2-ethylhexyl acrylate

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Remarks:

OECD 421 like

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2021

Materials and methods

Test guideline

Guideline:

other: modified 421 study (repoduction/developmental toxicity screening test)

Principles of method if other than guideline:

Range-finding study for OECD 443 (EOGRTS)

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-ethylhexyl acrylate

EC Number:

203-080-7

EC Name:

2-ethylhexyl acrylate

Cas Number:

103-11-7

Molecular formula:

C11H20O2

IUPAC Name:

2-ethylhexyl acrylate

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Research Models ans Services, Sulzfeld, Germany
- Age at study initiation: 14-15 weeks (male); 13 weeks (female)
- Housing: Type of cage: Polysulfonate cages type 2000P (H-Temp)
Exceptions: During mating (males and females) and females during gestation, lactation and after weaning: Polycarbonate cages type III
No. of animals per cage: Polysulfonate cages: -During pretreatment: up to 5 animals per sex and cage; -During premating: 2 animals per sex and cage
Polycarbonate cages: 1 animal
Exceptions: -During mating: 1 male/1 female per cage; -During rearing up to PND 13: 1 dam with her litter
- Diet (e.g. ad libitum): Mouse and rat maintenance diet "GLP" Granovit AG, Kaieraugust, Switzerland
- Water (e.g. ad libitum): ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24°C
- Humidity (%): 45-65%
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: feed

Details on route of administration:

Due to the weaknesses in the OECD422 based on technical difficulties, especially the preparation of the test substance in the application media (concentration analysis showed large variabilities and dosing formulations did not meet the acceptability criteria), the study is of limited reliability. To avoid these difficulties in requested OECD 443 including range-finding study it was decided to perform those tests by dietary route. Since 2EHA is an irritant monomer the local inflammatory effects in the stomach might also be reduced by application of the test substance via the diet.

Details on oral exposure:

DIET PREPARATION:
The test substance preparations will be prepared at intervals which guarantee that the test substance concentrations in the diet wil remain stable.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Concerning analytics, sampling for homogeneity and concentration control analysis was performed at the start of the administration period and once during gestation as well as lactation. Samples of all concentrations were measured by the Analytical Laboratory of the test facility.

Duration of treatment / exposure:

27 days (male); 62 days (female)

Frequency of treatment:

daily

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

3 000 ppm

Doses / concentrations 2

Dose / conc.:

7 500 ppm

Doses / concentrations 3

Dose / conc.:

15 000 ppm

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

During lactation, concentrations in the diet of the F0 females were reduced to 50%. At the request of the sponsor and based on the results of a previous 28-day range-finding study, the dose levels were selected.

Examinations

Observations and examinations performed and frequency:

OBSERVATIONS:
The parents' and the pups' state of health was checked each day, and parental animals were examined for their mating and reproductive performances.
A check for moribund and dead animals will be made twice daily from Mondays to Fridays and once daila on Saturdays, Sundays and public holidays.

DETAILED CLINICAL OBSERVATIONS:
A detailed clinical observation (DCO) was performed in all animals before initial test substance administration and, as a rule, thereafter at weekly intervals.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
Food consumption of the F0 parents was determined regularly once weekly before and after the mating period, as well as in dams during gestation days 7, 14 and 20 and lactation days 4, 7, 10 and 13.

BODY WEIGHT:
In general, the body weights of F0 animals were determined once a week. However, during gestation and lactation, F0 females were weighed on gestation days (GD) 0, 7, 14 and 20, and on postnatal days (PND) 0, 4, 7, 10 and 13.CAGE SIDE

Sacrifice and pathology:

GROSS NECROPSY:
All F0 parental were sacrificed by decapitation under isoflurane anesthesia. The exsanguinated animals were necropsied and assessed by gross pathology.
The following weights were determined in all animals sacrificed on schedule: Anesthetized animals, adrenal glands, epididymides, kidneys, liver, ovaries, prostate, seminal vesicles, spleen, testes and uterus with cervix.
Histological examination was performed on Adrenal glands, Kidneys, Liver, Spleen, Stomach (forestomach and glandular stomach) and macroscopic findings in both sexes.

