Reaction mass of 2,2'-(ethylenedioxy)diethanol and 2,2'-oxydiethanol and ethane-1,2-diol

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Effect on fertility: via oral route

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Additional information

There is no reproductive toxicity data available on the multiconstituent substance, but data is available on the main components from which it can be concluded that the substance does not have reproductive toxicity properties. Data on individual components:

 

Ethylene glycol (ethan-1,2-diol) :

DePass et al. (1986) reported a three-generation reproduction study. Male and female rats were given oral (feed) daily doses of 0.04, 0.2 and 1 g/kg/day. No reproductive effects associated with the inclusion of as much as 1 g/kg/day of EO in the diet were found. The NOAEL for parental animals and for offsprings was found to be > 1 g/kg.

NTP (1984) reported a fertility study and found a NOEL of 1000 mg/kg for parental and F1 male and female mice. Ethylene glycol was administered in drinking water in concentrations of approx. 500, 1000 and 2000 mg/kg/day. Exposure to ethylene glycol resulted in a small but significant decrease in the number of litters per breeding pair, in the number of live pups per pair and in the live pup weight. A significant number of pups in the 1.0% dose group (2000 mg/kg) were born with distinct facial deformities. In the retained litters at this dose, the facial deformities were more obvious with age. These malformed animals also exhibited fused ribs and shortened nasal, parietal, and/or frontal bones of the skull. When pups from the high dose group were raised to adulthood (with continued exposure to ethylene glycol) and mated, they exhibited decreased mating and fertility indices relative to controls handled in the same manner, but there were no effects on litter size, pup weight or sex ratio. The authors deemed ethylene glycol a "weak reproductive toxicant, but a potential teratogen".

 

Diethylene glycol (2,2’-oxydiethanol

Research(1990) reported a reproduction and fertility assessment. Diethylene glycol was administered via the drinking water. Male and female mice were given concentrations of 0, 0.35, 1.75 and 3.5% (= 0, 612, 3063 and 6125 mg/kg) 7 days before, during and 21 days after a 98-day cohabitation stage. In this experiment, diethylene glycol did not produce changes in the male or female reproductive capability. The NOAEL was found to be 3060 mg/kg/day.

Triethylene glycol (2,2’-(ethylenedioxy)diethanol):.

Triethylene glycol was tested in a two-generation study (Bossert et al., 1992). Male and female mice were given the test substance via the drinking water in concentrations of 0.3, 1.5 and 3% (= 590, 3300 and 6780 mg/kg bw/day). The test substance was not a reproductive toxicant in either generation of mice when administered at concentrations of up to 3%, although developmental toxicity was noted in the first generation as reduced pup body weight. The NOAEL for the parental animals was found to be 6780 mg/kg bw/day; NOAEL for fertility was also 6780 mg/kg bw/day.

Short description of key information:
MEG: Rats (3 generation study), NOAEL=1000mg/kg bw/day (oral feed). Mice (fertility study), NOAEL=1000mg/kg bw/day (drinking water)
DEG: Mice (reproduction and fertility assessment, drinking water), NOAEL=3060mg/kgbw/day
TEG: Mice (3 generation study, drinking water, NOAEL=6780mg/kgbw/day.

Effects on developmental toxicity

Description of key information

MEG: Inhalation (aerosol), whole body, rats: NOAEC (maternal) 1000mg/m3, NOAEC (devtox): 150mg/m3.  Mice NOAEC (maternal, devtox): 150mg/m3
MEG: Inhalation, nose only (aerosol), mice: NOAEC (maternal) 500mg/m3, NOAEC (1000mg/m3).
MEG: oral gavage, mice; NOAEL (maternal) 1000mg/kgbw/day. NOAEL (devtox) 150mg/kgbw/day. LOAEL (devtox) 500mg/kgbw/day.
MEG: oral gavage, rat: NOAEL (maternal) 1000mg/kgbw/day.  NOAEL (devtox) 500mg/kgbw/day, LOAEL (devtox) 1000mg/kgbw/day
MEG: oral gavage, rabbit; NOAEL (maternal) 1000mg/kgbw/day), NOAEL (devtox) 2000mg/kgbw/day
MEG: oral gavage, rat: NOAEL (maternal, devtox) 250mg/kgbw/day.
DEG: oral gavage, rabbit: NOAEL (maternal, devtox) 1000mg/kgbw/day
DEG: oral gavage, rats: NOAEL (maternal, devtox) 1000ml/kgbw/day
TEG: oral gavage, rats: NOAEL (maternal) 1ml/kgbw/day, NOAEL (devtox) 5ml/kgbw/day
TEG: oral gavage, mice: NOAEL (maternal) 5ml/kgbw/day, NOAEL (devtox): 0.5ml/kgbw/day, LOAEL (devtox): 5ml/kgbw/day

Additional information

There is no developmental toxicity data available on the multiconstituent substance, but data is available on the main components from which it can be concluded that the substance does not have developmental toxicity properties that are directly mediated by the substance itself. Data on individual components:

