Registration Dossier

Diss Factsheets

Administrative data

Key value for chemical safety assessment

Toxic effect type:
dose-dependent

Effects on fertility

Description of key information

No data is available for the 2-ethylhexyl-S-lactate itself. Therefore, available data from a two-generation study conducted with a suitable read-across partner was used to assess the reproductive toxicity of the target substance. Based on the results, no classification for reproductive toxicity is warranted for 2-ethylhexyl-S-lactate.

Link to relevant study records
Reference
Endpoint:
two-generation reproductive toxicity
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
For details and justification of read-across please refer to the read-across report attached to IUCLID section 13.
Reason / purpose for cross-reference:
read-across source
Vehicle:
unchanged (no vehicle)
Clinical signs:
no effects observed
Description (incidence and severity):
No treatment-related clinical signs were detected in males and females in either generation that survived to scheduled euthanasia.
Dermal irritation (if dermal study):
not examined
Mortality:
mortality observed, treatment-related
Description (incidence):
Lethality was observed in F0 and F1 dams consuming the 1.0 % diet during the post-weaning period. No treatment-related mortality occurred in any of the male groups exposed to DEHT or in the female groups exposed to 0.3 % or 0.6 % DEHT.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Mean weekly body weight gain in the F0 males in the 1.0 % group was reduced (15–25 %) during weeks 3–4, 4–5, and 6–7, resulting in a slightly reduced (5 %) mean body weight at termination in this group. No other differences in body weight or body weight gain were observed in the remaining groups of F0 males and females during the pre-mating period.
Food consumption and compound intake (if feeding study):
no effects observed
Description (incidence and severity):
Feed consumption for the F0 male and female rats was unaffected by DEHT exposurethroughout the entire generation (males) or during the pre-mating period (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:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
no effects observed
Description (incidence and severity):
No DEHT-related macroscopic or microscopic findings were observed for the parental animals in either generation.
Histopathological findings: neoplastic:
not examined
Other effects:
not examined
Reproductive function: oestrous cycle:
no effects observed
Description (incidence and severity):
The oestrous cycle of the F0 were unaffected by test diet administration of DEHT at all concentrations. Please see Table 2 in box "Any other information on results incl. tables".
Reproductive function: sperm measures:
no effects observed
Description (incidence and severity):
Spermatogenic assessment parameters (e.g. motility, morphology) in the F0 and F1 males were unaffected by DEHT exposure. Please see Table 3 in box "Any other information on results incl. tables".
Reproductive performance:
no effects observed
Description (incidence and severity):
Reproductive performance parameters (e.g. mating and fertility parameters, gestation lengths) for the F0 were unaffected by test diet administration of DEHT at all concentrations. Please see Table 2 in box "Any other information on results incl. tables".
Key result
Dose descriptor:
NOAEL
Remarks:
reproductive toxicity
Effect level:
10 000 mg/kg diet
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: no adverse signs of reproductive toxicity were observed
Key result
Dose descriptor:
NOAEL
Remarks:
parental toxicity
Effect level:
3 000 mg/kg diet
Based on:
test mat.
Sex:
male/female
Basis for effect level:
mortality
body weight and weight gain
organ weights and organ / body weight ratios
Critical effects observed:
yes
Lowest effective dose / conc.:
6 000 mg/kg diet
System:
hepatobiliary
Organ:
liver
Treatment related:
yes
Dose response relationship:
yes
Relevant for humans:
not specified
Clinical signs:
no effects observed
Description (incidence and severity):
No treatment-related clinical signs were detected in males and females in either generation that survived to scheduled euthanasia.
Dermal irritation (if dermal study):
not examined
Mortality:
mortality observed, treatment-related
Description (incidence):
Lethality was observed in F0 and F1 dams consuming the 1.0 % diet during the post-weaning period. No treatment-related mortality occurred in any of the male groups exposed to DEHT or in the female groups exposed to 0.3 % or 0.6 % DEHT.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Reduced mean body weight gain in the 0.6 % and 1.0 % F1 males groups, along with lower mean birth weights and decreased growth before weaning from the F0 maternal animals, resulted in reduced mean body weights throughout the generation for the F1 males in the 0.6 % and 1.0 % group. Similar to the F0 females, F1 female body weight gain after weaning in the 0.6 % and 1.0 % groups was similar to the control group (data not shown). However, as a result of reduced mean body weights during the pre-weaning period in the 0.6 % and 1.0 % F1 female group, pre-mating body weights in these groups were decreased relative to the control group, although only the 1.0 % group was significant statistically. No test article-related effects on mean weekly body weights were observed in the 0.3 % group F1 males and female groups.
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
Feed consumption for F1 female rats was unaffected by DEHT exposure throughout the entire generation (males) or during the pre-mating period (females). Correlating with the reduced mean body weights, feed consumption in the 0.6 % and 1.0 % F1 males was slightly reduced (10 %) during the first week after weaning (0.6 % group) or throughout the generation (1.0 % group); the differences from the control group were often statistically significant.
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):
Liver weight relative to final body weight was increased in both the F0 and F1 females in the 0.6 % and 1.0 % groups (p < 0.05). The increases in liver weight were attributed to DEHT exposure. These increases in liver weights were not unexpected, as this is a characteristic finding in animals exposed to high dose levels of DEHT. High dose levels of 2-ethylhexanol (a metabolite of DEHT) has been shown to cause an acute phase response and hypertrophy (Astill et al., 1996) in the liver when administered by oral gavage. Several statistically significant decreases were observed in mean absolute organ weights in the F1 adults. In most cases, however, these changes disappeared when compared relative to the body weights of the animals suggesting the differences were due to the decreased body weights. In addition, no correlative macroscopic or microscopic findings were observed in these tissues. Therefore the differences from the control group were not considered to be biologically relevant or adverse.
Gross pathological findings:
no effects observed
Description (incidence and severity):
No DEHT-related macroscopic or microscopic findings were observed for the parental animals in either generation.
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
no effects observed
Description (incidence and severity):
No DEHT-related macroscopic or microscopic findings were observed for the parental animals in either generation.
Histopathological findings: neoplastic:
not examined
Other effects:
not examined
Reproductive function: oestrous cycle:
no effects observed
Description (incidence and severity):
The oestrous cycle of the F0 were unaffected by test diet administration of DEHT at all concentrations. Please see Table 2 in box "Any other information on results incl. tables".
Reproductive function: sperm measures:
no effects observed
Description (incidence and severity):
Spermatogenic assessment parameters (e.g. motility, morphology) in the F0 and F1 males were unaffected by DEHT exposure. Please see Table 3 in box "Any other information on results incl. tables".
Reproductive performance:
no effects observed
Description (incidence and severity):