Statistics:

Food consumption (parental animals), body weight and body weight change (parental animals and pups; for the pup weights, the litter means were used) , gestation days: DUNNETT (two-sided)
Male and female mating indices, male and female fertility indices, females mated, females delivering, gestation index (females with liveborn pups), females with stillborn pups, females with all stillborn pups: FISHER'S EXACT (one-sided)
Mating days until day O pc, % postimplantation loss, with stillborn, %perinatal lass: WI LCOXON ( one-sided+) BONFERRONI-HOLM
Implantation sites, pups delivered, pups liveborn, life pups day x, with viability Index, survival index: WI LCOXON ( one-sided-) BONFERRONI-HOLM
% live male day x, % live female day x: WI LCOXON (two-sided)
Number of cycles and cycle length: KRUSKAL-WALLIS (twosided) and WILCOXON (two-sided)

Results and discussion

Results of examinations

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

Test group 3 (15000 ppm):
No test substance-related, adverse clinical signs
One incidental finding assessed as not related to treatment: One F0 female animal (No. 136) showed a mass palpable through the skin (>3 cm) in the region of the throat during gestation (from GD 25 onwards) and was sacrificed in a moribund condition for animal welfare reasons during lactation (PND 8). The same animal had only one implant and a dead pup leading to a complete litter loss.
Test group 2 (7500 ppm):
One incidental finding assessed as not related to treatment: One female animal (No. 126) with an injury in the neck.

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Test group 3 (15000 ppm):
Decrease in mean body weight (change) (BW SD 28: 5% below control) in males with a body weight loss during SD 0-7 (-2 g versus 13 g in control).
Decrease in mean body weight in females during gestation (8% below control).

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Food consumption was (statistically significantly) reduced in males (up to 20% below control) and females (up to 15% below control) of test group 3 and in males of test group 2 (up to 18% below control) during premating. During gestation, females of test group 3 recovered to values comparable to control whereas during lactation, mean food consumption showed a higher variation. The decrease in food consumption was assessed to be secondary due to the smell and taste of the test substance in the diet.

Gross pathological findings:

effects observed, non-treatment-related

Description (incidence and severity):

All gross lesions occurred individually and were considered incidental or spontaneous in nature and not related to treatment. One female animal of test group 3 (No. 136), sacrificed in a moribund state, showed macroscopically a mass of 50 mm in diameter in the cervical region correlating with a malignant myoepithelioma, and an enlarged spleen correlating with a massive extramedullary hematopoiesis. In addition, histopathology revealed in the liver a slight extramedullary hematopoiesis. These findings were most likely associated to the tumor and explain the moribund state of the animal; however, they were not considered treatment related.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Pathology:
Concerning pathology, in males of test group 3 (15000 ppm), a statistically significant relative weight increase of the kidneys (+10% above the control group) correlated with minimally to moderately increased eosinophilic droplets in the tubular epithelium in 8 out of 10 males. Increased eosinophilic droplets most likely represents an accumulation of α2u-globulin synthesized in the male rat liver, filtered by the glomerulus, and reabsorbed in the S2 segment of the proximal tubules. It is considered a treatment-related and male rat specific finding but does not represent a risk for humans since they do not synthesize this protein (Durham and Swenberg, 2013). Minimal tubular degeneration/regeneration in 2 out of 10 males and granular casts in 1 out of 10 were assessed as not relevant due to the low incidence and grading. Therefore, the findings in the male kidneys were considered treatment-related but not adverse. A statistically significant liver weight increase in males of test group 3 (+9% above the control group) was marginally above the historical control values and occurred without a histopathological correlate. Thus, it was regarded as treatment-related but not adverse. All other histopathological findings occurred individually and were considered incidental or spontaneous in nature and not related to treatment.
The mean absolute weight of the prostate in males of test group 3 (0.993 g) was statistically significantly decreased (-18%) compared to the control. This decrease was marginally below the historical control range (1.001 – 1.267 g), whereas the mean relative weight (0.276%) was within the normal range (0.264 – 0.33%) without a statistical significance and so it was regarded as not treatment-related. All other absolute and relative weight parameters did not show significant differences when compared to the control group 0.

Histopathological findings: neoplastic:

effects observed, non-treatment-related

Description (incidence and severity):

spontanous finding: myoepithelioma of the parotid glands in animal No. 136

Effect levels

Key result

Dose descriptor:

NOEL

Effect level:

7 500 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

histopathology: non-neoplastic

Target system / organ toxicity

Critical effects observed:

no