabbits (Brown et al., 1984; Feuston et al., 1990; Hanley et al., 1984; Hardin et al., 1984; Nagano et al., 1981). Embryotoxic effects, mainly caused by ethylene glycol monomethyl ether (EGME) and its metabolite methoxyacetic acid (MAA), and ethylene glycol monoethyl ether (EGEE) and its metabolite ethoxyacetic acid (EAA), include visceral and skeletal malformations as well as resorptions (Hanley et al., 1984; Hardin et al., 1984). Furthermore, we tested a series of six triazole derivatives. "
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ABSTRACT: The zebrafish embryotoxicity test (ZET) is a fast and simple method to study chemical toxicity after exposure of the complete vertebrate embryo during embryogenesis in ovo. We developed a novel quantitative evaluation method to assess the development of the zebrafish embryo based on specific endpoints in time, the general morphology score (GMS) system. For teratogenic effects a separate scoring list was developed. The relative effects of eight glycol ethers and six 1,2,4-triazole anti-fungals were evaluated in this system and results were compared with in vivo developmental toxicity potencies. Methoxyacetic acid and ethoxyacetic acid appeared as the most potent glycol ether metabolites, inducing growth retardation and malformations. Other glycol ethers showed no developmental toxicity. Flusilazole appeared the most potent triazole, followed by hexaconazole, cyproconazole, triadimefon, myclobutanil and triticonazole, respectively. In general, the potency ranking of the compounds within their class in the ZET was comparable to their in vivo ranking. In conclusion, the ZET with the GMS system appears an efficient and useful test system for screening embryotoxic properties of chemicals within the classes of compounds tested. This alternative test method may also be useful for the detection of embryotoxic properties of other classes of chemicals.
Available from: Rudolf Woutersen
- "Glycol ethers are widely used as solvents in cosmetics, printing inks, plastics, household and industrial cleaning products and textile dyes. Some of them have been shown to cause developmental toxicity through several routes of exposure in mice, rats and rabbits (Feuston et al., 1990; Hanley et al., 1984; Nagano et al., 1981; Wier et al., 1987). Frequently occurring malformations include spina bifida occulta, fused, small or missing digits and exencephaly. "
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ABSTRACT: The embryonic stem cell test (EST) has been proposed as an in vitro assay that might reduce animal experimentation in regulatory developmental toxicology. So far, evaluation of the EST was
not performed using compounds within distinct chemical classes. Evaluation within a distinct class of chemically related compounds
can define the usefulness of the assay for the chemical class tested. The aim of the present study was to evaluate the relative
sensitivity of the EST for a selected series of homologous compounds and to compare the data to the relative developmental
toxicity of the compounds in vivo. To this end a series of proximate developmentally toxic glycol ether alkoxy acid metabolites was tested in the EST. All
glycol ether alkoxy acid metabolites tested showed a concentration-dependent inhibition of cardiomyocyte differentiation at
noncytotoxic concentrations, with methoxyacetic acid as the most potent compound followed by ethoxyacetic acid, butoxyacetic
acid, and phenoxyacetic acid, respectively. The potency ranking of the compounds in the EST corresponds with the available
in vivo data. The relative differences between the potencies of the compounds appeared more pronounced in the in vivo studies than in the EST. A possible explanation for this discrepancy could be the difference in the kinetics of the compounds
in vivo as compared with their in vitro kinetics. This study illustrates that the EST can be used to set priorities for developmental toxicity testing within classes
of related compounds.
Available from: Ed Carney
- "All fetuses were then preserved in alcohol, eviscerated, stained with alizarin red-S (Dawson, 1926), and examined for skeletal alterations. In judging the toxicological significance of fetal alterations, the following criteria were considered: (1) statistical significance, and/or (2) historical control values, (3) dose-dependence, (4) occurrence in more than one fetus, and (5) consistency with previously reported developmental effects of EGME (Hanley et al., 1984b). "
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ABSTRACT: Commercial grade propylene glycol monomethyl ether (PGME), which is composed of > 99.5% alpha-isomer and < 0.5% beta-isomer, has been shown in several studies to have a low potential for developmental toxicity. Nonetheless, questions have been raised about potential human developmental toxicity due to beta-PGME, because it can be metabolized to 2-methoxypropionic acid (MPA), a compound bearing structural similarity to the teratogen, methoxyacetic acid (MAA). Accordingly, a series of in vivo developmental toxicity, whole embryo culture, and in vivo pharmacokinetic experiments were conducted in New Zealand White rabbits (highly sensitive to these compounds) to better understand the developmental toxicity potential of MPA and the kinetics of its formation from beta-PGME. For the in vivo developmental toxicity studies, groups of 20 inseminated rabbits were gavaged with 0, 10, 26, or 78 mg/kg/day of MPA on gestation day (GD) 7-19, followed by fetal evaluation on GD 28. Results with MPA were compared with those of rabbits similarly dosed with 0, 2.5, 7.5, or 15 mg/kg/day of MAA. Developmental toxicity no-observable-effect levels (NOEL) were approximately 10-fold higher for MPA (26 mg/kg/day) than for MAA (2.5 mg/kg/day). Also, the severity of effects caused by MPA was less than that of MAA, and unlike MAA, MPA was not selectively toxic to the fetus. This differential toxicity was also seen in whole embryo cultures of GD 9 rabbit embryos, in which there were no adverse effects of MPA (1.0, 5.0 mM) or its parent compound, beta-PGME (0.5, 2.0 mM), but severe dysmorphogenesis in 100% of embryos cultured in 5.0 mM MAA. The pharmacokinetics study showed rapid and complete conversion of beta-PGME to MPA, with a relatively long elimination half-life (33-44 h) for MPA. However, peak and AUC concentrations of MPA in blood associated with the MPA LOEL dose of 78 mg/kg/day were 1.3 mM and 52.9 mM-h/l, respectively, suggesting a relatively high threshold based on internal dosimetry. Taken together, these data indicate a negligible risk of developmental toxicity due to MPA formation from the small amounts of beta-isomer present in commercial PGME.
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