Ethylene glycol (ethan-1,2-diol)

Tyl (1985) reported a teratogenic study with rats and mice. Rats as well as mice were given inhalative (aerosol) concentrations of 150, 1000 or 2500 mg/m3 for 6 hours per day from gestation day 6 - 15. The NOAEC for maternal toxicity was found to be 1000 mg/m3 air and the NOAEC for developmental toxicity was found to be 150 mg/m3 air for rats. For mice, the NOAEL for maternal toxicity was found to be 150 mg/m3 air for maternal toxicity and about 150 mg/m3 air for developmental toxicity. Exposure to rats and mice to EG glycol aerosol during organogenesis resulted in minimal maternal toxicity in rats at 2500 mg/m3 and minimal fetotoxicity in rats at 1000 and 2500 mg/m3. There was no maternal or embryofetal toxicity at 150 mg/m3 (the no observable effect level) and no teratogenicity at any aerosol concentration employed. In mice, evidence of maternal and embryofetal toxicity, including teratogenicity, was obsered at 1000 and 2500 mg/m3. There were no observable effects to the mouse dams or conceptuses at 150 mg/m3. The amount of EG on the fur, groomed and ingested by the mice, may have been sufficient, per se, to produce the teratogenicity observed in mice in the present study. The role of inhaled ethylene glycol on teratogenesis cannot therefore be determined from this study.

Tyl (1988) reported a developmental toxicity evaluation by nose-only or whole-body exposure. Mice were given concentrations of 50, 1000 or 2500 mg/m3 (nose-only exposure) or 2100 mg/m3 (whole-body exposure) for 6 hours per day from gestation day 6 - 15. The NOAECs were as follows: 500 mg/m3 air for maternal toxicity for nose-only exposure, 1000 mg/m3 air for developmental toxicity for nose-only exposure, 150 mg/m3 air for maternal and developmental toxicity for the whole-body exposure. Exposure of pregnant CD-1 mice to EG aerosol during organogenesis by nose-only procedure produced maternal toxicity and developmental toxicity at 2500 mg/m3 expressed as reduced fetal body weights and increased skeletal variations. One skeletal malformation, fused ribs, was also increased in incidence in this group. Nose-only exposure to EG at 1000 mg/m3 resulted only in increased maternal absolute kidney weight. Whole-body exposure to 2100 mg/m3 EG aerosol produced maternal toxicity and developmental toxicity expressed as increased resorptions, reduced number of live fetuses, reduced fetal body weights, increased skeletal and total malformations and increased skeletal variations. Small but significant amounts of EG were found on the fur of satellite females exposed to 2500 mg/m3 EG by nose-only procedures.

Tyl (1989) reported a developmental toxicity study administered by gavage. Mice were given daily doses of 50, 150, 500 or 1500 mg/kg from gestation day 6 - 15. The NOELs were found to be 1500 mg/kg bw/day for maternal toxicity and 150 mg/kg bw/day for developmental toxicity. Exposure of pregnant mice to ethylene glycol during organogenesis by gavage produced developmental toxicity but no maternal toxicity at doses of 500 and 1500 mg/kg.

BRRC (1990) studied the developmental toxicity administered by gavage in rats which received daily oral doses of 150, 500, 100 or 2500 mg/kg/day (= 15, 50, 100 and 250 mg/l) from gestation day 6 - 15. The NOAEL for maternal toxicity was 1000 mg/kg and the NOEL for developmental toxicity was 500 mg/kg. Clear evidence of maternal toxicity at 2500 mg/kg/day and consistent evidence of fetotoxciity and teratogenicity at 1000 and 2500 mg/kg/day were recorded.

Tyl et al. (1993) reported a developmental toxicity study in rabbits. Animals were given orally (gavage) doses of 100, 500, 1000 and 2000 mg/kg/day from gestation day 6 - 19. The NOAEL for maternal toxicity was found to be 1000 mg/kg/bw/day and the NOAEL for developmental toxicity was found to be 2000 mg/kg bw/day. The sensitivity of New Zealand rabbits relative to that of Sprague-Dawley rats and Swiss mice for maternal and developmental toxicity from gavage administration of ethylene glycol during organogenesis can be determined for maternal toxicity: rabbits > mice > rats, and for developmental toxicity: mice > rats > rabbits.

NTP (1988) reported a developmental toxicity in rats which were gavaged with daily doses of 250, 1250 or 2250 mg/kg/d from gestation day 6 - 20. Administration of ethylene glycol (EG) to timed-mated rats resulted in no observed toxicity at 250 mg/kg/day. At 1250 mg/kg/day, the gestational period was lengthened, and maternal renal pathology was noted, but no adverse developmental effects were observed. At 2250 mg/kg/day, reduction of maternal body weight, weight gain, kidney weight and postpartum uterine weight were observed. In addition, gestation was lengthened and maternal renal pathology was present. Developmental toxicity at 2250 mg/kg/day included reduced pup body weight, reduced viability and increased malformation incidence (primarily hydrocephaly and abnormalities of the axial skeleton), but adverse effects upon other indices of postnatal development were not observed. The NOAEL was found to be 250 mg/kg for maternal and developmental toxicity.