Reproductive performance parameters (e.g. mating and fertility parameters, gestation lengths) for the F1 were unaffected by test diet administration of DEHT at all concentrations. Ovarian follicle counts for the F1 females in the high-exposure group were similar to the control values. Please see Table 2 in box "Any other information on results incl. tables".
Key result
Dose descriptor:
NOAEL
Remarks:
reproductive toxicity
Effect level:
10 000 mg/kg diet
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: no adverse signs of reproductive toxicity were observed.
Key result
Dose descriptor:
NOAEL
Remarks:
parental toxicity
Effect level:
3 000 mg/kg diet
Based on:
test mat.
Sex:
male/female
Basis for effect level:
mortality
body weight and weight gain
organ weights and organ / body weight ratios
Critical effects observed:
yes
Lowest effective dose / conc.:
6 000 mg/kg diet
System:
hepatobiliary
Organ:
liver
Treatment related:
yes
Dose response relationship:
yes
Relevant for humans:
not specified
Clinical signs:
no effects observed
Description (incidence and severity):
No treatment-related clinical signs were detected in males and females in either generation.
Dermal irritation (if dermal study):
not examined
Mortality / viability:
no mortality observed
Description (incidence and severity):
No mortality were observed.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
F1 male and female pup weights in the 0.3, 0.6, and 1.0 % groups were significantly reduced on PND 1 and 4. The mean pup weights in the F1 1.0 % group start to fall below the historic control group values by PND 7, with further reductions throughout the lactation period (coincidentally with decreases in feed consumption by the F1 1.0 % group dams). Despite the similarities with historic control group values, the replication of reduced mean pup body weights from PND 14–21 in the 0.6 % and 1.0 % group from both the F1 and F2 generation pups were considered related to treatment.
Food consumption and compound intake (if feeding study):
not examined
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
Sexual maturation:
no effects observed
Description (incidence and severity):
In the 1.0% F1 male animals a 5 % increase in age of balanopreputial separation was recorded. It is important to note that the mean day of attainment of balanopreputial separation in the 1.0 % F1 males was equal to the historic control value for this endpoint in the performing laboratory. In addition, There was no additional evidence of effects on male sexual development in the F1 male animals as all other measures of sexual function (fertility, sperm parameters, testicular weight, and histology) were unaffected. Therefore, the slight increase in age of balanopreputial separation in the 1.0 % group was not considered adverse. Thus, no adverse effects on sexual maturation were observed (balanopreputial separation; vaginal patency).
Anogenital distance (AGD):
not examined
Nipple retention in male pups:
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
Although several changes in the PND 21 absolute organ weights from the 0.6 % group were observed in the F1 and F2 pups, these changes disappeared when they were adjusted for the decreased body weights of these animals (data not shown). Changes in mean F1 and F2 male and female pup organ weights on PND 21 that were unrelated to decreased body weights included a reduced (13 %) mean relative spleen weight in the F1 male 1.0 % group and the F2 male (8 %) and female (11 %) 1.0 % groups, and a reduced (12 %) mean relative thymus weight in the F2 female 1.0 % group. In addition, mean relative brain weights were increased for both sexes in the F1 (25 %) and F2 (23–25 %) 1.0 % group and the F1 0.6 % female group (12 %). Increases in relative brain weights in the F1 male and female animals from the 0.6 % and 1.0 % dietary groups were considered to be related to the decreased terminal body weights of these animals rather than a direct effect of DEHT exposure.
Gross pathological findings:
no effects observed
Description (incidence and severity):
No macroscopic findings attributable to parental exposure to DEHT were noted at the scheduled necropsy of F1 and F2 pups euthanized on PND 21.
Histopathological findings:
not specified
Other effects:
not specified
Behaviour (functional findings):
not examined
Developmental immunotoxicity:
not examined
Key result
Dose descriptor:
NOAEL
Generation:
F1
Effect level:
3 000 mg/kg diet
Based on:
test mat.
Sex:
male/female
Basis for effect level:
body weight and weight gain
organ weights and organ / body weight ratios
Critical effects observed:
yes
Lowest effective dose / conc.:
10 000 mg/kg diet
Organ:
spleen
thymus
Treatment related:
yes
Dose response relationship:
yes
Relevant for humans:
not specified
Clinical signs:
no effects observed
Description (incidence and severity):
No treatment-related clinical signs were detected in males and females in either generation that survived to scheduled euthanasia.
Dermal irritation (if dermal study):
not examined
Mortality / viability:
no mortality observed
Description (incidence and severity):
No mortality occurred.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
In the F2 generation, the mean pup body weights in the 0.3 % and 0.6 % groups for PND 1 and 4 were comparable to concurrent control values. Although the PND 1 and PND 4 mean pup weights in the F2 1.0 % group were reduced significantly when compared to the concurrent control value, they were slight (3–4 %) and equivalent to historic control values. Thus these changes were considered of no biological relevance.
The mean pup weights in both the F1 and F2 1.0 % groups start to fall below the historic control group values by PND 7, with further reductions throughout the lactation period (coincidentally with decreases in feed consumption by the F1 and F2 1.0 % group dams). On PND 14 and 21, the mean pup weights from the F2 0.6 % group were reduced significantly when compared to the concurrent control values but were higher than the corresponding historic control values. Mean pup body weights for the F2 0.3 % group were comparable to concurrent control and historic control values at all time points. Despite the similarities with historic control group values, the replication of reduced mean pup body weights from PND 14–21 in the 0.6 % and 1.0 % group from both the F1 and F2 generation pups were considered related to treatment.
Food consumption and compound intake (if feeding study):
not examined
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
Sexual maturation:
not examined
Anogenital distance (AGD):
not examined
Nipple retention in male pups:
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
Although several changes in the PND 21 absolute organ weights from the 0.6 % group were observed in the F1 and F2 pups, these changes disappeared when they were adjusted for the decreased body weights of these animals (data not shown). Changes in mean F1 and F2 male and female pup organ weights on PND 21 that were unrelated to decreased body weights included a reduced (13 %) mean relative spleen weight in the F1 male 1.0 % group and the F2 male (8 %) and female (11 %) 1.0 % groups, and a reduced (12 %) mean relative thymus weight in the F2 female 1.0 % group. In addition, mean relative brain weights were increased for both sexes in the F1 (25 %) and F2 (23–25 %) 1.0 % group and the F1 0.6 % female group (12 %). Increases in relative brain weights in the F1 male and female animals from the 0.6 % and 1.0 % dietary groups were considered to be related to the decreased terminal body weights of these animals rather than a direct effect of DEHT exposure.
Gross pathological findings:
no effects observed
Description (incidence and severity):
No macroscopic findings attributable to parental exposure to DEHT were noted at the scheduled necropsy of F1 and F2 pups euthanized on PND 21.
Histopathological findings:
not examined
Other effects:
not examined
Behaviour (functional findings):
not examined
Developmental immunotoxicity:
not examined
Key result
Dose descriptor:
NOAEL
Generation:
F2
Effect level:
3 000 mg/kg diet
Based on:
test mat.
Sex:
male/female
Basis for effect level:
body weight and weight gain
organ weights and organ / body weight ratios
Critical effects observed:
no
Key result
Reproductive effects observed:
no

Analysis of diet

Analysis of diets containing DEHT indicated that the formulations were stable, homogenous, and within 10% of the target concentration.

Mean calculated Compound Consumption:

Table 1: Mean calculated compound consumption in mg/kg bw/day
  Males Females
Nominal Dietary Level Before Breeding After Breeding Before Breeding Gestation Lactation After Weaning
F0 generation
0.3% 182 133 223 184 478 207
0.6% 367 265 449 372 940 419
1.0% 614 447 783 595 1349 745
F1 generation
0.3% 256 159 275 206 516 227
0.6% 523 320 573 423 1036 486
1.0% 893 552 1021 697 1549 868

Reproductive parameters:

Table 2: Reproductive Parameters and Litter data for F1 Generation
Parameter 0 0.3 % 0.6 % 1.0 %
Mating pairs (n) 30 30 30 30
Estrous cycle length (days) 4.9 +/- 1.98 5.2 ± 1.24 4.8 ± 1.39 5.6 ± 2.90
Precoital interval (days) 3.7 ± 2.36 3.0 ± 1.38 3.1 ± 1.28 2.6 ± 1.62
Mating index (%) 93.3 100 100 93.3
Fertility index (%) 80.0 80.0 93.3 93.3
Gestation length (days) 21.6 ± 0.49 22.0 ± 0.32* 21.9 ± 0.2 21.9 ± 0.51
Total pups/litter (n) 14.3 ± 3.29 14.3 ± 3.25 14.5 ± 2.19 14.2 ± 2.13
Live pups/litter (n) 13.9 ± 3.18 14.0 ± 3.16 14.2 ± 2.02 13.7 ± 2.83
Gender ratio (% per litter) 50.3 ± 13.73 54.2 ± 13.96 51.2 ± 11.88 46.0 ± 14.82
Pup survival (% per litter)      
PND 0 97.6 ± 4.23 98.2 ± 3.86 98.0 ± 4.11 96.5 ± 13.62
PND 0-1 99.5 ± 1.76 99.5 ± 1.78 99.5 ± 1.89 98.1 ± 4.61
PND 0-4 (precull) 96.3 ± 4.93 97.1 ± 5.24 97.0 ± 4.32 94.7 ± 14.40
PND 4 (precull) - 21 99.5 ± 2.55 99.0 ± 3.53 100 ± 0.0 100 ± 0.0
*= p< 0.05

Spermatogenic assessments:

Table 3: Spermatogenic assessments
Parameter 0 0.3 % 0.6 % 1.0 %
F0 males
rats examined 29 30 29 30

Sperm concentration

(× 106/g)

      
left testis 105.4 ± 40.75 102.7 ± 27.92 111.6 ± 28.25 104.4 ± 25.58
left epididymis 454.6 ± 126.55 448.9 ± 132.08 460.0 ± 104.61 459.3 ± 98.61
Motility (%) 91.1 ± 3.52 90.5 ± 3.57 89.1 ± 4.86 89.3 ± 4.74
Morphology (% normal) 99.8 ± 0.43 99.8 ± 0.45 99.8 ± 0.34 99.8 ± 0.31
F1 males
rats examined 30 30 30 29

Sperm concentration

(× 106/g)

      
left testis 83.8 +/- 19.27 81.4 +/- 17.19 81.6 +/- 16.15 87.9 +/- 27.33
left epididymis 412.9 +/- 90.02 413.7 +/- 91.93 416.1 +/- 86.18 427.1 +/- 109.51
Motility (%) 85.3 +/- 12.99 86.0 +/- 7.20 81.7 +/- 13.94 85.7 +/- 9.37
Morphology (% normal) 99.9 +/- 0.23 99.5 +/- 0.84 99.6 +/- 0.93 99.7 +/- 0.34
Conclusions:
In a two-generation reproductive toxicity study conducted according to OECD 416, rats were exposed via diet to 10000, 6000 and 3000 mg/kg diet. Based on the results, the NOAEL for systemic toxicity in both growing and adult animals is 3000 mg/kg diet. The NOAEL for reproductive toxicity is 10000 mg/kg diet.
Executive summary:

In a two-generation reproductive toxicity study conducted according to OECD 416 groups of male and female Crl:CD rats (30/sex/dose) were exposed via diet to 10000, 6000 and 3000 mg/kg diet of di-2-etyhlhexyl terephthalate (DEHT). Parental animals were exposed for at least 70 consecutive days before mating for the F1 and F2 generations. Exposure of the males continued throughout the mating period until euthanasia. Exposure of the females continued throughout mating, gestation and lactation. F1 and F2 pups were weaned on postnatal day (PND) 21.

Exposure to DEHT did not affect clinical observations.However, mortality was observed in P0 and P1 dams consuming 10000 mg/kg diet during the post-weaning period. No treatment-related mortality occurred in any of the male groups exposed to DEHT or in the female groups exposed to 0.3 % or 0.6 % DEHT. Male rats consuming the 1.0 % in both parental generations gained weight more slowly than the controls. There were no indications of adverse effects on reproductive performance in either generation. Male and female mating and fertility indices, pre-coital intervals, spermatogenic endpoints, reproductive organ weights, lengths of oestrous cycle and gestation, live litter size, developmental landmarks, and postnatal survival were similar in all exposure groups. Additionally, ovarian follicle counts for the F1 females in the high-exposure group were similar to the control values. No adverse exposure-related macroscopic pathology was noted at any exposure level in either generation. Increases in liver weights were found in the male and female animals exposed to 6000 or 10000 mg/kg diet. Because there were no accompanying histopathologic changes, this effect was not considered adverse. Significant decreases in feed consumption in the female animals from the groups consuming 10000 mg/kg diet during lactation accompanied reduced postnatal pup body weights and rate of weight gain. Reductions in pup body weights later in lactation may also have been due to direct consumption of the treated feed by the pups or taste aversion to the same. Reduced relative spleen weight was found in male weanling pups from the high dose group in both generations and reduced relative spleen and thymus weights were found in female pups from the high dose group in the F2 generation at necropsy on PND 21. Therefore, for parental and pup systemic toxicity, 3000 mg/kg diet was considered as the NOAEL. As no adverse effects were seen for reproductive toxicity, 10000 mg/kg diet was considered the NOAEL for both generations.