Diethylene glycol (2,2’-oxydiethanol

BASF (1989) reported a prenatal toxicity study in rabbits with oral administration (gavage). The oral administration of diethylene glycol to pregnant Himalayan rabbits by stomach tube on day 7 through day 19 p.i. (= post insemination) in dosages of 100, 400 and 1000 mg/kg body weight/day led to no adverse effects which can be causally related to the test substance administration in both the does and in the fetuses. The observable differences between the control group and the substance-treated groups appeared either without a clear dose-response relationship and/or were assessed as being without biological relevance, because the relevant values/findings are to be found in a similar range within the historical control data. The NOAELs for maternal toxicity, embryotoxicity and fetotoxicity were found to be 1000 mg/kg bw/day.

Bushy(1992) reported a developmental toxicity study in rats with oral administration (gavage). Exposure of 1.0, 4.0 and 8.0 ml/kg/day from gestation days 6 - 15 resulted in evidence of severe maternal toxicity, including death and kidney injury, at the highest dose group and less severe maternal effects at the 4.0 ml-dose group. Developmental toxicity as evidenced by reduced fetal weight and delayed ossification was observed at 8.0 ml/kg/day. Minimal developmental toxicity was observed at 4.0 ml/kg/day. The NOELs for maternal and developmental toxicity were 1.0 ml/kg/day. There was no evidence of teratogenic effects at any dosage.

Triethylene glycol (2,2’-(ethylenedioxy)diethanol)

BRRC (1991) tested triethylene glycol by gavage. Doses of 1, 5 and 10 ml/kg were given to time-pregnant rats from gestation day 6 - 15 (study duration: 21 days). Maternal toxicity was seen at 5 and 10 ml/kg and fetotoxicity was observed at 10 ml/kg/day. There was a slight treatment-related increase in the incidence of two minor skeletal malformations at the high dose group. The NOEL for maternal toxicity was 1 ml/kg/d, and the NOEL for developmental toxicity was 5 ml/kg/d.

BRRC (1990) reported a developmental toxicity study with mice. Time-pregnant mice were given concentrations of 0.5, 5 and 10 ml/kg/d from gestation day 6 -15 via gavage (study duration: until gestation day 18). The administration of triethylene glycol resulted in maternal toxicity at 10 ml/kg/d and fetotoxicity at 10 and 5 ml/kg/d. The ratio of the adult lowest observable effect level to the developmental lowest observable effect level was greater than 1 indicating preferential susceptibility of the developing mouse fetus to triethylene glycol under these study conditions. The NOEL for maternal toxicity was 5 ml/kg/d and the NOEL for developmental toxicity was 0.5 ml/kg/d.

Justification for classification or non-classification

Within the traditional EU classification and labelling framework (directive 67/548) and GHS as it is implemented in the EU (regulation 1272/2008), classification of reproductive toxicants encompasses effects upon fertility and on the developing offspring (‘developmental toxicity’). Monoethylene glycol (MEG, ethan-1,2-diol) does not affect fertility in animals, but developmental toxicity has been noted in some species at high doses. MEG causes developmental toxicity in two rodent species (mouse and rat) but not in a nonrodent species (rabbit). In an effort to understand the relevance of these findings to humans, investigations have been made into the underlying basis for the effects in rats, and for the species differences in sensitivity between rats and rabbits. Developmental toxicity of MEG in rats occurs when administered on a daily basis by the oral route at high doses. The effect is due to the accumulation of a specific metabolite (glycolic acid, GA) around the developing foetus, which occurs in rats but not in rabbits. Current information indicates that humans would also not accumulate GA around the foetus. Concentrations of this metabolite may well be higher in smaller species in a gavage study due to their faster metabolism.

 

The available data support non-classification of MEG, based upon the following:

1. The effects in rodents are seen only under extreme exposure conditions, at high oral doses that are not relevant to humans during the normal handling and use of MEG and MEG-based products. The lowest LOAELs for developmental toxicity were ~500mg/kg in mice and 1000mg/kg in rats.
2. No effects are seen in rabbits at very high oral doses, clearly indicating that there are species differences.
3. Differences exist between rodents and non-rodents in the metabolism and distribution of EG, and its metabolite, GA.

No classification proposal regarding developmental toxicity/teratogenicity would be considered for the inhalation and dermal routes since the critical internal dose cannot be achieved by these routes. It should be noted that the whole body exposures using aerosols would have been confounded by oral intake through fur deposition and grooming and cannot therefore be used to determine no effect concentrations by inhalation.

Neither diethylene glycol (2,2’-oxydiethanol) nor triethylene glycol (2,2’-(ethylenedioxy)diethanol) showed any evidence of substance mediated developmental toxicity at levels below 1000mg/kgbw/day and in the absence of manifest maternal toxicity.

No classification is therefore warranted for the multiple component substance based on these three constituents.