This information is used in a read-across approach in the assessment of the target substance.

For justification of read-across please refer to the read-across report attached to IUCLID section 13.

Effect on fertility: via oral route
Endpoint conclusion:
no adverse effect observed
Effect on fertility: via inhalation route
Endpoint conclusion:
no study available
Effect on fertility: via dermal route
Endpoint conclusion:
no study available
Additional information

The target substance is very quickly enzymatically hydrolysed to ethylhexanol and L(+)-lactic acid, indicating that the compounds systemically available are lactic acid and ethylhexanol. Therefore, the requirements for reproduction toxicity shall be addressed based on information for lactic acid and ethylhexanol. As lactic acid is a ubiquitous and integral part of mammalian metabolism and therefore of minor toxicological relevance in comparison to ethylhexanol, the latter is the key factor for the toxicological assessment. No study is available elucidating the reproductive toxicity potential of the target substance. Thus, available data from a study conducted in accordance with OECD testing guideline 416 with the read-across partner di-2-ethylhexyl terephthalate was used to assess the potential of the target substance to induce reproductive toxicity. For more details on the read-across justification please refer to IUCLID section 13.

In a two-generation reproductive toxicity study conducted according to OECD guideline 416, groups of male and female Crl:CD rats (30/sex/dose) were exposed to dietary concentrations di-2-ethylhexyl terephthalate of 10000, 6000 and 3000 mg/kg diet. Parental animals were exposed for at least 70 consecutive days before mating for the F1 and F2 generations. Exposure of the males continued throughout the mating period until euthanasia. Exposure of the females continued throughout mating, gestation and lactation. F1 and F2 pups were weaned on postnatal day (PND) 21.

Exposure to DEHT did not affect clinical observations. However, mortality was observed in P0 and P1 dams consuming 10000 mg/kg diet during the post-weaning period. There were no indications of adverse effects on reproductive performance in either generation. Male and female mating and fertility indices, pre-coital intervals, spermatogenic endpoints, reproductive organ weights, lengths of oestrous cycle and gestation, live litter size, developmental landmarks, and postnatal survival were similar in all exposure groups. Additionally, ovarian follicle counts for the F1 females in the high-exposure group were similar to the control values. No adverse exposure-related macroscopic pathology was noted at any exposure level in either generation. Increases in liver weight were found in the male and female animals exposed to 6000 or 10000 mg/kg diet. Because there were no accompanying histopathological changes, this effect was not considered adverse. Significant decreases in feed consumption in the female animals from the groups consuming 10000 mg/kg diet during lactation were accompanied by reduced postnatal pup body weights and rate of weight gain. Reductions in pup body weights later in lactation may also have been due to direct consumption of the treated feed by the pups or taste aversion. Reduced relative spleen weight was found in male weanling pups from the high dose group in both generations and reduced relative spleen and thymus weights were found in female pups from the high dose group in the F2 generation at necropsy on PND 21. Based on the food consumption data, rats consuming diets containing 1 % DEHT (10000 mg/kg diet) resulted in exposures up to 893 mg/kg bw/d (males) or 1021 mg/kg bw/d (females). Based on the results, the NOAEL for parental and pup systemic toxicity, is considered to be 3000 mg/kg diet. As no adverse effects were seen for reproductive toxicity, 10000 mg/kg diet was considered the NOAEL for both generations.

In addition, supporting information was derived from available repeated dose toxicity studies, indicating that treatment to the source substance 2-ethylhexanol has no effects no effects on reproductive organs.

Effects on developmental toxicity

Description of key information

Two developmental toxicity studies in rats or rabbits are available to assess the reproductive/developmental toxicity potential of the target substance 2-ethylhexyl-S-lactate. In the first study (OECD 414), 2-ethylhexyl-S-lactate was administered to 12 mated female Wistar rats/dose by inhalation, nose only at dose levels of 0, 200 and 600 mg/m³ from gestation day 6 up to and including day 15 during 6-hour sessions.

During exposure the breathing rate was visibly increased in animals exposed to 600 mg/m³ during the entire treatment period and occasionally in animals exposed to 200 mg/m³. Furthermore, dams exposed to the test substance consumed less food than the controls, the difference being statistically significant at 600 mg/m³ only. At 200 mg/m³ this decrease was followed by a slight but statistically significant increase. The maternal LOAEC is 200 mg/m³ based on the increase in breathing rate and changes in food consumption; a maternal NOAEC could not be identified.

Slightly retarded ossification was seen in the foetuses of the dams exposed to 200 and 600 mg/m³, but this was considered to be a minor developmental effect, most likely attributable to the stress caused by combination of maintaining the animals in restraining tubes and the irritative properties 2-ethylhexyl lactate. The developmental NOAEC is considered to be 600 mg/m³.

In the second study, no treatment-related effects on developmental parameters were detected in a developmental toxicity test (OECD 414) after inhalation of 3-methyl-1-butanol in rabbits. The maternal NOAEC is considered to be 2.5 mg/L due to a slight retardation in body weight change after inhalation of 10 mg/L. The developmental NOAEC is considered to be 10 mg/L.

Link to relevant study records

Referenceopen allclose all

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
February 1996-August 1996
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
Only two dose levels instead of three and only 12 females per dose level were used, but the test results provide useful and reliable information.
Qualifier:
according to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
yes
Remarks:
, two instead of three dose levels were used, 12 instead of 20 animals per dose level were used
GLP compliance:
yes (incl. QA statement)
Limit test:
no
Species:
rat
Strain:
Wistar
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Harlan Winkelmann GmbH, Borchen, Germany
- Age at study initiation: 14-15 weeks
- Weight at study initiation: mean weight: 208 g
- Fasting period before study: none
- Housing: mated females were house individually in wire mesh cages (18 × 32 × 18 cm)
- Diet (e.g. ad libitum):the Institute's cereal-based rodent diet, ad libitum
- Water (e.g. ad libitum): tap water, ad libitum
- Acclimation period: 13 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3 °C
- Humidity (%):30-70 %
- Air changes (per hr): 10 air changes per hour
- Photoperiod (hrs dark / hrs light): 12 hours dark, 12 hours light

IN-LIFE DATES: From: February 7, 1996-March 19 and 20, 1996
Route of administration:
inhalation: aerosol
Type of inhalation exposure (if applicable):
nose only
Vehicle:
air
Details on exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: The animals were exposed to the test atmospheres in nose-only inhalation units. Each unit consisted of a cylindrical teflon-coated column, surrounded by a transparent cylinder. The column had a volume of ca. 50 L and consisted of a top assembly, with two rodent tube sections underneath and an exhaust section at the bottom. The rodent tube sections had 40 ports for animal exposure.
- Method of holding animals in test chamber: plastic animal holder (Batelle)
- Source and rate of air: humidified pressurized air
- Method of conditioning air: humidified
- System of generating particulates/aerosols: The low-concentration test atmosphere was generated by passing metered amounts of the test material using a roller pump (Golson, Villiers le Bel, France) to a compressed air driven, all glass nebulizer (Institute's design). The generated mixture of test material and air was subsequently mixed with metered amounts of pressurized air (using a rotameter) and was again mixed at the entrance of the exposure unit with metered amounts of pressurized air. The resulting test atmosphere was directed downward through the mixing chamber towards the animals' noses.
The high-concentration test atmosphere were generated by nebulizing the test material using compressed air driven steel nebulizers (Institute's design). These nebulizers consisted of an atomizer (Lechler Informatic Buro Holland, Oudorp, the Netherlands) and a glass jar containing the test materials. During operation, the test material was drawn through a suction tube to the atomizer and was blown against a baffle which was fitted below the nozzel orifice in such a way that the larger droplets were removed by impaction. The impacted test material drained back into the test material supply at the bottom of the jar. The resulting aerosol was also mixed with humidified pressurized air in the way described above and directed towards the animals.
- Temperature, humidity, pressure in air chamber: The daily mena temperature was 22.7 ± 0.6 °C, 22.6 ± 0.4 °C and 22.6 ± 0.4 °C for the control, low and high concentration level, respectively. The daily relative humidity was 56 ± 6 %, 52 ± 5 % and 52 ± 6 %, respectively. A positive pressure in the central column and a slightly negative pressure in the outer cylinder, which enclosed the entire animal holder, were maintained to prevent dilution of the test atmosphere by air leaking from the animal's thorax to the nose.
- Air flow rate: the mean daily airflows were 26.5, 55.9 and 70.4 L/min for the control, low and high concentration level, respectively
- Air change rate: given the volume of ca 50 L of each inhalation unit, the air change rate was calculated to be 0.53, 1.12 and 1.41 air changes per minute for the control, low, and high concentration level, respectively.
- Method of particle size determination: once per week (except for the control test atmosphere) using an 11-stage cascade impacter (Institute's design) with the largest cut off size of 4.2 µm. The Mass Median Aerodynamic Diameter (MMAD) and the mean geometric standard deviation (gsd) were calculated (Lee, 1972).
- Treatment of exhaust air: The test atmosphere was exchausted at the bottom of the unit.

TEST ATMOSPHERE
- Brief description of analytical method used: The actual concentration of 2-ethylhexyl lactate in the test atmosphere was detemined at least 3 times per exposure day by means of gravimetric analysis. Preliminary experiments had shown that the 2-ethylhexyl lactate test atmosphere almost exclusively consisted of aerosol and not of vapour and that gravimetrical analysus was a suitable method to measure the actual concentration in air. Measured test atmosphere samples were obtained by passing approximately 50 or 30 liters of test atmosphere for the low- and high-concentration level, respectively, at a mean sampling speed of 5 L/min, through fiber glass filters (Sartorius). Before and immediately after sampling the filters were weighed. The actual concentration was calculated by dividing the amount of test material on the filter by the sample volume.
- Samples taken from breathing zone: yes

VEHICLE (if applicable)
- Justification for use and choice of vehicle: compressed air was used to generate aerosols
- Composition of vehicle: compressed air
- Type and concentration of dispersant aid (if powder):
- Concentration of test material in vehicle:
- Lot/batch no. of vehicle (if required):
- Purity of vehicle:
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The actual concentration of 2-ethylhexyl lactate in the test atmosphere was detemined at least 3 times per exposure day by means of gravimetric analysis. Preliminary experiments had shown that the 2-ethylhexyl lactate test atmosphere almost exclusively consisted of aerosol and not of vapour and that gravimetrical analysus was a suitable method to measure the actual concentration in air. Measured test atmosphere samples were obtained by passing approximately 50 or 30 liters of test atmosphere for the low- and high-concentration level, respectively, at a mean sampling speed of 5 L/min, through fiber glass filters (Sartorius). Before and immediately after sampling the filters were weighed. The actual concentration was calculated by dividing the amount of test material on the filter by the sample volume.
Details on mating procedure:
- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: for mating two females were placed with one male
- Length of cohabitation: every consecutive morgning vaginal examinations were made to ascertain copulation by detection of a vaginal plug or sperm cells in a vaginal smear. Upon evidence of copulation, positive females were housed individually. This procedure was continued until the required number of females showed evidence of copulation.
- Verification of same strain and source of both sexes: yes
- Proof of pregnancy: vaginal plug or sperm in vaginal smear referred to as day 0 of pregnancy
Duration of treatment / exposure:
from gestation day 6 up to and including day 15
Frequency of treatment:
6 hours per day
Duration of test:
from gestation day 0 to day 21
No. of animals per sex per dose:
12 mated females per dose
Control animals:
yes, sham-exposed
Details on study design:
- Dose selection rationale:
Exposure levels selected were based on similar studies with ethyl lactate (TNO reports V90.322 and V91.416) showing moderate to severe nasal irritating and toxic (local) effects at levels of 600 and 2500 mg/m³, whereas sligh systemic toxicity (reduced food consumption and growth retardation) was observed at the 2500 mg/m³ level only. The No-Observed-Adverse-Effect level (NOAEL) in these studies was 200 mg/m³. In addition, the in vitro hydrolysing acitivity of these compounds by nasal olfactory epithelium was taken into account (TNO-report V92.339) with 2-ethylhexyl lactate showing an approximately 6.5 times higher affinity and a 2.5 times higher velocity than ethyl lactate. The target levels chosen for the present study, therefore, were: 0, 200 and 600 mg/m³.
- Rationale for animal assignment (if not random): The mated females were distributed ove the three experimental groups in such a way that the animals from the same day of pregnacy were, as far as possible, equally distributed over all groups. Females mated by the same male were placed in different groups.
Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Each mated female was observed daily from gestation day 0. Signs of ill health and reaction to treatment as well as mortatily were recorded. On working days, all cages were checked again late in the afternoon for dead or moribund animals to minimize loss of animals from the study. During weekends and holidays only one check per day was carried out.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: if necessary, the females were handled to appraise its physical condition

BODY WEIGHT: Yes
- Time schedule for examinations: body weights of mated females were recorded on gestation days 0, 6, 10, 15 and 21

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day #21
- Organs examined: the uteri (including the fetuses), ovaries and placentas.
The females killed on day 21 were examined for gross abnormalities and the dam that died during the study was also examined macroscopically.

OTHER:
Food consumption of mated females was measured for each animal individually by weighing the feeders on days 0, 6, 10, 15 and 21 of gestation.
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: number of live and dead fetuses; sex of fetuses, number of grossly visible malformed fetuses and fetuses with external abnormalities; weight of ovaries; weight of uterus, empty; weight of the fetuses; weight of placentas; gross evaluation of placentas
Fetal examinations:
- External examinations: Yes, all per litter
- Soft tissue examinations: Yes, half per litter
- Skeletal examinations: Yes, half per litter
- Head examinations: No
Statistics:
As a level of significance was considered: P < 0.05
Adult data:
Clinical and necropsy findings were evaluated by Fisher's exact probability test. Body weight, body weight gain, organ weights and food consumption data were subjected to one-way analysis of variance (ANOVA) followed by Dunnett's multiple comparison tests.
Mating, Caesarian section and litter data:
Fisher's exact probability test was used to evaluate fetal external, visceral and skeletal observations, the number of mated and pregnant females, females with live fetuses and male and female fetuses. Number of corpora lutea, implantations, live and dead fetuses, and early and later resorptions were evaluated by Kruskal-Wallis nonparametric analysis of variance followed by the Mann-Whitney U-test. Placental and fetal weight were evaluated by one-way analysis of variance (ANOVA) followed by Dunnett's multiple comparison tests.
Indices:
The following indices were calculated for each group at the Caesarian section:
Pre-implantation loss = ((number of corpora lutea - total number of implantation sites)/ number of corpora lutea ) × 100
Post-implantation loss = ((total number of implantation sites - number of live fetuses)/ total number of implantation sites) × 100
Fecundity index = (number of females pregnant/ number of males mated) × 100
Gestation index = (number of females with live fetuses/ number of females pregnant) × 100
Live fetus index = (number of live fetuses/ number of implantation sites) × 100
Sex ratio = (number of live male fetuses/ total number of live fetuses) × 100
Details on maternal toxic effects:
Maternal toxic effects:yes

Details on maternal toxic effects:
A visually increased breathing rate was observed in animals exposed to 600 mg/m³ during the entire treatment period and occasionaly in animals exposed to 200 mg/m³.
During the exposure period dams exposed to 2-ethylhexyl lactate tended to consume less food when compared with the controls. In the 600 mg/m³ the difference reached a level of statistical significance. After the exposure period animals of the 200 mg/m³ group consumed slightly more food than the controls (statistically significant), probably to compensate for the slight decrease in food intake during the preceeding exposure period.
Dose descriptor:
NOAEL
Effect level:
600 mg/m³ air (analytical)
Based on:
test mat.
Basis for effect level:
other: developmental toxicity
Dose descriptor:
LOAEL
Effect level:
200 mg/m³ air (analytical)
Based on:
test mat.
Basis for effect level:
other: maternal toxicity
Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
The slightly retarded ossification observed at the levels of 200 and 600 mg/m³, is most probably not due to systemic toxicity but might be related to stress caused by the combination of maintaining the animals in restraining tubes and the irritative properties of the test material. No teratogenic effects were observed in this study.
Dose descriptor:
NOAEL
Effect level:
600 mg/m³ air (analytical)
Based on:
test mat.
Basis for effect level:
other: teratogenicity
Abnormalities:
not specified
Developmental effects observed:
not specified
Conclusions:
2-Ethylhexyl lactate in not teratogenic or developmentally toxic.
Executive summary:

In a developmental toxicity study, 2-ethylhexyl lactate was administered to 12 mated female Wistar rats/dose by inhalation, nose only at dose levels of 0, 200 and 600 mg/m³ from gestation day 6 up to and including day 15 during 6-hour sessions.

During exposure the breathing rate was visually increased in animals exposed to 600 mg/m³ during the entire treatment period and occasionally in animals exposed to 200 mg/m³. Further, dams exposed to the test substance consumed less for than the controls, the difference being statistically significant at 600 mg/m³ only. At 200 mg/m³ this decrease was followed by a slight but statistically significant increase. The maternal LOAEC is 200 mg/m³ based on the increase in breathing rate and changes in food consumption; a maternal NOAEC could not be identified.

Slightly retarded ossification was seen in the foetuses of the dams exposed to 200 and 600 mg/m³, but was considered to be a minor developmental effect, most attributable to the stress caused by combination of maintaining the animals in restraining tubes and the irritative properties 2-ethylhexyl lactate. The developmental NOAEC is 600 mg/m³.

No teratogenic effects were observed; the teratogenic NOAEC is 600 mg/m³.

Endpoint:
developmental toxicity
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
For justification of read-across please refer to the read-across report attached to IUCLID section 13.
Reason / purpose for cross-reference:
read-across source
Details on mating procedure:
-
Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
Apart from indications of an irritant eye effect (reddish, lid closure, or slight discharge) observed only in rabbits during the exposure to 10 mg/L MEB there were no substance-induced clinical findings in any of the test groups at any time of the study.
Dermal irritation (if dermal study):
not examined
Mortality:
no mortality observed
Description (incidence):
None of the rabbits died during the experiment.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
MEB inhalation did not significantly influence the body weights and the body weight changes of rabbitsexposed to 0.5 or to 2.5 mg/liter. In rabbits exposed to the highest level of MEB (10 mg/L), there was a slight retardation in body weight increase throughout the whole exposure period. For MEB this was significant (p < 0.05) between days 7 and 10 pi. No biologically relevant or clearly concentration-related differences were apparent between the groups regarding corrected body weight gain.
Food consumption and compound intake (if feeding study):
not examined
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
Description (incidence and severity):
The uterus weight of the animals treatment groups do not show any significant differences in comparison to the controls.
Gross pathological findings:
no effects observed
Description (incidence and severity):
No gross-pathological findings were observed in any treatment group.
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
not specified
Histopathological findings: neoplastic:
not examined
Other effects:
not specified
Number of abortions:
no effects observed
Description (incidence and severity):
For detailed results please refer to Table 2 in box "Any other information on results incl. tables".
Pre- and post-implantation loss:
no effects observed
Description (incidence and severity):
For detailed results please refer to Table 2 in box "Any other information on results incl. tables".
Total litter losses by resorption:
no effects observed
Description (incidence and severity):
For detailed results please refer to Table 2 in box "Any other information on results incl. tables".
Early or late resorptions:
no effects observed
Description (incidence and severity):
For detailed results please refer to Table 2 in box "Any other information on results incl. tables".
Dead fetuses:
no effects observed
Description (incidence and severity):
For detailed results please refer to Table 2 in box "Any other information on results incl. tables".
Changes in pregnancy duration:
not specified
Changes in number of pregnant:
no effects observed
Description (incidence and severity):
For detailed results please refer to Table 2 in box "Any other information on results incl. tables".
Other effects:
not specified
Details on maternal toxic effects:
- Treatment with 10 mg/L MEB lead to a slight retardation in body weight increase throughout the whole exposure period. For MEB this was significant (p < 0.05) between days 7 and 10 pi.
- Apart from indications of an irritant eye effect (reddish, lid closure, or slight discharge) observed only in rabbits during the exposure to 10 mg/L MEB, no substance-induced clinical findings were observed in any of the test groups.
- No unscheduled mortality in pregnant rabbits occurred.
- No gross-pathological findings were observed.
- The uterine weights of the animals exposed to MEB were not significantly different from their respective controls.
- No effects were noted for: Conception rate, mean number of corpora lutea, implantation sites, pre-and post-implantational loss, number of resorptions and viable foetuses.- Treatment with 10 mg/L MEB lead to a slight retardation in body weight increase throughout the whole exposure period. For MEB this was significant (p < 0.05) between days 7 and 10 pi.
- Apart from indications of an irritant eye effect (reddish, lid closure, or slight discharge) observed only in rabbits during the exposure to 10 mg/L MEB, no substance-induced clinical findings were observed in any of the test groups.
- No unscheduled mortality in pregnant rabbits occurred.
- No gross-pathological findings were observed.
- The uterine weights of the animals exposed to MEB were not significantly different from their respective controls.
- No effects were noted for: Conception rate, mean number of corpora lutea, implantation sites, pre-and post-implantational loss, number of resorptions and viable foetuses.
Key result
Dose descriptor:
NOAEC
Remarks:
maternal toxicity
Effect level:
2.5 mg/L air (nominal)
Based on:
test mat.
Basis for effect level:
other: Retardation in body weight change and irritation of the eye observed in the 10 mg/L
Key result
Dose descriptor:
NOAEC
Remarks:
reproductive toxicity
Effect level:
10 mg/L air (nominal)
Based on:
test mat.
Basis for effect level:
other: No adverse effects seen on the fetal organisms in comparison to the untreated control
Abnormalities:
no effects observed
Fetal body weight changes:
no effects observed
Description (incidence and severity):
The mean foetal body weight changes were not affected by the treatment of the dams. The slight reductions observed in rabbits exposed to MEB were caused by the incidentally increased number of live foetuses per dam in the treated groups compared to the controls. For detailed results please refer to Table 2 in box "Any other information on results incl. tables".
Reduction in number of live offspring:
no effects observed
Description (incidence and severity):
No reduction in the number of live offspring per dam was observed. For detailed results please refer to Table 2 in box "Any other information on results incl. tables".
Changes in sex ratio:
no effects observed
Description (incidence and severity):
The sex ratio did not differ significantly between treated groups and controls. For detailed results please refer to Table 2 in box "Any other information on results incl. tables".
Changes in litter size and weights:
not specified
Changes in postnatal survival:
not specified
External malformations:
no effects observed
Description (incidence and severity):
The examination of foetuses for external changes revealed no malformations. One type of variation was recorded for the MEB treatment only (pseudoankylosis) in one foetus each after exposure to 0.5 and 2.5 mg/L and in two foetuses after exposure to 10 mg/L. This common finding had a similar incidence rate in historical controls (14/1348 or 1 % (% range/study, 0-3.6) foetuses in 14/225 or 6.2 % (% range/study, 0-21.4) litters).
Skeletal malformations:
no effects observed
Description (incidence and severity):
No adverse treatment related malformations were observed. However, various malformations of the sternebrae and/or the vertebral column were seen in the MEB exposure groups including the controls. The observed variations were related to the skull, the vertebral column, the sternum, and the ribs. They were seen in all groups without apparent concentration relationships or statistically significant differences between the groups. The examination of the foetuses for retardations revealed incomplete or missing ossification of the sternebra(e), skull, vertebral column or the distal extremities. These findings occurred without any biologically relevant differences between the groups.
Visceral malformations:
no effects observed
Description (incidence and severity):
The examination of the fetuses for soft tissue changes revealed no malformations.
Other effects:
not specified
Details on embryotoxic / teratogenic effects:
Details on embryotoxic/teratogenic effects:
- Sex distribution did not differ significantly between treated groups and the negative control group
- Mean placental and foetal weights were not affected by treatment.
- External changes in foetuses: No malformations were observed
- Soft tissue changes in foetuses: No malformations were observed.
- Skeletal examinations of the foetuses: No adverse treatment related malformations were observed. Various malformations of the sternebrae and/or vertebral column were seen in the exposure groups including the controls.
Key result
Dose descriptor:
NOAEC
Effect level:
10 mg/L air (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: No adverse signs of developmental toxicity were observed in all treatment groups.
Abnormalities:
no effects observed
Key result
Developmental effects observed:
no

Test concentration measured in inhalation chambers

Table 1: Concentrations measured in inhalation chambers
  MEB
test group mg/L ± SD
   
1 0.51 0.014
2 2.51 0.150
3 9.80 0.660

Summary of reproduction data in rabbits

Table 2: Summary of reproduction data in rabbits
Test group 0 1 2 3
mg/L 0 0.5 2.5 10
 
Number of animals 15 15 15 15
Number of dams 14* 15 15 15
Corpora lutea/dam 8.4 8.3 9.0 8.1
Implants/dam 6.8 6.9 7.5 7.8
% preimplantation loss 20.3 17.1 17.7 3.5
Live foetuses/dam 5.6 (2.73) 6.3 (1.76) 6.7 (2.16) 6.9 (1.41)
Dead foetuses/dam 1.1 0.5 0.8 0.9
% postimplantation loss 18.4 8.5 10.0 10.7
Sex ratio (m/f) 41.6:58.2 46.3:53.7 52.0:48.0 40.8:59.2
Mean foetal weight (g) 41.3 (4.40) 40.6 (3.85) 40.0 (3.71) 39.3 (3.92)
Mean placental weight (g) 4.9 (0.98) 4.7 (0.74) 4.7 (0.72) 4.4 (0.38)

Note: numbers in parantheses indicate standard deviation

*= one not pregnant animal

Summary of all classified foetal external, soft tissue and skeletal observations in rabbits:

Table 3: Summary of all classified foetal external, soft tissue and skeletal observations in rabbits
Test group 0 1 2 3
mg/L 0 0.5 2.5 10
 
Number of litters evaluated 14 15 15 15
Number of foetuses evaluated 79 96 100 103

Alteration
Total malformations
Fetuses 3 (3.8)a 3 (3.1) 5 (5.0) 5 (4.9)
Litters 3 (21.4)b 3 (20.0) 4 (26.7) 3 (20.0)
Mean % affected foetuses 
per litter 4.3 (8.52)c 3.9 (9.29) 9.9 (25.88) 5.8 (13.10)
Total variations
Foetuses 21 (26.6) 27 (28.1) 30 (30.0) 45a(43.7)
Litters 9 (64.3)b 14 (93.3) 14 (93.3) 15* (100)

Mean % affected foetuses per litter

20.9 (20.80)c

27.7 (13.60)

32.8 (23.83)

44.1** (16.35)

Total retardations

Foetuses

51 (64.6)a

57 (59.4)

60 (60.0)

73 (70.9)

Litters

12 (85.7)b

15 (100.0)

15 (100.0)

15 (100)

Mean % affected fetuses 

per litter

67.1 (32.00)c

61.8 (23.51)

60.9 (21.86)

70.6 (24.40)

Note: Significantly different from control at * = p < 0.05 and ** = p < 0.01. Numbers in parentheses indicate:

a = percentage of foetuses affected, b = percentage of litters affected and c = standard deviation

Conclusions:
No treatment-related effects on developmental parameters were detected in a developmental toxicity (OECD 414) after inhalation of 3-methyl-1-butanol in rabbits. The maternal NOAEC is considered to be 2.5 mg/L due to a slight retardation in body weight change after inhalation of 10 mg/L. The developmental NOAEC is considered to be 10 mg/L.
Executive summary:

In a developmental toxicity study (OECD 414), 3-methyl-1 -butanol (MEB) (98.6 % purity) was administered to 15 female Himalayan rabbits per concentration in clean air (whole body exposure for 6 hours/day) at dose levels of 0, 0.5, 2.5 and 10 mg/L from day 7 through day 19 of gestation. There were no treatment-related effects on mortality, clinical signs, or pathology parameters. The maternal NOAEC is considered to be 2.5 mg/L as a slight retardation was observed in body weight change. No treatment related effects were noted in developmental parameters. The developmental NOAEC is therefore 10 mg/L. The developmental toxicity study in the rabbit is classified acceptable and satisfies the guideline requirement for a developmental toxicity study (OPPTS 870.3700; OECD 414) in rabbits.

This information is used in a read-across approach in the assessment of the target substance.

For justification of read-across please refer to the read-across report attached to IUCLID section 13.

Effect on developmental toxicity: via oral route
Endpoint conclusion:
no study available
Effect on developmental toxicity: via inhalation route
Endpoint conclusion:
no adverse effect observed
Effect on developmental toxicity: via dermal route
Endpoint conclusion:
no study available
Additional information

The target substance is very quickly enzymatically hydrolysed to ethylhexanol and L(+)-lactic acid, indicating that the compounds systemically available are lactic acid and ethylhexanol. Therefore, the requirements for developmental toxicity shall be addressed based on information for lactic acid and ethylhexanol. Lactic acid is a ubiquitous and integral part of mammalian metabolism and therefore of minor toxicological relevance in comparison to ethylhexanol, which is the key factor for the toxicological assessment.

Two developmental toxicity studies in rats or rabbits are available to assess the reproductive/developmental toxicity potential of the target substance 2-ethylhexyl-S-lactate.

In the first study (OECD 414), the target substance was administered to 12 mated female Wistar rats/dose by inhalation, nose only, at dose levels of 0, 200 and 600 mg/m³ from gestation day 6 up to and including day 15 during 6-hour sessions. During exposure the breathing rate was visibly increased in animals exposed to 600 mg/m³ during the entire treatment period and occasionally in animals exposed to 200 mg/m³. Furthermore, dams exposed to the test substance consumed less food than the controls, the difference being statistically significant at 600 mg/m³ only. At 200 mg/m³ this decrease was followed by a slight but statistically significant increase. The maternal LOAEC is 200 mg/m³ based on the increase in breathing rate and changes in food consumption; a maternal NOAEC could not be identified. Slightly retarded ossification was seen in the foetuses of the dams exposed to 200 and 600 mg/m³, but this was considered to be a minor developmental effect, most likely attributable to the stress caused by combination of maintaining the animals in restraining tubes and the irritative properties of 2-ethylhexyl lactate. As no adverse effects on developmental parameters were seen, the developmental NOAEC is considered to be 600 mg/m³.

No study is available elucidating the developmental toxicity potential of the target substance in a non-rodent species. Thus, available data from a study comparable to OECD testing guideline 414 with the read-across partner 3-methyl-1-butanol was used to assess the potential of the target substance to induce reproductive toxicity. For more details on the read-across justification please refer to IUCLID section 13.

In this developmental toxicity study (equivalent to OECD 414), 3-methyl-1-butanol (MEB) (98.6 % purity) was administered to 15 female Himalayan rabbits per concentration in clean air (whole body exposure for 6 hours/day) at dose levels of 0, 0.5, 2.5 and 10 mg/L from day 7 through day 19 of gestation. There were no treatment-related effects on mortality, clinical signs, or pathology parameters. The maternal NOAEC is considered to be 2.5 mg/L as a slight retardation in body weight change was observed. No treatment related effects were noted on developmental parameters. The developmental NOAEC is therefore 10 mg/L.

Justification for classification or non-classification

Based on the available data, the target substance 2-ethylhexyl-S-lactate does not require classification for reproductive/developmental toxicity in accordance with the CLP Regulation 1272/2008.

Additional information